Search

Reservoir operations are influenced by hydroclimatic variability, reservoir characteristics (i.e., size and purpose), policy regulation, as well as operators' experiences and justification. Data‐driven reservoir operation models based on long‐term historical records shed light on understanding reservoir operation rules and patterns. This study applies generic data‐driven reservoir operation models (GDROMs) developed for 452 data‐rich reservoirs with diversified operation purposes across the CONUS to explore typical operation rules and patterns. We find that the operating policies of any of these reservoirs can be modeled with a small number (1–8) of typical operation modules. The derived modules applied to different conditions of the 452 reservoirs can be categorized into five basic types, that is, constant release, inflow‐driven piecewise constant release, inflow‐driven linear release, storage‐driven piecewise constant release, and storage‐driven nonlinear (or piecewise linear) release. Additionally, a joint‐driven release module, constructed from these five basic types, has been identified. The analysis further shows the module application transition patterns featuring operation dynamics for reservoirs of different operation purposes, sizes, and locations. The typical module types can be used as "Lego" bricks to build operation models, especially for data‐scarce reservoirs. These module types and their application and transition conditions can inform Standard Operation Policy (SOP) and Hedging Policy (HP) with specific inflow, storage, and/or both conditions. Key Points: Five basic types of operation modules are categorized for 452 reservoirsSeasonal patterns for module application transition are identified for reservoirs with different sizes, operation purposes, and locationsThe basic types of modules and operation patterns inform reservoir operation modeling [ABSTRACT FROM AUTHOR]

Copyright of Journal of Drainage & Irrigation Machinery Engineering / Paiguan Jixie Gongcheng Xuebao is the property of Editorial Department of Drainage & Irrigation Machinery Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Ordnance Industry Automation is the property of Editorial Board for Ordnance Industry Automation and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Reservoir operation rule curves are crucial for managing water supply and power generation in reservoirs. As the number of objectives and management requirements increase, there is a growing demand for optimized operation rule curves. The objective of this study is to explore the most effective forms of reservoir operation rule curves, focusing on the case of the Nierji Reservoir and considering the dual objectives of water supply and power generation. The parameter–simulation–optimization framework, specifically employing the NSGA-II algorithm, was used to analyze and compare two basic forms of operation rule curves: the shared type and independent type. The impact of these curves on water supply potential and multi-objective optimization results with various water demand scenarios was assessed. The analysis revealed that the choice of operation rule curve form can influence the maximum water supply potential of the reservoir to some extent. The independent type operation rule curve was significantly more effective in enhancing the water supply potential for industrial and domestic users, resulting in a notable increase of 3.5 × 108 m3. Additionally, it also proved beneficial for environmental users, with an increase of 1 × 108 m3. Conversely, the shared type operation rule curve demonstrated similar functionality to the independent type curve with fewer decision variables, particularly when the water demand was relatively low. In scenarios with high water demand, the independent type curve outperformed the shared type curve by generating 6549 superior, non-dominated solutions for multi-objective optimization, specifically focused on maximizing reservoir operation benefits. In conclusion, selecting the appropriate form of reservoir operation rule curve is crucial to balance different reservoir functional objectives and achieve optimal results. Further research could focus on quantifying the specific benefits and trade-offs associated with each type of curve in order to provide more robust evidence for the advantages of a complex reservoir system. [ABSTRACT FROM AUTHOR]

In order to reveal the mathematical mechanism of generating grey numbers and the law of grey number evolution, the extension principle of grey set is proposed in this paper firstly, which provides a theoretical basis for grey number operation. Secondly, based on the possibility function of grey set, the concept and properties of grey convex set are given. According to grey convex set, the definitions of grey real number, universal grey real number and interval grey number are put forward. Thirdly, the basic operation rules of grey real number are given based on the extension principle, and the operations of data block expression are further given to meet the reversibility of grey real number operation. Finally, the sufficient and necessary condition for the reversibility of universal grey real number operation is given, and it is proved that the grey real number operations using data block expression are reversible. Examples show that the grey real number operations using data block expression proposed in this paper are feasible and effective. The research results enrich the grey system theory and provide a theoretical basis for grey algebra research. [ABSTRACT FROM AUTHOR]

