Field testing parameter sensitivity of the two-term infiltration equation using differentiated linearization

Knowledge of soil hydraulic conductivity in the vadose zone is important in many agronomic, engineering and environmental areas. Transient tension infiltrometer experiments can be used to estimate the hydraulic conductivity, K0, corresponding to a given pressure head by the single-test (TST) method that uses the coefficients C1 and C2 of the two-term infiltration equation. The “Differentiated Linearization” (DL) method has been proposed to estimate these coefficients when a layer of contact material is used for the experiment. A field test of the DL and TST methods was conducted on a sandy loam and a clay soil. Eliminating the early-time influence of the contact layer was easy when the sorp…

Accuracy of Saturated Soil Hydraulic Conductivity Estimated from Numerically Simulated Single‐Ring Infiltrations

The single-ring pressure infiltrometer (PI) method is widely used to determine saturated soil hydraulic conductivity, K s , directly in the field. The original and still most common way to analyze the data makes use of the steady-state model developed by the Canadian School in the 90s and two (two-ponding-depth, TPD, approach) or more (multiple-ponding-depth, MPD, approach) depths of ponding. The so-called Wu method based on a generalized infiltration equation allows analysis of the transient infiltration data collected by establishing a single ponding depth of water on the infiltration surface. This investigation, making use of simulated infiltration runs for initially unsaturated sand to …

On Infiltration and Infiltration Characteristic Times

In his seminal paper on the solution of the infiltration equation, Philip (1969), https://doi.org/10.1016/b978-1-4831-9936-8.50010-6 proposed a gravity time, tgrav, to estimate practical convergence time and the time domain validity of his infinite time series expansion, TSE, for describing the transient state. The parameter tgrav refers to a point in time where infiltration is dominated equally by capillarity and gravity as derived from the first two (dominant) terms of the TSE. Evidence suggests that applicability of the truncated two-term equation of Philip has a time limit requiring higher-order TSE terms to better describe the infiltration process for times exceeding that limit. Since …

Determinazione della distribuzione granulometrica del suolo mediante diffrattometria laser

Source shape and data analysis procedure effects on hydraulic conductivity of a sandy-loam soil determined by ponding infiltration runs

Performing ponding infiltration runs with non-circular sources could represent a good means to sample completely an area of interest. Regardless of the shape of the source, predicting the expected reliability of the collected data by infiltrometers should facilitate soil hydraulic characterisation and also allow a more conscious use of the field data. The influence of the shape of the infiltration source (i.e., circular or square) and the analysis procedure of the steady-state infiltration data on the saturated hydraulic conductivity, Ks, of a sandy-loam soil was tested in this investigation. Circular and square surfaces sampled with the pressure infiltrometer (PI) yielded similar estimates…

Erosione e conservazione del suolo

18. Monitoraggio, Previsione e Controllo dell’Erosione Idrica

assente - capitolo di libro

Origine ed evoluzione della equazione universale per il calcolo della perdita di suolo

Misure dell’erodibilità del suolo a scala di parcella nell’area sperimentale di Sparacia

Connectivity in hydrology and sediment dynamics

Connectivity has emerged as a significant conceptual framework for understanding the transfer of surface water and sediment through landscapes. The concept has been widely adopted in the field of catchment hydrology but has also been valuable to investigate rates of soil erosion by water and sediment export across landscapes. To study connectivity, we gathered a group of scientists that worked on synthesizing and consolidating all theories and aspects of connectivity research. Within the EU-funded ESSEM COST Action CONNECTEUR (ES1306), five working groups were established: (a) theory, (b) measuring, (c) modelling, (d) indices, and (e) society. One of the outputs of this COST Action is this …

Supporting USLE-MM reliability by analyzing soil loss measurement errors

Sampling the collected suspension in a storage tank is a common procedure to obtain soil loss data. A calibration curve of the tank has to be used to obtain actual concentration values from those measured by sampling. However, literature suggests that using a tank calibration curve was not a common procedure in the past. For the clay soil of the Sparacia (Italy) experimental station, this investigation aimed to establish a link between the relative performances of the USLE-M and USLE-MM models, usable to predict plot soil loss at the event temporal scale, and soil loss measurement errors. Using all available soil loss data, lower soil loss prediction errors were obtained with the USLE-MM (e…

Il fattore di pratica antierosiva della USLE

Testing Soil Encasing Materials for Measuring Hydraulic Conductivity of a Sandy-Loam Soil by the Cube Methods

The Cube Method (CM) and the Modified Cube Method (MCM) were developed for measuring vertical (K v ) and horizontal (K h ) saturated hydraulic conductivity of a single soil sample. By these methods, a cube of soil is carved out in situ and a suitable material is applied to enclose the cube in a tightly fitting casing before moving the sample to the laboratory. Problems may be associated with the use of gypsum, originally used to encase soil. The suitability of molten wax and expandable polyurethane foam to encase a soil cube was tested for a sandy-loam soil. Wax-treated samples yielded lower conductivity results than untreated samples by a maximum factor of 3.7. The observed discrepancies w…

Comparing Physical Quality of Forest and Pasture Soils in a Sicilian Watershed

Forest and pasture soils should have differing properties due, for example, to differing root characteristics or livestock trampling rates, but contradictory results are reported in the literature. The surface soil physical and hydraulic properties of five forest and pasture sites were determined in a Sicilian watershed. In general, forest soils had a significantly lower bulk density, b (by 17 to 35%), and a higher field saturated hydraulic conductivity, Kfs (by a factor of 3.4-11.5) than pasture soils. Differences between water retention characteristics of forest and pasture soils were low when high levels of organic matter, OM, content (> 7.1%) were detected for both land uses. The mean …

Effetti della copertura forestale sulle caratteristiche idrologiche del suolo

Impacts of thinning of a Mediterranean oak forest on soil properties influencing water infiltration

[EN] In Mediterranean ecosystems, special attention needs to be paid to forest¿water relationships due to water scarcity. In this context, Adaptive Forest Management (AFM) has the objective to establish how forest resources have to be managed with regards to the efficient use of water, which needs maintaining healthy soil properties even after disturbance. The main objective of this investigation was to understand the effect of one of the AFM methods, namely forest thinning, on soil hydraulic properties. At this aim, soil hydraulic characterization was performed on two contiguous Mediterranean oak forest plots, one of them thinned to reduce the forest density from 861 to 414 tree per ha. Th…

Determining hydraulic properties of a loam soil by alternative infiltrometer techniques

Testing infiltrometer techniques to determine soil hydraulic properties is necessary for specific soils. For a loam soil, the water retention and hydraulic conductivity predicted by the BEST (Beerkan Estimation of Soil Transfer parameters) procedure of soil hydraulic characterization was compared with data collected by more standard laboratory and field techniques. Six infiltrometer techniques were also compared in terms of saturated soil hydraulic conductivity, Ks. BEST yielded water retention values statistically similar to those obtained in the laboratory and Ks values practically coinciding with those determined in the field with the pressure infiltrometer (PI). The unsaturated soil hyd…

Il fattore climatico dell’equazione universale per il calcolo della perdita di suolo

Response to ‘comment on “predicting event soil loss from bare plots at two Italian sites”’

In this paper, a response to the comment by Dr. Kinnell on “Predicting event soil loss from bare plots at two Italian sites”’ (Bagarello et al., Catena 109, 96–102, 2013) is provided.

Un criterio per la determinazione della tolleranza della perdita di suolo

Testing the shape-similarity hypothesis between particle-size distribution and water retention for Sicilian soils

Application of the Arya and Paris (AP) model to estimate the soil water retention curve requires a detailed description of the particlesize distribution (PSD) but limited experimental PSD data are generally determined by the conventional sieve-hydrometer (SH) method. Detailed PSDs can be obtained by fitting a continuous model to SH data or performing measurements by the laser diffraction (LD) method. The AP model was applied to 40 Sicilian soils for which the PSD was measured by both the SH and LD methods. The scale factor was set equal to 1.38 (procedure AP1) or estimated by a logistical model with parameters gathered from literature (procedure AP2). For both SH and LD data, procedure AP2 …

Estimating the macroscopic capillary length from Beerkan infiltration experiments and its impact on saturated soil hydraulic conductivity predictions

International audience; The macroscopic capillary length, λc, is a fundamental soil parameter expressing the relative importance of the capillary over gravity forces during water movement in unsaturated soil. In this investigation, we propose a simple field method for estimating λc using only a single-ring infiltration experiment of the Beerkan type and measurements of initial and saturated soil water contents. We assumed that the intercept of the linear regression fitted to the steady-state portion of the experimental infiltration curve could be used as a reliable predictor of λc. This hypothesis was validated by assessing the proposed calculation approach using both analytical and field d…

A new expression of the slope length factor to apply USLE-MM at Sparacia experimental area (Southern Italy)

Abstract Predicting soil loss due to water erosion by empirical models is useful to assess the severity of the phenomenon in an area of interest and to predict the effect of alternative soil erosion control practices. The USLE scheme cannot be used at the Sparacia experimental area (Sicily, South Italy) to predict event soil loss per unit plot area, Ae, because experimental data suggest that, generally, Ae does not increase with plot length, λ. The USLE-MM scheme uses the runoff coefficient, QR, as an additional independent variable in order to develop an empirical model allowing prediction of storm soil loss values that do not necessarily increase with λ. According to this model, Ae is exp…

A simplified falling-head tecnique for rapid determination of field-saturated hydraulic conductivity

Simplified measurements of the field-saturated hydraulic conductivity, K fs , require short duration experiments, small water volumes, and easily transportable equipment. A simplified falling-head (SFH) technique for the rapid determination of K fs has been developed and tested. The technique consists in applying a small volume of water on a soil surface, confined by a ring inserted a short distance into the soil, and then measuring the time from the application of water to the instant at which the surface area is no longer covered by water. A measurement of the initial and field-saturated soil water contents, and an estimate of the α* parameter of the Gardner's exponential model are then u…

6. Processi di Trasporto nel Suolo

assente - capitolo di libro

Determinazione delle caratteristiche idrologiche dei suoli

Using Beerkan experiments to estimate hydraulic conductivity of a crusted loamy soil in a Mediterranean vineyard

Abstract In bare soils of semi-arid areas, surface crusting is a rather common phenomenon due to the impact of raindrops. Water infiltration measurements under ponding conditions are becoming largely applied techniques for an approximate characterization of crusted soils. In this study, the impact of crusting on soil hydraulic conductivity was assessed in a Mediterranean vineyard (western Sicily, Italy) under conventional tillage. The BEST (Beerkan Estimation of Soil Transfer parameters) algorithm was applied to the infiltration data to obtain the hydraulic conductivity of crusted and uncrusted soils. Soil hydraulic conductivity was found to vary during the year and also spatially (i.e., ro…

Fitting particle size distribution models to data from Burundian soils for the BEST procedure and other purposes

Testing the Beerkan Estimation of Soil Transfer (BEST) soil particle size distribution (PSD) model is necessary to evaluate the applicability of the BEST procedure for characterising soil hydraulics. In this investigation, the fitting performance of the BEST PSD model was tested using a database of 114 Burundian soils with 14 measured particle size fractions for each soil sample, and also by considering a reduced number of measured particle size fractions for a sample. The fitting performance of the model developed by Fredlund et al. (2000) (FR model) was also considered for comparative purposes. On average, the BEST model yielded satisfactory results (i.e., mean relative error, E r ¯ = 3.9…

Comparing different methods to determine soil physical quality in a mediterranean forest and pasture land

Soil physical quality (SPQ) can be assessed by different experimental methodologies and criteria and the optimal/critical values or ranges for SPQ indicators are still approximate. Sampling soils with minimal anthropic pressures should allow improvements in SPQ assessment. Different experimental methodologies and criteria were applied to sample a Mediterranean oak forest (Quercus ilex L.) and pasture land, in Sicily, with a varying degree of anthropic disturbance. Soil water retention was determined in the laboratory and the field, using the BEST (Beerkan Estimation of Soil Transfer parameters) procedure of soil hydraulic characterization. Capacity-based indicators, the S index, and locatio…

Testing the BEST procedure to estimate the soil water retention curve

The BEST (Beerkan Estimation of Soil Transfer parameters) procedure is attractive for simple soil hydraulic characterization but there is the need to test the reliability of the predictions. In this investigation, the BEST procedure to predict water retention of 199 Sicilian soils was evaluated. The BEST water retention model performed well (relative error, Er≤0.05) for approximately 80% of the soil samples. Low errors were obtained in soils with a high clay, cl, content (≥44%), whereas both high and low Er values were obtained in soils with a lower cl content. The BEST particle size distribution (PSD) model was accurate for 50% of the samples and the fitting accuracy increased with cl, wit…

Misura delle proprietà fisiche e idrauliche del suolo a monte dell’abitato di Giampilieri

Nell’indagine si è saggiata l’applicabilità della metodologia BEST di caratterizzazione idraulica del suolo in un sito posto a monte dell’abitato di Giampilieri, dove nel 2009 si è verificato un evento alluvionale catastrofico. Lo strato superficiale di suolo ha mostrato caratteristiche eluviali mentre quello più profondo (-0.30 m), apprezzabilmente più compatto e meno permeabile in condizioni di saturazione e con un maggiore contenuto di argilla, ha presentato i caratteri di uno strato illuviale. I risultati delle misure hanno suggerito la possibilità di formazione, durante gli eventi meteorici intensi e prolungati, di una falda idrica sospesa e lo sviluppo di pressioni positive che contri…

