Prediction of soil texture distributions using VNIR-SWIR reflectance spectroscopy

Abstract Reflectance spectroscopy provides an alternate method to non-destructively characterize key soil properties. Different approaches, including chemometrics techniques or specific absorption features, have been proposed to estimate soil properties from visible and near-infrared (VNIR, 400-1200 nm) and shortwave infrared (SWIR, 1200-2500 nm) reflectance domains. The main goal of this study was to test the performance of two distinct methods for soil texture estimation by VNIR-SWIR reflectance measurements: i) the Continuum Removal (CR) technique that was used to correlate specific spectral absorption features with clay, silt and sand content, and ii) the Partial Least-Squares Regressio…

Valutazione del Deflusso superficiale con il Metodo CN-NRCS

Sono descritti i lineamenti del metodo CN-NRCS introdotto negli anni 50. La diffusione del metodo soprattutto nel campo applicativo e professionale va attribuita alla semplicità della formulazione ed all’essenzialità del modello descritto dal solo parametro CN deducibile da tabelle estese e complete. Alla disamina della struttura del modello e dei suoi parametri segue una estesa descrizione dei metodi di taratura del parametro CN a scala di bacino. Sono quindi riportati i risultati della taratura di un campione di 61 bacini siciliani di cui si dispongono serie consistenti di piogge e contemporanee portate giornaliere. Infine sono proposte alcune applicazioni esemplificative del metodo e ven…

RUNOFF CURVE NUMBER METHOD IN SICILY: CN DETERMINATION AND ANALYSIS OF THE INITIAL ABSTRACTION RATIO

The Curve Number method is widely used in hydrology because it’s simply based on a single parameter, CN, that represents the basin absorption. In this paper CN is evaluated at basin scale from rainfall-runoff multi-daily events (Mockus, 1964), in the observation period 1940-1997 (record length mean equal to 20 years), for 61 Sicilian basin with three different methods: NEH4 method, Asymptotic fitting method (Hawkins, 1990, Hawkins et al., 2002, Hawkins et al., 2009), Least squares method (Woodward et al., 2006, Hawkins et al., 2009). A first analysis of Sicilian watershed behavior indicates a major occurrence of standard CN response (42 basins), rather than complacent response (11 basins) a…

Caratterizzazione idrologica dei bacini siciliani col metodo del Curve Number

Analisi preliminare per la caratterizzazione idrologica del bacino dell'Alcantara secondo il modello CN-NRCS

Scaling properties of topologically random channel networks

Abstract The analysis deals with the scaling properties of infinite topologically random channel networks (ITRNs) fast introduced by Shreve (1967, J. Geol. , 75: 179–186) to model the branching structure of rivers as a random process. The expected configuration of ITRNs displays scaling behaviour only asymptotically, when the ruler (or ‘yardstick’) length is reduced to a very small extent. The random model can also reproduce scaling behaviour at larger ruler lengths if network magnitude and diameter are functionally related according to a reported deterministic rule. This indicates that subsets of rrRNs can be scaling and, although rrRNs are asymptotically plane-filling due to the law of la…

Brevi considerazioni su piogge intense e potenzialità di produzione del deflusso superficiale in Sicilia

Vengono presentati i metodi aggiornati per la stima delle precipitazioni intense massime annue di fissato tempo di ritorno in Sicilia. Dall‟osservazione della distribuzione spaziale dei parametri assunti nei modelli di stima emergono aree a maggior rischio riguardo l‟intensità di pioggia, qui commentate. Il richiamo a recenti studi che riguardano la produzione del deflusso superficiale a scala media annua o a scala di evento, consente di avanzare alcune considerazioni di tipo spaziale, con particolare attenzione all‟area del messinese, su questa importante propensione idrologica notoriamente fonte di dissesto idrogeologico e di pericolo alluvionale. The updated methods for the estimation of…

Variabilità delle serie storiche di temperatura e precipitazione in Sicilia

A regional analysis of longer time series of temperature and rainfall, in Sicily, was performed. Trends and rainfall-temperature correlation was investigated, finding tipical droughty behaviour.

