Watershed characteristics and physico-chemical analysis of lakes and reservoirs in North Western, Ethiopia

摘要

This study investigates the physico-chemical characteristics of Lakes and reservoirs in relation to the watershed condition of North Western Ethiopia. A mosaic image from Landsat 8 Operational Land Imager (OLI) path/ row 169/052, 169/053, 170/052, and 170/053 for March, 2018 is used for land cover analysis. Physico-chemical parameters including Surface water temperature, pH, Turbidity, Electrical conductivity, Total dissolved solid (TDS), and Nitrate concentration have been measured using Thermometer, pH meter, Turbidity meter, Conductivity /TDS meter, and Photometer, respectively. The findings revealed that the higher areal coverage of the catchments was recorded for Gudera-Geray-Tikurwuha catchments (3371 km2) where all these three water bodies are found within the same catchment followed by Tirba Catchment (1395 km ). Other water bodies such as Zengena and Bahire Giyorgis are within independent catchment area 684 km2 and 278 km2), respectively. High levels in physico-chemical properties (turbidity, TDS and conductivity) were observed in Lake Bahire Giyorgis, Geray and Tikurwuha reservoirs whereas, these levels were considerably lower in the highland water bodies of Tirba and Zengena. These findings indicated clear differences in watershed and physico-chemical characteristics among the water bodies under consideration. These differences could be attributed to the different patterns of land use, source of pollution, vegetation cover and geochemistry of the catchments areas. Moreover, it has been noticed that the water use and abstraction by local community is not in proper management. Most of the agricultural practices such as irrigation, farming, and fishing, are implemented without considering sustainable management of the water bodies. Municipal wastes are also affecting the water bodies particularly the Tikur Wuha reservoir. Therefore, it is demanding to conduct further research on water quality, sediment load, trends in water volume and detailed study on biological components to come up with sustainable solution for the lakes and reservoirs.