Soil hydraulic properties determined by infiltration experiments and different heights of water pouring

Abstract Establishing the dependence of the soil hydraulic characterization carried out by an infiltration experiment on the procedure used to apply water on the confined soil surface may help to better interpret the collected data and also to develop more accurate strategies for soil hydraulic characterization. Soil was sampled at four Sicilian sites with both the Simplified Falling Head (SFH) technique and the Beerkan Estimation of Soil Transfer parameters (BEST) procedure and two heights of water application (0.03 and 1.5 m). The most appropriate BEST algorithm to analyze the data was determined and the effect of the height of water pouring on the measured soil hydraulic properties was e…

PREVISIONE E MITIGAZIONE DEI FENOMENI DI DISSESTO IDROGEOLOGICO IN AMBIENTI SEMI-ARIDI MEDITERRANEI

Nella relazione viene affrontato il tema del dissesto idrogeologico in ambienti semi-aridi mediterranei, con particolare riferimento a differenti aspetti fenomenologici e modellistici del deflusso e dell’erosione idrica accelerata a scala parcellare e di bacino. Dapprima si approfondisce il tema della relazione tra l’erosione per unità di superficie e la lunghezza della pendice. Quindi si esamina il legame tra l’erosione per solchi e altre forme di erosione canalizzata. Successivamente si propone un’analisi critica dei modelli in atto disponibili per la previsione dell’erosione parcellare. In seguito si tratta il tema dell’approccio empirico per la stima della produzione di sedimenti. Poi s…

Determinazione delle proprietà idrauliche del suolo in una pendice naturale

Qualità fisica del suolo in un’area ad uso agricolo tradizionale della Sicilia centrale

Nella memoria viene valutata la qualità fisica dei suoli di un’area in cui sono presenti usi del suolo a basso impatto tipici della collina interna siciliana. La valutazione è stata effettuata utilizzando i tradizionali indici basati sulla curva di ritenzione idrica, integrati da misure della porosità dinamica effettuate con l’infiltrometro a depressione. Secondo le classificazioni comunemente adottate, condizioni di qualità fisica prossime a quelle ottimali si sono riscontrate solamente nel suolo sottoposto ad avvicendamento colturale e lavorato secondo pratiche tradizionali. Nel rimboschimento, la qualità fisica dello strato superficiale è risultata non ottimale anche come conseguenza del…

MISURA DELL’ERODIBILITA’ DEL SUOLO NELLE PARCELLE SPERIMENTALI DI SPARACIA, IN SICILIA

Nell’indagine è stata effettuata una determinazione sperimentale del fattore di erodibilità del suolo, K, della USLE basata sulle misure effettuate nel suolo argilloso di Sparacia. Il valore medio annuo del suddetto fattore, misurato su parcelle di lunghezza, , comprese tra 11 e 44 m, è risultato decrescente con . La stima indiretta del fattore di erodibilità è risultata del 46% inferiore rispetto alla misura effettuata nella parcella di riferimento, lunga cioè 22 m, e si è attestata su un valore intermedio tra le misure di K ottenute nelle parcelle di 33 e 44 m. Un simile effetto di scala è stato riconosciuto anche con riferimento ai valori annui e a quelli stagionali del fattore di erod…

Verifica sperimentale del fattore L della USLE-MM nell’area di Sparacia

Attività di ricerca, monitoraggio e modellazione dei processi erosivi nell'area pilota di Sparacia

INDAGINE SULL’ IDROREPELLENZA DEL SUOLO DI UNA PINETA ARTIFICIALE MEDITERRANEA

Nell’indagine è stata caratterizzata l’idrorepellenza del suolo di una pineta artificiale Mediterranea utilizzando sia il tradizionale Water Drop Penetration Time (WDPT) test che due indici desunti da esperimenti di infiltrazione condotti con il MiniDisk Infiltrometer (MDI). In particolare, il Repellency Index (RI) è stato calcolato come rapporto tra i valori di sorptività misurati con etanolo e acqua, mentre il Water Repellency Cessation Time (WRCT) è stato ricavato utilizzando l’informazione acquisita nella fase idrofobica e in quella idrofila del processo di infiltrazione con acqua. Tutti gli indici hanno inequivocabilmente indicato che la lettiera di Pinus pinaster è altamente idrofobic…

Variability of near-surface saturated hydraulic conductivity for the clay soils of a small Sicilian basin

Abstract Proper characterization of saturated hydraulic conductivity, Ks, of clay soils in a hillslope or a basin is still a challenge for soil science. In this investigation, the clay soils of the Maganoce (Sicily, Italy) basin were sampled at 19 sampling sites by the BEST procedure of soil hydraulic characterization. More OM implied less compact conditions (decreasing dry soil bulk density; coefficient of determination, R2 = 0.67), more stability to water of the soil aggregates (increasing water stable aggregates; R2 = 0.83) and, consequently, higher Ks values (R2 = 0.54). Variability of Ks was lower in the steeper zones of the basin than in the flatter ones. A comparison with the Ks data…

Approfondimenti su alcune tecniche infiltrometriche per la misura delle conducibilità idraulica del suolo saturo

Nella memoria vengono approfonditi alcuni aspetti della misura in campo della conducibilità idraulica del suolo saturo, Kfs, con tecniche infiltrometriche. In primo luogo, è stata determinata la frequenza degli insuccessi con una prova del tipo Two- Ponding-Depth effettuata con l’infiltrometro ad anello singolo (PI). La suddetta frequenza è risultata più elevata in due suoli franco-argillosi (40%) che in uno franco-sabbioso (25%). Un contenuto idrico iniziale elevato ha costituito una possibile causa di fallimento della misura. L’esclusione dal data set delle prove che hanno fornito valori del parametro * ricadenti al di fuori del range 1-100 m-1 è risultata ininfluente solo nel caso in cu…

Testing assumptions and procedures to empirically predict bare plot soil loss in a Mediterranean environment

Empirical prediction of soil erosion has both scientific and practical importance. This investigation tested USLE and USLE-based procedures to predict bare plot soil loss at the Sparacia area, in Sicily. Event soil loss per unit area, Ae, did not vary appreciably with plot length, l, because the decrease in runoff with l was offset by an increase in sediment concentration. Slope steepness, s, had a positive effective on Ae and this result was associated with a runoff coefficient that did not vary appreciably with s and a sediment concentration generally increasing with s. Plot steepness did not have a statistically detectable effect on the calculations of the soil erodibility factor of both…

I fattori topografici della USLE e la carta dell’erosione massima

Confronto tra differenti metodologie di valutazione della qualità fisica del suolo in un’area a pascolo e bosco della Sicilia

Il concetto di qualità fisica del suolo (SPQ, Soil Physical Quality) viene ormai largamente utilizzato, soprattutto in ambito agricolo. Un suolo agricolo di buona qualità fisica possiede caratteristiche strutturali favorevoli sia all’ancoraggio della coltura sia allo sviluppo dell’apparato radicale della pianta nonché un’adeguata ripartizione tra pori di diverse dimensioni, in modo da favorire simultaneamente l’areazione e la ritenzione idrica nel mezzo poroso. Per la valutazione della SPQ sono determinanti le misure di ritenzione idrica del suolo, che possono essere analizzate con diverse metodologie. Alcune indagini recenti segnalano tuttavia che la scelta della metodologia di analisi del…

Establishing a soil loss threshold for limiting rilling

In this paper a frequency analysis of event soil loss measurements collected in the period 1999–2012 at the microplots and plots of the Sparacia Experimental Area in Sicily, southern Italy, was developed. The analysis was carried out using the annual maximum soil loss measurements normalized by the mean soil loss measured at a given temporal and spatial scale. The empirical frequency distribution of the normalized variable was well fitted by two Gumbel’s theoretical probability distributions discriminated by a value of the normalized variable equal to 2. This last value discriminates between the relatively low and frequent values of the normalized variable and the high and rare ones. The an…

Influence of the pressure head sequence on the soil hydraulic conductivity determined with tension infiltrometer

An increasing and a decreasing sequence of pressure head, h0, values were applied with the tension infiltrometer (TI) to determine the corresponding hydraulic conductivity, K0. The pressure head sequence is expected to influence the K0 results given the hysteretic nature of the hydraulic conductivity relationship. The objective of this study was to evaluate the influence of the selected pressure head sequence on the hydraulic conductivity of a sandy loam soil measured by a multipotential TI experiment. Twenty experiments were carried out by applying h0 values varying between -150 and +5 mm (site A). The h0 values ranged from -150 to -10 mm in another 20 spots (site B). Both wetting and dryi…

Regional analysis of soil erodibility in Sicily

Variable scale effects on hillslope soil erosion during rainfall-runoff processes

Abstract The variation of soil erosion across scales remains a controversial issue. A theoretical framework, coupling the normalized Green-Ampt equation for infiltration, 1D kinematic wave model for overland flow, and WEPP erosion modeling approaches for soil erosion, was used to explain and quantify the direct effect of scale on the soil erosion process. The results show that the relation between interrill erosion and slope length accords with a power-law decreasing trend, while the relation of rill erosion versus slope length shows a power-law increasing trend. Moreover, the power-law scaling of interrill erosion becomes more prominent with an increase of rainfall duration and intensity b…

Processi erosivi e messa in sicurezza del territorio siciliano

Determining short-term changes in the hydraulic properties of a sandy-loam soil by a three-run infiltration experiment

Soil structure-dependent parameters can vary rapidly as a consequence of perturbing events such as intense rainfall. Investigating their short-term changes is therefore essential to understand the general behaviour of a porous medium. The aim of this study is to gain insight into the effects of wetting, perturbation and recovery processes through different sequences of Beerkan infiltration experiments performed on a sandy-loam soil. Two different three-run infiltration experiments (LHL and LLL) were carried out by pouring water at low (L, non-perturbing) and high (H, perturbing) heights above the soil surface and at short time intervals (hours, days). The results demonstrate that the propos…

A NEW VERSION OF THE USLE-MM FOR PREDICTING BARE PLOT SOIL LOSS AT THE SPARACIA (SOUTH ITALY) EXPERIMENTAL SITE

Improving empirical prediction of plot soil erosion at the event temporal scale has both scientific and practical importance. In this investigation, 492 runoff and soil loss data from plots of different length,  (11 <  < 44 m), and steepness, s (14.9 < s < 26.0%), established at the Sparacia experimental station, in Sicily, south Italy, were used to derive a new version of USLE-MM model, by only assuming a value of one for the topographic length, L, and steepness, S, factors for  = 22 m and s = 9%, respectively. An erosivity index equal to (QREI30)b1, QR and EI30 being the runoff coefficient and the event rainfall erosivity index, respectively, with b1 > 1 was found to be …

Valutazione del fattore colturale per le coperture agrarie

MANUAL SAMPLING AND TANK SIZE EFFECTS ON THE CALIBRATION CURVE OF PLOT SEDIMENT STORAGE TANKS

In many experimental soil erosion plots, runoff is collected and carried by a conveyance system to a sequence of storage tanks. If the soil loss is measured by collecting, after mixing, samples of the stored suspension, then a calibration curve between the actual mean concentration (C) and the measured concentration (Cm) in the storage tank occurs. The aim of this article was to evaluate experimentally the factors affecting the relationship between C and Cm. For a sandy loam soil, the replicated measurements of Cm (20 samples) for two values of the actual concentration (C = 5 and 25 g/L) showed that the variability of the measurements of Cm is low and confirmed the reliability of a calibrat…

Verifica applicativa di tre modelli di stima dell’erosione idrica mediante il concetto di modello fisico

VERIFICA DEL MODELLO CSI PER LA STIMA DELLA PERDITA DI SUOLO

La previsione dell’erosione idrica alla scala temporale del singolo evento riveste particolare interesse dal momento che la perdita di suolo complessiva di un periodo pluriennale è generalmente determinata dagli eventi più rilevanti. Recentemente, utilizzando le misure di perdita di suolo ottenute su parcelle nude installate in tre stazioni sperimentali italiane (Sparacia, in Sicilia; Masse, in Umbria; Caratozzolo, in Calabria), è stato sviluppato un modello empirico, denominato CSI (Central and Southern Italy), per la stima della perdita di suolo alla scala dell’evento. La presente memoria riporta i risultati della verifica di applicabilità del suddetto modello che è stata condotta utilizz…

Twenty years of scientific activity at Sparacia experimental area. Quaderni di Idronomia Montana 33

The main purpose of this booklet is to give to the participants to the Palermo’s Conference of the EU COST ACTION ES1306 - CONNECTING EUROPEAN CONNECTIVITY RESEARCH - CONNECTEUR a general idea of the scientific activity that was carried out in the past 20 years on the basis of the data collected at the Sparacia experimental station for soil erosion measurement, in Sicily, South Italy. The booklet includes a presentation of the experimental site, a description of the applied methods and procedures for measuring soil erosion processes at the Sparacia experimental area, and an illustration of the developed methodologies for predicting soil erosion from plots, small basins, rills and gullies. I…

Factors Influencing Point Measurement of Near-surface Saturated Soil Hydraulic Conductivity in a Small Sicilian Basin

Hydraulic conductivity of saturated soil, Ks, controls many hydrological processes. Parameterization of basin hydrological models in terms of Ks is complicated and uncertain owing to the very high spatial variability of this soil property. A small Sicilian basin was intensively sampled by the simplified falling head technique to obtain spatially distributed Ks data, and an attempt to explain their spatial variability on the basis of soil physical characteristics, digital elevation model-derived topographic attributes and land cover was carried out. High Ks values were obtained when clay content was low and both elevation and mean slope were high. Moreover, differences in Ks among land cover…