Copyright of Pearl River is the property of Pearl River Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Pearl River is the property of Pearl River Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

With the generalisation of intuitionistic fuzzy sets (IFSs), picture fuzzy sets (PFSs) have been developed based on membership, neutral membership, and non-membership degrees. Compared with IFSs, PFSs can more accurately represent uncertainty in real-world decision-making problems. Recently, the research on decision-making theories and methods under picture fuzzy environments has been rapidly developing. Therefore, this manuscript presents a systematic review of picture fuzzy decision-making theories and methods, including the context in which this field was developed, the current status and advancements of this field, and the main research results obtained with the picture fuzzy information. First, this review introduces the development process of PFSs and the current status of corresponding theories. Next, the basic theories based on PFSs, including operations rules, measures, and aggregation operators are introduced. Afterward, this review summarises the current research on multi-criteria decision-making (MCDM), multi-criteria group decision-making (MCGDM), and large-scale group decision-making (LSGDM) methods with picture fuzzy information. Finally, future research directions of picture fuzzy decision-making theories and methodologies are discussed. [ABSTRACT FROM AUTHOR]

Drainage facilities are key infrastructure elements of urban stormwater drainage system (USDSs) for flood mitigation during short-duration extreme rainstorms. To obtain the optimal operation rules of drainage facilities within the shortest response time, a novel framework and approach was developed in this study. In the proposed approach, a complex USDS based on Storm Water Management Model (SWMM) was developed to simulate rainfall runoff and provide hydraulic characteristics, and was linked to the particle swarm optimization (PSO) algorithm to design short-term operation rules. Also, to overcome computational inefficiencies of the PSO algorithm to meet the requirements of response time, multisurrogate models in combination with radial basis function network (RBFN), kriging model, and artificial neural network (ANN) were coupled in the optimization search process to substantially reduce the number of evaluations. A practical case in Yinchuan city of China was then taken for the application. The proposed approach demonstrated high performance in flood mitigation compared with the current operation rules for pumping stations and water gates, with the core area inundations reduced to almost 0 (10 years), and the reduction rate being 71.22% (30 years) and 55.16% (50 years), respectively. In addition, the number of pump switches and the water level of the storage tanks were limited within the allowable range to ensure the reasonable and safe operation of the pumping stations. The new method required only 120 evaluations to obtain the optimal solution, which could provide sufficient response time for operators and thus serve as a practical and highly effective way to reduce urban inundation. [ABSTRACT FROM AUTHOR]

Copyright of Tecnología y Ciencias del Agua is the property of Instituto Mexicano de Tecnologia del Agua (IMTA) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

ABSTRACT This study verified the suitability of using precipitation forecasts in defining operation rules for the Cruzeta reservoir in Rio Grande do Norte, Brazil. The operation rules were developed through reservoir operation simulation–optimization, using a genetic algorithm. The performance indicators were analyzed in five operation scenarios: standard operating policy (SOP), current reservoir rationing rule (C), rationing without forecast (R), rationing with forecast (RF), and rationing with perfect forecast (RPF). The SOP scenario better met the total demand but made the system very susceptible to supply collapse. The results of the RF and RPF scenarios showed better compliance with the priority demands and the total demand during the dry periods. Changing from RF to RPF scenario, there is a small improvement in the evaluation indexes. The use of rules integrating the seasonal weather forecast is thus recommended.

China has a very large number of reservoirs, and the operation of high-density reservoir networks impacts the terrestrial water cycle and the land- atmosphere moisture and energy exchange, which brings challenges to the understanding of hydrological processes and the hydrologic simulation and forecasting. In this regard, this study focuses on the Poyang Lake basin (PLB) and over 1000 reservoirs in the basin, and developed a reservoir network scheme in terms of the reservoir water balance, reservoir release rules, and routing methods with the sectioned two-dimensional diffusion wave equation. The scheme was then fully coupled to the land surface- hydrological model CLHMS through surface water, subsurface water, evapotranspiration and energy balance. Results indicate that the scheme can well capture the reservoir operation, and can enhance the accuracy of streamflow simulation; the reservoirs in the PLB can decrease the runoff by 3. 7% —6. 0% in the wet season, increase the runoff by 5. 9% — 12. 6% in the dry season, and decrease the multi- year average runoff by 0. 6% —1. 5% for the Gan, Fu and Xin River. Spatially, reservoirs have a more prominent regulating effect on the streamflow in the middle and northern part of the basin. The newly modified land surface-hydrologic model in this study can provide an analyzing tool and model basis for multidisciplinary research of atmosphere, hydrology and water resources, thereby supporting the sustainable use of water resources in areas under changing environment. [ABSTRACT FROM AUTHOR]

