Estimating the Effect of Land Use Change on the Rate of Sedimentation in Awoja Catchment.

Abstract

Very many lakes and rivers are faced with a problem of sediment delivery which results into reduction of the water quality and quantity, reducing the availability of water needed for various purposes and also increasing the costs incurred to purify the water so as to improve its quality. The sediment delivery rates are highly influenced by the existing land use activities which either support erosion or act as barriers to erosion. This report covers the classification of land use activities and how they have been changing over the years and estimates the sediment delivery rates over the so as to understand how changes in land use affect the sediment delivery rates in Awoja catchment, Uganda. The Universal Soil Loss Equation (USLE) was used together with a Geographic Information System and remotely sensed data to determine the influence of changes in land use on the sediment delivery rate for the years 1988, 1995, 2009 and 2017. Six land use cover types were identified which include open water, forests, cropland, bushland, and wetland and finally built up and bare ground which were classified as one. Results indicated built up and bare land registered the most significant increase of 327.13%, followed by cropland with an increase of 39.04% and open water increasing by 8.51%. Reduction was registered with forest cover by 60.71%, bushland by 52.43% and wetland by 66 29%. The mean sediment yield rates were estimated as 6.80 ton/ha/yr in 1988, 7.81 ton/ha/yr in 1995, 13.26 ton/ ha/yr in 2009 and 23.95 ton/ha/yr in 2017. The results indicated that any change to bare land and cropland from another class is very risky as they were found to be the major source of sediment while forests were found to be the most effective barriers to soil loss and hence sedimentation