A pedotransfer function for estimating the soil erodibility factor in Sicily

The soil erodibility factor, K, of the Universal Soil Loss Equation (USLE) is a simple descriptor of the soil susceptibility to rill and interrill erosion. The original procedure for determining K needs a knowledge of soil particle size distribution (PSD), soil organic matter, OM, content, and soil structure and permeability characteristics. However, OM data are often missing and soil structure and permeability are not easily evaluated in regional analyses. The objective of this investigation was to develop a pedotransfer function (PTF) for estimating the K factor of the USLE in Sicily (south Italy) using only soil textural data. The nomograph soil erodibility factor and its associated firs…

Improved Beerkan run methodology to assess water impact effects on infiltration and hydraulic properties of a loam soil under conventional- and no-tillage

Beerkan infiltration experiments with three water pouring heights (low, L = 3 cm; intermediate, M = 100 cm; high, H = 200 cm) were performed on both a no-tilled (NT) and a conventionally tilled (CT) bare loam soil to determine the surface soil hydraulic properties by the BEST-steady algorithm. Saturated soil hydraulic conductivity, Ks, significantly and monotonically decreased from the L to the H runs (from 236 to 37 mm h‒1) and lower Ks values were detected under CT (163–23 mm h‒1) than NT (346–51 mm h‒1) for each water pouring height. For both soil management practices, the gravitational potential energy, Ep, of the water used for the infiltration runs, explained most of the variance in t…

Distribuzioni di probabilità della perdita di suolo parcellare

Delay times for saturation overland flow in forest soils

Valutazione del fattore colturale per le coperture forestali

Using the simplified falling head technique to detect temporal changes in field-saturated hydraulic conductivity at the surface of a sandy loam soil

Abstract Determining temporal changes in field-saturated hydraulic conductivity ( K fs ) is important for understanding and modeling hydrological phenomena at the field scale. Little is known about temporal variability of K fs values measured at permanent sampling points. In this investigation, the simplified falling head (SFH) technique was used for an approximately 2-year period to determine temporal changes in K fs at 11 permanent sampling points established at the surface of a sandy loam soil. Additional K fs measurements were obtained by the single-ring pressure infiltrometer (PI) technique to also compare the SFH and PI techniques. The lowest mean values of K fs , M ( K fs ), were det…

A simple field method to measure the hydrodynamic properties of soil surface crust

The hydraulic resistance of the surface crust was determined by a combination of two infiltrometric techniques: first, a surface measurement of steady-state infiltration rate is conducted by a mini-disk tension infiltrometer (MDI); then, the surface crust is removed, its thickness is measured, and a ponded infiltration test is performed at the same site. The Beerkan Estimation of Soil Transfer parameters (BEST) method is applied to estimate the hydraulic properties of the underlying soil provided the particlesize distribution and the bulk density are known. Under the assumption of a unit gradient of hydraulic head below the soil crust, the pressure head at the interface crust-soil is derive…

Predicting soil loss on moderate slopes using an empirical model for sediment concentration

Summary The objective of this investigation was to estimate event soil loss per unit area from bare plots in central and southern Italy using an empirical model for sediment concentration. The analysis was developed using data collected on bare plots differing in length (11–44 m) and slope (10–26%) at three Italian stations (Masse, Umbria; Caratozzolo, Calabria; Sparacia, Sicily). At first, an analysis was carried out, using the experimental data collected at Sparacia, to establish a relationship between sediment concentration and hydrological variables, such as runoff, rainfall amount and single storm erosion index. Then, an empirical model to estimate plot soil loss as a function of rainf…

A Plot-scale uncertainty analysis of saturated hydraulic conductivity of a clay soil

Abstract Simulating soil hydrological processes at the plot or field scale requires using spatially representative values of the saturated soil hydraulic conductivity, Ks. Sampling campaigns should yield a reliable mean of Ks with a sustainable workload since measuring Ks at many points is challenging. Uncertainty analysis can be used to determine the lowest number of measurements that yield a mean Ks value with a specified accuracy level. Potential and limitations of this analysis were tested in this investigation for different extents of the sampled area and sampling densities. A clay soil was sampled intensively on two plots (plot area = 44 m2), two dates and using both small (0.15 m in …

Correspondence between theory and practice of a Beerkan infiltration experiment

The Beerkan infiltration experiment is carried out by inserting the ring a short depth into the soil and establishing a positive head of water on the infiltration surface for at least a part of the run. Nevertheless, the data are analyzed by assuming a fully unconfined infiltration process (ring insertion depth, d = 0 cm) and a null ponded depth of water (H = 0 cm). The influence of ring insertion and ponded water on an infiltration process of 2 h sampled every minute was tested in this numerical investigation. Five soils varying from sand to silt loam, three ring radii (5–15 cm), and the Beerkan-specific range of values for both d and H (between 0 and 1 cm) were considered. The differences…

Saturated Soil Hydraulic Conductivity

This chapter deals primarily with field measurement of saturated soil hydraulic conductivity, K fs . Well or borehole permeameter techniques, specifically developed for subsurface soil measurements above the water table, are initially illustrated. Particular attention is paid to establishment of steady flow under constant head in an uncased borehole, widely developed both theoretically and experimentally in the last 30 years. Situations involving cased boreholes, transient flow, or falling head processes are then described. These variants have received a renewed interest in the last few years. New data analysis procedures have been proposed and this circumstance allows us to obtain subsurfa…

Using a transient infiltrometric technique for intensively sampling field-saturated hydraulic conductivity of a clay soil in two runoff plots

The point measurement of soil properties allows to explain and simulate plot scale hydrological processes. An intensive sampling was carried out at the surface of an unsaturated clay soil to measure, on two adjacent plots of 4 × 11 m2 and two different dates (May 2007 and February–March 2008), dry soil bulk density, ρb, and antecedent soil water content, θi, at 88 points. Field-saturated soil hydraulic conductivity, Kfs, was also measured at 176 points by the transient Simplified Falling Head technique to determine the soil water permeability characteristics at the beginning of a possible rainfall event yielding measurable runoff. The ρb values did not differ significantly between the two d…

Predicting maximum annual values of event soil loss by USLE-type models

Abstract Previous experimental investigations showed that a large proportion of total plot soil erosion over a long time period is generally due to relatively few, large storms. Consequently, erosion models able to accurately predict the highest plot soil loss values have practical importance since they could allow to improve the design of soil conservation practices in an area of interest. At present USLE-based models are attractive from a practical point of view, since the input data are generally easy to obtain. The USLE was developed with specific reference to the mean annual temporal scale but it was also applied at the event scale. Other models, such as the USLE-M and the USLE-MM, app…

A field assessment of the Simplified Falling Head technique to measure the saturated soil hydraulic conductivity

Abstract The Simplified Falling Head (SFH) technique to measure field saturated soil hydraulic conductivity, Kfs, has received little testing or comparison with other techniques. Different experiments were carried out to i) determine the effect of ring size on the measured conductivity; ii) compare the SFH and Pressure Infiltrometer (PI) techniques in a clay loam soil; and iii) evaluate the approach used in the SFH methodology to estimate the α* parameter. Sampling a relatively large number of sites allowed to detect statistically significant relationships between the Kfs values obtained with rings differing in diameter (0.15 and 0.30 m, respectively). The ring size effect was substantial (…

Testing infiltration run effects on the estimated water transmission properties of a sandy-loam soil

Abstract Testing factors influencing determination of soil water transmission properties by an infiltrometer method helps better interpretation of the collected data and allows the development of appropriate sampling strategies for the intended use of the data. These factors include the soil water content at the start of the experiment, the height from which water is poured onto the soil surface, and the duration of the infiltration run. A sandy-loam soil was sampled with the BEST (Beerkan Estimation of Soil Transfer parameters) procedure of soil hydraulic characterization and two heights of pouring of water (0.03 and 1.5 m) under three different initial soil water content, θ i (0.12 ≤ θ i …

Estimating field-saturated soil hydraulic conductivity by a simplified Beerkan infiltration experiment

Field-saturated soil hydraulic conductivity, Kfs, is highly variable. Therefore, interpreting and simulating hydrological processes, such as rainfall excess generation, need a large number of Kfs data even at the plot scale. Simple and reasonably rapid experiments should be carried out in the field. In this investigation, a simple infiltration experiment with a ring inserted shortly into the soil and the estimation of the so-called α* parameter allowed to obtain an approximate measurement of Kfs. The theoretical approach was tested with reference to 149 sampling points established on Burundian soils. The estimated Kfs with the value of first approximation of α* for most agricultural field s…

Testing simple scaling in soil erosion processes at plot scale

Abstract Explaining scale effects for runoff and erosion improves our understanding and simulation ability of hydrological and erosion processes. In this paper, plot scale effects on event runoff per unit area (Qe), sediment concentration (Ce) and soil loss per unit area (SLe) were checked at El Teularet-Sierra de Enguera experimental site in Eastern Spain. The measurements were carried out for 31 events occurring in the years 2005 and 2007 in bare ploughed plots ranging from 1 to 48 m2. The analysis established the scaling relationship by dimensional analysis and self-similarity theory, and tested this relationship at different temporal scales ranging from event to annual scale. The dimens…

Application of minidisk infiltrometer to estimate water repellency in Mediterranean pine forest soils

Assessment of soil water repellency (SWR) was conducted in the decomposed organic floor layer (duff) and in the mineral soil layer of two Mediterranean pine forests, one in Italy and the other in Spain, by the widely-used water drop penetration time (WDPT) test and alternative indices derived from infiltration experiments carried out by the minidisk infiltrometer (MDI). In particular, the repellency index (RI) was calculated as the adjusted ratio between ethanol and water soil sorptivities whereas the water repellency cessation time (WRCT) and the specifically proposed modified repellency index (RIm) were derived from the hydrophobic and wettable stages of a single water infiltration experi…

Variable power-law scaling of hillslope Hortonian rainfall–runoff processes

Hydrological studies focused on Hortonian rainfall–run-off scaling have found that the run-off depth generally declines with the plot length in power-law scaling. Both the power-law proportional coefficient and the scaling exponent show great variability for specific conditions, but why and how they vary remain unclear. In the present study, the scaling of hillslope Hortonian rainfall–run-off processes is investigated for different rainfall, soil infiltration, and hillslope surface characteristics using the physically based cell-based rainfall-infiltration-run-off model. The results show that both temporally intermittent and steady rainfalls can result in prominent power-law scaling at the …

Statistical distribution of soil loss and sediment yield at Sparacia experimental area, Sicily

Abstract An analysis of the statistical distribution of event soil loss was carried out using the data collected in the period 1999–2008 at the microplots and plots of the Sparacia experimental area (Sicily, Italy). For a given microplot size, the analysis allowed to establish that the soil loss frequency distribution was skewed. Using the soil loss normalized by the event mean value, the analysis also showed that the frequency distributions corresponding to different microplot and plot sizes were overlapping, i.e. all distributions were extracted by the same statistical population. The developed analysis allowed to suggest that the soil loss of a given return period can be estimated using …

Determinazione dell’erodibilità dei suoli

A test of the Beerkan Estimation of Soil Transfer parameters (BEST) procedure

Abstract The Beerkan Estimation of Soil Transfer parameters (BEST) procedure is attractive for a simple soil hydraulic characterization but testing the ability of this procedure to estimate soil properties is necessary. The BEST predictions were compared with soil water retention and hydraulic conductivity data measured in the laboratory and the field, respectively, at ten Sicilian field sites. Provided that BEST yielded physically possible scale parameters of the soil characteristic curves in most of the four replicated infiltration runs at a site, the measured water retention was satisfactorily predicted (i.e., not statistically significant differences between measurements and predictions…

ASSESSMENT OF THE SIMPLIFIED FALLING HEAD TECHNIQUE TO MEASURE THE FIELD SATURATED SOIL HYDRAULIC CONDUCTIVITY

The Simplified Falling Head (SFH) technique to measure field saturated soil hydraulic conductivity, Kfs, has received little testing or comparison with other techniques. Different experiments were carried out to i) determine the effect of ring size on the measured conductivity; ii) compare the SFH and Pressure Infiltrometer (PI) techniques in a clay loam soil; and iii) assess the indirect approach to estimate the * parameter used in the SFH methodology. Sampling a relatively large number of sites allowed to detect a statistically significant relationship between the Kfs values obtained with rings differing in diameter (0.15 and 0.30 m, respectively). This relationship suggested that a meas…

CALIBRAZIONE DI MODELLI USLE-DERIVATI MEDIANTE I MASSIMI ANNUALI DELLA PERDITA DI SUOLO PER EVENTO

Numerosi risultati sperimentali hanno evidenziato che la perdita di suolo pluriennale di una parcella è influenzata apprezzabilmente dall’erosione che si verifica in un numero complessivamente limitato di eventi particolarmente gravosi. Conseguentemente, un intervento di conservazione del suolo calibrato sull’erosione media annua può risultare poco efficace in occasione degli eventi meteorici più significativi dal punto di vista dell’erosione complessiva. La disponibilità di modelli di previsione dell’erosione idrica parcellare in grado di fornire stime accurate dei valori più elevati della perdita di suolo alla scansione del singolo evento erosivo riveste pertanto interesse pratico, potend…

