Assessing soil erosion risk in a peri-urban catchment of the Lake Victoria basin.
Assessing soil erosion risk in a peri-urban catchment of the Lake Victoria basin.
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DOI：
10.1007/s40808-022-01565-6
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发表时间：
2023
影响因子：
3
通讯作者：
Tessema, Bezaye
中科院分区：
文献类型：
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作者：
Ssewankambo, Gyaviira;Kabenge, Isa;Nakawuka, Prossie;Wanyama, Joshua;Zziwa, Ahamada;Bamutaze, Yazidhi;Gwapedza, David;Palmer, Carolyn Tally;Tanner, Jane;Mantel, Sukhmani;Tessema, Bezaye
土壤侵蚀和沉积造成水质恶化、流域水文和整个生态系统生态地球化学发生不利变化。因此，了解集水区的土壤侵蚀模式对保护规划至关重要。这项研究是在城郊内默奇森湾（IMB）集水区的维多利亚湖的北方海岸，因为大多数土壤侵蚀研究在撒哈拉以南非洲一直集中在农村景观。该研究试图通过使用修订的通用土壤流失方程（RUSLE）模型绘制侵蚀热点来确定泥沙来源。在ArcGIS 10.5软件中建立RUSLE模型，模型因子包括降雨侵蚀力、土壤可蚀性、坡长和坡度、土地覆被和支护措施。运行该模型，绘制侵蚀风险图，并进行实地评估，以确定地面实况调查结果，并确定其他热点。RUSLE模型侵蚀率的面积百分比为：0-2 t ha−1年−1为66.8%; 2-5 t ha−1年−1为10.8%; 5-10 t ha−1年−1为10.1%; 10-50 t ha−1年− 1为9%; 50-100 t ha−1年−1为3.3%。平均侵蚀风险为7 t ha−1年−1，总流域侵蚀风险为197，400 t ha − 1年−1，农田和陡峭地区（坡度系数> 20）为主要热点（> 5 t ha−1年−1）。实地考察发现，裸露的土壤，marrum（砾石）道路和无衬里的排水渠道作为其他沉积物来源。这项研究提供了第一次评估侵蚀风险在这个城市周边集水区，作为确定缓解优先事项的基础。建议将有针对性的水土保持措施纳入实际规划，重点是已确定的非常规热点，以改善维多利亚湖的沉积物污染。
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.