| Title: | Soil erosion modelling and risk assessment in data scarce rift valley lake regions, Ethiopia |
| Authors: | Aga, A.O., B. Chane and A.M. Melesse |
| Year: | 2018 |
| Journal: | Water |
| Volume (Issue): | 10(11) |
| Pages: | |
| Article ID: | 1689 |
| DOI: | 10.3390/w10111684 |
| URL (non-DOI journals): | |
| Model: | SWAT |
| Broad Application Category: | hydrologic and pollutant |
| Primary Application Category: | sediment loss and transport |
| Secondary Application Category: | BMP and/or cropping system assessment |
| Watershed Description: | 7,285 km^2 Lake Ziway drainage area, located in the central Ethiopian Rift Valley basin in central Ethiopia. |
| Calibration Summary: | |
| Validation Summary: | |
| General Comments: | |
| Abstract: | To prolong the useful life of lakes and reservoirs, prioritizing watersheds by severity and
risk of soil erosion is an essential index to develop sound sediment management plans. This study
aims to predict soil erosion risk and sediment yield using Soil and Water Assessment Tool (SWAT)
model in Lake Ziway basin, Ethiopia, and the model result is validated with lake bathymetric changes.
The SUFI-2 program was applied for a model calibration and the performance of the model was
assessed. The catchment prioritization study indicated that some sub-basins having the same soil
type and land use but a higher slope gives higher sediment yield. This confirms that, in the basin,
the upland is the main source of sediment for the lake, hence the variation of sediment yield is
more sensitive to terrain slope. Furthermore, the soil conservation scenarios demonstrated in SWAT
that reduce the slope length of the watershed by 50% for a slope greater than 5% are decreasing
the sediment yield of the basin by 55%. The bathymetric differencing of the lake indicates that the
sediment was accumulating at a rate of 3.13 t/ha/year while a calibrated SWAT model resulted in
5.85 t/ha/year. The identified reasons for these variations are the existence of outlet for the lake,
floodplain depositions and abstraction of sediment (sand mining) from the tributary rivers before
flowing to the lake. |
| Language: | English |
| Keywords: | SWAT; watershed prioritization; sediment yield; reservoir sedimentation; bathymetry;
Lake Ziway |