Sulla possibilità di estendere l'informazione climatica del passato attraverso le serie dendrocronologiche

E’ noto che, a parte alcune eccezioni, la misura sistematica delle variabili meteorologiche in Italia ha avuto inizio a metà del XIX secolo. Non diversamente, in Sicilia si dispone di un numero limitato di serie storiche pluviometriche di consistenza pari a 100-120 anni e termometriche di 60-70 anni. L’obiettivo di una più approfondita conoscenza del clima passato, in Sicilia, può essere perseguito estendendo alcune serie storiche climatiche disponibili, mediante la dendroclimatologia, scienza che permette, attraverso l’analisi degli anelli annuali di accrescimento degli alberi, di legare l’entità di tale accrescimento alle cause che lo hanno generato e, in particolare, alle condizioni clim…

STIMA DELLA RADIAZIONE SOLARE GIORNALIERA IN SICILIA MEDIANTE I DATI DI TEMPERATURA MASSIMA E MINIMA

Effetto di opere di sistemazione filtranti sulla qualità delle acque fluviali

Curve Number: Empirical Evaluation and Comparison with Curve Number Handbook Tables in Sicily

The curve number (CN) method is widely used for estimating direct runoff depth from rainstorms. The procedure is on the basis of the parameter CN, a lumped expression of basin absorption and runoff potential, and a second parameter, initial abstraction (IA), which represents the interception, infiltration, and surface depression during the early part of a storm. The evaluation of CN in Sicily at a basin scale from rainfall-runoff multiday events is done using rainfall-runoff observations during the period 1940–1997 (mean record length of 20 years) in 61 Sicilian watersheds using three different methods: (1) the national engineering handbook, section 4 hydrology (NEH4) method (NEH4M) (the me…

Discussion of "Analysis of extreme rainfall trends in sicily for the evaluation of depth-duration-frequency curves in climate change scenarios" by Lorena Liuzzo and Gabriele Freni

In the original paper, the Authors investigated the presence of trends in extreme rainfall depths of duration d = 1, 3, 6, 12 and 24 hours, in Sicily. Trend analysis was performed by using the Mann-Kendal non-parametric test, which was applied at-site, for a number of 65 raingauges well distributed in the region, for the period 1950-2008. In order to overcome the gap of missing data, six years moving average series were considered in the Author’s analysis. In this discussion, the discussers highlighted some important observations about the paper presented by the Authors: i) The Authors applied the non-parametric Mann Kendall test to moving average series of rainfall data. The use of moving …

Empirical determination of the average annual runoff coefficient in the Mediterranean area

Runoff estimation in ungauged basin is a challenge for the hydrological engineers and planners. For an y hydrological study on an ungauged basin, a methodology has to be appropriately selected for the determination of runoff at its outlet. Several meth ods have been used to estimate the basin runoff production. In this study the empirical Kennessey m ethod to determine average annual runoff coefficien t, RC, is tested on 61 Sicilian basins characterized b y different climate conditions, surface permeabilit y, mean slope and vegetation cover. A comparison between observed and calculated RC showed that a calibration of the Kennessey model could be necessary. The slight and not satisfying impr…

Empirical Investigation of Curve Number Method Parameters in the Mediterranean Area

AbstractThe curve number (CN) method is widely used as a technique for estimating surface runoff depth from rainstorms. This simply lumped method is based on the main parameter CN, which represents the lumped expression of basin absorption, and on a parameter that represents interception, infiltration during the early part of a storm, and surface depression storage, called initial abstraction. In this paper, CN is evaluated at the basin scale from rainfall-runoff multiday events, in the observation period 1940–1997 (recorded length mean equal to 20 years) for 61 Sicilian basins with three different methods: NEH4 method, asymptotic fitting method, and a least-squares method. A first analysis…

River Conservation and Phytodepuration in a Mid-Mediterranean Streambed: A Sicilian Case Study

AbstractFor landslide mitigation purposes, a system of two screen dams was created along the main channel of the Capreria River in Sicily. The de facto constructed wetlands occasioned behind the flow-path barriers produced, for several years, an appreciable reduction of organic load of the upstream municipal wastewaters from the nearby town of Riesi, Italy. This coincidence inspires the prospect of promoting a multifunctional role for these slope-stabilization works, thereby allowing them to be viewed from an intriguing and innovative planning perspective.

