Land use change dynamics and its effects on surface runoff in Manafwa catchment Mount Elgon

Abstract

Although land use and land cover processes are observed to be prevalent, their effects on surface runoff in highland environments is yet to be ascertained. Essentially, the surface runoff in these highland environments is critical on both hazard and degradation processes. The gist of this study was to assess the nature of land use and cover changes and their effects on surface runoff in Manafwa catchment. The objectives of the study were to quantify the spatial and temporal changes in land use in Manafwa catchment from 1973 to 2020 and to assess the effects of these land use changes on the surface runoff in the Manafwa catchment. A non-experimental design was applied in the study. Land use change was quantified using both the unsupervised and supervised classification methods in Arc GIS 10.5. To understand the effects on surface runoff, curve numbers were used to calculate the amount of surface runoff flowing from the catchment into the water bodies. The results for objective one revealed a shift towards agriculture and built up area and a reduction in the forest cover. Reductions were also observed in spatial coverage of forests by up to 10%. On the other hand, agriculture and built up areas increased gradually over the study period (1973-2020) by up to 35% and 276% respectively. The surface runoff computation from different land uses, revealed that agriculture contributed the highest amount of run off while forest had the least which was approximately 30,428 m3 and 4,968 m3 respectively. This study recommends an agro forestry approach and an adoption of water conservation with farmers