Determining beneficial operation rules for complex reservoir cascades is challenging due to the variability of river inflows, multiple water users, and the computational burden imposed by optimization calculations. Water managers of Sri Lanka face the challenge of balancing water releases for hydropower and for irrigated agriculture in the Mahaweli project. This study derived Mahaweli reservoir operation policies—reservoir rule curves and water allocation rules—by optimizing hydropower generation and agricultural yield. We derived operation rules for three reservoirs and one water diversion structure, because these offer the main opportunities for controllability of hydropower and irrigation. We used a multiobjective evolutionary algorithm to optimize hydropower and agriculture yields for 1,000 synthetically generated reservoir inflows that capture the natural variability of the monsoon seasons. The optimization problem was simplified by focusing on the main components of the cascade and by carrying out the computation in two stages. Despite the simplification, the operation rules derived using multiobjective optimization enhanced hydropower and agriculture yield compared with the values from current rules. The solution set exposed the trade-off between energy and agricultural yield objectives. Risk-neutral and risk-averse optimized rules and trade-offs between the objectives provide information that can be used to adapt water management practices for different hydrological conditions, which can be beneficial to thousands of people. Water managers of similar reservoir cascades can use the method to select policies considering trade-offs among objectives. [ABSTRACT FROM AUTHOR]

Obtaining optimal operation rules for cascade reservoirs is crucial for making the most of the comprehensive benefits of reservoirs. However, the operation of cascade reservoirs is generally complex, which involves with challenges including various decision variables, multiple conflicting objectives and constraints. In this paper, a new algorithm named multi-objective tangent algorithm (MOTA) is proposed for optimizing operation rules of cascade reservoirs with the objectives of hydropower generation, ecology and navigation. The performance of MOTA is firstly validated through several well-known benchmark problems. Then it is applied to a case study of cascade reservoirs optimization in China's Pearl River. Using observed inflow data (1956-2015) of cascade reservoirs, a uniform Pareto front is obtained eventually via MOTA after 1000 generations. The optimal operation rules fully considers the comprehensive benefits of hydropower generation, ecology and navigation in China's Pearl River. The optimal operation rules can be used as a guidance tool for decision makers, through the objectives' tradeoff without having to embed a priori preferences in the decision process. Finally, this paper use observed inflow data (2016) of cascade reservoirs for examining the operational rule to comprehend the analysis under different optimal operation rules. The obtained results show that MOTA can be a viable alternative for generating optimal operation rules for cascade reservoirs planning and management.

Study region: A large, densely populated area nearby Padova (Veneto Region, Italy) is exposed to floods owing to the Brenta-Bacchiglione river network, which is formed by two main rivers and by a set of interconnected channels, control structures and pump stations. Study focus: The Brenta and Bacchiglione rivers suffer from an increasing pressure in terms of flood events, especially for urban sprawl, anthropogenic modifications of drainage networks, and climate change. Finding and implementing effective remedies is hard in developed countries due to the presence of several constraints. Optimal flood management in complex river networks is then a way to reduce flood hazard, at a relatively low cost compared to structural measures. Hence, optimal operation rules for floodgates at an existing control structure are searched for to control the upstream water level and to divert a proper amount of the Bacchiglione discharge into the Brenta River. The operation rules have been endorsed by the Civil Engineering Department in charge of flood management and have been implemented in the flood forecasting Early Warning System of the Regional Civil Protection Office. New hydrological insights: The proper operation of control structures allows reducing flood risk by balancing the water discharge in the river networks. The engagement of end-users proves beneficial as it fosters exchange of knowledge and allows for the effective adoption of research outcomes in decision making.