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…

Analisi della tendenza climatica dell'evapotraspirazione nel territorio siciliano

Long effective evapotranspiration (E) series was derived from the longest temperature series available in Sicily. The regional trend analysis performed has shown a slight upward trend of E.

Studio preliminare e piano di recupero dei laghi Laudemio e Zapano

Analisi regionale delle variazioni a lungo termine di grandezze climatiche in Sicilia

Estimation of Daily Solar Radiation from Measured Air Temperature Extremes in the Mid-Mediterranean Area

AbstractDaily solar radiation Rs at ground level is a necessary input variable required for the evaluation of evapotranspiration and crop growth, development, and yield-simulation models. Nevertheless, it is measured in few weather stations and at many locations it is not observed; also, available Rs temporal series are generally no longer than a few years. A valid surrogate of Rs measurement is the diurnal air-temperature range (ΔT); indeed, ΔT is inversely proportional to cloudiness and therefore could be a good indicator of atmospheric transmittance. As opposed to Rs, daily maximum and minimum air temperatures are measured at many locations and their observations in developed countries b…

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 (…

CONFRONTO TRA DATI DI TEMPERATURA RILEVATI IN AREE URBANE E IN AREE AGRICOLE LIMITROFE

Il fenomeno noto come “isola di calore urbana” (Urban Heat Island, UHI), che riguarda prevalentemente i paesi più industrializzati, consiste nell’aumento della temperatura dell’aria nei centri abitati per effetto dell’urbanizzazione. La verifica di tale fenomeno è stata eseguita in Sicilia instaurando un confronto tra le temperature massime, minime e le escursioni termiche di coppie di stazioni di misura, poste rispettivamente all’interno e all’esterno di alcuni centri urbani minori nel periodo 2002-2005. L’analisi è stata sviluppata a scala annuale e semestrale (separando la stagione tipicamente secca, da Aprile a Settembre, da quella umida), in modo da rilevare in quali periodi dell’anno …

DISCUSSION “Curve Number Derivation for Watersheds Draining Two Headwater Streams in Lower Coastal Plain South Carolina, USA” by Thomas H. Epps, Daniel R. Hitchcock, Anand D. Jayakaran, Drake R. Loflin, Thomas M. Williams, and Devendra M. Amatya

Epps et al. (2013) derived Curve Number (CN) values for two forested headwater watersheds in the Lower Coastal Plain of South Carolina during the 2008-2011 period from rainfall-runoff data, resulting in 23 events for the Upper Debidue Creek (UDC) watershed and in 20 events for Watershed 80 (WS80). D’Asaro and Grillone analyzed the P, CN data of the UDC watershed finding an evident “complacent” behavior, characterized by a declining CN with increasing P but without approaching a stable value at large storms. In this case, the traditional runoff CN equation does not fit well with the rainfall-runoff data that indicate a partial source area watershed behavior and are more aptly modeled by the …

A “Case Study” for the Estimation of Daily Solar Radiation from Measured Air Temperature Extremes in the Mid-Mediterranean Area

Una metodologia probabilistica semplificata di riproduzione del ruscellamento superficiale sul versante: possibili riscontri applicativi

Il lavoro presenta un modello semplificato per la riproduzione del reticolo di ruscellamento superficiale sul versante. Il modello richiede solo due parametri, il primo è legato alla capacità di produzione del deflusso del versante, nella condizione iniziale del processo, il secondo dipende dal grado di divagazione del reticolo. Tali parametri, in chiave idrologica, danno conto degli effetti che principalmente influenzano la risposta idrologica del versante: l’intensità di pioggia, la macroscabrezza e la pendenza del versante stesso. L’attendibilità del modello richiede, ovviamente, una validazione sperimentale che al momento è stata solo avviata.

Gravity-Driven Infiltration and Subsidence Phenomena in Posidonia oceanica Residues

A simplified infiltration model for highly permeable porous media was introduced, assuming the matric potential gradient as negligible compared to the gravitational gradient. This model enabled us to determine the delay time, i.e., the time that the water front takes (from the beginning of rainfall) to reach the bottom of the highly permeable layer. Posidonia oceanica (Linnaeus) Delile residues were used as a porous media, in order to study the infiltration process that provides salt leaching under natural rainfall when these residues are arranged in a storage area, before reusing. By using a laboratory rainfall simulator, delay times were measured to verify the applicability of the aforeme…

Stima della radiazione solare giornaliera in sicilia mediante i dati di temperatura massima e minima

By using thermometric data series from 36 sicilian stations , the authors use different relationship for indirect determination of daily solar radiation. The best performance was given by Hargreaves-Samani formula which is then parameterized by the authors for the investigated region.

