Utilizing inactive storage in a dam reservoir during extreme drought periods (original) (raw)
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Role of storage dams in management of water during drought periods
Iran is an arid and semi-arid country. Storage dams have played a valuable role in controlling of destructive floods and management of water usage. A number of large dams have become dry in recent years due to long droughts and over-withdrawals. Environmental experts have exploited this as a pretext against storage dams considering dam construction in Iran being wasteful and unsystematic. Storage dams have, in an intangible manner, a more valuable role during drought periods than during wet periods. A significant example is Sepidroud dam. Despite the recent 15-year drought, over-withdrawals and construction of several storage dams upstream, its 1750 MCM big reservoir spilled downstream during a recent flood. Performance of Sepidroud dam and its role in management of runoff in great Qezel Owzan basin will be analyzed along with investigation of changes in rainfall depth and pattern, runoff coefficients, and occurred droughts and floods in different basins in Iran. Recent droughts, over-withdrawals from water resources, effects of construction of storage dams upstream, and interbasin water transfer will be investigated to better represent the magnificent role of Sepidroud dam. Investigation shows empty reservoirs of dams during drought periods may not indicate to carry over design of dams and their wastefulness.
Optimum operation of storage dams, case study: Gorganroud basin, Golestan dam, I.R. Iran
Construction of storage dams is one of the most effective, though cost consuming, methods of water resources management. Role of hydrology in a dam system design is very important. Estimation of sediment yield, floods magnitudes and volumes, potential basin yield and selection of required volume of reservoir for flood control play considerable role in sizing a dam and its reservoir and in preparation of its operation guideline. These whole are of great importance in management of water resources in a basin. If flood forecast and warning system is installed properly, based on hydrologic studies, in upstream subbasins of a dam, allocating reasonable volume of reservoir for flood routing, with its operation guideline, would be possible. This would prevent occurrence of serious damages and losses at downstream. Moreover, floods would be stored to be used to meet perpetual demands.
TECHNICAL NOTES Drought Storage Allocation Rules for Surface Reservoir Systems
This technical note develops a simple drought storage allocation rule to minimize evaporative and seepage water losses from a system of reservoirs. Such a rule might have value during a prolonged drought, when the value of lost water is likely to be particularly high. Typically, concentrating water storage in one or a few reservoirs reduces overall water losses compared to "balancing" storage among reservoirs. Paradoxically, concentrating storage during a drought tends to minimize reservoir surface area available for recreation, increasing recreation losses even as it minimizes water losses.
Evaluation of variation of useful storage of reservoir in stream dams by GSTARS3 software
African journal of agricultural research
Stream dams are small dams. If the conditions of site are not suitable for construction of reservoir dams, stream dams will be constructed. These dams have small reservoirs. These dams are without gate or these are controlled by gates. The major problem of stream dams is sedimentation special in rivers with high sediment load. In gated stream dams, flushing is accomplished by opening of the gates in flood condition. Construction of physical model is very difficult for evaluation of efficiency of flushing in removal sediment from reservoir of stream dam. Also the cost of construction of physical model is very high. Development of mathematical models is essential for modeling of successive processes of sedimentation and flushing in useful lifetime of stream dams. Because of variation of boundary conditions in successive processes of sedimentation and flushing of gated stream dams, Available mathematical models can not model continuously these processes at total of yield period. In this research, the long term sedimentation and flushing process will be simulated by development of a mathematical model. Modified mathematical model can simulate successive processes of sedimentation and flushing in useful lifetime of stream dams for different conditions of use of reservoir. The time and cost of simulation by modified mathematical model is very low. Also accuracy of this model is acceptable for simulation. In this research, the case study is successive stream dams on the Dez River in Iran (Dez1 Dam, Dez2 Dam and Dez3 dam) for evaluation of efficiency of modified mathematical model.
Mathematical Analysis for the Loss of Future Storage Capacity at Maithon Reservoir, India
2013
Reservoir siltation is inevitable because of continuous deposition of silts, pollutants etc due to soil erosion from upstream part of river and domestic / industrial waste intrusion in the river. The pace of siltation process can only be retarded which would indirectly aid to life of the reservoir. This paper presents a study on the future storage capability along with reliability in the serviceability of the Maithon reservoir, India. The surveyed capacity elevation data for the year 1956, 1965, 1971, 1979, 1987, 1994, 2002 and 2010 were considered for the analysis. A graphical relation for storage loss at different stages such as dead storage, live storage, flood storage level and overall capacity loss are presented. Mathematically linear trend equations of the above relations are developed with vide validation with the original surveyed data. From the above equations the loss of storage capacity in the future years are also found out at the various stages of the reservoir storage.
News Storing Water in Dam Reservoirs: Why is it Necessary ?
