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This paper addresses the doubts regarding the spatial characteristics of the commonly used rules for parallel reservoir system operation. The rules based on aggregation-decomposition determine the system total release first and then assign this release to individual reservoirs, without considering the water demand distribution in the river network. In this paper, a conceptual model for parallel reservoir systems with distributed water demands is proposed. Three specific optimality conditions are derived for determining the optimal analytical solution. A rigorous proof shows that the aggregation-decomposition-based rules are a special case of the derived rules. An efficient algorithm is then developed based on the optimality conditions and shortage allocation index (SAI), in which a larger SAI indicates taking a higher percentage of the system water shortage, as release or storage. Unlike traditional algorithms that modify the violated variables empirically, we propose a criterion in terms of relative deviation indicators to determine the crucial priority of variable modification. This criterion can effectively address constraint violations. The optimal rules along with the solution algorithm are then demonstrated by the operation of a parallel reservoir system in the Shiyang River Basin, China. The results show that the proposed rules and algorithm are more efficient and effective than traditional algorithms and aggregation-decomposition-based rules, especially in dry seasons with more binding constraints.

The Lancang-Mekong River basin (LMRB) is facing blooming water resources infrastructure development, long-term transboundary conflicts and trade-offs between economic goals and ecosystem services provision. Yet, most studies optimizing the pathway towards sustainable infrastructure operation have lacked multi-sectoral and cross-country perspectives. Here, we quantify how and to what extent transboundary cooperation generate economic and environmental co-benefits by jointly using a coupled simulation-optimization approach and cooperative game theoretical analysis. We find that full cooperation outweighs non- or partial cooperation modes to promote economic benefits by 5 to 27%, and to minimize the losses in fishery and sediment transport from 14% and 33% to 8% and 10%, respectively. Full cooperation becomes more beneficial and stable alongside infrastructure expansion, climate change, and the degree of satisfying hydrological needs for river ecosystems. These findings underscore the importance of full cooperation for sustaining socio-environmental systems and highlight the needs of benefit reallocation mechanism and designed flow management for stabilizing basin-level full cooperation in the LMRB.

Short instrumental streamflow records in the South and East Tibetan Plateau (SETP) limit understanding of the full range and long-term variability in streamflow, which could greatly impact freshwater resources for about one billion people downstream. Here we reconstruct eight centuries (1200−2012 C.E.) of annual streamflow from the Monsoon Asia Drought Atlas in five headwater regions across the SETP. We find two regional patterns, including northern (Yellow, Yangtze, and Lancang-Mekong) and southern (Nu-Salween and Yarlung Zangbo-Brahmaputra) SETP regions showing ten contrasting wet and dry periods, with a dividing line of regional moisture regimes at ~32°−33°N identified. We demonstrate strong temporal nonstationarity in streamflow variability, and reveal much greater high/low mean flow periods in terms of duration and magnitude: mostly pre-instrumental wetter conditions in the Yarlung Zangbo-Brahmaputra and drier conditions in other rivers. By contrast, the frequency of extreme flows during the instrumental periods for the Yangtze, Nu-Salween, and Yarlung Zangbo-Brahmaputra has increased by ~18% relative to the pre-instrumental periods.

Source identification is fundamental for managing sudden river water pollution; however, it is a challenging task. Although numerous studies have investigated this issue, most involve optimization or statistical models for instantaneous pollution and do not consider the reverse propagation and release processes. Herein, we propose an approach for identifying the release process of non-instantaneous point source pollution in rivers, based on reverse flow and pollution routing. The identification approach can trace the historical trajectory of pollutants and their release processes, providing the necessary information for treating accidental pollution. The effectiveness and efficiency of the proposed approach were tested and demonstrated using hypothetical and real-world river cases. The results indicated that the approach identified the release process with high accuracy, and second-round identification using the ensemble Kalman filter could generally improve the identification results from the reverse routing model. This approach was feasible in different cases of observation error, although the error considerably reduced its accuracy. The identification results were also found to be substantially influenced by release duration, with a shorter release time corresponding to an inferior identification result. Nevertheless, the approach worked well in real-world river cases and was generally not affected by the release location, pollutant diffusion, or river geomorphology. In addition, the new approach has advantages in computational efficiency and applicability over traditional methods.