Durum wheat yield uncertainty under different tillage management practices and climatic conditions

Abstract In the field of conservative agriculture, no-till (NT) management has been receiving increasing interest, with 45 million ha of land under no-till management in 1999 to 155 million ha in 2014. Up until now, no-till has only been observed to perform better under rainfed conditions, especially in dry climates mainly because the reduced tillage system retains more soil moisture. However, the adoption of alternative agricultural practices (NT) can be improved only if uncertain and consequent assumption of risk is well known and accepted. For these reasons, the aim of this research is (i) to define durum wheat suitability under NT soil management in terms of yield success probability an…

Curve Numbers Seasonal Variation in Mid-Mediterranean Area

AbstractThe curve number (CN) method is a popular technique for estimating a rainstorm event’s direct runoff (Q from its storm depth P). It relies on the parameter CN, a lumped expression of a wate...

Monitoraggio del contenuto idrico del suolo in un versante calanchivo in Sicilia

Analisi regionale delle piogge intense in Sicilia

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…

Distribuzione di probabilità della portata di piena a scala di versante generata da deflusso hortoniano

Biotechnical characteristics of root systems in erect and prostrate habit rosmarinus officinalis L. accessions grown in a mediterranean climate

Rosmarinus officinalis L. is a shrub species typically found in the Mediterranean Basin area. Studies carried out in Sicily on the biodiversity of the genus Rosmarinus found only one species (Rosmarinus officinalis L.) with varying morphology (erect habit and prostrate habit). The species does not require high input, managing to thrive even in marginal areas, and is a medicinal and aromatic species of great agronomic and economic interest, being one of the top 20 species most-used in Italy and with highest wholesale revenues. Studies carried out on the species in Italy are recent, as is the whole medicinal and aromatic plants sector, and have mostly regarded agrotechniques. This study shows…

Standard Asymptotic Response and Expected Runoff from Curve Number Theory

The Standard Asymptotic response is a common finding with rainfall-runoff analysis with the Curve Number method. Widely-observed in data analyses, it is the secondary relationship between the data-defined CN and the causative rainfall P, for which the empirical fitting equation CN(P) = CN∞+ (100-CN∞)exp(-kP) has been found to fit well. This is an unexpected variation in the handbook methodology. It is investigated here on a “theoretical” basis by using the handbook tabled values of CN for the three AMC classes, I, II, and III; the storm-to-storm S (=1000/CN-10); and the observed 12-50-88 percent conditional probabilities for the ARC classes. With this, and treating S as a variable across th…

Parametrizzazione del metodo del Curve Number per i bacini siciliani

Idrosemina Naturalistica

Le applicazioni di idrosemina generalmente tendono a ricostituire un adeguato livello di copertura vegetale, per migliorare l’efficacia contro fenomeni erosivi e di instabilità dei versanti, ma spesso trascurano l’aspetto naturalistico. Si utilizzano cioè miscele di specie erbacee che spesso pongono scarsa attenzione all’ecologia del sito di intervento. All’approccio tecnico occorre quindi affiancare quello naturalistico, che, dal contesto vegetazionale, scarti le specie alloctone e condizioni la scelta delle specie erbacee da utilizzare. Il caso studio della discarica di Termini Imerese (Palermo), prevedeva un ricoprimento vegetale di 7,4 ha mediante idrosemina direttamente sul terreno di …

Simplified Probabilistic-Topologic Model for Reproducing Hillslope Rill Network Surface Runoff

AbstractThis work presents a simplified probabilistic-topologic model for reproducing rill network surface runoff on a square-plane hillslope. The model requires only two parameters: the first is related to the production capacity of overland flow of the hillslope, at the initial conditions of the process, and the second depends on the sinuosity of the rill network. From a hydrological point of view, the following parameters account for the effects that essentially delineate the hydrologic response of a natural hillslope: rainfall intensity, hillslope roughness, and slope. Obviously, the reliability of the model is pending experimental validation that has only just begun. However, a prelimi…

