Abstract:Fourteen popular, representative infiltration models, some physically based, some semi-empirical and some empirical, were selected for a comparative evaluation. Using the Nash and Sutcliffe efficiency criterion, the models were evaluated and compared for 243 sets of infiltration data collected from field and laboratory tests conducted in India and the USA on soils ranging from coarse sand to fine clay. Based on a relative grading scale, the semi-empirical Singh-Yu general model, Holtan model and Horton model were graded respectively as 6Ð52, 5Ð57 and 5Ð48 out of 10. The empirical Huggins and Monke model, modified Kostiakov and Kostiakov model were graded as 5Ð57, 5Ð30 and 5Ð22, respectively. The physically based non-linear and linear models of Smith-Parlange were graded as 5Ð48 and 5Ð22, respectively. Other models were ranked lower than these models. All the models generally performed poorly in field tests on Georgia's sandy soils, except the Robertsdale loamy sand.
Watershed is considered to be the ideal unit for management of the natural resources. Extraction of water-shed parameters using Remote Sensing and Geographical Information System (GIS) and use of mathematical models is the current trend for hydrologic evaluation of watersheds. The Soil and Water Assessment Tool (SWAT) having an interface with ArcView GIS software (AVSWAT2000/X) was selected for the estimation of runoff and sediment yield from an area of Suni to Kasol, an intermediate watershed of Satluj river, located in Western Himalayan region. The model was calibrated for the years 1993 & 1994 and validated with the observed runoff and sediment yield for the years 1995, 1996 and 1997. The performance of the model was evaluated using statistical and graphical methods to assess the capability of the model in simulating the run-off and sediment yield from the study area. The coefficient of determination (R2) for the daily and monthly runoff was obtained as 0.53 and 0.90 respectively for the calibration period and 0.33 and 0.62 respectively for the validation period. The R2 value in estimating the daily and monthly sediment yield during calibration was computed as 0.33 and 0.38 respectively. The R2 for daily and monthly sediment yield values for 1995 to 1997 was observed to be 0.26 and 0.47
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