Indici di erosività per la stima della perdita di suolo a scala di evento

Run duration effects on the hydrodynamic properties of a loam soil estimated by steady-state infiltration methods

Steady-state methods for the analysis of single-ring infiltration data are commonly applied. However, the duration of an infiltrometer experiment is often established quite subjectively based on the assumption that in general infiltration stabilizes rather quickly in the field. For a loam soil, the effect of the duration of a beerkan run on sorptivity, S, and saturated hydraulic conductivity, Ks, was tested by using the BEST (Beerkan Estimation of Soil Transfer parameters)-steady method and SSBI (Steady version of the Simplified method based on a Beerkan Infiltration run) method for data analysis. The standard experiment, based on a total of 15 water volumes each establishing an initial pon…

Testing an adapted beerkan infiltration run for a hydrologically relevant soil hydraulic characterization

Abstract Literature raises doubts about the usability of infiltrometer methods to characterize soils in a hydrological perspective since these methods often yield excessively high infiltration rates or saturated soil hydraulic conductivity, Ks, values. For a loam (AR) and a silty-clay (RO) soil, beerkan infiltration runs were adapted in the perspective to obtain usable soil data to predict rainfall partition into infiltration and rainfall excess. In particular, the initially nearly dry soil was sampled with different water volumes (15 or 30) and heights of water application (low, L, 0.03 m, and high, H, 1.5 m), and the BEST-steady algorithm was applied to determine sorptivity, S, and Ks. Th…

Misura della conducibilità idraulica del suolo con l’infiltrometro a depressione a dischi concentrici

Monitoring plot soil erosion and basin sediment yield at Sparacia experimental area

Appendix – Additional Measurements

This appendix deals with the determination of different soil physical and hydraulic characteristics used in the analysis and/or interpretation of the infiltration experiments. The core method and the excavation method for measurement of soil bulk density are initially presented. Determination of soil water content by the thermo-gravimetric and the Time Domain Reflectometry methods is then illustrated. Subsequently, field measurement of soil water matric potential by tensiometers is discussed. Laboratory determination of the soil water retention curve by tensiometric and pressiometric techniques is also described. Finally, different methods to test water stability of soil aggregates are illu…

Testing laboratory methods to determine the anisotropy of saturated hydraulic conductivity in a sandy–loam soil

Abstract Anisotropy, a (the log of the ratio of horizontal to vertical conductivity, log 10 ( K h / K v )), of saturated soil hydraulic conductivity, K s , affects transport processes in soil but is not routinely measured, probably because practical and validated methods are lacking. The objective of this investigation was to determine the effects of different constant-head laboratory and sampling procedures on anisotropy of saturated hydraulic conductivity measurements. The sequence of K s measurements was varied (vertical conductivity, K v , first, then horizontal, K h , second and vice versa) for an experimental set-up considering five variables: 1) water ponding type (Mariotte or siphon…

Effect of a Heavy Rainstorm on the Surface Hydrodynamic Properties of a Sandy-Loam Soil

Changes in surface-soil hydrodynamic properties associated with torrential natural rainstorms are largely unknown. This investigation aimed at verifying if the surface hydrodynamic properties of a sandy-loam soil varied due to the heavy rainfall event (130 mm in nearly three hours) that occurred in the summer of 2020 at Palermo (Italy) and also to establish if soil recovery processes occurred soon after the event. The soil of an orchard was sampled immediately before the rainstorm and a few days and 1.5 months later. The rainstorm determined a moderate decrease (by 1.8 times) of the saturated soil hydraulic conductivity, Ks, and an increase of its relative variability. In the subsequent wee…

19. Valutazione del Rischio di Desertificazione

assente - capitolo di libro

Spatial variability of the relationships of runoff and sediment yield with weather types throughout the Mediterranean basin

Este artículo contiene 16 páginas, 6 figuras, 2 tablas.

Evaluation of clogging in full-scale subsurface flow constructed wetlands

Abstract Treatment processes that occur in constructed wetlands can result in gradual clogging of the porous medium. Clogging may result in hydraulic malfunction and/or reduced treatment performance. The aim of this study was to analyze the hydraulic aspects of horizontal subsurface flow (H-SSF) constructed wetlands (CWs), and, in particular, to investigate the clogging phenomena through in situ measurements of hydraulic conductivity of the gravel bed, quantification of accumulated clog matter and flow paths visualization by means of tracer tests. Removal efficiencies of chemical and physical contaminants were also assessed. Experiments were carried out in three full-scale H-SSF CWs in Sici…

Variabilità delle misure parcellari di perdita di suolo nell'area sperimentale di Sparacia

Polyester microplastic fibers affect soil physical properties and erosion as a function of soil type

Microplastics are recognized as a factor of global change contaminating many environmental compartments. Agricultural soils are very likely to receive microplastic contamination and are of particular concern due to their role in food production. Microplastic fibers have already been shown to be able to affect soil properties, but their effect on different soil types is poorly understood. Moreover, limited information is available on how the presence of this pollutant can affect soil water erosion processes, which are extremely important issues in many environments. In the light of this, we performed two experiments (carried out on a microscale) to investigate how the presence of polyester m…

Effect of plot size on measured soil loss for two Italian experimental sites

The objective of this investigation was to determine empirically the plot width and length effects on runoff volume, Ve, soil loss, Ae, and sediment concentration, Ce, by using data collected, at the temporal scale of the erosive event, on bare plots differing in width (2 to 8 m) and length (11 to 22 m) for two Italian stations (Masse, Umbria; Sparacia, Sicily). Mean results differed by a maximum factor of 1.6 for Ve, 1.8 for Ae and 1.2 for Ce when plots differing in width were compared and by a maximum factor of 1.4 for Ve, 1.2 for Ae and 1.3 for Ce when comparison between plot lengths was conducted. Differences between two plot widths or two plot lengths were not statistically significant…

Stima dell'erosione idrica parcellare in due siti sperimentali italiani

Simulazione dei deflussi per il bacino sperimentale SPA1 di Sparacia

Laboratory evaluation of falling-head infiltration for saturated soil hydraulic conductivity determination

Falling-head one-dimensional infiltration procedures, such as the simplified falling-head (SFH) technique, yield estimates of saturated soil hydraulic conductivity, Ks, with parsimonious and rapid experiments. Factors that can influence determination of Ks by the SFH technique were tested in the laboratory on three repacked soils differing by particle diameter ranges (0-2000, 0- 105 and 105-2000 mm, respectively). Using the theoretically calculated depth of ponding on the infiltration surface, D, instead of the measured one had a small impact on the Ks calculations (means differing by a factor of 1.1-1.2, depending on the soil). For the finest soil, Ks decreased by 3.1 times as D increased …

Testing soil water repellency in a Sicilian area two years after a fire

The water drop penetration time (WDPT) technique was applied in 2018 to check persistence of soil water repellency (SWR) in a Sicilian mountain area affected by a wildfire on June 2016. A total of four sites, that were severely water repellent immediately after burning, were sampled. Depending on the site, wettable soil conditions, less SWR and maintenance of a noticeable SWR were detected two years later. At the site showing a near-constant SWR, WDPTs were particularly high in the top soil layer (0-0.03 m) and they appreciably decreased more in depth. Signs of decreasing SWR in drier soil conditions and in association with coarser soil particles were also detected at this site. High gradie…

Predicting soil loss in central and south Italy with a single USLE-MM model

Purpose: The USLE-MM estimates event normalized plot soil loss, Ae,N, by an erosivity term given by the runoff coefficient, QR, times the single-storm erosion index, EI30, raised to an exponent b1> 1. This modeling scheme is based on an expected power relationship, with an exponent greater than one, between event sediment concentration, Ce, and the EI30/Pe(Pe= rainfall depth) term. In this investigation, carried out at the three experimental sites of Bagnara, Masse, and Sparacia, in Italy; the soundness of the USLE-MM scheme was tested. Materials and methods: A total of 1192 (Ae,N, QREI30) data pairs were used to parameterize the model both locally and considering all sites simultaneously. …

RELAZIONI TRA I POOLS DI CARBONIO NEI REGOSUOLI DELLA RISERVA NATURALE ORIENTATA MONTE GALLO (PA)

A test of water pouring height and run intermittence effects on single-ring infiltration rates

Assessing how the infiltration process depends on the water impact energy improves interpretation of hydrological processes. Impact energies vary with the height of water pouring; that is, the distance between the water delivery point and the soil surface. The effects of the height of water pouring on infiltration in an initially near saturated soil can be tested in the field by two repeated Beerkan infiltration runs separated by a short pause (30 min) and using both low (non-perturbing) and high (perturbing) heights of water application. The double two-stage Beerkan run methodology was applied in two soils. The infiltration rate at the end of the perturbing stage of the experiment was 0.2–…

Comparison of unconfined and confined unsaturated hydraulic conductivity

Abstract The field tension infiltrometer (TI) and the laboratory unit hydraulic gradient (UHG) methods are widely applied to determine the near-saturated soil hydraulic conductivity, K . Comparison between the two methods is relevant given that they differ in the explored soil volume (undetached or detached) and in the flow process (unconfined or confined). The objective of this investigation was to compare unconfined and confined measurements of unsaturated hydraulic conductivity. Twenty TI experiments were conducted in a relatively coarse-textured soil having an appreciable hysteretic behavior by using two different dry-to-wet-to-dry (DTWTD) sequences of pressure head, h 0 , values that d…

L’evento alluvionale dell’Ottobre 2009 nel Messinese

La carta dell'erosione massima per gli studi dei processi di desertificazione in Sicilia

An Evaluation of the Single-test Tension Infiltrometer Method for determining the Hydraulic Conductivity of Lateral Capillarity Domain Soils

Abstract The transient and the steady-state single-test tension infiltrometer methods are expected to provide poor hydraulic conductivity K0 estimates in soils situated in the lateral capillarity domain. To evaluate the best strategy for conducting a single-test experiment in these soils, infiltration experiments were numerically simulated for a sandy loam and a clay soil by using two initial pressure heads (−1 and −100 m), four pressure heads at the soil surface (from −0·15 m to −0·01 m), and a maximum duration of 4 h (sandy loam soil) and 12 h (clay soil). The most accurate predictions of K0, differing by a factor of between 0·9 and 1·1 from the true value, were obtained in wet conditions…

La carta dell'erosione potenziale del territorio siciliano

Comparing Alternative Algorithms to Analyze the Beerkan Infiltration Experiment

The increasing interest in the Beerkan Estimation of Soil Transfer parameters (BEST) procedure of soil hydraulic characterization justifies an assessment of alternative methods to analyze infiltration data. The BEST-slope and BEST-intercept algorithms allow estimation of soil sorptivity, S, and saturated soil hydraulic conductivity, Ks, using the transient part of the experimental infiltration curve and the slope and the intercept, respectively, of the linear portion of this curve. With reference to 401 runs performed in Sicily (Italy) and Burundi, this investigation showed that these two algorithms differed by the number of successful runs (positive S and Ks values), with BEST-intercept yi…

A simplified approach to estimate water retention for Sicilian soils by the Arya-Paris model

Application of the Arya and Paris (AP) model to estimate the soil water retention curve requires a detailed description of the particle-size distribution (PSD) because the scale factor a, relating the pore length of an ideal soil to that of the natural one, depends on the particle size distribution parameters. For a dataset of 140 Sicilian soils that were grouped in five texture groups, the logistic and linear models were applied to evaluate a, and the water retention values predicted by the AP model were compared with the measured ones. Using the parameters proposed by Arya et al. (1999), the two models yielded similar unsystematic root mean error of estimate (RMSEu). Therefore, their pote…

Comparing two applicative criteria of the soil erosion physical model concept

The physical model represented by a replicated plot has been suggested to be the best possible, unbiased, real world model to predict plot soil erosion. The aim of this investigation was to compare the original applicative criterion of the physical model concept proposed by Nearing with that later suggested by Bagarello et al. The comparison was performed by using three empirical soil erosion models (the Universal Soil Loss Equation [USLE], a modified USLE [USLE-MM], and the Central and Southern Italy [CSI] model) and plot soil loss data collected at the experimental station of Sparacia, in Sicily (southern Italy). The investigation showed that (i) the new criterion was generally more restr…

Metodi transitori per la misura in campo della conducibilità idraulica del suolo

A comprehensive analysis of Universal Soil Loss Equation-based models at the Sparacia experimental area

Improving Universal Soil Loss Equation (USLE)‐based models has large interest because simple and reliable analytical tools are necessary in the perspective of a sustainable land management. At first, in this paper, a general definition of the event rainfall‐ runoff erosivity factor for the USLE‐based models, REFₑ = (QR)ᵇ¹(EI₃₀)ᵇ², in which QR is the event runoff coefficient, EI₃₀ is the single‐storm erosion index, and b₁ and b₂ are coefficients, was introduced. The rainfall‐runoff erosivity factors of the USLE (b₁ = 0 and b₂ = 1), USLE‐M (b₁ = b₂ = 1), USLE‐MB (b₁ ≠ 1 and b₂ = 1), USLE‐MR (b₁ = 1 and b₂ ≠ 1), USLE‐MM (b₁ = b₂ ≠ 1), and USLE‐M2 (b₁ ≠ b₂ ≠ 1) can be defined using REFₑ. Then t…

Testing different approaches to characterize Burundian soils by the best procedure

