This study aimed at characterising the land use in the Simiyu catchment of Lake Victoria and using land-uses of 1975 and 2006 and comparing the relative impact of land-use change on sediment loading into the Lake. Remote sensing using the package ILIWIS 3.0. was used to identify and characterize the land-use while Soil and Water Assessment Tool (SWAT) was used to quantify sediment loading from the 1975 and 2006 land-use scenarios. The results of this study indicate that there was an expansion of agricultural land from 19.33% to 73.43% of the catchment at an annual change rate of 2.9%. Furthermore, the land-use of 1975-yielded less sediment loading compared to that of 2006. Model simulation at the catchment outlet for sediment reported a total yield of 98,467 tons/yr while the actual measured sediment loading had the value of 2,075,114 tons/yr. Hence, the model underestimated sediment yield in the catchment. With good model performance, developing management plans to control sediment loading into Lake Victoria can be achieved using the SWAT model.