| Title: | Streamflow and sediment yield prediction for watershed prioritization in the Upper Blue Nile River Basin, Ethiopia |
| Authors: | Ayele, G.T., E.Z. Teshale, B. Yu, I.D. Rutherfurd and J. Jeong |
| Year: | 2017 |
| Journal: | Water |
| Volume: | 9(10) |
| Pages: | |
| Article ID: | 782 |
| DOI: | 10.3390/w9100782 |
| URL (non-DOI journals): | |
| Model: | SWAT |
| Broad Application Category: | hydrologic & pollutant |
| Primary Application Category: | critical source area assessment |
| Secondary Application Category: | sediment loss and transport |
| Watershed Description: | 287 km^2 Koga River, which is a tributary of the Gilgel Abay River located in the headwaters region of the Blue Nile River system in northwest Ethiopia. |
| Calibration Summary: | |
| Validation Summary: | |
| General Comments: | |
| Abstract: | Inappropriate use of land and poor ecosystem management have accelerated land
degradation and reduced the storage capacity of reservoirs. To mitigate the effect of the increased
sediment yield, it is important to identify erosion-prone areas in a 287 km2 catchment in Ethiopia.
The objectives of this study were to: (1) assess the spatial variability of sediment yield; (2) quantify
the amount of sediment delivered into the reservoir; and (3) prioritize sub-catchments for watershed
management using the Soil andWater Assessment Tool (SWAT). The SWAT model was calibrated and
validated using SUFI-2, GLUE, ParaSol, and PSO SWAT-CUP optimization algorithms. For most of the
SWAT-CUP simulations, the observed and simulated river discharge were not significantly different
at the 95% level of confidence (95PPU), and sources of uncertainties were captured by bracketing more
than 70% of the observed data. This catchment prioritization study indicated that more than 85% of
the sediment was sourced from lowland areas (slope range: 0–8%) and the variation in sediment yield
was more sensitive to the land use and soil type prevailing in the area regardless of the terrain slope.
Contrary to the perception of the upland as an important source of sediment, the lowland in fact was
the most important source of sediment and should be the focus area for improved land management
practice to reduce sediment delivery into storage reservoirs. The research also showed that lowland
erosion-prone areas are typified by extensive agriculture, which causes significant modification of
the landscape. Tillage practice changes the infiltration and runoff characteristics of the land surface
and interaction of shallow groundwater table and saturation excess runoff, which in turn affects the
delivery of water and sediment to the reservoir and catchment evapotranspiration. |
| Language: | English |
| Keywords: | land use change; watershed prioritization; reservoir sedimentation; Blue Bile river basin;
sediment yield; SWAT-CUP |