Assessment of Spatiotemporal Variation of Water Quality of Lake Tana, Ethiopia

Zelalem R. Womber; Fasikaw Atanaw Zimale; Mebrahtom G. Kebedew; Mastewal Lemma Assefa; Dessalegn Worku Ayalew

doi:10.20372/pjet.v1i1.1271

Zelalem R. Womber Department of Soil Resources and Watershed Management, College of Agriculture, Woldia University, Woldia, Ethiopia
Fasikaw Atanaw Zimale Faculty of Civil and Water Resource Engineering, Bahir Dar Institute of Technology, Bahir Dar University, Bahir Dar, Ethiopia
Mebrahtom G. Kebedew Faculty of Civil Engineering, Mekele University
Mastewal Lemma Assefa Faculty of Civil and Water Resource Engineering, Bahir Dar Institute of Technology, Bahir Dar University, Bahir Dar, Ethiopia
Dessalegn Worku Ayalew Department of Soil Resources and Watershed Management, College of Agriculture, Woldia University, Woldia, Ethiopia

DOI: https://doi.org/10.20372/pjet.v1i1.1271

Keywords: Water Quality, Water Hyacinth, Lake Tana, Spatiotemporal, Ethiopia

Abstract

Lakes are freshwater resources that contribute significantly to the maintenance of local ecosystems and ecological functions and services, including water supply, irrigation, hydroelectric production, aquaculture, and extreme flood and drought management. These services are declining, especially in developing countries such as Ethiopia, due to rapid population growth and human activities that have accelerated land degradation. Recently, Lake Tana shows signs of water hyacinth and is now found in the Fogera and Dembia floodplains. The lake resources are being abused, leading to resource degradation and ecosystem disruption. Studies of the physicochemical parameters of Lake Tana are limited to the banks of the lake and this study was conducted to investigate selected physicochemical water quality parameters of Lake Tana not limited to the banks of the lake. Four field trips were made in 2018 to measure transparency or Secchi Disc Depth (SDD), Total Dissolved Solids (TDS), Electrical Conductivity (EC), Temperature (T0), and to collect water samples at 20 sampling locations for Suspended Sediment Concentration (SSC) and turbidity analysis. The result was analyzed spatiotemporally, statistically and graphically using R Statistical software and ArcGIS. Accordingly mean values of SSC of 205.7, 190.8, 377.4, 422.7 mg/l, turbidity of 20.1, 41.2, 90.8, 72.1 NTU, SDD of 0.78, 0.56, 0.40, 0.31 m, TDS of 93.6, 94.8, 90.8, 88.3 ppm, T0 of 24.3, 24.3, 23.5, 22.7 0C, and EC of 143.3, 143.9, 135.9, 131.4 Âµmhos/cm were found for May, June, July and August 2018 respectively. The analysis revealed that the sediment concentration had a higher spatiotemporal variation along the inlets of tributary rivers and in the centre of the lake Temperature and total dissolved solids results also showed that it is appropriate for water hyacinth development and expansion over the lake surface. By treating the nutrient-rich sediment with optimal management techniques such as soil and water conservation, minimizing recession agriculture near the lake, and enhancing wetland management, it may be possible to change the physicochemical water quality and the dynamics of water hyacinth expansion.