Reservoir Sedimentation: Assessment and Environmental Controls appraises the issues of sedimentation in reservoirs and discusses measures that can be employed for the effective management of sediment to prolong the operational life of reservoirs. It provides information for professional consultants and policymakers to enable them to manage dams in the best possible way, in order to ensure their sustainability as well as the sustainability of water resources in general. It examines the effects of anthropogenic intervention and management of sediment in dams and reservoirs, as water resources become more sensitive and the demand for clean water continues to increase.

Features:


Examines the issue of sedimentation in dams and reservoirs and presents water management strategies to alleviate environmental issues


Presents methods to help ensure the environmental sustainability of dams and reservoirs, as well as the sustainability of water resources- with consideration of climate change and increased demand


Illustrates the spatial distribution of sedimentation characteristics for several dams using geographic information systems (GIS)


Explains the relationships between loss in capacity and catchment characteristics


Examines regional variation in sediment yield, defines geomorphic regions on the basis of similar hydrometeorology, physiography, geology, and vegetation affecting reservoirs

Reservoir Sedimentation: Assessment and Environmental Controls

Water quality sustainability assessment using the DPSIRO dynamic model: a case study of Ethiopian Lake Tana water

Climate change most likely to increase the soil erosion (SE) and sediment yield (SY) rate by changing the rainfall–runoff erosivity in many locations worldwide. Global climate model output is commonly used to appraise the impact of climate change on SE and SY. However, determining the suitable climate model is challenging for the accurate simulation of future SE and SY. Therefore, The Revised Universal Soil Loss Equation (RUSLE) coupled with Sediment Delivery Ratio (SDR) model was used to estimate the SE and SY in the humid sub-tropical catchment. We also evaluated the high-resolution regional climate models (RCMs) using five statistical bias correction methods (linear scaling, empirical quantile mapping, quantile mapping with linear transformation, quantile mapping with smoothing spline, and quantile mapping with gamma distribution) for future simulation of the SE and SY. Our result suggests that quantile mapping with gamma distribution-based bias correction method and ICHEC-EC-EARTH-RCA model best project the changes in precipitation and consequently, the rainfall–runoff erosivity factor in the catchment. It is estimated that a 3.67–11.08% increase in rainfall–runoff erosivity may result in a 3.7–11.76% increase in SE and SY in the catchment under the representative concentration pathway (RCP) 4.5 and RCP 8.5 emission scenarios. In addition to this 1.6-thousand-hectare area will be included in high (10–20 t ha−1 year−1) to very severe (> 80 t ha−1 year−1) SE intensity class during the near (2020–2049) and far future (2070–2099) period. The result also revealed that the increasing rate of SE and SY will be observed in the sub-catchment numbers 10, 18, 20, 23, 24, 27, 29 located in the middle part of the catchment under the RCP 8.5 scenario. The result may help the policymakers to strengthen the conservation strategy and more informed decisions for the management of catchment in and around the area.

https://link.springer.com/content/pdf/10.1007/s40808-021-01117-4.pdf

Modelling the impact of climate change on soil erosion and sediment yield: a case study in a sub-tropical catchment, India

Sediment accumulation in a dam reservoir is a common happening environmental problem throughout the world. Topographic conditions, land use land cover change, the intensity of rainfall, and the soil characteristics are the major driving factors for sedimentation to occur. The effect of sedimentation in a dam reservoir is very visible in the watershed as a result of hilly topographic conditions, high rainfall intensity, thin land cover, and less soil infiltration capacity. In this paper, an integrated RUSLE and GIS technique was implemented to estimate a mean annual sediment yield based on spatial and temporal variations in Nashe dam reservoir situated in Fincha catchment, Abaya River basin, Ethiopia. Spatial and temporal estimation of mean annual sediment yield was estimated using the Revised Universal Soil Loss Equation (RUSLE) model and GIS. Historical 6-year (2014-2019) rainfall for the temporal variations and other physical factors such as soil erodibility, slope and length steepness, management and land used land cover, and support practice for spatial variations were used as sediment driving factors. The mean annual sediment yield ranges from 0 to 2712.65 t ha-1 year-1 was seen. Spatially, Very high, high, moderate, low, and very low sediment yield severity with total area coverage with 25%, 10%, 30%, 15%, and 20% in 2017, 2015, 2019, 2014, and 2018 respectively. The information about the spatial and temporal variations of the severity of sediment yield in RUSLE model has a paramount role to control the entry of sediment into the dam reservoir in this watershed. The results of the RUSLE model can also be further considered along with the watershed for planning strategies for dam reservoirs in the catchment.