Budyko-type models in hydrology are simple but efficient descriptions of the vegetation-mediated hydrologic cycle in catchments. Based on hypothesized similarities between vegetation and human water consumption interactions in terms of water demand, constraints, and system functioning as well as catchment processes and outcomes, a corresponding Budyko-type framework is proposed here for human water consumption at the catchment scale. To validate this framework, socioeconomic data (human water consumption and economic and agricultural structure data), as well as hydrometeorological data, for 51 human-impacted catchments located in 10 major river basins in China were assembled. The results demonstrate (1) similar observed patterns to the traditional Budyko curves, with two limits and a monotonous increase shape; (2) the same functional form and mathematical features of the derived Budyko-type equation. Parameters of the new Budyko-type model for human consumption are estimated and analyzed based on the concept of water productivity. This study suggests that the functioning of both social and hydrologic subsystems within catchment systems can be explored within a common conceptual framework, thus providing a unified socio-hydrologic basis for the study of human–water systems.

Dams heavily impact the Lancang-Mekong River, leading to water-use conflicts for hydropower, food production, and ecosystem sustainment. Basin-scale cooperation has been shown to yield incr...

The design and operation of reservoirs based on conventional flood-limited water levels (FLWL) implicitly adopts the assumption of hydrological stationarity. As such, historical-record-based FLWL may not be the best choice for flood-control operations due to the inherent non-stationarity of rainfall inputs. With maturing flood forecasts, this study focuses on establishing linkage between FLWL and skill of forecast, thus developing a “dynamic pre-storm level” approach for reservoir flood-control operations. The approach utilizes forecast flood magnitude, forecast skill and exceedance probability of forecast error to determine the pre-storm reservoir storage for each flood event. The exceedance probability of forecast error for each incoming flood is used as the reservoir flood control standard instead of the probability of a static return interval flood. This approach is demonstrated in a hypothetical situation in the Three Gorges Reservoir in China. The results show that under zero-forecast-skill conditions, the proposed dynamic pre-storm level matches well with the Three Gorges Reservoir-designed FLWL, and, as the forecast accuracy/skill increase, the proposed approach can make better use of the increased forecast accuracy, thereby maximizing floodwater utilization and reservoir storage. In this way, coupling the new approach with FLWL allows for more efficient and economic day-to-day reservoir operations without adding any flood risk. This study validates the usefulness of dynamic water level control during flood season, considering the improvement of flood forecast accuracy.

Groundwater (GW) overexploitation is a critical issue in North China with large GW level declines resulting in urban water scarcity, unsustainable agricultural production, and adverse ecological impacts. One approach to addressing GW depletion was to transport water from the humid south. However, impacts of water diversion on GW remained largely unknown. Here, we show impacts of the central South-to-North Water Diversion on GW storage recovery in Beijing within the context of climate variability and other policies. Water diverted to Beijing reduces cumulative GW depletion by ~3.6 km3, accounting for 40% of total GW storage recovery during 2006–2018. Increased precipitation contributes similar volumes to GW storage recovery of ~2.7 km3 (30%) along with policies on reduced irrigation (~2.8 km3, 30%). This recovery is projected to continue in the coming decade. Engineering approaches, such as water diversions, will increasingly be required to move towards sustainable water management., The authors here address water sustainability in the greater area of Beijing, China. Specifically, the positive effects towards Beijing groundwater levels via water diversion from the Yangtze River to the North are shown.

Electricity production by hydropower is negatively affected by drought. To understand, monitor and manage risks of less than normal streamflow for hydroelectricity production (HP) at the global sca...