Abstract The Beerkan Estimation of Soil Transfer parameters (BEST) procedure seems attractive for soil hydraulic characterization but it has received little testing so far. The objective of this investigation was to test BEST with different application approaches for some soils in Burundi, where there is the need of using simple methods to characterize soils. Most (14) of the 19 sampled sites had a clay soil texture whereas texture ranged from silty clay to loam in the other cases. On average, the fitting ability of both the particle size distribution (PSD) model (mean relative error, Me ( E r ) = 2.0%) and the cumulative infiltration model ( Me ( E r ) = 2.3%) was good according to recomme…

Using the single-ring infiltrometer method to detect temporal changes in surface soil field-saturated hydraulic conductivity

Abstract Determining temporal changes in field-saturated hydraulic conductivity ( K fs ) is important for understanding and modelling hydrological phenomena at the field scale. Little is known about the sensitivity of temporal change estimates to the method used for measuring K fs . The objective of this study was to compare temporal changes in K fs obtained in the surface layer of a clayey soil using two application procedures of the single-ring infiltrometer method. Rings installed permanently at the beginning of a 1.5-year study period (permanent sites, PSs, sample size N =16) and rings installed immediately before conducting the infiltrometer measurement (non-permanent sites, NPSs, N =1…

Estimating the USLE soil erodibility factor in Sicily, South Italy

The Universal Soil Loss Equation (USLE) is used by professionals and technicians to predict soil loss by water erosion and to establish soil conservation measures. One of the key elements of the USLE is the K factor, which is a measure of the soil erodibility. Given the difficulty in collecting sufficient data to adequately measure K, early in the USLE's history the soil erodibility nomograph method was developed to allow estimation of K based on standard soil properties. Since the nomograph approach was developed based on a small number of soils in the United States, it is necessary for other contexts to check the nomograph's ability to predict the soil's true erodibility. Considering that…

Testing steady-state analysis of single-ring and square pressure infiltrometer data

Testing reliability of the saturated soil hydraulic conductivity, Ks, estimated by applying the steady-state single-ring (SR) model to the quasi steady-state infiltration rates obtained with a single-ring pressure infiltrometer (PI) increases confidence in the estimated Ks values. Determining a means to estimate Ks from infiltration data collected with a square infiltrometer allows the use of sources of different shapes. Using numerically simulated infiltration rates for six homogeneous soils ranging in texture from sand to silty clay loam, this investigation suggested an overall good performance of the SR model, with estimated Ks values differing by not more than 25% from the true values f…

Comparing theoretically supported rainfall-runoff erosivity factors at the Sparacia (South Italy) experimental site

Interpreting rainfall‐runoff erosivity by a process‐oriented scheme allows to conjugate the physical approach to soil loss estimate with the empirical one. Including the effect of runoff in the model permits to distinguish between detachment and transport in the soil erosion process. In this paper, at first, a general definition of the rainfall‐runoff erosivity factor REFe including the power of both event runoff coefficient QR and event rainfall erosivity index EI30 of the Universal Soil Loss Equation (USLE) is proposed. The REFe factor is applicable to all USLE‐based models (USLE, Modified USLE [USLE‐M] and Modified USLE‐M [USLE‐MM]) and it allows to distinguish between purely empirical m…

An assessment of the Beerkan method for determining the hydraulic properties of a sandy loam soil

Abstract Establishing the ability of the Beerkan Estimation of Soil Transfer parameters (BEST) procedure to reproduce soil properties is necessary for specific soil types. In this investigation, the BEST predictions for a sandy loam soil were compared with water retention data obtained by a standard laboratory method and with the saturated soil hydraulic conductivity, K s , obtained by both the Wu et al. (1999) method, applied to the BEST infiltration data, and the Simplified Falling Head (SFH) technique. When the original BEST-slope algorithm with the infiltration constants fixed at β = 1.9 and γ = 0.79 was applied, the agreement between the predicted and the measured retention data was sa…

Funzioni di pedotrasferimento per la determinazione della curva di ritenzione idrica dei suoli siciliani

Il ricorso alle funzioni di pedotrasferimento (PTF) rende possibile una stima relativamente agevole delle caratteristiche di ritenzione idrica del suolo. Una riproduzione accurata delle misure per un’area di interesse presuppone però l’accertamento delle prestazioni delle PTF esistenti ed, eventualmente, lo sviluppo di PTF alternative. Utilizzando 217 curve di ritenzione misurate in Sicilia, nell’indagine è stata dapprima verificata l’applicabilità di alcune delle più diffuse PTF disponibili in letteratura. Tale verifica ha evidenziato che i risultati migliori competono alle PTF che includono, tra le variabili indipendenti, la densità apparente del suolo. Poiché tale proprietà fisica non se…

Plot-scale measurement of soil erosion at the experimental area of Sparacia (southern Italy)

Obtaining good quality soil loss data from plots requires knowledge of the factors that affect natural and measurement data variability and of the erosion processes that occur on plots of different sizes. Data variability was investigated in southern Italy by collecting runoff and soil loss from four universal soil-loss equation (USLE) plots of 176 m2, 20 ‘large’ microplots (0·16 m2) and 40 ‘small’ microplots (0·04 m2). For the four most erosive events (event erosivity index, Re ≥ 139 MJ mm ha−1 h−1), mean soil loss from the USLE plots was significantly correlated with Re. Variability of soil loss measurements from microplots was five to ten times greater than that of runoff measurements. D…

Infiltration Measurements for Soil Hydraulic Characterization

This book summarises the main results of many contributions from researchers worldwide who have used the water infiltration process to characterize soil in the field. Determining soil hydrodynamic properties is essential to interpret and simulate the hydrological processes of economic and environmental interest. This book can be used as a guide to soil hydraulic characterization and in addition it gives a complete description of the treated techniques, including an outline of the most significant research results, with the main points that still needing development and improvement.

Calibrazione di un torbidimetro ottico per la misura della perdita di suolo a scala di parcella

Testing a new automated single ring infiltrometer for Beerkan infiltration experiments

International audience; The Beerkan method along with BEST algorithms is an alternative technique to conventional laboratory or field measurements for rapid and low-cost estimation of soil hydraulic properties. The Beerkan method is simple to conduct but requires an operator to repeatedly pour known volumes of water through a ring positioned at the soil surface. A cheap infiltrometer equipped with a data acquisition system was recently designed to automate Beerkan infiltration experiments. In this paper, the current prototype of the automated infiltrometer was tested to validate its applicability to the Beerkan infiltration experiment under several experimental circumstances. In addition, t…

Influence of the rainfall measurement interval on the erosivity determinations in the Mediterranean area

Summary The single-storm erosion index, EI, of the USLE and RUSLE models may vary appreciably with the rainfall measurement interval, Δ t . However, the effect of Δ t on EI has not been investigated in the Mediterranean area. Approximately 700 erosive events and 1.5 years of rainfall energies measured by a rainfall impact measurement device were used to evaluate the effect of the rainfall measurement interval (5 min ⩽ Δ t  ⩽ 60 min) on the erosivity determinations in the Mediterranean semi-arid area of Sicily. According to both literature and practical considerations, a reference time interval equal to 15 min was used in this investigation. Hourly rainfall data led to an appreciable underes…

Indagine di campo sull'efficacia del vetiver per la conservazione del suolo e dell'acqua

Testing the “physical model concept” by soil loss data measured in Sicily

The best possible model to predict the erosion from an area of land has been suggested to be a physical model of the area that has similar soil type, land use, size, shape, slope and erosive inputs. Therefore, a replicated plot has to be considered the best possible, unbiased, real world model. In this paper the physical model concept was tested by using soil loss data collected on plots of different length at the experimental station of Sparacia, in Sicily (South Italy). This investigation supported the conclusions that i) a coefficient of determination between measured and predicted soil loss values of 0.77 has to be considered as the best-case prediction scenario and ii) an uncalibrated …

Subsurface flow and large-scale lateral saturated soil hydraulic conductivity in a Mediterranean hillslope with contrasting land uses

Abstract The lateral saturated hydraulic conductivity, Ks,l , is the soil property that mostly governs subsurface flow in hillslopes. Determinations of Ks,l at the hillslope scale are expected to yield valuable information for interpreting and modeling hydrological processes since soil heterogeneities are functionally averaged in this case. However, these data are rare since the experiments are quite difficult and costly. In this investigation, that was carried out in Sardinia (Italy), large-scale determinations of Ks,l were done in two adjacent hillslopes covered by a Mediterranean maquis and grass, respectively, with the following objectives: i) to evaluate the effect of land use change o…

Sicily: climatic and hydrologic features

VERIFICA DI IPOTESI E PROCEDURE NELLA STIMA EMPIRICA DELLA PERDITA DI SUOLO PARCELLARE IN UN AMBIENTE MEDITERRANEO

La stima dell’erosione idrica mediante approcci empirici ha interesse sia scientifico sia applicativo. Nella presente indagine è stata condotta una verifica di ipotesi e procedure adottate nella USLE e in modelli basati sullo schema USLE per la stima della perdita di suolo da parcelle di suolo nudo nell’area sperimentale di Sparacia, in Sicilia. La perdita di suolo per unità di superficie del singolo evento erosivo, Ae, non è significativamente dipendente dalla lunghezza parcellare, λ, in quanto all’aumentare di λ si riduce il deflusso ma cresce la concentrazione dei sedimenti. I valori di Ae sono crescenti con la pendenza parcellare, s, in quanto il coefficiente di deflusso non varia appre…

Thematic Issue on Soil Water Infiltration

Interpretive Summary: When water is applied to the land surface through irrigation or rainfall, it infiltrates into the soil surface and percolates deeper through the soil profile under the influence of gravity and capillary forces. Soil infiltration is one of the most complex processes within the terrestrial hydrologic cycle, yet the process is only partially understood. Infiltration is affected by the physical, chemical and biological properties of the soil, vegetation cover, rainfall, irrigation properties, and management practices. Measurement of infiltration rate is essential in studies concerning water budget, hydrology, runoff, erosion, irrigation, drainage and water conservation. Ho…

Effect of laboratory procedures on the integrity of a sandy-loam soil sample for bi-directional measurement of saturated hydraulic conductivity

Practical and validated methods to measure anisotropy of saturated, Ks, or field-saturated, Kfs, soil hydraulic conductivity on a single soil sample are still lacking. The objective of this investigation was to test factors affecting anisotropy measured in a sandy-loam soil by the constant-head laboratory permeameter and the modified cube method. The ratio, RK, between the conductivity results obtained with a long (6 h) and a short (0.5 h) duration run varied from a minimum of 0.29 to a maximum of 0.88 with the considered experimental procedure, differing by both the employed constant-head device (Mariotte bottle, siphon) and the initial soil water content (unsaturated, saturated). Maximum …

Comparing Beerkan infiltration tests with rainfall simulation experiments for hydraulic characterization of a sandy-loam soil

[EN] Saturated soil hydraulic conductivity, K-s, data collected by ponding infiltrometer methods and usual experimental procedures could be unusable for interpreting field hydrological processes and particularly rainfall infiltration. The K-s values determined by an infiltrometer experiment carried out by applying water at a relatively large distance from the soil surface could however be more appropriate to explain surface runoff generation phenomena during intense rainfall events. In this study, a link between rainfall simulation and ponding infiltrometer experiments was established for a sandy-loam soil. The height of water pouring for the infiltrometer run was chosen, establishing a sim…

Predicting plot soil loss by empirical and process-oriented approaches. A review

Soil erosion directly affects the quality of the soil, its agricultural productivity and its biological diversity. Many mathematical models have been developed to estimate plot soil erosion at different temporal scales. At present, empirical soil loss equations and process-oriented models are considered as constituting a complementary suite of models to be chosen to meet the specific user need. In this paper, the Universal Soil Loss Equation and its revised versions are first reviewed. Selected methodologies developed to estimate the factors of the model with the aim to improve the soil loss estimate are described. Then the Water Erosion Prediction Project which represents a process-oriente…

Estimating saturated soil hydraulic conductivity by the near steady-state phase of a Beerkan infiltration test

Abstract Single-ring infiltration experiments carried out in the field, such as the Beerkan runs, allow easy and inexpensive characterization of soil hydraulic properties, and specifically saturated soil hydraulic conductivity, Ks, by maintaining the functional connection of the sampled soil volume with the surrounding soil. However, a single infiltration experiment is not enough to determine Ks. The simplest way to obtain the necessary additional data is based on the assessment of the soil texture and structure characteristics. In this investigation, a simplified method, named SSBI (Steady version of the Simplified method based on a Beerkan infiltration run), was developed to estimate Ks b…

I servizi ecosistemici forestali connessi alla tutela del suolo e delle acque

Effective Practices in Mitigating Soil Erosion from Fields

Soil erosion by water is a natural process that cannot be avoided. Soil erosion depends on many factors, and a distinction should be made between humanly unchangeable (e.g., rainfall) and modifiable (e.g., length of the field) soil erosion factors. Soil erosion has both on-site and off-site effects. Soil conservation tries to combine modifiable factors so as to maintain erosion in an area of interest to an acceptable level. Strategies to control soil erosion have to be adapted to the desired land use. Knowledge of soil loss tolerance, T, i.e., the maximum admissible erosion from a given field, allows technicians or farmers to establish whether soil conservation practices need to be applied …

Conducibilità idraulica del suolo: Metodi di misura nelle applicazioni idrologiche