Power system stabilizers play an important role in reducing the low-frequency oscillation. In this article, the problem of robustly selecting the parameters of the power system stabilizers is studied. A new neural-like P systems optimization algorithm is proposed in order to optimize the power system stabilizer parameters. First, the structure of the neural-like P systems is established. Then, the operation rules, including forgetting rule, spiking rule, evolving rule, and transferring rule, are designed. Furthermore, a new objective function is constructed on the eigenvalues and damping ratio. Finally, the proposed algorithm is tested on the 16-machine and 68-bus system. The simulation results show the effectiveness and robustness of the proposed methods to select the optimal power system stabilizer parameters for damping out the low f oscillation. [ABSTRACT FROM AUTHOR]

The target of this paper was to simulate natural flow regime in reservoir ecological operation. Fifteen indicators were designed to assess flow regime on the basis of major characteristics of flow regime and applied in the objective function of the reservoir ecological operation model. A hydrological year was divided into several periods according to the staged hydrological features. Then rules of ecological water supply were proposed with the consideration of real-time available water. The reservoir ecological operation model was solved successfully since the complexity was reduced by layering different water supply tasks. This model was applied in the Wanjiazhai Reservoir. The results show that a) the indicators designed in this paper and their application in the reservoir ecological operation model can reduce the differences between ecological water supply and natural flow regime; b) the ecological water supply rules based on the staged hydrological features and real-time available water can tap the potentials of ecological water supply; c) the water utilization ratio above the Wanjiazhai Reservoir need to be controlled within 40% to maintain the river health while serious ecological damage will occur if the water utilization ratio is higher than 60% in the long-term. [ABSTRACT FROM AUTHOR]

The operation of a reservoir system for flood resources utilization is a complex problem as it involves many variables, a large number of constraints and multiple objectives. In this paper, a new algorithm named multi-objective cultured evolutionary algorithm based on decomposition (MOCEA/D) is proposed for optimizing the hierarchical flood operation rules (HFORs) with four objectives: upstream flood control, downstream flood control, power generation and navigation. The performance of MOCEA/D is validated through some well-known benchmark problems. On achieving satisfactory performance, MOCEA/D is applied to a case study of HFORs optimization for Three Gorges Project (TGP). The experimental results show that MOCEA/D obtains a uniform non-dominated schemes set. The optimized HFORs can improve the power generation and navigation rate as much as possible under the premise of ensuring flood control safety for small and medium floods (smaller than 1% frequency flood). The obtained results show that MOCEA/D can be a viable alternative for generating multi-objective HFORs for water resources planning and management. [ABSTRACT FROM AUTHOR]

In order to analyze the year-end water level of multi-year regulating reservoir of the cascade hydropower system, this paper studied the joint operation optimization model of cascade reservoirs and its solving method based on multi-dimensional dynamic programming, and analyzed the power generation impact factors of cascade system that contains multi-year regulating reservoir. In particular, taking the seven reservoirs in the middle and lower reaches of Yalong River as an example, the optimal year-end water levels of multi-year regulating reservoir under the multi-year average situation and different inflow frequencies situation were studied. Based on the optimal calculation results of multi-dimensional dynamic programming, the inflow frequency difference considered operation rule of year-end water level of Lianghekou reservoir was extracted using the least square principle. The simulation results showed that, compared with the fixed year-end water level in multi-year, the extracted rule can improve the cascade power generation by more than 400 million kWh in an average year, representing an increase of 0.4%. This result means that the extracted rule can give full play to the regulation performance of multi-year regulating reservoir and improve the conversion efficiency of hydropower resources in cascade system. This is of great significance to the practical operation of cascade reservoirs system that contains multi-year regulating reservoir.