Cooperation in transboundary river basins can make water resources systems more efficient and benefit riparian stakeholders. However, in a basin with upstream and downstream stakeholders that have different interests, non-cooperative outcomes have often been observed. These can be described by a one shot prisoners’ dilemma game where non-cooperation (defection) is a dominant equilibrium strategy. However, cooperative outcomes have also been observed in several transboundary settings, such as the Lancang-Mekong River Basin (LMRB) in Asia. Such cooperation motivates our research effort to refine relevant game theoretic descriptions to account for the evolution of players’ behaviors, from conflict to cooperation. In this study, a repeated game model is proposed to analyze evolutionary transboundary cooperation. A generalized evolutionary cooperation pattern with four stages is summarized, starting with non-cooperation and ending with in-depth cooperation. The LMRB and three other typical transboundary river management case studies are chosen to validate our theoretical findings. Upstream and downstream stakeholder behaviors are analyzed for these case studies, in accordance with a game payoff matrix that accounts for incentives to cooperate. The results indicate that patience and incremental benefits can lead stakeholders to adopt a cooperative equilibrium strategy if appropriate institutional mechanisms are in place. Such mechanisms can be developed through negotiations that recognize the wide range of stakeholder interests that may influence the decision to cooperate. Our analysis suggests that game theory can provide useful insights into the conditions and institutional mechanisms that foster cooperative strategies for managing transboundary water resources.

Pollution risk from the discharge of industrial waste or accidental spills during transportation poses a considerable threat to the security of rivers. The ability to quickly identify the pollution source is extremely important to enable emergency disposal of pollutants. This study proposes a new approach for point source identification of sudden water pollution in rivers, which aims to determine where (source location), when (release time) and how much pollutant (released mass) was introduced into the river. Based on the backward probability method (BPM) and the linear regression model (LR), the proposed LR–BPM converts the ill-posed problem of source identification into an optimization model, which is solved using a Differential Evolution Algorithm (DEA). The decoupled parameters of released mass are not dependent on prior information, which improves the identification efficiency. A hypothetical case study with a different number of pollution sources was conducted to test the proposed approach, and the largest relative errors for identified location, release time, and released mass in all tests were not greater than 10%. Uncertainty in the LR–BPM is mainly due to a problem with model equifinality, but averaging the results of repeated tests greatly reduces errors. Furthermore, increasing the gauging sections further improves identification results. A real-world case study examines the applicability of the LR–BPM in practice, where it is demonstrated to be more accurate and time-saving than two existing approaches, Bayesian–MCMC and basic DEA.

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.

Delivery in water markets is generally operated by agencies through channel systems, which imposes physical and institutional market constraints. Many water markets allow water users to post selling and buying requests on a board. However, water users may not be able to choose efficiently when the information (including the constraints) becomes complex. This study proposes an innovative two-phase model to address this problem based on practical experience in China. The first phase seeks and determines the optimal assignment that maximizes the incremental improvement of the system's social welfare according to the bids and asks in the water market. The second phase sets appropriate prices under constraints. Applying this model to China's Xiying Irrigation District shows that it can improve social welfare more than the current pool exchange method can. Within the second phase, we evaluate three objective functions (minimum variance, threshold-based balance, and two-sided balance), which represent different managerial goals. The threshold-based balance function should be preferred by most users, while the two-sided balance should be preferred by players who post extreme prices.

Water rights and water markets are increasingly important as cost-effective tools for managing scare water resources by stimulating efficiently uses. A clear and stable water rights system is necessary for sustaining world’s agricultural productions and global food security. However, knowledge gap still exists on identifying the critical elements and their interactions in the water rights system in the context of changing environments. This paper establishes a systematic framework of water rights based on the current practices in China. The relationships among water rights, water entitlements, water-abstraction permits, water rights certificates and seasonal allocations are explained. The water trading rules, trading systems among regions, sectors and individual famers as well as the trading platforms and brokers in China are also discussed for managerial implications. Suggestions are provided to improve China’s water rights and markets by drawing upon the experiences of current practices according to the proposed framework.

