scholarly journals Revisiting Water Supply Rule Curves with Hedging Theory for Climate Change Adaptation

2019 ◽  
Vol 11 (7) ◽  
pp. 1827 ◽  
Author(s):  
Wenhua Wan ◽  
Jianshi Zhao ◽  
Jiabiao Wang
Keyword(s):  
Water Supply ◽  
Reservoir Operation ◽  
Flood Control ◽  
Climate Adaptation ◽  
Changing Environment ◽  
Specific Expression ◽  
Rule Curves ◽  
Operation Rule ◽  
Practical Tool ◽  
Adaptive Operation

Conventional reservoir operation rule curves are based on the assumption of hydrological stationarity. The aggravating non-stationarity under the changing environment rocked this foundation. The hedging theory is one of the options for adaptive operation based on hydrological forecasts, which can provide a practical tool for optimal reservoir operation under a changing environment. However, the connections between hedging theory and rule curves are not clear. This paper establishes the linkage of rule curves and hedging theory by analyzing three fundamental problems surrounding the design of conventional rule curves, namely the law and design of water supply rule curves, the determination of flood control storage, and the division of refill and drawdown circle. The general interpretation of the conventional water supply rule curves with hedging theory is conducted. Both the theoretical analyses and the Danjiangkou Reservoir case study reveal that, based on the historical records, the rule curves can be interpreted as a specific expression of hedging theory. This intrinsic linkage allows us to propose a more general and scientific method of updating rule curves in the context of non-stationarity. On this basis, the rule-curve-based climate adaptation strategies are figured out using hedging theory. This research is helpful for practical adaptive operation of reservoirs in the changing environment.

Identifying the key water levels in reservoir operation on ecological objectives

2014 ◽  
Vol 14 (6) ◽  
pp. 1160-1167 ◽  
Author(s):  
Haixia Wang ◽  
Jinggang Chu ◽  
Chi Zhang ◽  
Huicheng Zhou
Keyword(s):  
Water Supply ◽  
Water Level ◽  
Reservoir Operation ◽  
Water Levels ◽  
Rule Curves ◽  
Operation Rules ◽  
Operation Rule ◽  
Water Level Variations ◽  
Time Periods ◽  
Ecological Objectives

This paper investigates the influences of reservoir water level variations of the operation rule curves on different objectives, especially on ecological objectives. Five representative ecological objectives are selected besides industrial and domestic (I&D) and agricultural water supply objectives. They can reflect the impacts of reservoir operation on different attributes of ecological flow regime in the Biliuhe Reservoir case study, Northeastern China. Sensitivities of water supply and ecological objectives caused by water level variations of I&D and agricultural operation rule curves are analyzed by using a variance-based sensitivity analysis method – Sobol's method. Results show that impacts of individual water levels and their interactions on ecological objectives are very different. Also the ecological objectives do not always conflict with water supply objectives. This study provides new insights for reservoir managers to improve downstream aquatic ecosystem by adjusting water levels not only at individual time periods but also at some interacting time periods. Furthermore, it helps us better understand the influence mechanism of water level changes on different objectives, and provides guidance for the development of reservoir operation rules.

Deriving reservoir operating rules considering ecological demands of multiple stations

2021 ◽  
pp. 1-59
Author(s):  
Chen Wu ◽  
Yibo Wang ◽  
Jing Ji ◽  
Pan Liu ◽  
Liping Li ◽  
...  
Keyword(s):  
Reservoir Operation ◽  
Flood Control ◽  
Optimization Models ◽  
Ecological Indicator ◽  
Generation Model ◽  
Hydropower Generation ◽  
Rule Curves ◽  
Constraints Model ◽  
Operating Rule ◽  
Operating Rule Curves

Reservoirs play important roles in hydropower generation, flood control, water supply, and navigation. However, the regulation of reservoirs is challenged due to their adverse influences on river ecosystems. This study uses ecoflow as an ecological indicator for reservoir operation to indicate the extent of natural flow alteration. Three reservoir optimization models are established to derive ecological operating rule curves. Model 1 only considers the maximization of average annual hydropower generation and the assurance rate of hydropower generation. Model 2 incorporates ecological objectives and constraints. Model 3 not only considers the hydropower objectives but also simulates the runoff and calculates the ecological indicator values of multiple downstream stations. The three models are optimized by a simulation-optimization framework. The reservoir ecological operating rule curves are derived for the case study of China's Three Gorges Reservoir. The results represent feasible schemes for reservoir operation by considering both hydropower and ecological demands. The average annual power generation and assurance rate of a preferred optimized scheme for Model 3 are increased by 1.06% and 2.50%, respectively. Furthermore, ecological benefits of the three hydrologic stations are also improved. In summary, the ecological indicator ecoflow and optimization models could be helpful for reservoir ecological operations.

