Search results for " sistemazioni idraulico-forestali"
showing 10 items of 760 documents
Improved Beerkan run methodology to assess water impact effects on infiltration and hydraulic properties of a loam soil under conventional- and no-ti…
2021
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…
Determining Probability Distribution of Hillslope Peak Discharge by Using an Analytical Solution of Kinematic Wave Time of Concentration.
2016
Hillslope hydrology is fundamental for understanding the flood phenomenon and for evaluating the time of concentration. The latter is a key variable for predicting peak discharge at the basin outlet and for designing urban infrastructure facilities. There have been a multitude of studies on the hydrologic response at the hillslope scale, and the time of concentration has been derived for different approaches. One approach for deriving hillslope response utilizes, in a distributed form, the differential equations of unsteady overland flow, specifically developed at the hydrodynamic scale, in order to account for the spatial heterogeneity of soil characteristics, topography, roughness and veg…
A time domain triangle method approach to estimate actual evapotranspiration: Application in a Mediterranean region using MODIS and MSG-SEVIRI produc…
2016
Abstract In this study, spatially distributed estimates of regional actual evapotranspiration (ET) were obtained using a revised procedure of the so called “triangle method” to parameterize the Priestley–Taylor ϕ coefficient. In the procedure herein proposed, named Time-Domain Triangle Method (TDTM), the triangular feature space was parameterized considering pairs of T s –VI values obtained by exploring, for each pixel, only their temporal dynamics. This new method was developed using time series products provided by MODIS and MSG-SEVIRI sensors. Moreover the proposed procedure does not depend on ancillary data, and it is only based on remotely sensed vegetation indices and day–night time l…
Portable central baffle flume
2022
This paper investigated the hydraulic characteristics of the triangular central baffle (TCB) flume. Laboratory tests were carried out to determine the flume dimensions. The field applicability of the proposed portable device was examined by on-farm installation. According to the laboratory tests, when the contraction ratio, r, was less than 0.39, the flow capacity was not affected by the ratio between the flume’s floor height and the throat width. The laboratory analysis also showed that there was no significant effect of installing an entrance ramp on the stage-discharge relationship for r<0.39, while the entrance ramp increased the discharge capacity for r>0.39. The stage-discharge …
Plot rill erosion measurements by close-range photogrammetry using natural events at Sparacia experimental area
2018
Recently, many investigations were carried out in order to check the applicability of both close-range and UAV (Unmanned Aerial Vehicle) photogrammetry to measure soil erosion processes. For measuring rill erosion occurring on a 22 m long and 26% sloped plot occurred on 24 October 2016 at the Sparacia experimental area, a terrestrial photographic relief and a low altitude aerial relief were carried out by no-professional quadricopter and camera. The three-dimensional (3D) DTM and the quasi-tridimensional (DEM) models were obtained. An extraction method of the rill network using DEM and convergence index was applied and a subsequent separation of rills into contributing and non-contributing …
CALIBRAZIONE DI MODELLI USLE-DERIVATI MEDIANTE I MASSIMI ANNUALI DELLA PERDITA DI SUOLO PER EVENTO
2016
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…
EFFETTI DELLA PENDENZA PARCELLARE SULLA PERDITA DI SUOLO STIMATA CON LA USLE-MM
2015
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 …
DEDUZIONE DEL FATTORE L DELLA USLE-MM NELLE PARCELLE SPERIMENTALI DI SPARACIA, IN SICILIA
2010
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…
A comprehensive analysis of Universal Soil Loss Equation-based models at the Sparacia experimental area
2020
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…
Estimating rainfall erosivity by aggregated drop size distributions
2016
Rainfall erosivity is defined as the potential of the rain to cause erosion, and it can be represented by rainfall kinetic power. At first in this paper, the raindrop size distributions (DSD) measured by an optical disdrometer located at Palermo in the period June 2006–March 2014 and aggregated for intensity classes, are presented. Then an analysis of raindrop size characteristics is carried out, and the reliability of Ulbrich's distribution, using both the maximum likelihood and momentum estimate parameter methods, is tested. The raindrop size measurements are used to determine the experimental rainfall kinetic power values, which are compared with the ones calculated by a theoretically de…