Predictings Sediment Loading into Masinga Reservoir and its Storage Capacity Reduction (original) (raw)
Related papers
2014
Abstract: It is estimated that the annual loss in storage capacity of the world’s reservoirs due to sedimentation is around 0.5 – 1.0%. For many reservoirs, however, annual depletion rates are much higher and can go up to 4 % or 5%, such that they lose the majority of their capacity after only 25 – 30 years. The Masinga reservoir, one of the main reservoirs in Kenya, designed for hydropower generation, public water supply and irrigation is faced with severe sedimentation. The designed sediment load into this reservoir in 1981 was estimated to be 3.0 x 106 m3 per year (about 1 % per annum reservoir reduction). By 2000, annual sediment loading had increased to over 11.0 x 106 m3, nearly four times, thus reducing the designed capacity by more than 15%. As land degradation has become more evident with increasing land use change within Masinga catchment over the years, the operation and life span of Masinga reservoir is thus under imminent danger from erosion and sedimentation. There is ...
Evaluation of Sediment Management Strategies on Reservoir Storage Depletion Rate: A Case Study
Doboku Gakkai Ronbunshuu B, 2010
Sedimentation aspects have a major role during the design of new reservoir projects because life of the reservoir mainly depends upon sediment handling during reservoir operation. Therefore, proper sediment management strategies should be adopted to enhance the life span of reservoirs. Basha Reservoir is one of the mega water resources projects which are being planned to construct on the Indus river. Under this study, the efficiency of four sediment management strategies were evaluated by using the RESSASS model. The reservoir management strategies considered for sediment simulation of Basha reservoir include the normal operation, raising of MoL, draw-down the MoL (flushing) and controlling the sediment inflows. Under normal operation, the model predicted the life span of Basha reservoir around 55-60 years. But by raising of Mol 2.0 m/year implemented after 35 years of operation may add 10-15 years more to the lifespan of the reservoir. However, by adopting the flushing operation to draw-down the MoL at El. 1010 m initiated after 35 years of operation, it may also add about 15-20 years more. Moreover, the results obtained by considering 50% reduction in sediment inflow due to implementation of river basin management projects upstream of Basha within 30 years of reservoir operation, depicts that the life of the reservoir will be more than 100 years. It is therefore concluded that proper sediment mitigation measure can significantly enhance the lifespan of planned reservoirs.
Irrigation and Drainage Systems
This paper introduces a combined modelling approach using a simple water budget model (THC-model) and a 3D reservoir sedimentation model (MOHID Water) to adapt reservoir operation and visualise their effects on the sediment deposition. By this, an effective combined sediment-water management can be identified under semi-arid conditions for dry, median and wet years. Results are presented for the reservoirs of the Tuyamuyun Hydro-Complex (THC), which is located in the lower Amu Darya River. The determination of the actual and usable reservoir storage volume shows that siltation will significantly adversely affect the ability of the in-stream Channel Reservoir to regulate seasonal demand for both irrigation and municipal water supply. However, modelling scenarios results confirm the effectiveness of adapted operation rules for the THC reservoirs and show that the operation of large dams could be modified according to a combined sediment-water management. The experience gained during this study emphasizes the fact that the concept of a combined reservoir management of sediments as well as water can be an efficient measure to improve the sustainable long-term use of reservoirs and to contribute towards a safe water supply in water crisis regions.
Applied Water Science
Globally the average annual loss of reservoir capacity is approximately 1%. Pakistan is confronting major issue of sedimentation which is continuously depleting the useful storage of reservoirs. GSTARS3 model was used to determine the rate of deposition and sediment pattern of Chashma Reservoir since its operation. The model was calibrated and validated for bathymetric survey of 2008 and 2012. The results of GSTARS3 were incorporated to a GIS software to visualize sediment accumulation in reservoir. The study reveals that sediment flushing of the Chashma Reservoir can be carried out during flood season at a pond level of 638.15 ft. (194.51 m). However, its negative impact if any on the hydropower generation needs to be analysed. Accordingly, modified operation rules would be required.
