Use of geospatial technology in monitoring of water quality: case study lake Naivasha, Kenya.

Abstract

Lake Naivasha has an important ecological, economic and social role in Kenya. There are justified and substantiated concerns on the health of Lake Naivasha. The main issues are: deterioration of water quality, increase of nutrient inflow into the Lake (Eutrophication), and waste emanating from agriculture zones and settlements. The objective of this study was to examine water quality in terms of three parameters; turbidity, total suspended matter and chlorophyll concentration over a period of 10 years, to establish the values and trend of water quality parameters and evaluate if they conform to the stipulated acceptable standards. Medium Resolution Imaging Spectrometer (MERIS) satellite images were used to extract the surface water quality parameters understudy. These images were obtained from European Space Agency (ESA) online portal. A water parameter extraction algorithm in the Basic ERS and Environmental Satellite (EnviSat) (A) Aster and MERIS (BEAM) tool box was used to extract the water quality parameter values. The conventional methods of water quality measurement and monitoring are expensive, and it is very difficult to use conventional field methods to monitor more than a small fraction of this large resource. Satellite remote sensing can be used since it is a cost-effective way to gather the information needed for regional water quality assessments in water bodies such as Lake Naivasha. Results of this study have shown that Lake Naivasha has high level of eutrophication with chlorophyll concentration above 44 mg/m3. The Total Suspended Matter (TSM) levels were found to be within Kenya’s National Environment Management Authority (NEMA) stipulated values of 30 mg/l while the turbidity parameter values were found to above the European Commission stipulated standard of 1 NTU. The lake trophic state was found to be eutrophic based on the chlorophyll concentration from the analysis of 44.2 mg/m3 – 49.73 mg/m3 which is within the stipulated range of 20 mg/m3 to 56 mg/m3. The study has demonstrated that Geospatial Technology can be used successfully to extract water quality parameter values and for the purpose of monitoring the trend over a large extent of the lake, within a shorter time frame and more cost effectively than the traditional / conventional methods of water quality parameter measurements.