Il fattore di erodibilità del suolo e la carta dell’erosione potenziale

Calibrating storage tanks for soil erosion measurement from plots

Many plots for soil loss measurements are equipped with a sequence of tanks for measuring runoff volume and sediment concentration. The stored water volume is easily determined by a water depth measurement while the sediment concentration is often measured by collecting samples of the mixed suspension. In this paper, using the Π-theorem of dimensional analysis, the functional relationship describing the mixing of the suspension in the tank is expressed in a dimensionless form. The recognized dimensionless groups allow the establishment, for given soil and water depth in the tank, of the relationship (calibration curve) between the actual and the measured concentration. The calibration curve…

3. Elementi di Idrologia del Suolo

assente - capitolo di libro

Soils with Specific Features

This chapter deals with some specific features of soil that are relevant for interpretation of infiltration experiments. Infiltration in water repellent soils is first examined. After summarizing the causes of hydrophobicity, phenomena associated to infiltration in water repellent soil, including reduced infiltration rates and irregular wetting front advance, are illustrated. The Water Drop Penetration Time (WDPT), the Molarity of an Ethanol Droplet (MED) and the Repellency tests for quantitative assessment of soil water repellency are presented. Particular attention is given to estimation of subcritical soil water repellency by means of soil sorptivity measurements conducted with infiltrat…

DEDUZIONE DEL FATTORE L DELLA USLE-MM NELLE PARCELLE SPERIMENTALI DI SPARACIA, IN SICILIA

Nell’indagine è stato messo a punto un modello alternativo per la stima della perdita di suolo parcellare che riproduce anche la relazione tra Ae e  dedotta sperimentalmente. L’approccio utilizzato è quello della USLE-MM, che presuppone l’introduzione, nel set di variabili indipendenti, del coefficiente di deflusso parcellare. Nel modello proposto, il fattore topografico L stabilisce un legame crescente tra Ae e  ma la perdita di suolo dovuta a un fissato evento di pioggia può anche diminuire al crescere della lunghezza allorquando, come verificato sperimentalmente, all’incremento di  risulta associata una diminuzione del deflusso. La verifica del modello proposto con set di dati indipen…

ESTIMATING SOIL PARTICLE-SIZE DISTRIBUTION FOR SICILIAN SOILS

The soil particle-size distribution (PSD) is commonly used for soil classification and for estimating soil behavior. An accurate mathematical representation of the PSD is required to estimate soil hydraulic properties and to compare texture measurements from different classification systems. The objective of this study was to evaluate the ability of the Haverkamp and Parlange (HP) and Fredlund et al. (F) PSD models to fit 243 measured PSDs from a wide range of 38 005_Bagarello(547)_33 18-11-2009 11:55 Pagina 38 soil textures in Sicily and to test the effect of the number of measured particle diameters on the fitting of the theoretical PSD. For each soil textural class, the best fitting perf…

Predicting the water retention characteristic of Sicilian soils by pedotransfer functions.

Variability of soil hydraulic conductivity and Gardner's alpha for different soils of south Italy

Monitoraggio e previsione dell'erosione idrica

Comments on “Predicting the Effect of Rock Fragments on Saturated Soil Hydraulic Conductivity”

Indagine di laboratorio su una metodologia innovativa per la determinazione della conducibilità idraulica del suolo con l'infiltrometro a depressione

Estimation of hydrodynamic properties of a sandy-loam soil by two analysis methods of single-ring infiltration data

Abstract Beerkan infiltration runs could provide an incomplete description of infiltration with reference to either the near steady-state or the transient stages. In particular, the process could still be in the transient stage at the end of the run or some transient infiltration data might be loss. The Wu1 method and the BEST-steady algorithm can be applied to derive soil hydrodynamic parameters even under these circumstances. Therefore, a soil dataset could be developed using two different data analysis methods. The hypothesis that the Wu1 method and BEST-steady yield similar predictions of the soil parameters when they are applied to the same infiltration curve was tested in this investi…

Predicting unit plot soil loss in Sicily, south Italy

Predicting soil loss is necessary to establish soil conservation measures. Variability of soil and hydrological parameters complicates mathematical simulation of soil erosion processes. Methods for predicting unit plot soil loss in Sicily were developed by using 5 years of data from replicated plots. At first, the variability of the soil water content, runoff, and unit plot soil loss values collected at fixed dates or after an erosive event was investigated. The applicability of the Universal Soil Loss Equation (USLE) was then tested. Finally, a method to predict event soil loss was developed. Measurement variability decreased as the mean increased above a threshold value but it was low als…

Use of BEST Procedure to Assess Soil Physical Quality in the Baratz Lake Catchment (Sardinia, Italy)

Conversion of Mediterranean maquis and/or natural forest into agro-pastoral lands is a cause of soil degradation in many Mediterranean areas. Indicators of soil physical quality (SPQ) quantitatively linked to soil hydraulic properties are a valuable tool to assess the effect of land use changes. In this investigation, the Beerkan Estimation of Soil Transfer parameters (BEST) procedure for soil hydraulic characterization was used to estimate SPQ indicators. Four areas of the Baratz Lake watershed, Sardinia, Italy, characterized by both typical natural vegetation (holm oak [ Quercus ilex L.] forest and high maquis) and degraded vegetation (grassland established after fire or clearing of the m…

Comparing different application procedures of the water drop penetration time test to assess soil water repellency in a fire affected Sicilian area

Abstract The Water Drop Penetration Time (WDPT) technique was applied in two subsequent years (2016 and 2017) to check surface soil water repellency (SWR) in a Sicilian mountain area affected by a wildfire on June 2016. A total of 93 sites were sampled and from 3 to 100 droplets were used to characterize a site. The detected SWR varied with the severity of the wildfire, being practically absent in the unburnt control area and slight to extreme in the burnt areas. The percentage of extremely repellent sites increased with wildfire severity. SWR vanished one year after the passage of the fire in sites where fire severity was moderate but it persisted in the case of a severe wildfire. In gener…

An assessment of the global impact of 21st century land use change on soil erosion

Human activity and related land use change are the primary cause of accelerated soil erosion, which has substantial implications for nutrient and carbon cycling, land productivity and in turn, worldwide socio-economic conditions. Here we present an unprecedentedly high resolution (250 × 250 m) global potential soil erosion model, using a combination of remote sensing, GIS modelling and census data. We challenge the previous annual soil erosion reference values as our estimate, of 35.9 Pg yr−1 of soil eroded in 2012, is at least two times lower. Moreover, we estimate the spatial and temporal effects of land use change between 2001 and 2012 and the potential offset of the global application o…

An Introduction to Soil and Water Infiltration

This chapter provides a short presentation of general characteristics of the soil. Basic concepts concerning soil water content and potential and flow of water in the porous medium are then reported since these concepts are diffusely used throughout this book. The infiltration process is finally illustrated considering different modeling approaches. In particular, development of analytical infiltration models is described with reference to one-dimensional gravity-free water absorption, one-dimensional gravity driven infiltration, one-dimensional gravity and capillary driven infiltration and, finally, three-dimensional gravity and capillary driven infiltration.

Indagine sulla qualità fisica di alcuni suoli siciliani

La valutazione della qualità fisica del suolo rappresenta un aspetto di notevole importanza negli studi agronomici e ambientali. Nell’indagine è stato approfondito il tema dell’applicabilità in Sicilia dell’indice di qualità fisica del suolo S, basato sulla misura della curva di ritenzione idrica. Il suddetto indice assume valori crescenti nel passaggio da un suolo di qualità scadente ad uno di buona qualità. Conformemente alle attese, i valori di S, determinati per 199 campioni di suolo, si sono ridotti all’aumentare del contenuto di argilla e di limo, della densità apparente e del fattore di erodibilità del suolo. Inoltre, l’acqua disponibile e la capacità di aerazione sono aumentate mono…

Approfondimenti sul Cube Method per la misura della conducibilità idraulica del suolo

Evaluation of soil physical quality under different soil land uses in a small Sicilian watershed

Sustainability of extensive rain fed agriculture needs assessment of land use effects on soil physical and hydraulic properties. Several soil physical quality indices were determined for four adjacent areas in a small Sicilian watershed, that were characterized by a different land use, namely cropland (C), olive grove (O), grassland (G) and eucalyptus plantation (E). Soil texture was similar for the considered areas, even if the no-tilled soils (G and E) showed a higher clay content in the top layer (0-20 cm) than in the lower layer (20-40 cm). The bulk density of the top layer ranged between 1.20-1.43 g cm-3 (C < G < O < E), with significant differences between C and E. In the lower layer,…

Scale effects on plot runoff and soil erosion in a mediterranean environment

Explaining scale effects for runoff and erosion improves our understanding of hydrological and erosion processes. In this investigation, plot-scale effects on event runoff per unit area, Qe, sediment concentration, Ce, and soil loss per unit area, SLe, were checked at the Sparacia (Italy) site. Similar information on the scale effects was obtained with different dependent variables, i.e., individual values of Qe, Ce, and SLe for each plot or the mean of their replicated values, and scale indicators, i.e., plot length, l, or plot area, A. The most common result, occurring for 57 to 62% of the events depending on the considered variable, was the lack of any scale effect. When scale effects we…

Using Static and Dynamic Indicators to Evaluate Soil Physical Quality in a Sicilian Area

Both capacitive indicators derived from the water retention curve and dynamic measurements of the flow-weighted mean pore radius, R0, were used to assess the soil physical quality of two agricultural areas (cropland and olive orchard) and two natural areas (grassland and managed woodlot plantation) potentially subject to soil degradation. The overall idea of the study was to investigate whether a dynamic indicator quantitatively derived from hydraulic conductivity measurements could be used to supplement the traditionally applied capacitive indicators retrieved from water retention measurements. According to the available criteria, only the surface layer of the cropland site showed optimal …

Water transmission properties of a sandy-loam soil estimated with Beerkan runs differing by the infiltration time criterion

Abstract The Beerkan method consists of a ponded infiltration experiment from a single ring inserted a small depth into the soil. Fixed, small volumes of water are repeatedly poured into the ring to maintain a quasi-zero head on the soil surface. According to the standard Beerkan infiltration run, a new water volume is poured on the infiltration surface when the previously applied volume has completely infiltrated and the soil surface is entirely exposed to air (ta criterion). However, water could also be applied when the soil exposition to air begins (to criterion) or half the soil surface is exposed to air (tm criterion). The effect of the infiltration time criterion on determination of t…

Soil physical quality in a Sicilian agricultural area

A comparison between the single ring pressure infiltrometer and simplified falling head techniques

Testing the relative performances of the single ring pressure infiltrometer (PI) and simplified falling head (SFH) techniques to determine the field saturated soil hydraulic conductivity, Kfs, at the near point scale may help to better establish the usability of these techniques for interpreting and simulating hydrological processes. A sampling of 10 Sicilian sites showed that the measured Kfs was generally higher with the SFH technique than the PI one, with statistically significant differences by a factor varying from 3 to 192, depending on the site. A short experiment with the SFH technique yielded higher Kfs values because a longer experiment with the PI probably promoted short-term swe…

A Comprehensive Check of Usle-Based Soil Loss Prediction Models at the Sparacia (South Italy) Site

At first, in this paper a general definition of the event rainfall-runoff erosivity factor for the USLE-based models, REFe = (QR)b1(EI30)b2, in which QR is the event runoff coefficient, EI30 is the single-storm erosion index and b1 and b2 are coefficients, was introduced. The rainfall-runoff erosivity factors of the USLE (b1 = 0, b2 = 1), USLE-M (b1 = b2 = 1), USLE-MB (b1 ≠ 1, b2 = 1), USLE-MR (b1 = 1, b2 ≠ 1), USLE-MM (b1 = b2 ≠ 1) and USLE-M2 (b1 ≠ b2 ≠ 1) can be defined using REFe. Then, the different expressions of REFe were simultaneously tested against a dataset of normalized bare plot soil losses, AeN, collected at the Sparacia (south Italy) site. As expected, the poorest AeN predict…

Comparing two methods of analysis of single-ring infiltrometer data for a sandy – loam soil

The single-ring pressure i n filtrometer (PI) with the steady-state Two-Ponding-Depth (TPD) applic ation method were developed to simulta neously determine the saturated soil hydraulic conductivity, K , and the α ⁎ -parameter in the fi eld. Methods of analysis of transient PI data are also available but they have received little testing so far. The transient WU method and the TPD method were compared for a sandy-loam soil. A linearization technique o f the in filtration curve yielded more reliable K fs fs and α ⁎ results (i.e., falling within expected ranges) than a non-linear optimization technique. The WU method gave both positive and reasonable K and α ⁎ values for all infi ltration tests. U…

Testing the concentric-disk tension infiltrometer for field measurement of soil hydraulic conductivity

Abstract The concentric-disk tension infiltrometer (CDTI) may be used to simultaneously measure the confined ( K c ) and the unconfined ( K u ) soil hydraulic conductivity, but it has received little testing. Comparison between K c and K u can be affected by the calculation approach applied to analyze unconfined steady-state infiltration rates. The objectives of this investigation were to: i) establish the effect of the calculation approach on the estimates of K u ; and ii) compare the K c and K u values measured by the CDTI. A clay soil, a structureless sandy loam soil, and a sandy loam soil with a relatively high gravel content were sampled using a disk of radius equal to 107.5 mm, compri…