SCENARIOS OF SEDIMENT CONTROL SOLUTION FOR MRICA RESERVOIR, BANJARNEGARA, CENTRAL JAVA, INDONESIA
Situated in the main catchment area of the Great Serayu River, the reservoir with its 148.29 million m3should last 60 years from 1988. However, due to bad land use condition on its upper stream, it is estimated that its life will only last for another 12 years. Data from 2011 had shown that 59.49 million m3 has covered by sediment, which meant that 60% from of its efective volume is left for the reservoir to function. The reservoir’s electricity plant(PT. Indonesia Power) produced an average of 180,000 MWH per year, which meant that it supplies electricity for the whole Java island. This prospect will threaten to paralizethe economy of Indonesia. Moreover, we are also facing extreme condition caused by climate change.There is the need to seek solution to address this serious sedimentation problem. In this paper, several scenarios are presented. They include technical solutions such as sediment control dams, Sabo System, Garung Scheme, Asahi Scheme, and a non- technical solution, which isLand Use Planning. Each of the schemes will be elaborately explained and conceptually presented to proof each advantage and disadvantage dealing withsedimentation.Since this is a study of solution scenarios for an important environmental usage and it corresponds directly to human safety, a risk assessment is used as the method to grade each scenario. Using parameters to assess these scenarios based on vulnerability assessment concept by BBC (Bogardi, Birkmann, Cardona)each will be assessed in terms ofsocial, environmental and economical point of view. This study will provide the authorities of Mrica Reservoir and related stakeholdersto control further sedimentation process, and even to alleviate this problem in the future.
Sediment distribution and its impacts on Hirakud Reservoir (India) storage capacity
Lakes & Reservoirs: Science, Policy and Management for Sustainable Use, 2016
Construction of dams causes reduced flow velocities, inducing gradual deposition of sediments carried by the inflowing stream, and resulting in sedimentation and ultimately diminishing reservoir storage capacity. This study focuses on sedimentation of Hirakud Reservoir in Odisha, India, using available reservoir capacity and numerical simulation data. Reduced trap efficiency, observed and projected capacity curves, rising reservoir bed level and the capacities of the different storage zones for various projected years are analysed. The area-reduction method indicates the loss in the live, gross and dead storage will be 58%, 63% and 100%, respectively, of their original capacities by 2057, which represents 100 years of impounding of water in the reservoir. If the present sediment inflow rate continues without regular flushing of the deposited sediment, it is predicted the reservoir bed level will rise to the full reservoir level of 192.02 m by the year 2110. Brune's trap efficiency and step method indicate the gross storage zone of Hirakud Reservoir will be completely depleted by the end of 2110, with the trap efficiency reduced to zero. The empirical area-reduction method is found to be more suitable for determining the storage capacities of Hirakud Reservoir in the absence of sedimentation survey data. An attempt was also made to solve the combined hydrodynamic and sediment transport equations numerically to predict morphological changes in Hirakud Reservoir. The finite-element code TELEMAC-2D and finite-volume code for SISYPHE, respectively, were applied to solve the above set of equations in order to predict the bed profiles at different reservoir cross sections for the period of 1958-2008. Analysis of the simulated results demonstrates that, considering the model inputs, the model performs well in simulating the morphology and dynamic characteristics of a reservoir. Projection of the numerical results indicates a complete loss of reservoir operational life due to sedimentation by around 2150.
Applied Geomatics, 2020
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 m 3 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 m 3 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 m 3. 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.
