Dynamics of eutrophication and its linkage to water hyacinth on lake tana, upper Blue Nile, Ethiopia: Understanding land-lake interaction and process

Abstract

The increasing population has put an immense pressure on our natural resources leading to water pollution and land degradation. The need for new agricultural areas, urbanization and industrial development have been responsible for resources degradation and pollution. Eutrophication can be resulted due to substantial driven enrichment of seasonal cycle of nutrients like phosphorus and nitrogen. So, this study is aimed at evaluating the (1) spatial and temporal dynamics of eutrophication on Lake Tana, (2) linkage between eutrophication and water hyacinth infested area (3) lake-land linkage of nutrients and water hyacinth infestation. To evaluate the dynamics of eutrophication, the samples were taken from 143 points at 0.5 m depth of the lake in August (2016), December (2016) and March (2017). To see the lake-land linkage of nutrients, two major nutrients (P and N) were collected at the major tributary rivers. The trophic status index of TP, SDD and Chl-s was determined by adopting Carlson’s model by using spatial analyst tool of ArcGIS. The result of this study showed that the trophic status index of the lake is shifting from mesotrophic to eutrophic condition. The growth of the invasive weed in the northeastern part of the lake is caused by the spatial distribution of nutrient and eutrophication as well as the depth, wind direction and the extent of large floodplain. This study will help to manage and control the pollution of Lake Tana and the expansion of water hyacinth.