Impact of land use land cover change on water quality of Athi River Basin, Kenya

Abstract

Studies on Land use/land cover (LULC) changes from 2015 to 2023 were analyzed to understand the spatial variation in water quality within the Athi River Basin. Data was extracted from Landsat 8 imagery from the USGS archive and analyzed using Google Earth Engine. Land use land cover (LULC) changes analyzed include six categories namely Bare-lands, Built-up, Farmlands, Forestlands, Grasslands, and Open-waters. Pearson correlation analysis was employed to assess the spatial LULC differences in water quality at different sampling stations within the mid-reaches of the Athi River Basin. Ground truthing surveys involving interviews were conducted to determine land use activities influencing water quality. The findings revealed significant LULC changes between 2015 and 2023. Barelands decreased by 7.06%, while built-up areas rose slightly by 0.29%. Farmland grew by 0.52%, forestlands by 4.54%. Grasslands increased by 2.77%, while open waters declined by 1.24% from 2015 to 2023. The result on spatial LULC differences indicated significant influence on water quality. Urbanization and agricultural activities generate pollutants such as Total Dissolved solids (TDS), Electrical Conductivity (EC), Biological Oxygen Demand (BOD5), cadmium, and chromium across the stations. Drought in open water with a -0.85 correlation result increases pollutants and dilution effect which worsens the water quality over time. The interview survey identified four land use drivers and a natural factor affecting water quality. Respondents cited climatic factors, agriculture, and settlement as primary drivers of water quality degradation, with industry and commercial activities as secondary drivers in the Athi River Basin. Climatic factors were associated with Grasslands and Farmlands. Agriculture impacted Forestlands and open waters, and Settlement influenced Bare-lands, Grasslands, and Forestlands. Industry affected Built-up/others and open waters, while commercial activities relate to Built-up. In conclusion, the Government of Kenya should enforce the regulations on environmental management, water resource conservation, sustainable land use, public health protection, irrigation control, forest preservation, and aquatic ecosystem conservation to safeguard the water quality of the Athi River Basin.