Assessing soil erosion risk in a peri‑urban catchment of the Lake Victoria basin
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Date
2022
Journal Title
Journal ISSN
Volume Title
Publisher
Modeling Earth Systems and Environment
Abstract
Soil erosion and sedimentation contribute to deteriorating water quality, adverse alterations in basin hydrology and overall
ecosystem biogeochemistry. Thus, understanding soil erosion patterns in catchments is critical for conservation planning.
This study was conducted in a peri-urban Inner Murchison Bay (IMB) catchment on the northern shores of Lake Victoria
since most soil erosion studies in Sub-Saharan Africa have been focused on rural landscapes. The study sought to identify
sediment sources by mapping erosion hotspots using the revised universal soil loss equation (RUSLE) model in appendage
with field walks. RUSLE model was built in ArcGIS 10.5 software with factors including: rainfall erosivity, soil erodibility,
slope length and steepness, land cover and support practices. The model was run, producing an erosion risk map and field
assessments conducted to ground-truth findings and identify other hotspots. The percentage areas for RUSLE modelled
erosion rates were: 66.8% for 0–2 t ha−
1 year−
1; 10.8% for 2–5 t ha−
1 year−
1; 10.1% for 5–10 t ha−
1 year−
1; 9% for 10–50
t ha−
1 year−
1 and 3.3% for 50–100 t ha−
1 year−
1. Average erosion risk was 7 t ha−
1 year−
1 and the total watershed erosion
risk was 197,400 t year−
1, with croplands and steep areas (slope factor > 20) as the major hotspots (> 5 t ha−
1 year−
1). Field
walks revealed exposed soils, marrum (gravel) roads and unlined drainage channels as other sediment sources. This study
provided the first assessment of erosion risk in this peri-urban catchment, to serve as a basis for identifying mitigation priorities.
It is recommended that tailored soil and water conservation measures be integrated into physical planning, focusing
on identified non-conventional hotspots to ameliorate sediment pollution in Lake Victoria.
Description
Keywords
Land use land cover, Inner Murchison Bay catchment, Geographical information system
Citation
Ssewankambo, G., Kabenge, I., Nakawuka, P., Wanyama, J., Zziwa, A., Bamutaze, Y., ... & Tessema, B. (2022). Assessing soil erosion risk in a peri-urban catchment of the Lake Victoria basin. Modeling Earth Systems and Environment , 1-17. https://doi.org/10.1007/s40808-022-01565-6