dc.description.abstract |
Contaminants are serious water quality concern in the Giligel Abbay river basin. Increased
N and P contaminants on the river are burdens from the watershed joining it through runoff
and leaching. This study aimed to identify the source of pollution, quantifying the
contaminant loads to the Giligel Abay river, and testing the application of the Soil and
Water Assessment Tool (SWAT) to model N and P transport processes under wet and dry
seasons from 1992-2012. The sensitivity analysis of the SWAT model was undertaken for
different parameters to identify main sensitive parameters for non-point source pollution
in this watershed. Themain sensitive parameters for the watershed were CN2.mgt,
GWQMN.gw, and SOL_ALB. Among them, the most sensitive parameter for the SWAT
model was found to be the curve number (CN2). The performance of SWAT was found
reasonably well based on various performance evaluation criteria such as stream flow,
sediment, and contaminant loads parameters which are at the boundary of good to
excellent. The analysis result from the watershed showed a significant difference in N and
P with the introduction of grazing and fertilizer application, an average annual contaminant
load from the watershed was4933.33 ton/yr. and 1150.57 ton/yr. respectively. The
temporal variation of pollutions was statistically significant (p<0.05) averagely for dry
(December to March) and wet (July) seasons. Spatial analysis using GIS resulted
significant color difference showing spatial variation of parameters along the Giligel Abay
Watershed. Assessment result indicates higher pollutant loading in 8 sub basins among the
total 35. With further refining and updating the SWAT model, it can be applied for
quantifying the amount of nitrogen and phosphorus through GIS based sustainable
management of systems saves time, money and helps for effective watershed protection
and so the river water quality.
Keywords: stream flow, Sediment, Water Quality, SWAT_ Upper Giligel Abbay
catchment |
en_US |