The water operation and management of the Chonnabot barrage project เท Khonkaen Province relied on the operator's experience rather than appropriate operation rules for the gate level. Consequently, problems were sometimes experienced especially when seasonal changes arise. The control of barrage gates in both dry season to rainy season (July-September) and rainy season to dry season(October-December) will abruptly affect the water level upstream and downstream. Thus, the aim of this study was to develop the operation rules for controlling the gates of the Chonnabot Barrage during the seasonal changes. The Artificial Neural Networks(ANN) model was applied to determine the relationship between the tide and the lifted up distance of the gates. As the study result, it was found that the distance value during the seasonal changes obtained from ANN model will cause less fluctuation of water level upstream and downstream during the day than those from conventional practices. As a result, when experiencing seasonal change period from dry to rainy season, small pumping pontoons at the up and down streams of Choan-nabot Barrage will not be overturned. เท addition, The bank erosion will be less than the past record. [ABSTRACT FROM AUTHOR]

Reservoir operations are increasingly being asked to consider environmental flow, which is needed to sustain a healthy river ecosystem. The Indicators of Hydrologic Alteration (IHA) is a tool that is used widely to describe environmental flow regimes, but few studies have explicitly included its parameters in multi-objective reservoir operation models. With the goal of incorporating detailed environmental flow requirements into reservoir operations, this study proposes a two-objective reservoir operation model that includes explicit IHA constraints. A series of formulae is developed to calculate IHA parameters without using a loop or conditional statement, which allows operators to manage environmental flow directly. An experimental operation of the Jinghong reservoir in the upstream portion of the Mekong Basin is conducted to apply the method. The economic objective is defined by hydropower production (HP), while the environmental flow objective is represented by a weighted aggregate eco-index (EI) based on IHA parameters. Five scenarios with different objective functions and constraints are compared, and the results show that the scenario with “HP–EI” as its objective achieved optimal benefits for both indices. Hard EI and explicit IHA constraints led to significant loss of HP that can be attributed to variations of inflow. To make this model more convenient for practical use, operation rule curves are regressed from the optimized results of the model. Finally, policy implications of the operation with economic and environmental objectives and some limitations are discussed. The quantification method of IHA parameters provides significant reference value for reservoir environmental operation issues. [ABSTRACT FROM AUTHOR]

The extensive constructions of reservoirs change the hydrologic characteristics of the associated watersheds, which increases the complexity of watershed flood control decisions. By evaluating the impacts of the multi-reservoir system on the flood hydrograph, it becomes possible to improve the effectiveness of the flood control decisions. This study compares the non-reservoir flood hydrograph with the actual observed flood hydrograph using the Lutaizi upstream of Huai River in East China as a representative case, where 20 large-scale/large-sized reservoirs have been built. Based on the total impact of the multi-reservoir system, a novel strategy is presented to evaluate the contribution of each reservoir to the total impact. According their contributions, the 'highly effective' reservoirs for watershed flood control are identified via hierarchical clustering. Moreover, the degree of impact of the reservoir operation rules on the flood hydrograph are estimated. We find the multi-reservoir system of Huai River has a significant impact on flooding at the Lutaizi section, on average reducing the flood volume and peak discharge by 13.92 × 10 m and 18.7% respectively. Under the current operation rules, the volume and peak discharge of flooding at the Lutaizi section are reduced by 13.69 × 10 m and 1429 m/s respectively. Each reservoir has a different impact on the flood hydrograph at the Lutaizi section. In particular, the Meishan, Xianghongdian, Suyahu, Nanwan, Nianyushan and Foziling reservoirs exert a strong influence on the flood hydrograph, and are therefore important for flood control on the Huai River. [ABSTRACT FROM AUTHOR]

Although many optimization models and methods are applied to the optimization of reservoir operation at present, the optimal operation decision that is made through these models and methods is just a retrospective review. Due to the limitation of hydrological prediction accuracy, it is practical and feasible to obtain the suboptimal or satisfactory solution by the established operation rules in the actual reservoir operation, especially for the mid- and long-term operation. In order to obtain the optimized sample data with global optimality; and make the extracted operation rules more reasonable and reliable, this paper presents the multi-dimensional dynamic programming model of the optimal joint operation of cascade reservoirs and provides the corresponding recursive equation and the specific solving steps. Taking Li Xianjiang cascade reservoirs as a case study, seven uncertain problems in the whole operation period of the cascade reservoirs are summarized after a detailed analysis to the obtained optimal sample data, and two sub-models are put forward to solve these uncertain problems. Finally, by dividing the whole operation period into four characteristic sections, this paper extracts the operation rules of each reservoir for each section respectively. When compared the simulation results of the extracted operation rules with the conventional joint operation method; the result indicates that the power generation of the obtained rules has a certain degree of improvement both in inspection years and typical years (i.e., wet year; normal year and dry year). So, the rationality and effectiveness of the extracted operation rules are verified by the comparative analysis. [ABSTRACT FROM AUTHOR]

