Evaluation of reservoir sedimentation using bathymetry survey: a case study on Adebra night storage reservoir, Ethiopia

Abstract

Reservoir sedimentation is a serious challenge that reduces reservoir life. Because it decreases the initial capacity of the reservoir and has an impact on drinking water supply, irrigation, and hydropower activities. Inadequate land activities and poor management techniques cause soil erosion and reduce reservoir storage capacity. As a result, accurate sediment estimation was assist in the adoption of sustainable land-use activities and best management practices that lead to effective reservoir operations. The main objective of this study was to evaluate the rate of sedimentation and remaining capacity of Adebra night storage reservoir (NSR) using a bathymetric survey and Arc-GIS 10.8. A comparison of original and current reservoir capacity was used to evaluate the quantity of sediment deposition in the reservoir. The latter was developed using Arc-GIS 10.8 and a bathymetry survey that was used to develop the TIN surface and evaluate reservoir volume. The Adebra NSR reservoir capacity was decreased by the accumulation of sedimentation from 36,902 m3 in 2012 to 27,722 m3 in 2020. The results of this study showed that the Adebra night storage reservoir had lost on average 24.8% of its capacity due to sedimentation, during 8 years of operation. The average deposition rate of sedimentation in Adebra NSR was estimated to be 1147.5 m3/year, with a loss rate of 3.1% per year. The value of sedimentation rates found in live storage of the reservoir area was 1147.5 m3/year. At the current time, the expected life of the night storage reservoir was reduced due to a lack of proper soil conservation practices in the reservoir catchment areas. In general, the study finding showed that the capacity of NSR was reduced by the accumulation of sedimentation year to year throughout the design period. Therefore, to improve the capacity of NSR should be planning and implementing different techniques of sediment control and removal, depending on the estimation of sediment production from watersheds of inlets and outlets of reservoirs.

Evolution of Sedimentation in a Headrace Canal for Hydroelectric Production Case of the Shongo Basin of the Inga Complex from February 2020 to May 2021 (Kongo Central Province/DR Congo)

“…Currently there are several methods to quantify the sediment deposited in a dam reservoir (Schleiss et al, 2016) among others empirical methods using mathematical equations. Topographic methods have been used by (Mekonnen et al, 2022) in Spain, Italy (Diaz, Mongil-Manso, & Navarro, 2014), in the reservoir of Obruk dam located in Çorum province in Türkiye (Ilçi et al, 2017) and are proving to be effective in assessing the volumes of sediments trapped by the reservoirs (Ramos-Diez et al, 2017). Geographic Information Systems are an important tool (Schleiss et al, 2016) allowing the overlay of several layers of information to be used in clustered or distributed models.…”

Land use/land cover change impact on streamflow using Arc-SWAT model, in case of Fetam watershed, Abbay Basin, Ethiopia

“…The availability and competition for water will vary as a result of land use/land cover change (LULCC) and climate change, which are brought on by regional and global economic development (Dibaba et al 2020;Disse et al 2018;Mekonnen et al 2022). High rainfall variability, rising food and water needs, frequent hydrological extremes, and rapid population growth all contribute to the environment's continued degradation by affecting the availability of various biophysical resources.…”

“…There is a chance that climate change will put further strain on the accessibility and availability of water. Interest in how these changes will affect the hydrological process will grow as a result of the projected negative environmental implications of these changes (Alemu et al 2022;Dibaba et al 2020;Mekonnen et al 2022). The demand for fresh water is correlated with changes in lifestyle, economic growth, and population size.…”

“…The change in land use/cover in a given area is a result of environmental and socioeconomic issues, as well as human activity over time and space. Increases and decreases in population growth in the system, climate, financial development, and physical elements such as landscape, grade condition, and soil type all have an impact on Land Uses land Cover (LULC) changes (Mekonnen et al 2022: Moges et al 2017Tewabe and Fentahun 2020).…”

“…This constant land use/cover shift has changed the water stability of the catchment through altering the quantity and shapes of the mechanisms of streamflow, which include groundwater flow, surface runoff, and lateral flow. These effects have increased the degrees of water management challenges in study areas (Chen et al 2020;Chimdessa et al 2019;Mekonnen et al 2022).…”