Sedimentation Problem in Khassa Chai Reservoir and Methods of Combat
Tikrit University College of Engineering Civil Engineering Department , 2014
Reservoir sedimentation is one of the severe problems which faces dams as sediments occupy spaces within reservoirs storage, hence, decreasing live water storage which is the main purpose of dams construction. Iraq is one of the countries that will face significant shortage in water income as a result of both the increment in water demand and of the reduction of water shares from the source countries. Thus, the existing dams in the Iraq represent a strategic resource to fulfil water demands, and the sedimentation at these dams are studied to assess the quantity of sediments that reach to these reservoirs and decrease available water volume and useful life of reservoir. In the current study, Khassa Chai Dam, which is still under construction, located in the north east of Iraq and its main watershed basin covers an area of about 412 km2 between Kirkuk and Al Sulaymaniyah governorates has been selected to estimate and predict the amount of sediment yield based on 30 years of daily climate data and the events of different intensity rainstorms. AGWA (Automated Geospatial Watershed Assessment tool) model has been used to simulate Khassa Chai Dam catchment area. This model utilizes the GIS (Geographic Information System) application to analyse the required data from GIS layer for DEM (Digital Elevation Model), Soil type, Land use and Land cover by interference with the required climate data. The results of this study identified the amount of sediment yield and water inflow to the reservoir. They also identified the sub watersheds which have high affinity for soil erosion, sediment yield, and delivery ratio within the main catchment area watershed manage these sub watersheds by applying certain techniques and methods which may decrease the sediment yield that reaches to the reservoir.
Zenodo (CERN European Organization for Nuclear Research), 2022
Sengguruh and Sutami Reservoir are facing severe sedimentation problems, that causes a significant decrease in storage capacity. Sengguruh Reservoir leaves ± 5.85% of the initial capacity, while the Sutami Reservoir only leaves ± 51.94% of the initial capacity which affects the capacity of energy generation, fulfillment of irrigation water, raw water and flood control. Erosion and sedimentation analysis was carried out using the USLE method to determine sedimentation potential based on 2019 land use, reservoir storage capacity analysis using bathymetry results to determine sedimentation rates and prediction of reservoir life, and sediment balance analysis to determine appropriate sediment management efforts. Integrated sediment management from upstream to downstream (reservoir) is a solution. Watershed conservation is the most important effort in sediment management, because watershed conservation can reduce sedimentation potential by 3,16%. Management and construction of sediment control structures on the Brantas River and Lesti River as well as construction of retaining structures and waste processing at the settlement pond location upstream of the Sengguruh Reservoir can reduce reservoir sedimentation by 6.95%. Sediment dredging of 250,000 m 3 /yr for Sengguruh Reservoir and flushing every 3 (three) years can increase the storage capacity by 9.45%. Meanwhile, in Sutami Reservoir, through dredging efforts of at least 400,000 m 3 /yr, can maintain the function of the reservoir for the next 135 years.
Journal of King Saud University - Engineering Sciences, 2016
In this study, a calibrated hydrologic model, Soil and Water Assessment Tool (SWAT) interfaced with Geographical Information System (GIS) tool was used to study the effect of different sediment management methods in a watershed (12,992 km 2) upstream of Jebba Lake, Nigeria. Sediment management strategies considered are (i) reforestation of the watershed, (ii) application of vegetative filter strip (VFS) and (iii) construction of stone bunds. Cost analysis of implementing the selected erosion control measures within the watershed was also carried out to compare the cost effectiveness of each of the management strategies. The results showed that application of VFS, reforestation, and stone bunds to critical zones of the watershed reduced the sediment yield up to 65.6%, 63.4% and 12% respectively while the financial analysis of implementing reforestation, VFS and stone bunds revealed 84.9%, 73.3% and 70.5% reduction respectively in the costs to be incurred if sediments are allowed to accumulate in the dam. From this analysis, it can be concluded that the sediment management scenarios considered in this study are cost effective and sustainable when compared with the costs incurred in tackling the effect due to reservoir sedimentation. Overall, the study showed that hydrological models such as SWAT can be used to study strategies for water resource management. In addition, it can provide policy makers the decision support tools to evaluate the cost and benefits of adopting Best Management Practices (BMPs) particularly for sediment control in erosion prone watersheds.