Pareto archived dynamically dimensioned search (PA-DDS) is one of the meta-heuristic methods available to solve multiobjective reservoir operation problems. This study uses this method to optimize reservoir operation rules with the objectives of maximizing the power generation and water supply. The performance of PA-DDS is compared with the nondominated sorting genetic algorithm-II (NSGA-II) in terms of a hypervolume indicator and the distribution of optimized nondominated solutions (NDSs) in a case study of Hanjiang cascade reservoirs in China. The results indicate that PA-DDS can increase the amount of power generation and water supply, respectively. Moreover, the uncertainty in reservoir operation optimized by both methods is analyzed in terms of the NDS distribution and the trade-off relationship between water supply and power generation. The results demonstrate that PA-DDS outperforms NSGA-II not only in the Pareto front approximation (NDS), but also with an increase in water supply by about 300 million m³/year for Hanjiang cascade reservoir operation. [ABSTRACT FROM AUTHOR]

The purpose of the reservoir operation during flood period is to obtain the outflow hydrograph as flat as possible. Although simple in case of a unique reservoir, the problem becomes very complex for large systems with cascade reservoirs. Based on the well-known hydraulic software Mike Flood by DHI, a simulation-optimization model containing wave propagation equations, constraints related to the state or decision variables as well as an objective function were developed for obtaining optimal coordinated rules of complex systems of hydraulic structures (storage reservoirs, flood control reservoirs, polders and diversions). The optimization algorithms used in the modelling process to minimize the objective function are: Nelder-Mead and Genetic Algorithms. The decision variables are represented by the water levels in the reservoirs at which the outlets should be open or closed. The optimization algorithms find a configuration of the decision variables of all the reservoirs that guarantee their coordinated operation leading to minimum outflow discharges. A complex case-study involving the coordinated operation of the hydraulic structures on Jijia River is presented. [ABSTRACT FROM AUTHOR]

During the past several decades, numerous reservoirs have been built across the world for a variety of purposes such as flood control, irrigation, municipal/industrial water supplies, and hydropower generation. Consequently, the timing and magnitude of natural streamflow have been altered significantly by reservoir operations. In addition, the hydrological cycle is also modified by land-use/land-cover change and by climate change. To understand the fine-scale feedback between hydrological processes and water management decisions, a distributed hydrological model embedded with a reservoir component is desired. In this study, a multi-purpose reservoir module with predefined complex operational rules was integrated into the Distributed Hydrology Soil Vegetation Model (DHSVM). Conditional operating rules, which are designed to reduce flood risk and enhance water supply reliability, were adopted in this module. The performance of the integrated model was tested over the upper Brazos River Basin in Texas, where two U.S. Army Corps of Engineers managed reservoirs, Lake Whitney and Aquilla Lake, are located. The integrated model was calibrated and validated using observed reservoir inflow, outflow, and storage data. The error statistics were summarized for both reservoirs on a daily, weekly, and monthly basis. Using the weekly reservoir storage for Lake Whitney as an example, the coefficient of determination (R 2 ) was 0.85 and the Nash-Sutcliff Efficiency (NSE) was 0.75. These results suggest that this reservoir module holds promise for use in sub-monthly hydrological simulations. With the new reservoir component, the DHSVM provides a platform to support adaptive water resources management under the impacts of evolving anthropogenic activities and substantial environmental changes. [ABSTRACT FROM AUTHOR]