Thermal inertia modeling for soil surface water content estimation: A laboratory experiment

We are proposing a new method for estimating soil surface water content from thermal inertia distributions retrieved from visible–near infrared (VISNIR)and thermal infrared (TIR) images. A drying experiment was conducted on three fi ne-textured soils while acquiring multispectral VIS-NIR and TIR images. Simultaneous measurements of soil water content and thermal inertia were conducted by the thermogravimetric method and the heat pulse technique, respectively. Direct measurements were used to test the thermal inertia approach proposed by Murray and Verhoef that requires only knowledge of soil porosity and can be easily inverted to derive soil water content from thermal inertia. For the three…

Probability distribution of peak discharge at hillslope scale derived by an eco-hydrological approach

UTILIZZO DELLA TERMOGRAFIA DI LABORATORIO PER LA STIMA DEL CONTENUTO IDRICO DEL SUOLO

INDAGINE ECOIDROLOGICA SU UN VERSANTE CALANCHIVO IN SICILIA

Derivation of slope factor S of the USLE at basin scale by geomorphological approach

Empirical methods to determine average annual runoff coefficient in Sicilian basins

STIMA SPEDITIVA DELL'EROSIONE IDRICA CON MODELLO USLE A SCALA DI BACINO

Viene proposto uno schema applicativo della formula universale di Wichemeier, a scala di bacino, per la stima della perdita specifica di suolo. In tale approccio, i fattori USLE a scala di bacino, sono dei parametri concentrati che esprimono il modo complessivo con cui il bacino risponde alle sollecitazioni erosive. Nel modello proposto, il fattore di pendenza viene ricavato per generazione di uno schema topologico 3D, semplificato, della rete idrografica. Per i fattori colturale (C ) e di erodibilità dei suoli (K), viene ipotizzato che all’interno del bacino siano sempre presenti tutti i valori possibili di C o di K e che il fattore a scala di bacino coincida con il valor medio delle distr…

Applicazione di tecniche di regionalizzazione alle portate al colmo di piena siciliane

Probability Distribution of Peak Discharge at the Hillslope Scale Generated by Hortonian Runoff

In this work, the probability distribution of peak discharge at the hillslope bottom is determined hypothesizing a prevalent Hortonian mechanism of runoff production for a given rainfall duration. As is well known, the probability distribution of peak discharge depends on the probability of both the rainfall event as well as that of the antecedent soil moisture conditions. In particular, the probability of the rainfall event is calculated according to the familiar rainfall duration-intensity-frequency approach, whereas the ecohydrological method from the literature is used here to define the probability of the antecedent soil moisture conditions. The latter depends on a set of parameters de…

REGIONAL FREQUENCY ANALYSIS FOR EXTREME RAINFALL IN SICILY

POSSIBILI MODIFICAZIONI DELLE COMPONENTI DEL BILANCIO IDROLOGICO INDOTTE DALLE VARIAZIONI CLIMATICHE

Confronto tra dati di temperatura rilevati in aree urbane e in aree agricole limitrofe

The Urban Heat Island phenomenon (UHI) was investigated in Sicilian region. On the basis of a temperature data pairs detected in a sample of urban and corresponding countryside, analysis was developed. The first results show the present of UHI effect.

Informazione agro-idrologica per l'ottimizzazione dell'irrigazione

Un modello di inerzia termica per la stima del contenuto idrico del suolo da immagini termiche e multispettrali

A thermal inertia model for soil water content retrieval using thermal and multispectral images

Soil moisture is difficult to quantify because of its high spatial variability. Consequently, great efforts have been undertaken by the research community to develop practical remote sensing approaches to estimate the spatial distribution of surface soil moisture over large areas and with high spatial detail. Many methodologies have been developed using remote sensing data acquiring information in different parts of the electromagnetic spectrum. Conventional field measurement techniques (including gravimetric and time-domain reflectometry) are point-based, involve on-site operators, are time expensive and, in any case, do not provide exhaustive information on the spatial distribution of soi…

Primo contributo all'estensione di alcune serie climatiche siciliane mediante analisi di serie dendrocronologiche

Comparison between Curve Number empirical values and Curve Number obtained by handbook tables at basin scale in Sicily, Italy

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 …