Using plot soil loss distribution for soil conservation design

Abstract Soil conservation design is generally based on the estimation of average annual soil loss but it should be developed taking into account storms of a given return period. However, use of frequency analysis in soil erosion studies is relatively limited. In this paper, an investigation on statistical distribution of soil loss measurements was firstly carried out using a relatively high number of simultaneously operating plots of different lengths, λ (11, 22, 33 and 44 m) at the experimental station of Sparacia (southern Italy). Using a simple normalization technique, the analysis showed that the probability distribution of the normalized soil loss is independent of both the scale leng…

Studi applicativi per la realizzazione della carta dell'erosione potenziale del territorio siciliano e del relativo sistema informativo territoriale

Verifica del concetto di modello fisico in due stazioni di misura dell’erosione parcellare

Physical and hydraulic characterization of a clay soil at the plot scale

Summary The soil physical and hydraulic properties have to be determined for interpreting and simulating many hydrological processes. An investigation was carried out to determine the physical and hydraulic characteristics of a clay soil at the plot scale. An intensive sampling of the surface soil layer of two plots of 4 × 11 m2 was carried out by measuring, for each plot, dry soil bulk density, ρb, and antecedent soil water content, θi, at 88 sampling points and field-saturated soil hydraulic conductivity, Kfs, at 176 sampling points. A wide range of Kfs values (0.7–5107 mm h−1) were measured by the Simplified Falling Head (SFH) technique. For each variable, the two plots yielded very simi…

A modified applicative criterion of the physical model concept for evaluating plot soil erosion predictions

Abstract In this paper, the physical model concept by Nearing (1998. Catena 32: 15–22) was assessed. Soil loss data collected on plots of different  widths (2–8 m), lengths (11–44 m) and steepnesses (14.9–26.0%), equipped in south and central Italy, were used. Differences in width between plots of given length and steepness determined a lower data correlation and more deviation of the fitted regression line from the identity one. A coefficient of determination between measured, M , and predicted, P , soil losses of 0.77 was representative of the best-case prediction scenario, according to Nearing (1998). The relative differences, Rdiff  = ( P − M ) / ( P + M ), decreased in absolute value a…

Estimating hydraulic conductivity of a crusted loamy soil from beerkan experiments in a Mediterranean vineyard

In bare soils of semi-arid areas, surface crusting is a rather common phenomenon due to the impact of raindrops. Water infiltration measurements under ponding conditions constitute a common way for an approximate characterization of crusted soils. In this study, the impact of crusting on soil hydraulic conductivity was assessed in a Mediterranean vineyard (western Sicily, Italy) under conventional tillage. The BEST (Beerkan Estimation of Soil Transfer parameters) algorithm was applied to the infiltration data to obtain the hydraulic conductivity of crusted and uncrusted soils. Soil hydraulic conductivity was found to vary during the year and also spatially (i.e., rows vs. inter-rows) due to…

Monitoraggio della perdita di suolo parcellare nell'area sperimentale di Sparacia

A Check of Water Drop Impact Effects on Surface Soil Saturated Hydraulic Conductivity

The post-tillage dynamics of the surface soil saturated hydraulic conductivity, Ks, was studied at the Masse experimental station (central Italy, silty-clay-loam soil). A sequence of experiments was performed by rainfall simulation on two replicated micro-plots (width 1 m, length 0.92 m, slope 16%) established on bare soil. Each high-intensity rainfall simulation was preceded by a low-intensity wetting phase. The soil water content, w, was measured before wetting and both before and after simulation. Runoff was measured at 5 min intervals. The infiltration rate was calculated as the difference between rainfall intensity and runoff rate. Finally, Ks was assumed to be equal to the infiltratio…

SULLA APPLICABILITÀ DELLA USLE-MM PER LA STIMA DISTRIBUITA DELLA PRODUZIONE DI SEDIMENTI

Nella memoria è presentata una nuova versione del modello distribuito SEDD (SEdiment Delivery Distributed model) che accoppia la RUSLE o la USLE-MM con un criterio spazialmente distribuito per la stima dei processi di trasferimento delle particelle erose all’interno di un bacino idrografico. In particolare, viene proposta l’applicazione a scala di bacino di un fattore di erosività, che tiene conto anche del processo di deflusso a scala di versante, e di un fattore di erodibilità del suolo determinati utilizzando le misure parcellari condotte nell’area sperimentale di Sparacia in Sicilia. Il modello è stato calibrato utilizzando le misure dei deflussi liquidi e solidi effettuate nei bacini s…

Monitoraggio della perdita di suolo nell'area sperimentale di Sparacia

A laboratory analysis of falling head infiltration procedures for estimating the hydraulic conductivity of soils

Abstract Falling head (FH) infiltration procedures can give rapid estimates of the field saturated hydraulic conductivity ( K fs ) of soils. The objectives of this investigation were to develop a procedure for estimating both the K fs and the α ⁎ parameter of the exponential hydraulic conductivity function from a FH experiment, and to compare FH procedures differing by experimental and computational demands. A total of 33 FH experiments were carried out on repacked, sandy loam and loam soil cores. A two level (TL) analysis was applied to determine a value of α ⁎ for each soil core. K fs was then calculated by three different approaches, ranging from the fitting approach (FA) that used the m…

Comparing two methods of analysis of single-ring infiltrometer data for a sandy–loam soil

Abstract The single-ring pressure infiltrometer (PI) with the steady-state Two-Ponding-Depth (TPD) application method were developed to simultaneously determine the saturated soil hydraulic conductivity, K fs , and the α ⁎-parameter in the field. Methods of analysis of transient PI data are also available but they have received little testing so far. The transient WU method and the TPD method were compared for a sandy-loam soil. A linearization technique of the infiltration curve yielded more reliable K fs and α ⁎ results (i.e., falling within expected ranges) than a non-linear optimization technique. The WU method gave both positive and reasonable K fs and α ⁎ values for all infiltration t…

Field and laboratory approaches for determining sodicity effects on saturated soil hydraulic conductivity

Abstract Dilution of high-sodicity soil water by low-sodicity rainfall or irrigation water can cause declining soil hydraulic conductivity (K) by inducing swelling, aggregate slaking and clay particle dispersion. Investigations of sodicity-induced reduction in K are generally restricted to repacked laboratory cores of air-dried and sieved soil that are saturated and equilibrated with sodic solution before tests are conducted. This approach may not yield a complete picture of sodicity effects in the field, however, because of loss of antecedent soil structure, small sample size, detachment of the sample from the soil profile, reliance on chemical equilibrium, and differing time scales betwee…

APPROCCIO METODOLOGICO PER LA VALUTAZIONE DELLA QUALITÀ DEI SUOLI NELLA R.N.O. MONTE GALLO (PA)

Simplified estimation of field saturated soil hydraulic conductivity from ponded infiltration data

Simple and reasonably rapid experiments are desirable to conduct a spatially distributed determination of field-saturated soil hydraulic conductivity, Kfs, that is a highly variable soil property. Bagarello et al. (2012) recently developed a simplified approach to estimate Kfs that is based on a ponded field infiltration experiment. A cylinder is inserted to a short depth into the soil, so to produce a minimal disturbance of the porous medium, and the infiltration time of a few small volumes of water repeatedly applied at the surface of the confined soil is measured. Calculating Kfs needs to determine the slope of the linearized cumulative infiltration vs. time relationship, the ring radius…

Testing alternative erosivity indices to predict event soil loss from bare plots in Southern Italy

Methods for predicting unit plot soil loss for the ‘Sparacia’ Sicilian (Southern Italy) site were developed using 316 simultaneous measurements of runoff and soil loss from individual bare plots varying in length from 11 to 44 m. The event unit plot soil loss was directly proportional to an erosivity index equal to (QREI30)1·47, being QREI30 the runoff ratio (QR) times the single storm erosion index (EI30). The developed relationship represents a modified version of the USLE-M, and therefore it was named USLE-MM. By the USLE-MM, a constant erodibility coefficient was deduced for plots of different lengths, suggesting that in this case the calculated erodibility factor is representative of a…

INFLUENCE OF PARTICLE-SIZE DISTRIBUTION MEASUREMENT METHOD ON THE PREDICTION OF SOIL WATER RETENTION CURVE

Application of the Arya and Paris (AP) model to estimate the soil water retention curve requires detailed particle-size distributions (PSD) that can be obtained by fitting a continuous model to traditional sieve-hydrometer (SH) data or using the laser diffraction (LD) method. The AP model was applied to 40 Sicilian soils for which PSD was measured by both SH and LD methods. The scale factor  was set equal to 1.38 (procedure AP1) or estimated by a logistic model with parameters gathered from literature (procedure AP2). To simplify application of the AP model, a relationship for estimating a soil-specific  value from clay content was developed (procedure OPT). For both SH and LD data, proce…

Theoretical prediction of rainfall intensity for a small rainfall simulator

In this contribution, a theoretical approach was developed for predicting rainfall intensity for a small rainfall simulator. The developed equation was tested for two different devices and different pressure head and water temperature values. The proposed relationship was found to have a good predictive ability of rainfall intensity. The proposed theoretical approach could be usable with other devices that operate on the same principles of the simulator considered in this investigation.

Beerkan Estimation of Soil Transfer parameters (BEST) across soils and scales

Abstract Theories and models used in soil hydrological sciences rely on the knowledge of the spatially and temporally variable soil hydraulic properties, i.e. the water retention and hydraulic conductivity curves. Obtaining reliable experimental information on these curves for an area of interest is not easy and it still remains a challenge for soil scientists. In 2006, a simple and physically based methodology was proposed to completely characterize the soil using a single ring infiltration experiment in the field and determination of soil particle size distribution, initial and final soil water content and dry soil bulk density. This methodology, named BEST – Beerkan Estimation of Soil Tr…

EFFETTI DELLA PENDENZA PARCELLARE SULLA PERDITA DI SUOLO STIMATA CON LA USLE-MM

La USLE-MM è un modello previsionale della perdita di suolo alla scala dell’evento erosivo che introduce il coefficiente di deflusso parcellare nel set di variabili indipendenti della USLE e consente la previsione di una perdita di suolo per unità di superficie non necessariamente crescente con la lunghezza della pendice. Tale circostanza, che la USLE non è in grado di riprodurre, è stata ampiamente riscontrata in letteratura e nell’area sperimentale di Sparacia. Il fattore climatico della USLE-MM è pari ad una potenza del prodotto del coefficiente di deflusso per l’indice di aggressività della pioggia di Wischmeier e Smith (1978). Il modello USLE–MM è stato originariamente dedotto facendo …

Testing assumptions and procedures to empirically predict bare plot soil loss in a Mediterranean environment

Empirical prediction of soil erosion has both scientific and practical importance. This investigation tested USLE and USLE-based procedures to predict bare plot soil loss at the Sparacia area, in Sicily. Event soil loss per unit area, Ae, did not vary appreciably with plot length, λ, because the decrease in runoff with λ was offset by an increase in sediment concentration. Slope steepness, s, had a positive effective on Ae, and this result was associated with a runoff coefficient that did not vary appreciably with s and a sediment concentration generally increasing with s. Plot steepness did not have a statistically detectable effect on the calculations of the soil erodibility factor of bot…

Manual packing and soil reuse effects on determination of saturated hydraulic conductivity of a loam soil

Abstract Performing laboratory measurement of saturated hydraulic conductivity, Ks, of sieved soil is important for many scientific purposes such as testing theories and methods to determine Ks. A given soil mass can be used only once or it can be reused after a previous use. Little is known on the dependence of the Ks measurements on both the applied packing method and the reuse of the same soil mass. This lack of knowledge makes comparisons among different investigations more or less uncertain. Four packing methods were tested on an initially dry loam soil by measuring Ks with the simplified falling head (SFH) technique. The four methods differed by the used compacting procedure (dropping…

Statistical check of USLE-M and USLE-MM to predict bare plot soil loss in two Italian environments

The USLE-M and the USLE-MM estimate event plot soil loss. In both models, the erosivity term is given by the runoff coefficient, QR, times the single-storm erosion index, EI30. In the USLE-MM, QREI30is raised to an exponent b1> 1 whereas b1= 1 is assumed in the USLE-M. Simple linear regression analysis can be applied to parameterize both models, but logarithmically transformed data have to be used for USLE-MM. Parameterizing the USLE-MM with nonlinear regression of untransformed data could be a more appropriate procedure. A statistical check of the two suggested models (USLE-M and USLE-MM), considering two alternative parameterization procedures for the USLE-MM, was carried out for the Mass…

Predicting event soil loss from bare plots at two Italian sites

Abstract Including runoff in USLE-type empirical models is expected to improve plot soil loss prediction at the event temporal scale and literature yields encouraging signs of the possibility to simply estimate runoff at these spatial and temporal scales. The objective of this paper was to develop an estimating procedure of event soil loss from bare plots (length = 11–44 m, slope steepness = 14.9–16.0%) at two Italian sites, i.e. Masse, in Umbria, and Sparacia, in Sicily, having a similar sand content (5–7%) but different silt (33% at Sparacia, 59% at Masse) and clay (62% and 34%, respectively) contents. A test of alternative erosivity indices for the Masse station showed that the best perf…

Applicazione della USLE-MM per la stima distribuita della produzione di sedimenti

Field and Numerical Tests of the Two-Ponding Depth Procedure for Analysis of Single-Ring Pressure Infiltrometer Data