Real-Time Reservoir Operation by Tree-Based Model Predictive Control Including Forecast Uncertainty

2020 ◽  
Author(s):  
Gokcen Uysal ◽  
Rodolfo-Alvarado Montero ◽  
Dirk Schwanenberg ◽  
Aynur Sensoy
Keyword(s):  
Water Supply ◽  
Real Time ◽  
Predictive Control ◽  
Reservoir Operation ◽  
Lead Time ◽  
Flood Control ◽  
Closed Loop ◽  
Multi Stage ◽  
Streamflow Forecasts ◽  
Related Technique

<p>Streamflow forecasts include uncertainties related with initial conditions, model forcings, hydrological model structure and parameters. Ensemble streamflow forecasts can capture forecast uncertainties by having spread forecast members. Integration of these forecast members into real-time operational decision models which deals with different objectives such as flood control, water supply or energy production are still rare. This study aims to use ensemble streamflows as input of the recurrent reservoir operation problem which can incorporate (i) forecast uncertainty, (ii) forecasts with a higher lead-time and (iii) a higher stability. A related technique for decision making is multi-stage stochastic optimization using scenario trees, referred to as Tree-based Model Predictive Control (TB-MPC). This approach reduces the number of ensemble members by its tree generation algorithms using all trajectories and then proper problem formulation is set by Multi-Stage Stochastic Programming. The method is relatively new in reservoir operation, especially closed-loop hindcasting experiments and its assessment is quite rare in the literature. The aim of this study is to set a TB-MPC based real-time reservoir operation with hindcasting experiments. To that end, first hourly deterministic streamflows having one single member are produced using an observed flood hydrograph. Deterministic forecasts are tested with conventional deterministic optimization setup. Secondly, hourly ensemble streamflow forecasts having a lead-time up to 48 hours are produced by a novel approach which explicitly presents dynamic uncertainty evolution. Produced ensemble members are directly provided to input to related technique. Uncertainty becomes much larger when managing small basins and small rivers. Thus, the methodology is applied to the Yuvacik dam reservoir, fed by a catchment area of 258 km<sup>2</sup> and located in Turkey, owing to its challenging flood control and water supply operation due to downstream flow constraints. According to the results, stochastic optimization outperforms conventional counterpart by considering uncertainty in terms of flood metrics without discarding water supply purposes. The closed-loop hindcasting experiment scenarios demonstrate the robustness of the system developed against biased information. In conclusion, ensemble streamflows produced from single member can be employed to TB-MPC for better real-time management of a reservoir control system.</p>

scholarly journals Optimal Multi-Reservoir Operation for Hydropower Production in the Nam Ngum River Basin

2020 ◽  
Vol 24 (5) ◽  
pp. 1-13
Author(s):  
Bounhome Kimmany ◽  
Piyatida Ruangrassamee ◽  
Supattra Visessri
Keyword(s):  
Water Balance ◽  
River Basin ◽  
Balance Equation ◽  
Optimization Model ◽  
Reservoir Operation ◽  
Water Balance Equation ◽  
Rule Curves ◽  
Minlp Model ◽  
Hydropower Production ◽  
Operation Rule

This research aims to investigate optimal hydropower production of multi-reservoirs in Lao PDR and develop optimal reservoir rule curves. The Nam Ngum 1 and 2 (NN1 and NN2, respectively) reservoirs in the Nam Ngum River basin (NNRB), which is located in the middle of Laos, are selected as study areas. Mixed integer nonlinear programming (MINLP) is developed as an optimization model to maximize the hydropower production of joint reservoir operation of NN1 and NN2. The optimal operation rule curves are established by using the storage level estimated by the optimization model. Given the limited sideflow data, an integrated flood analysis system (IFAS) and water balance equation are used to simulate the sideflow into NN1 reservoir. A good fit is observed between the monthly streamflow simulated by IFAS and that calculated by the water balance equation. Compared with the observed data, the MINLP model can increase the annual and monthly hydropower production by 20.22% (6.01% and 14.21% for NN1 and NN2, respectively). The water storage level estimated by the MINLP model is used to build the operation rule curves. Results show that the MINLP model of multi-reservoir is a useful and effective approach for multi-reservoir operations and is expected to hold high application value for similar reservoirs in NNRB.

