Effect of land use/cover change on sediment load of the Mpanga river sub-catchment

Abstract

Like other countries in the sub-Saharan Africa, Uganda is not an exception to the effects of land use/cover changes on the environment. Specifically, the study intended to determine the effects of land use/cover changes on sediment load in the Mpanga sub-catchment. A series of images from Landsat and Sentinel acquired for 2000, 2010 and 2020 were classified using a supervised classification procedure in a 10.4 Geographical Information System software to determine the land use/cover changes. The Soil and Water Assessment Tool was used to model the sediment yield in the sub basins of Mpanga micro catchment. Results showed a variable and increasing trend in expansion of agricultural lands and built-up areas between 2000-2020. Grasslands and wetlands were the most affected land cover types experiencing the highest level of changes in the study area. Results of projection to 2030 and 2040 revealed that there will be a further increase of agricultural land and built up areas with most of the expansion occurring at the expense of grasslands and wetlands land cover types. The pattern of sediment load from 2000-2020 is increasing across the years with 4,161 tonnes and 6,740 tonnes of sediment realised in 2000 and 2020 respectively. There was a variation in sediment loading taking place across different sub-basins of the Mpanga sub-catchment. Built-up areas and agricultural lands were the major contributors of sediment loading in the catchment. This study has therefore shown that land use/cover changes have an effect on sediment loading in the River Mpanga-sub-catchment. It is recommended that the Ministry of Agriculture, Animal Industry and Fisheries and the Ministry of Water and Environment as well as the Ministry of Urban Planning collaboratively promote sustainable agriculture and urban planning to minimise actions that lead to sediment loading in the catchment.