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Spatio-temporal Analysis of Sediment Yield Estimation Using Integrated RUSLE and GIS Technique: Case of Nashe Dam Reservoir, Abay Basin, Ethiopia

Soil erosion, sediment yield, and sediment transport associated with flash flooding in arid regions result in reservoir storage losses, decreased infiltration, high evaporation rates, and degradation of downstream channels. However, the lack of observational data from wadi systems and an empirical formula to compute sediment yield has hindered reservoir trapping evaluation, maintenance, and management. Therefore, this research aimed to estimate the annual soil loss in the upstream catchment area of a reservoir based on the Revised Universal Soil Loss Equation (RUSLE) with a remote sensing dataset. The sediment trapped in the Assarin Dam reservoir in Oman was estimated by coupling unmanned aerial vehicle (UAV) surveys with photogrammetry analysis to assess the reservoir siltation. Among the previous sediment trapping events, seven sets of field observation data were collected to investigate the relationship between soil loss at the catchment scale and sediment deposition volumes in the reservoir. The RUSLE method was applied to estimate soil erosion using independent factors such as rainfall erosivity, soil erodibility, topography, cover management and conservation practices. A remote sensing dataset and geographic information system (GIS) environments were used to analyse the quantitative and spatial distribution of the RUSLE parameters. Two drone surveys were conducted over the reservoir before and after a flash flood. The trapped sediment volume was estimated to be approximately 9,075 m3 (11,343 ton) per event, representing approximately 1.26 % of the total reservoir capacity. This computed volume was validated using measurements from monitored sediment scale bars sited throughout the Assarin Dam reservoir, yielding an accuracy of 79 %. From the RUSLE results, the annual soil erosion was estimated to be 196,599 ton/ha yr−1, of which approximately 5.8 % was trapped in the reservoir. Spatial-temporal variability in the rainfall patterns and the corresponding runoff discharges led to high sediment delivery at the outlet of the basin. After analysing available data from previous field surveys in Oman, a new formula for estimating the sediment yield in Wadi Assarin was developed. The results of this research, which represent the first of their type in the Middle East and North Africa (MENA) region, can support reservoir management practices and show that UAV-based photogrammetry is suitable for measuring trapped sediment volumes. 

Assessment of sediment yield and deposition in a dry reservoir using field observations, RUSLE and remote sensing: Wadi Assarin, Oman

Sedimentation is a significant issue for agricultural dams in Ethiopia, as it diminishes the capacity limit and life expectancy of the repositories. The procedure of sedimentation begins from the very first moment of the seizing of water in some random supply. Even though an arrangement is made for each reservoir during anticipating a specific stockpiling limit, explicitly for silt testimony, called dead storing, a significant part of the sediments gets kept for a long time of the supply's life in zones other than the dead storing, and this pattern cannot be turned around at a simple expense. This investigation is focused on the examination of persuasive sedimentation forms in the close by many dams found in the south Gondar zone catchment situated inside the Upper Blue Nile Basin of Ethiopia and spotlights on the appraisal of yearly sedimentation rate. Spatial investigation and displaying examines were directed dependent on the Revised Universal Soil Loss Equation and GIS to decide silts yield and level of effect of every store for a given scene, precipitation, and catchment heterogeneity. Field perceptions and soil testing were done to decide the components that lead to repository sedimentation. Spatial Data on the dams in south Gondar zone catchment were likewise gathered from the Ministry of Agriculture, which were utilized for ground-truthing, GIS-based computations, and model approval. The average specific sediment rate and silt delivery proportion were seen as 4059.2 t km−2 year−1 and 72.67%, individually. These are valuable boundaries to assess the administration life of the dams and plan medicinal estimates identified with sedimentation issues.

