Evaluation of SWAT model - subdaily runoff prediction in Texas watersheds

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Title: Evaluation of SWAT model - subdaily runoff prediction in Texas watersheds
Author: Palanisamy, Bakkiyalakshmi
Abstract: Spatial variability of rainfall is a significant factor in hydrologic and water quality modeling . In recent years , characterizing and analyzing the effect of spatial variability of rainfall in hydrologic applications has become vital with the advent of remotely sensed precipitation estimates that have high spatial resolution . In this study , the effect of spatial variability of rainfall in hourly runoff generation was analyzed using the Soil and Water Assessment Tool (SWAT ) for Big Sandy Creek and Walnut Creek Watersheds in North Central Texas . The area of the study catchments was 808 km2 and 196 km2 for Big Sandy Creek and Walnut Creek Watersheds respectively . Hourly rainfall measurements obtained from raingauges and weather radars were used to estimate runoff for the years 1999 to 2003 . Results from the study indicated that generated runoff from SWAT showed enormous volume bias when compared against observed runoff . The magnitude of bias increased as the area of the watershed increased and the spatial variability of rainfall diminished . Regardless of high spatial variability , rainfall estimates from weather radars resulted in increased volume of simulated runoff . Therefore , weather radar estimates were corrected for various systematic , range -dependent biases using three different interpolation methods : Inverse Distance Weighting (IDW ) , Spline , and Thiessen polygon . Runoff simulated using these bias adjusted radar rainfall estimates showed less volume bias compared to simulations using uncorrected radar rainfall . In addition to spatial variability of rainfall , SWAT model structures , such as overland flow , groundwater flow routing , and hourly evapotranspiration distribution , played vital roles in the accuracy of simulated runoff .
URI: http : / /hdl .handle .net /1969 .1 /5921
Date: 2007-09-17

Citation

Evaluation of SWAT model - subdaily runoff prediction in Texas watersheds. Available electronically from http : / /hdl .handle .net /1969 .1 /5921 .

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