Impact of land use change on water quality and productivity :

Abstract

Aquatic systems are important sources of water for domestic use, agriculture and fisheries. In fact, 70% of Ugandans depend on agriculture and fisheries for their livelihood. The Ugandan population is growing at a very fast rate of more than 3% per annum, which is among the highest in the world. Increase in human population has been accompanied by rapid conversion of land into agricultural fields and urban areas, resulting in deforestation, wetland drainage and pollution from agrochemicals. This has in turn, resulted into increased situation and nutrient enrichment in aquatic ecosystems thereby affecting their quality and productivity. Therefore, the main objective of this study was to examine the impact of land use and cover changes on water quality and productivity using Lake Wamala as a case study. The study used qualitative methods that involved reconnaissance visits, observations and photography to describe land use and cover changes and collection of environmental and biological indicators of land use and' cover change, Quantitative methods were also used in experiments about testing physicochemical and biological water quality parameters of Lake Wamala, they were also used in the analysis to derive means standard errors and statistical significances of physico-chemical and biological parameters. Results show that there is an exponential increase in Uganda's human population from 1911 to 2014. This trend of population increment was also registered by the districts of Mubende and Mityana from 1991 to 2014. There were reciprocal changes between land and water, with high vegetation cover having dominated in 1990 with 87.2%, in 2005 with 49.5%, in 2010 with 78.4% and in 2015 with 44.7%. Moderate vegetation cover was: observed in 1995 with 69.3%, and low vegetation cover in 2000 with 62.9%. The results further show high primary production of the sampled transects that ranged between 1354.6-164.2 mg of 02m2h-1. The study concluded that there was an exponential increase in human population size around Lake Wamala catchment over the years accompanied by multiple unsustainable land use practices within the ripanan areas of the lake that undermine the. quality and productivity of Wamala waters. The study made several recommendations, including advocating for better coordination of initiatives to conserve Lake Wamala by District authorities, strengthening use of available population control methods and sensitization of the farmers, fisher men and women bordering the lake to ensure that they avoid cultivating up to the shores.