A spatial analysis and modeling study of sedimentation impacts on dams found in south Gondar zone, Ethiopia

This specific study was conducted on the Abrajit reservoir in east Gojjam, Amhara region, Ethiopia. The general objective of the study was to investigate reservoir siltation and determination of the remaining valuable life span of the reservoir using ArcGIS 10.5 version and Golden surfer 16 latest version. A bathymetric survey using echo-sounding equipment (Garmin GPSMAP421s) was conducted and a topo map of reservoir data was used for assessment of the sediment volume. The accumulated sediment volume was estimated by subtracting the triangular interconnected network (TIN) map of the initial bed level from the currently measured bed level. The result of the research revealed that to date, 343,700.1 m3 bulk of sediment was accumulated in the reservoir that reduces 20% of the total reservoir capacity. In the results from the bathymetric investigation and software analysis, annually 28,641.675 m3 year−1 amount of sediment is coming from the catchments to the reservoir that contributed 1.66% of annual reservoir volume reduction. The measured recent storing capacity for the Abrajit Dam was 1,388,870 m3. From a comparison of remaining reservoir storage and annual sediment load, the reservoir will not serve more than 12 years. The estimated specific sediment yield (SSy) was found to be 4733.387 ton km−2 year−1. Therefore, to improve the estimated life span of the reservoir, watershed management is very important and further study is required to identify the area where watershed conservation will focus in the future. Upon the findings, the reservoir volume is running to reduce and it cannot serve all the demand what it designed for during the dry season. As a result, operation curves should be mandatory to give water service for the critical water needs, and regular monitoring of sediment accumulation in the reservoir is recommended.

Reservoir sedimentation and estimating dam storage capacity using bathymetry survey: a case study of Abrajit Dam, Upper Blue Nile basin, Ethiopia

This particular examination was led on the Abrajit reservoir in the North Gojjam sub-basin, Blue Nile basin, Ethiopia. The overall target of the examination was to explore the supply siltation and assurance of the current stockpiling limit of the repository utilizing ArcGIS 10.5 variant and Golden surfer 16 most recent rendition. A bathymetric study utilizing reverberation sounding gear (Garmin GPSMAP421s) was directed for appraisal of present-day impoundment of the repository, and a pre-impoundment geographical guide of the store was inferred by digitizing existing geological guide utilized during dam development. Bathymetric differencing was utilized to explore and measure the circulation and gauge volumes of kept residue, long haul normal yearly silt motions, and remaining water stockpiling limit. The consequence of the examination uncovered that to date, 343,700.1 m3 volume of residue was amassed in the supply that decreases 20% of the complete store limit. Results from the bathymetric examination and programming investigation, every year a sum of 28,641.675 m3 year−1 measure of residue is keeping to the supply that contributed 1.66% of yearly repository volume decrease. This was determined by partitioning the aggregated volume of residue to the past worked year of the repository by considering a similar measure of dregs that have been storing in each working year. The deliberate late putting-away limit with respect to the Abrajit Dam was determined by taking away the assessed cumulative silt volume from the plan stockpiling of the repository, and it is 1,388,870 m3. From a correlation of residual repository stockpiling and yearly dregs load, the store would not serve over 12 years. The evaluated explicit residue yield was seen as 4733.387 ton km−2 year−1. In this manner, to improve the evaluated life range of supply watershed the executives are significant and further examination is required to recognize the region where watershed protection will concentrate on what’s to come. Upon the discoveries, the store volume is rushing to decrease and it cannot serve all the interest what it intended for during the dry season. Therefore, activity bends ought to be required to give water administration for the basic water needs, and regular observing of silt gathering in the store is suggested.

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Examining Reservoir Sedimentation and Estimating Dam Stockpiling Limit Utilizing Bathymetry Overview: A Contextual Investigation of Abrajit Dam, North Gojjam Sub-basin, Blue Nile basin, Ethiopia

Roman Abebe

Papers

A spatial analysis and modeling study of sedimentation impacts on dams found in south Gondar zone, Ethiopia

Reservoir sedimentation and estimating dam storage capacity using bathymetry survey: a case study of Abrajit Dam, Upper Blue Nile basin, Ethiopia

Examining Reservoir Sedimentation and Estimating Dam Stockpiling Limit Utilizing Bathymetry Overview: A Contextual Investigation of Abrajit Dam, North Gojjam Sub-basin, Blue Nile basin, Ethiopia