Due to simultaneous impoundment of reservoirs on the Yangtze River, the water level of Dongting Lake has decreased in recent years, which has threatened the health of the lake’s ecosystem. To mitigate the adverse effects resulting from conventional reservoir operation, an ecologically oriented reservoir optimization model was developed to maintain the water level of Dongting Lake as close as possible to the ecological water level while simultaneously maximizing hydropower production from the Three Gorges Reservoir (TGR). The relationship between the water level of the lake and the amount of water released from the reservoir was modeled using the support vector regression method, and the bi-objective optimization model was solved using the chaos-genetic algorithm. The applicability of the model was demonstrated in a case study of the TGR considering five regulatory scenarios. Relative to conventional operation, the numerical results indicate that the proposed optimized operational schemes could increase the hydropower production of the TGR while maintaining a water level near the EWL in Dongting Lake. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to derive the general optimality conditions of the commonly used operating policies for reservoirs in parallel with joint water demand, which are defined in terms of system-wide release rules and individual reservoir storage balancing functions. Following that, a new set of release rules for individual reservoirs are proposed in analytical forms by considering the optimality conditions for the balance of total water delivery utility and carryover storage value of individual reservoirs. Theoretical analysis indicates that the commonly used operating policies are a special case of the newly derived rules. The derived release rules are then applied to simulating the operation of a parallel reservoir system in northeastern China. Compared to the performance of the commonly used policies, some advantages of the proposed operation rules are illustrated. Most notably, less water shortage occurrence and higher water supply reliability are obtained from the proposed operation rules. [ABSTRACT FROM AUTHOR]

Water quantity and quality joint operation of dams and floodgates is a cost-effective way to improve a river basin's water environment at present. It has become a hot topic in integrated basin management. The Huai River basin is a unique region in China with a high density of dams and floodgates and is facing serious water pollution problems because accidental water pollution events have occurred many times. Taking Shaying River and Guo River, which are the two seriously polluted tributaries in the Huai River basin, as the study area, this paper considers objectives of flood control, pollution prevention, and water supply, and a water quantity and quality joint-operation model of dams and floodgates was established. By analyzing the operation rules of various composed scenarios, a three-stage operation method (TSOM) of water quantity and quality was proposed based on the model. The study area was decomposed into two subsystems: Subsystem I is the Shaying River and Subsystem II is the Guo River. Two typical operation scenarios were selected to be simulated. The simulation result of the May 1, 2004, scenario demonstrated that the water quality of the main monitoring sections with the joint operation was better than that with the empirical operation under the same water quality standard. The simulation result of the April 10, 2012, scenario explained that Subsystem I had an obvious compensation effect on Subsystem II in the process of joint operation. Furthermore, the TSOM summarized from 216 scenarios under the condition of different water quantity and quality in time and space can make the operation model more practical and exercisable. The joint operation of dams and floodgates will play a positive role in improving the current water quality of the main stream in the Huai River. This paper will provide scientific decision making for antipollution operation and technical support to achieve the integrated management in the Huai River basin. [ABSTRACT FROM AUTHOR]

With the rapid development of cascade hydropower stations in recent decades, the cascade system composed of multiple reservoirs needs unified operation and management. However, the output distribution problem has not yet been solved reasonably when the total output of cascade system obtained, which makes the full utilization of hydropower resources in cascade reservoirs very difficult. Discriminant criterion method is a traditional and common method to solve the output distribution problem at present, but some shortcomings cannot be ignored in the practical application. In response to the above concern, this paper proposes a new total output operation chart optimization model and a new optimal output distribution model, the two models constitute to a double nested model with the goal of maximizing power generation. This paper takes the cascade reservoirs of Li Xianjiang River in China as an instance to obtain the optimal total output operation chart by the proposed double nested model and the 43 years historical runoff data, progressive searching method and progressive optimality algorithm are used in solving the model. In order to take the obtained total output operation chart into practical operation, mean value method and stepwise regression method are adopted to extract the output distribution ratios on the basis of the optimal simulation intermediate data. By comparing with discriminant criterion method and conventional method, the combined utilization of total output operation chart and output distribution ratios presents better performance in terms of power generation and assurance rate, which proves it is an effective alternative method to deal with the cascade reservoirs joint operation problem. [ABSTRACT FROM AUTHOR]

