A Guided SWAT Model Application on Sediment Yield Modeling in Pangani River Basin: Lessons Learnt
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Date
2008-12-10
Journal Title
Journal ISSN
Volume Title
Publisher
Universidade Federal da Paraíba
Abstract
The overall objective of this paper is to report on the lessons learnt from applying Soil
and Water Assessment Tool (SWAT) in a well guided sediment yield modelling study.
The study area is the upstream of Pangani River Basin (PRB), the Nyumba Ya Mungu
(NYM) reservoir catchment, located in the North Eastern part of Tanzania. It should be
noted that, previous modeling exercises in the region applied SWAT with preassumption
that inter-rill or sheet erosion was the dominant erosion type. In contrast, in
this study SWAT model application was guided by results of analysis of high temporal
resolution of sediment flow data and hydro-meteorological data. The runoff component
of the SWAT model was calibrated from six-years (i.e. 1977–1982) of historical daily
streamflow data. The sediment component of the model was calibrated using one-year
(1977–1988) daily sediment loads estimated from one hydrological year sampling
programme (between March and November, 2005) rating curve. A long-term period
over 37 years (i.e. 1969–2005) simulation results of the SWAT model was validated to
downstream NYM reservoir sediment accumulation information. The SWAT model
captured 56 percent of the variance (CE) and underestimated the observed daily
sediment loads by 0.9 percent according to Total Mass Control (TMC) performance
indices during a normal wet hydrological year, i.e., between November 1, 1977 and
October 31, 1978, as the calibration period. SWAT model predicted satisfactorily the
long-term sediment catchment yield with a relative error of 2.6 percent. Also, the
model has identified erosion sources spatially and has replicated some erosion
processes as determined in other studies and field observations in the PRB. This result
suggests that for catchments where sheet erosion is dominant SWAT model may
substitute the sediment-rating curve. However, the SWAT model could not capture the
dynamics of sediment load delivery in some seasons to the catchment outlet.
Description
Keywords
Modelling, Pangani river basin, sediment yield, sediment rating curve, SWAT
Citation
Ndomba, P.M., Mtalo, F.W. and Killingtveit, A., 2008. A guided swat model application on sediment yield modeling in pangani river basin: lessons learnt. Journal of Urban and Environmental Engineering, 2(2), pp.53-62.