Title: Examining sediment accumulation pattern and storage capacity loss of Lake Ziway, Ethiopia

Authors: Alemu O. Aga

Addresses: Faculty of Civil Technology, Department of Water Works Construction Technology, Ethiopia Technical University (FTVTI), 2RGF + MHJ, Addis Ababa, P.O. Box 190310, Ethiopia

Abstract: To estimate Lake Ziway (Ethiopia) sedimentation and life time of reservoirs, multi-year, repeated acoustic surveying techniques were applied. The lake's old bathymetry of the year 2005 and new 2017 lake bathymetry were generated by collecting lake depth. The sediment distribution pattern between the years was analysed by subtracting their raster maps and the sediment thickness was generated by subtracting the old bottom elevation from the new by using ArcGIS 10.2. From this, the total amount of sediment deposited in 12 years was 17.75 million cubic metres, which gives an average thickness of 4.2 cm. After 12 years, the lake has lost about 1.12% of its volume. Assuming a constant rate over the period, the annual sedimentation is 1.479 million cubic metres or 1.81 million ton/year. Based on the calculated sediment rate, the lake will lose its volume by 0.093% annually and its half-life is estimated as 519.5 years.

Keywords: bathymetry; reservoir capacity; sedimentation; capacity curve; Lake Ziway.

DOI: 10.1504/IJW.2023.133993

International Journal of Water, 2023 Vol.15 No.3, pp.232 - 247

Received: 05 Aug 2022
Accepted: 30 May 2023
Published online: 09 Oct 2023 *