Multidisciplinary models are useful for integrating different disciplines when addressing water planning and management problems. We combine water resources management, water quality and habitat analysis tools that were developed with the decision support system AQUATOOL at the basin scale. The water management model solves the allocation problem through network flow optimization and considers the environmental flows in some river stretches. Once volumes and flows are estimated, the water quality model is applied. Furthermore, the flows are evaluated from an ecological perspective using time series of aquatic species habitat indicators. This approach was applied in the Tormes River Water System, where agricultural demands jeopardize the environmental needs of the river ecosystem. Additionally, water quality problems in the lower part of the river result from wastewater loading and agricultural pollution. Our methodological framework can be used to define water management rules that maintain water supply, aquatic ecosystem and legal standards of water quality. The integration of ecological and water management criteria in a software platform with objective criteria and heuristic optimization procedures allows realistic assessment and application of environmental flows to be made. Here, we improve the general methodological framework by assessing the hydrological alteration of selected environmental flow regime scenarios.Editor D. Koutsoyiannis; Guest editor M. AcremanCitation Paredes-Arquiola, J., Solera, A., Martinez-Capel, F., Momblanch, A., and Andreu, J., 2014. Integrating water management, habitat modelling and water quality at the basin scale and environmental flow assessment: case study of the Tormes River, Spain. Hydrological Sciences Journal, 59 (3–4), 878–889. [ABSTRACT FROM PUBLISHER]

Floods are a very interesting subject owing to their relationship with dam safety. Question 94 of the 24th ICOLD Congress has dealt with flood discharge, which is very important from the operation point of view. This article describes the submitted reports, in which present experiences and trends are shown: new methodologies and design standards, specific risks that arise during flood routing, impact of new flood computations on existing dams and upgrading actions. [ABSTRACT FROM AUTHOR]

The paper focuses on the development of reservoir operating rules for dry and rainfall events, and their implementation in the case of the Ghézala dam located in northern Tunisia (characterized by Mediterranean climate). Rainfall events are defined in terms of depth and duration that are correlated to each other. A depth analysis per event is performed, conditioned on the event duration. The gamma distribution provides a good fit to depth per event, especially for events lasting at least 6 days. The event duration fits a geometric distribution, whereas the dry events during the rainy season fit a negative binomial distribution. The climatic cycle length is fitted to a gamma distribution. On this basis, many 50-year synthetic event series were generated. Every synthetic streamflow sequence obtained from synthetic rainfall sequences as well as the one derived from the historic rainfall events time series were optimized and optimal decisions were formulated. These decisions were assessed by means of multiple regression analysis to estimate the relation between the optimal decision to every stage (dry or rainfall event) and other system variables. Optimal rules, which have a linear form, were derived by predetermined useful storage interval and depend on storage, inflows and downstream demand at dry or rainfall event t. The range of t is 1–13 days (rainfall event) and 1–57 days (dry event). The rules were satisfactory for every predetermined useful storage interval. The simulated dam performance generated by the operation rules was compared with the deterministic optimum operation and the historical operation. Also included is the comparison of the implicit stochastic optimization-based operation policy per event during the water years 1985–2002. [ABSTRACT FROM AUTHOR]

In order to analyze the year-end water level of multi-year regulating reservoir of the cascade hydropower system, this paper studied the joint operation optimization model of cascade reservoirs and its solving method based on multi-dimensional dynamic programming, and analyzed the power generation impact factors of cascade system that contains multi-year regulating reservoir. In particular, taking the seven reservoirs in the middle and lower reaches of Yalong River as an example, the optimal year-end water levels of multi-year regulating reservoir under the multi-year average situation and different inflow frequencies situation were studied. Based on the optimal calculation results of multi-dimensional dynamic programming, the inflow frequency difference considered operation rule of year-end water level of Lianghekou reservoir was extracted using the least square principle. The simulation results showed that, compared with the fixed year-end water level in multi-year, the extracted rule can improve the cascade power generation by more than 400 million kWh in an average year, representing an increase of 0.4%. This result means that the extracted rule can give full play to the regulation performance of multi-year regulating reservoir and improve the conversion efficiency of hydropower resources in cascade system. This is of great significance to the practical operation of cascade reservoirs system that contains multi-year regulating reservoir. [ABSTRACT FROM AUTHOR]