RUNOFF AND SEDIMENT MODELING USING SWAT IN GUMERA CATCHMENT, ETHIOPIA

Abstract

The purpose of the study was to examine the applicability of the SWAT model on Gumera river basin upstream of Lake Tana, Ethiopia (area,1600 km2), for simulating and predicting Runoff and sediment yield. The Gumera river basin was discretized into 24 smaller sub-basins. Arc SWAT interface is used for geo-processing of the data. The semi automated [SUF12] and fully automated [ParaSol] calibration process built in SWAT-CUP programming were used to calibrate the model parameters using time series data of 1994 to 2002 and validated with the observed runoff and sediment yield from years 2003 to 2006. The performance of the model was evaluated using statistical and graphical methods to assess the capability of the model in simulating the runoff and sediment yield for the study area. The coefficient of determination (112) for the daily and monthly runoff was obtained as 0.72 by using (paraSol) and 0.83 in (SUFI2) respectively for the calibration period and 0.79 (parasol) and 0.93 (SUFI2) respectively for the given validation period. The R2 and NS coefficient for estimating the monthly sediment yield during nine years calibration period was computed as 0.61 and 0.60 respectively, for model validation of sediment the value of R2 and NS was 0.84 and 0.83 respectively and finally prediction of Runoff is done near Gumera dam site and at the inlet of Lake Tana.