Changes in land-use and land-cover have negatively affected the hydrology of Ragati River. It is one of the many rivers in Kenya that are considered as hot spots due to over abstraction especially during the dry season. This study aimed at evaluating the effects of land use and land cover changes which are important in ensuring sustainable use of the water resource. This study aimed at achieving the following objective: i)To analyze land use activities and land cover changes within Ragati River catchment area from 1990 to 2010; ii)To analyze the discharge of Ragati River during low flow and high flow seasons; iii) To assess the response of the sub-catchment to land-use and land cover change; iv) To evaluate the measures taken to mitigate negative effects of land use and land cover changes on the Ragati catchment. Satellite data was integrated in GIS to examine the extent of land-use and cover change in the sub-catchment. Both quantitative and qualitative data were used in this study. Various data types such as socio-economic data, land-use data, rainfall data and river flow data were collected in order to supplement information from landsat images. Analysis was done using classified landsat images of 1990, 2000 and 2009. SPSS and Ms Excel were used to analyse descriptive data. This study revealed that between 1988 and 2000 the dense forest decreased by 15%, land under perennial crops increased by 4.26%, cropland increased by 11%, settlement increased by 45.30% while closed woodland decreased by 4.6%. The results also show some change between 2000 and 2009. This can be attributed to increased campaign on reforestation of Mt. Kenya forest. Land under perennial crops decreased by 57%, crop land further by 4.04%, settlement increased by 49.41% while closed woodland decreased further by 3%. Over abstraction of water and river bank encroachment are some of the causes of changes in the volume of water flowing in the river. This study recommends that water users should be made aware of the importance of sustainable use of the water resource.