Effects of land use and land cover change on water quality in south and north rukuru river catchment

Abstract

South and North Rukuru River are major rivers that sustain the ecosystems and biodiversity of Vwaza Wildlife Reserve and Nyika National Park. Regardless of their significance, they have been affected by massive land use and land cover changes driven by different factors. It is against this background that this study was conducted in North and South Rukuru catchment areas to analyse the effects of land use and land cover change on water quality. The research specifically: investigated land use and land cover activities with direct influence on water quality, determined temporal changes in catchment land use and land cover and measured the quality of water from South and North Rukuru river. Focus Group Discussion (FDGs), Key Informant Interviews (KII), Geographical Information System (GIS) and Remote Sensing and laboratory data analysis were used to generate data for this study. The results, revealed that there was an increase in built-up areas by 1991% and 1168%, respectively, which is extremely considered high and destructive to these catchment areas under study. In the first decade, Forest land also decreased by -72% and the decreasing trend continued to -59% in the second decade. The results statistically further revealed significant increase at P<0.05 in built-up area, agriculture activities, bareland and grassland among the seven classes studied. Laboratory analysis water quality results indicated physical parameters such as power of hydrogen(pH) (7.3-7.9), electrical conductivity(EC) (71.62-136.2µm/cm), dissolved oxygen(DO) (5.6-7.8mg/l), temperature(˚Ϲ) (24˚Ϲ-27.9˚Ϲ), nitrate (0.22-33.397mg/l), phosphate (0.055-2.358), fluoride (0.007-0.506) and chloride (11.86-55.58) were within permissible maximum limits set by the Malawi Bureau of Standards (MBS).The study further justified the importance of putting into consideration the effects of LULCC on ecosystems and water quality in planning and proper catchment management.