Application of SWAT Model for Mountainous Catchment
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Date
2007
Journal Title
Journal ISSN
Volume Title
Publisher
FWU Water Resources Publications
Abstract
A GIS based hydrologic model, SWAT (Soil and Water Assessment Tool) was applied for
modeling the WeruWeru catchment at the foot slopes of Mt. Kilimanjaro in Northern Tanzania.
The catchment has an approximate drainage area of 101 km2
and a mean annual precipitation
between 1500mm and 3000mm. The water balance modeling was performed on annual and
monthly bases using spatial and temporal data.
A statistical weather generator file WXGEN was prepared for ten years to generate climatic data
and fill in gaps in the measured records of climatic data. Various GIS data preprocessor modules
involving watershed delineation, input map characterization and processing, stream and outlet
definition, the computation of the geomorphic parameters, and characterization of the
landuse/land cover and soil were developed in the course of modeling. Surface runoff
computation was done using Soil Conservation Service-Curve Number (SCS-CN) method; and
Muskingum routing method was used for flow routing.
The Rainfall-Runoff modeling was based on a long term global water balance simulation for 15
years (1972-1986) and temporal calibration technique. The Nash and Sutcliff efficiency criterion
(R2
) and the Index of Volumetric Fit (IVF) were adopted for the measure of efficiency of the
performance of the model. An R2
of 82% and 59% was obtained during calibration and
verification periods respectively.
The predicted mean daily stream flow was found to be 1.92m3
/s exactly as observed during the
water balance simulation. Besides, modeling result gave a total annual water yield of 597.1mm,
from which the annual surface water component was 155.8mm and that of the base flow
component was 441.4mm in the long term simulation period with IVF unity. While
demonstrating the catchment is rich in ground water sources as a result of high magnitude of
precipitation and good water retention capacity, this study shows that SWAT model can be a
potential monitoring tool for watersheds in mountainous catchments.
Description
Keywords
GIS, hydrologic, SWAT (Soil and Water Assessment Tool)
Citation
Birhanu, B.Z, Ndomba, P.M., and Mtalo, F.W., (2007). ''Application of SWAT Model for Mountainous Catchments.” FWU Water Resources Publications Vol.06, ISSN 1613-1045 pp 182-187