Water quality monitoring of Lake Victoria using GIS and Satellite Imagery

Abstract

Water is world’s most valuable asset. In Uganda, the biggest natural water resource is Lake Victoria. It serves different purposes such as fishing, navigation, eco-conservation and supply of fresh water for various purposes such as irrigation, industrial use and drinking. However, the lake is under a threat of continuous pollution from different point and non-point sources. The Ministry of Water and Environment of the Republic of Uganda set up several water sampling points to monitor water quality in Lake Victoria. However, there is a need for methods that help in real time routine monitoring of water quality in an economical and reliable way as compared to always taking water samples and testing for various parameters in a laboratory. The main objective of this research project was therefore to examine the potential of relying chiefly on GIS and Remote Sensing techniques to monitor water quality in Lake Victoria. The study area included 12,718.1 km2 of Lake Victoria shared by 10 districts of Kalangala, Masaka, Kalungu, Mpigi, Wakiso, Kampala, Mukono, Buikwe, Jinja and Buvuma. Empirical models for Landsat 8 satellite images were developed for four water parameters: BOD, TP, CHL-A and Turbidity. The models were then used to produce water quality maps of Lake Victoria over the study period of 5 years from 2015 to 2019. The water quality in the lake was compared with the standards of United Nations Environment Program (UNEP) through the International Water Quality Guidelines for Ecosystems (IWQGES) as well as other environmental regulatory authorities. Site visits to some point locations in the study area were conducted to identify potential sources for the water pollution. Results showed relatively good water quality off the shores of Lake Victoria as compared to the poorer quality water on and near the shores; there was also a significant increase in lake pollution over the study period. Satellite imagery showed a huge potential of monitoring lakes and discovering their mysteries especially for potential pollution sources. To reverse pollution and its impacts, it was recommended that all the stakeholders from the authorities, academia and the general public have roles to play. Environmental action for Lake Victoria basin recovery should focus UN SDGs 6 (Clean water and sanitation for all), 12 (Sustainable consumption and production), 13 (Climate action), 14 (Life below water) and 15 (Life on land). There is an urgent need for a regional initiative for a well detailed Lake Victoria catchment management plan, tackling point and non-point pollution, mass sensitization, buffer zone restoration and adopting new modern and efficient ways that favor real-time monitoring of the Lake, for example satellite imagery. Advanced environmental research is still needed but the citizens too should take it a personal responsibility to sustainably manage Lake Victoria water resources and preserve the catchment from further degradation.