GIS and Remote Sensing Based Assessment of Water Quality Changes in Lake Malawi

The aim of this paper is to evaluate the changes in water quality. The parameters used in this study include Secchi Disk Transparency, Chlorophyl and Total Suspended Sediments as they are highly correlated with satellite datasets. Data processing and analysis included spectral correction, radiometric correction, mosaicking, water index calculation, water mask creation, water quality parameter calculation based on Krizanich (2009) model, Trophic State Indices, significance tests, land cover changes and areal coverages. The results of the study indicate that there were both positive and negative changes in the absolute water quality parameters between 1990 and 2011. There was a similar scenario for coverages of water with diminishing and improving water quality values. Thus, there were both spatial and temporal none uniform variations of water quality in the study area. Significant tests for the water quality changes for 10 year epochs yielded the following P values; 0.752, 0.909, 0.998, 0.750, 0.965 for Chlorophyll, Suspended Sediments, Secchi Disk Transparency, Trophic State Index (Chl) and Trophic State Index (SDT) respectively. This entails that there has been significant changes in water quality parameters. Strong relationships were established when coverages of declining water quality were used against the land cover changes in correlation analysis. The results suggested that human activities have played an upper hand in the depletion of forest resources on the catchment and has resulted in the decline in water quality in the lake.