scholarly journals Dynamic rule curves for multipurpose reservoir operation for different floods

2019 ◽  
Vol 11 (4) ◽  
pp. 1001-1008
Author(s):  
C. Chaleeraktrakoon ◽  
A. Worawiwat
Keyword(s):  
Climate Change ◽  
Impact Assessment ◽  
Return Period ◽  
Reservoir Operation ◽  
Flood Control ◽  
Peak Discharge ◽  
Operational Performance ◽  
Rule Curves ◽  
Stepwise Manner ◽  
Multipurpose Reservoir

Abstract Dynamic flood control rule curves (DFCRCs) that balance the use of conservation space between flood control and conservation purposes are usually necessary for the operation of a multipurpose reservoir. This paper therefore proposes a procedure to apply the DFCRCs of an historically-based actual flood for reservoir operation versus different floods whose hydrograph shapes vary widely. The proposal uses related-size characteristics (e.g. net retention of the DFCRCs and peak discharge of associated outflows) in a stepwise manner from those of the smallest return period to those of the largest one. Illustrative applications of the procedure to the operation of the multipurpose Ubol Ratana Dam (The Nam Pong Basin, Thailand) have indicated that it enables the DFCRCs to ensure the reservoir's operation against various floods. Its operational results for the large and moderate floods in 1990 and 1995 are comparable to those of historically based floods. In addition, impact assessment of climate change on the operational performance has shown that the system could not protect the areas upstream and downstream of the dam from the HadCM3A2 and HadCM3B2 floods at the 80th and 95th percentile levels during the future 2050s period.

scholarly journals Collaborative and Adaptive Dam Operation for Flood Control

2018 ◽  
Vol 13 (4) ◽  
pp. 660-667
Author(s):  
Kenji Someya ◽  
Keyword(s):  
Flood Control ◽  
River Flow ◽  
Flood Damage ◽  
Extra Effort ◽  
Flow Capacity ◽  
The People ◽  
Integrated Operation ◽  
Operation Rule ◽  
Dam Operation ◽  
Adaptive Operation

Flood control by a dam is generally executed to follow the predetermined operation rule, which can determine the required outflow discharge in accordance with the change in inflow. However, when flood damage could be reduced by using the dam flood control capacity to its limit, the dam would be expected to store as much water as possible without any regard to the predetermined operation. Occasionally, an adaptive operation for flood control would be effective in such cases, for example, to reduce dam outflow discharge compared to the predetermined outflow discharge to match river flow capacity, which is low in some downstream parts of a dam, or to ease one river to flow down quickly by storing and retarding another river flow by dams. However, such an adaptive operation is non-typical and requires extra effort in addition to being risky to dam managers and the people along the rivers. This paper introduces two cases of adaptive flood control for the flood control executed in the Yodo river in 2009 and 2013 and then describes the systems applied in the Kizugawa Dams Integrated Operation and Management Office (KDIIMO), Japan Water Agency (JWA) to execute an adaptive operation for flood control in a safer manner.

scholarly journals Multiobjective water resources systems analysis using genetic algorithms - application to Chou-Shui River Basin, Taiwan

2003 ◽  
Vol 48 (10) ◽  
pp. 71-77 ◽  
Author(s):  
J.-T. Kuo ◽  
W.-C. Cheng ◽  
L. Chen
Keyword(s):  
Genetic Algorithms ◽  
Water Supply ◽  
River Basin ◽  
Research Work ◽  
Weighting Method ◽  
Trade Off ◽  
Water Resources Systems ◽  
Weighting Factors ◽  
Rule Curves ◽  
Central Taiwan

Multipurpose operation is adopted by most reservoirs in Taiwan in order to maximize the benefits of power generation, water supply, irrigation and recreational purposes. A multiobjective approach can be used to obtain trade-off curves among these multipurpose targets. The weighting method, in which different weighting factors are used for different purposes, was used in this research work. In Taiwan, most major reservoirs are operated by rule curves. Genetic algorithms with characteristics of artificial intelligence were applied to obtain the optimal rule curves of the multireservoir system under multipurpose operation in Chou-Shui River Basin in central Taiwan. The model results reveal that different shapes of rule curves under different weighting factors on targets can be efficiently obtained by genetic algorithms. Pareto optimal solutions for a trade-off between water supply and hydropower were obtained and analyzed.

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