Assessing the effects of land cover (LC) change on water quality using satellite imagery

Abstract

Surface waters are the most important economic resource for humans which provide water for agricultural, industrial and anthropogenic activities. Surface water quality plays vital role in protecting aquatic ecosystems. Unplanned urbanization, intense agricultural activities and deforestation are positively associated with cloropyhll-a and turbidity water quality parameters. The objective of this study was to examine the land cover change around Murchison bay catchment and determine the effect of these changes on water quality focusing on chlorophyll-a and turbidity. thirteen water-sampling stations were selected and samples were collected and analyzed according to standard analytical procedures for accurate validation of satellite data. An Earth Resources Data Analysis System (ERDAS) Imagine image processor and Geographical Information System (GIS) was used for the digital analysis of Landsat image series (1986, 2001, 2010 and 2018) for deriving the land cover change trend of the catchment. Preliminary results showed that built-up and open water have increased between 1986 and 2018 from 17.99% to 36.9% and 4.16% to 4.19% respectively while forest, vegetation, and wetlands declined from 10.83% to 7.94%, 49.06% to 37.93% and 17.83% to 13.07% respectively. Clorophyll-a and turbidity followed the same trend of increase from 183.6µg/L to 215.6 µg/L and 2(NTU) to 13(NTU) within the same study period. The results indicate that the increase in built-up and high vegetation cover are positively correlated with average change of chlorophyll and turbidity, this is because of the anthropogenic activities within the catchment. Water pollution prevention strategies to ensure prevention of pollution and protection of water resources in the bay watershed is recommended.