Abstract The two-ponding depth (TPD) analysis procedure of single-ring infiltrometer data can yield invalid results, i.e., negative values of the field-saturated soil hydraulic conductivity or the matric flux potential, denoting failure of the two-level run. The objective of this study was to test the performance of the TPD procedure in analyzing the single-ring infiltrometer data of different types of soils. A field investigation carried out in western Sicily, Italy, yielded higher failure rates (40%) in two clay loam soils than in a sandy loam soil (25%). A similar result, i.e., fine-textured soils yielding higher failure rates than the coarse-textured one, was obtained using numerically …

Elementi di difesa dei versanti

USING A TRANSIENT INFILTROMETRIC TECHNIQUE FOR INTENSIVELY SAMPLING FIELD-SATURATED HYDRAULIC CONDUCTIVITY OF A CLAY SOIL IN TWO RUNOFF PLOTS

Point measurement of soil properties allows to explain and simulate plot scale hydrological processes. An intensive sampling was carried out at the surface of an unsaturated clay soil to measure, on two adjacent plots of 4×11 m2 and two different dates (May 2007 and February-March 2008), dry soil bulk density, rb, and antecedent soil water content, qi, at 88 points. Field-saturated soil hydraulic conductivity, Kfs, was also measured at 176 points by the transient Simplified Falling Head technique to determine the soil water permeability characteristics at the beginning of a possible rainfall event yielding measurable runoff. The rb values did not differ significantly between the two dates b…

Effetto della dimensione dell'anello sulla conducibilità idraulica del suolo saturo misurata con la tecnica SFH

Nel lavoro è stata esaminata la relazione tra la conducibilità idraulica del suolo saturo, Kfs, misurata in campo con la tecnica Simplified Falling Head (SFH) e la dimensione della superficie campionata con una singola prova. L’indagine è stata condotta in un suolo franco-sabbioso ed in uno franco-limoso, esplorando la medesima superficie complessiva (0.71 m2) con anelli di diametro compreso tra 0.15 e 0.30 m. Nel suolo franco-sabbioso, le misure di Kfs effettuate con gli anelli piccoli sono risultate significativamente più elevate di quelle ricavate con gli anelli grandi. In particolare, i valori medi hanno mostrato una discrepanza di un fattore 1.7 e il ricorso agli anelli piccoli ha dete…

Measuring the USLE soil erodibility factor in the unit plots of Sparacia (southern Italy) experimental area

The Universal Soil Loss Equation (USLE) is still widely used to predict soil loss by water erosion and to establish soil conservation measures. In this model, the soil erodibility factor K accounts for the susceptibility of the soil to be eroded due to the detachment and transport processes operated by the erosive agents. According to the USLE scheme, the K factor should be measured on unit plots, i.e., bare plots of given length (22 m) and steepness (9%) tilled along the maximum slope direction, but there is little evidence that there ever existed an actual unit plot between the plots used to develop the USLE. Given the difficulty in collecting sufficient data to adequately measure K, the …

A comparison between the single ring pressure infiltrometer and simplified falling head techniques

Testing the relative performances of the single ring pressure infiltrometer (PI) and simplified falling head (SFH) techniques to determine the field saturated soil hydraulic conductivity, Kfs, at the near point scale may help to better establish the usability of these techniques for interpreting and simulating hydrological processes. A sampling of 10 Sicilian sites showed that the measured Kfs was generally higher with the SFH technique than the PI one, with statistically significant differences by a factor varying from 3 to 192, depending on the site. A short experiment with the SFH technique yielded higher Kfs values because a longer experiment with the PI probably promoted short-term swe…

Determining hydraulic properties of a loam soil by alternative infiltrometer techniques

Testing infiltrometer techniques to determine soil hydraulic properties is necessary for specific soils. For a loam soil, the water retention and hydraulic conductivity predicted by the BEST (Beerkan Estimation of Soil Transfer parameters) procedure of soil hydraulic characterization was compared with data collected by more standard laboratory and field techniques. Six infiltrometer techniques were also compared in terms of saturated soil hydraulic conductivity, Ks. BEST yielded water retention values statistically similar to those obtained in the laboratory and Ks values practically coinciding with those determined in the field with the pressure infiltrometer (PI). The unsaturated soil hyd…

DETERMINING THE SATURATED HYDRAULIC CONDUCTVITY OF A LOAM SOIL WITH DIFFERENT INFILTROMETER TECHNIQUES

The saturated soil hydraulic conductivity, Ks, is one of the most important soil hydraulic properties since it controls many hydrological processes. This hydrodynamic parameter depends on soil texture and structure and it is very difficult to measure. Infiltrometer techniques are becoming very popular to determine Ks in the field but testing alternative approaches is necessary for specific soil types. For a loam soil, the estimated Ks values with six infiltrometer techniques were compared. The so-called BEST procedure of soil hydraulic characterization, the pressure infiltrometer (PI), single head experiments with both the tension infiltrometer (TI) and the mini disk infiltrometer (MDI), th…

Analysis of soil loss data from plots of differing length for the Sparacia experimental area, Sicily, Italy

Widely used models of the soil erosion process, such as the empirical universal soil loss equation (USLE) and revised USLE (RUSLE), suggest that soil loss, i.e. the mass of soil lost by water erosion per unit surface area, increases with slope length, λ, although contrasting experimental results may be found in the literature. Experiments were carried out at the Sparacia site, Sicily, to establish the influence of plot length on soil loss. This was tested using data characterised by a high number of replicated, bare plots of different lengths (0.25, 0.4, 1, 2, 5, 11, 22, 33 and 44 m), simultaneously operating in the 1999–2008 period. Event soil losses did not vary significantly with λ or ev…

Un nuovo modello distribuito per la stima della produzione di sedimenti

Estimating field-saturated soil hydraulic conductivity by a simplified Beerkan infiltration experiment

Field-saturated soil hydraulic conductivity, Kfs, is highly variable. Therefore, interpreting and simulating hydrological processes, such as rainfall excess generation, need a large number of Kfs data even at the plot scale. Simple and reasonably rapid experiments should be carried out in the field. In this investigation, a simple infiltration experiment with a ring inserted shortly into the soil and the estimation of the so-called a* parameter allowed to obtain an approximate measurement of Kfs. The theoretical approach was tested with reference to 149 sampling points established on Burundian soils. The estimated Kfs with the value of first approximation of a* for most agricultural field s…

Unsaturated Soil Hydraulic Properties

In the first part of this chapter, the tension infiltrometer (TI) technique is illustrated. After having described apparatus and instruments as well as the operative procedures in the field, the solutions based on the Wooding’s equation for steady-state flow are presented. Specific focus is given to the multi-potential approaches that allow determination of unsaturated soil hydraulic conductivity, K 0, corresponding to a sequence of pressure head values, h 0, imposed on the soil surface. The analytical model proposed by Haverkamp et al. (1994) to describe three-dimensional transient infiltration from a circular source is introduced and a single-test approach is presented that allows estimat…

Alternative analysis of transient infiltration experiment to estimate soil water repellency

The repellency index (RI) defined as the adjusted ratio between soil‐ethanol, Se, and soil‐water, Sw, sorptivities estimated from minidisk infiltrometer experiments has been used instead of the widely used water drop penetration time and molarity of ethanol drop tests to assess soil water repellency. However, sorptivity calculated by the usual early‐time infiltration equation may be overestimated as the effects of gravity and lateral capillary are neglected. With the aim to establish the best applicative procedure to assess RI, different approaches to estimate Se and Sw were compared that make use of both the early‐time infiltration equation (namely, the 1 min, S1, and the short‐time linear…

Monitoraggio della perdita di suolo a differenti scale spaziali nell'area di Sparacia

Misura della conducibilità idraulica del suolo saturo con i metodi del cubo

Cover and Management Factor for Sicilian Vineyard Systems

Using static and dynamic indicators to evaluate soil physical quality in a Sicilian area

Both capacitive indicators derived from the water retention curve and dynamic measurements of the flow-weighted mean pore radius, R0, were used to assess the soil physical quality of two agricultural areas (cropland and olive orchard) and two natural areas (grassland and managed woodlot plantation) potentially subject to soil degradation. The overall idea of the study was to investigate whether a dynamic indicator quantitatively derived from hydraulic conductivity measurements could be used to supplement the traditionally applied capacitive indicators retrieved from water retention measurements. According to the available criteria, only the surface layer of the cropland site showed optimal …

Impact of reforestations with exotic and native species on water repellency of forest soils

Forest duff layer is usually water repellent due to the hydrophobic organic compounds resulting from degradation of tree tissues. Transition from hydrophobic to wettable conditions, or vice versa, is largely controlled by water content. The objective of this investigation was to assess the influence of soil moisture on the degree of soil water repellency (WR) in exotic and native tree forests. Occurrence of WR was investigated by the water drop penetration time (WDPT) and the ethanol percentage (EP) tests. Sampling was conducted in the forest soils of two exotic species (Pinus pinaster, P, and Eucaliptus camaldulensis, E), used in the past for reforestation, and two native species (Quercus …

Verifica della USLE-MM per il bacino sperimentale SPA2 in Sicilia

An evaluation of the single-test tension infiltrometer method for determining the hydraulic conductivity of lateral capillary domain soils

Ring diameter effects on determination of field-saturated hydraulic conductivity of different loam soils

Abstract Establishing ring diameter effects on the field-saturated soil hydraulic conductivity, Kfs, determined with ponding infiltrometer methods can help to find a compromise between the need to sample a large area with an individual measurement and the impracticality of using large rings in the field. Five ring sizes (diameter, D = 5.5, 10.9, 16.0, 27.8 and 31.8 cm) were used to determine Kfs by the simplified falling head (SFH) technique in four loamy soils with different salinity (electrical conductivity of saturated extract, ECe = 0.9–29.4 dS/m) and sodicity (exchangeable sodium percentage, ESP = 2.7–81.3%) levels. According to USDA classification, two soils were non-saline, non-sodic…

BEST-2K Method for Characterizing Dual-Permeability Unsaturated Soils with Ponded and Tension Infiltrometers

This study presents a new method (BEST-2K) that extends the existing BEST methods for use in characterizing the water retention and hydraulic conductivity functions of matrix and fast-flow regions in dual-permeability soils. BEST-2K requires input information from two water infiltration experiments that are performed under ponded (Beerkan) and unsaturated (tension infiltrometer) conditions at the surface. Other required inputs include water content measurements and the traditional BEST inputs (particle size distribution and bulk density). In this study, first, a flowchart of the BEST-2K method was developed and illustrated with analytically generated data for a synthetic dual-permeability s…

Testing a Simplified Approach to Determine Field Saturated Soil Hydraulic Conductivity

Abstract Interpreting and simulating hydrological processes need a large number of field saturated soil hydraulic conductivity, Kfs , data that should be collected with simple and rapid field experiments. A Simplified method based on a Beerkan Infiltration run (SBI method) was recently developed and tested successfully on Burundian soils. With the SBI method, a cylinder is inserted to a short depth into the soil and the infiltration time of a few small volumes of water repeatedly applied at the surface of the confined soil is measured. Calculating Kfs needs the slope of the linearized cumulative infiltration vs. time relationship and an estimate of the so called α* parameter. In this invest…

Assessing changes in rainfall erosivity in Sicily during the twentieth century

Changes in rainfall erosivity are an expected consequence of climate change. Long-term series of the single storm erosion index, EI, may be analysed to detect trends in rainfall erosivity. An indirect approach has to be applied for estimating EI, given that long series of rainfall intensities are seldom available. In this paper, a method for estimating EI from the corresponding rainfall amount, he, was developed for Sicily. This method was then applied at 17 Sicilian locations, representative of different climatic zones of the region, to generate a long series (i.e. from 1916 to 1999 in most cases) of EI values. Linear and step (step located at 1970) trends in annual and seasonal erosivity …

Agro-meteorological characteristics and soil properties in the Ruyigi area, Burundi

Comparison of 1D and 3D hydraulic conductivity measured by the concentric-disk tension infiltrometer.

Measurement of Water Soil Erosion at Sparacia Experimental Area (Southern Italy): A Summary of More than Twenty Years of Scientific Activity

The main purpose of this article is to give a general idea of the scientific activity that was carried out starting from the 2000s on the basis of the data collected in the plots installed at the Sparacia experimental station for soil erosion measurement in Sicily, South Italy. The paper includes a presentation of the experimental site, a description of the methods and procedures for measuring soil erosion processes both available in the literature and applied at the Sparacia station (sediment sampling and water level reading in the storage tanks for total erosion measurements; profilometer, and Structure from Motion technique for rill erosion measurements), and the main results obtained in…

Influenza della tecnica di misura della distribuzione granulometrica sulla stima della curva di ritenzione idrica del suolo

Le distribuzioni granulometriche ottenute sia con il tradizionale metodo per stacciatura-sedimentazione (SH) che con il metodo della diffrattometria laser (LD) sono state utilizzate per determinare le curve di ritenzione idrica di 40 suoli siciliani attraverso modello di Arya e Paris (AP). La curve di ritenzione idrica determinate con il metodo SH sono risultate più accurate di quelle ottenute dal metodo LD. Fra le differenti procedure applicative utilizzate, i risultati migliori si sono ottenuti utilizzando per ciascun suolo un valore del parametro  determinato attraverso una procedura di ottimizzazione. Infine, è stata proposta una relazione tra il parametro  e il contenuto in argilla c…

Elementi di Idrologia del Suolo

Contenuto idrico del suolo, Potenziale dell'acqua nel suolo, Moto della acqua nel suolo

5. Qualità Fisica del Suolo

assente - capitolo di libro

Confronto della perdita di suolo da parcelle di differente lunghezza nell'area di Sparacia