SUMMARY The world population is growing by leaps and bounds and the impact of this growth on water resources is such that we shall need more water for drinking, agriculture, energy generation, industrial production, and so on. Moreover, lifestyle is changing all over the world and a direct impact of this trend is a very significant increase in water use. For these reasons, demand for water is steadily increasing throughout the world. However, freshwater resources are limited and unevenly distributed both in time and place. In addition to this, seasonal variations and climatic irregularities in flow lead to the inefficient use of river 1 runoff, with flooding and drought causing problems of catastrophic proportions. From the beginning of the human history, for almost 5 000 years, dams have served to ensure an adequate supply of water by storing water in times of surplus and releasing it in times of scarcity, thus also preventing or mitigating floods and making a significant contribution to the efficient management of finite water resources that are unevenly distributed and subject to large seasonal fluctuations. In the other words, the construction of dams in the concept of water resources management has always been considered as a basic requirement to harmonize the natural hydrological regime with the human needs for water and water related services. Purposes to be served by such a project usually include water supply, irrigation, flood control, hydropower generation, navigation, recreation, pollution abatement, industrial use, fish and wildlife conservation and other environmental considerations, salinity and sediment control, and recharge of groundwater. To meet these purposes, a number of dams are constructed to control and regulate the natural flows. This regulation function is obviously the main reason for creating reservoirs by constructing dams.
Watershed Sediment and Its Effect on Storage Capacity: Case Study of Dokan Dam Reservoir
Water, 2018
Dokan is a multipurpose dam located on the Lesser Zab River in the Iraq/Kurdistan region. The dam has operated since 1959, and it drains an area of 11,690 km 2. All reservoirs in the world suffer from sediment deposition. It is one of the main problems for reservoir life sustainability. Sustainable reservoir sediment-management practices enable the reservoir to function for a longer period of time by reducing reservoir sedimentation. This study aims to assess the annual runoff and sediment loads of the Dokan Dam watershed using the soil and water assessment tool (SWAT) model to evaluate the relative contributions in comparison with the total values delivered from both watershed and Lesser Zab River and to identify the basins with a high sediment load per unit area. These help in the process of developing a plan and strategy to manage sediment inflow and deposition. The SUFI-2 program was applied for a model calibrated based on the available field measurements of the adjacent Derbendekhan Dam watershed, which has similar geological formations, characteristics and weather. For the calibration period (1961-1968), the considered statistical criteria of determination coefficients and Nash-Sutcliffe model efficiency were 0.75 and 0.64 for runoff while the coefficients were 0.65 and 0.63 for sediment load, respectively. The regionalization technique for parameter transformation from Derbendekhan to Dokan watershed was applied. Furthermore, the model was validated based on transformed parameters and the available observed flow at the Dokan watershed for the period (1961-1964); they gave reasonable results for the determination coefficients and Nash-Sutcliffe model efficiency, which were 0.68 and 0.64, respectively. The results of SWAT project simulation for Dokan watershed for the period (1959-2014) indicated that the average annual runoff volume which entered the reservoir was about 2100 million cubic meters (MCM). The total sediment delivered to the reservoir was about 72 MCM over the 56 years of dam life, which is equivalent to 10% of the reservoir dead storage. Two regression formulas were presented to correlate the annual runoff volume and sediment load with annual rain depth for the studied area. In addition, a spatial distribution of average annual sediment load was constructed to identify the sub basin of the high contribution of sediment load.
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.
A Novel Methodology for Multiple-Year Regulation of Reservoir Active Storage Capacity
Water
Reservoir design entails the determination of the required storage capacity over multiple years of low flow conditions to ensure the coverage of multiple-purpose water demands. Dam operation depends on many factors that may result in the decrease of required safe yields, leading to inadequate outflow supplies in the design period. This study addresses two issues: (a) the computation of reservoir active storage capacity performed with the aid of the new concept of a zero-height dam, a procedure easy to interpret physically and implement computationally; and (b) the generation of appropriate inflow data, provided that a substantial record of monthly inflows is available. The treatment of the inflow data for the generation of inflow sequences for any desired regulation period is performed by two original methods (First and Second), which are entirely different from other available methods and allow for the selection of a reservoir capacity with the desired level of exceedance probabili...
Sustainability
Reservoir sedimentation is often seen as a site-specific process and is usually assessed at an individual reservoir level. At the same time, it takes place everywhere in the world. However, estimates of storage losses globally are largely lacking. In this study, earlier proposed estimates of sedimentation rates are applied, for the first time, to 47,403 large dams in 150 countries to estimate cumulative reservoir storage losses at country, regional, and global scales. These losses are estimated for the time horizons of 2022, 2030, and 2050. It is shown that 6316 billion m3 of initial global storage in these dams will decline to 4665 billion m3 causing a 26% storage loss by 2050. By now, major regions of the world have already lost 13–19% of their initially available water storage. Asia-Pacific and African regions will likely experience relatively smaller storage losses in the next 25+ years compared to the Americas or Europe. On a country level, Seychelles, Japan, Ireland, Panama, a...