Drought threatens both social and economic development, and it is necessary to develop a comprehensive drought index and a method of predicting future drought occurrence to enable effective associated management and warnings. However, barring a few, current drought indexes are not comprehensive; for example, they ignore the ability to recover from drought, and drought prediction does not consider spatial and temporal characteristics. In this study, the Sustainability Index (SI), which considers reliability, resilience, and vulnerability, was used to identify agricultural drought, and the Cellular Automata-Markov (CA-Markov) was used in drought prediction. In order to reflect the characteristics of crop water deficit in agricultural drought, this paper uses the Permanent Wilting Point (PWP) as the threshold; droughts are defined as soil moisture

US Department of Energy; National Basic Research Program of China (2015CB953703); National Natural Science Foundation of China (91537210, 41371328); Austrian Science Funds

Human activities, such as dam construction, significantly altered the flow regimes in the Mekong River, particularly after the completion of two large dams, namely Xiaowan and Nuozhadu in 2010 and 2014, respectively. Streamflow data from 1960 to 2014 obtained from five stations located along the Mekong mainstream are divided into three periods, i.e., the pre-impact period (1960–1991), the transition period (1992–2009), and the post-impact period (2010–2014). The flow regimes were investigated using eco-flow metrics and indicators of hydrologic alteration (IHA). The results show that the construction and initial filling of the upstream dams reduced the annual streamflow in the upstream Chiang Saen gauging station, whereas no clear effect was observed in the downstream Stung Treng station. The operation of dams reduces the streamflow in wet seasons and increases the streamflow in dry seasons, resulting in a unique seasonal variation in the streamflow based on eco-flow metrics in the Chiang Saen gauging station, observed from 2010 to 2014. In addition, the maximum flow values decreased significantly in the Chiang Saen gauging station during the year corresponding to the completion of the upstream dams. The construction and operation of dams clearly have significant impacts on low pulse duration. It is observed that climate change dictated the changes in the annual streamflow during the transition period 1992–2009 (82.28%), whereas human activities contributed more in the post-impact period 2010–2014 (61.88%). The results of this study could provide a reference for reservoir operation in the upstream regions considering both ecological and economic benefits of such operations, as well as maximize the interests of stakeholders in this region.

In flood control operation, the maximum release from a reservoir is minimized to lessen flood risks. Two properties of the minimax problem are derived by formulating the multi-period decision process as a recursive two-stage model. First, the cost-to-go function, which represents the maximum release in the remaining periods, is a non-decreasing function of the carryover storage. Second, monotonic relationships exist between the initial storage of the two-stage model and the optimal decisions of release and carryover storage. The two properties hold not only in the deterministic case with a given streamflow scenario, but also in the stochastic case with an ensemble of streamflow scenarios. The monotonic relationships are incorporated into the dynamic programming (DP) and sampling stochastic DP (SSDP). Two novel algorithms—improved DP (IDP) and improved SSDP (ISSDP)—are developed. The algorithms are applied to a case study of the Danjiangkou Reservoir in Central China. IDP and ISSDP respectively obtain the same decisions as DP and SSDP, and they are more computationally efficient. The execution times of IDP and ISSDP increase linearly with the number of storage discretizations, while those of DP and SSDP increase quadratically. With 1000 discretizations of reservoir storage, IDP and ISSDP derive optimal decisions at 0.939 and 97.453 s, respectively, whereas DP and SSDP finish at 115.931 and 6372.915 s, respectively. These results suggest that IDP and ISSDP can be useful tools for flood control operation – testing different flood scenarios and determining the optimal decisions.

Agricultural irrigation accounts for the largest proportion of freshwater use worldwide, and canal automation potentially improves conveyance efficiency in irrigation canal systems. In this...

Confronted with diverse water management schemes, policymakers in arid basins face difficulty in choosing a particular scheme due to a lack of appropriate tools to estimate possible physica...

Multiple stakeholders in transboundary river basins would benefit from cooperation, but how and why stakeholders can achieve this cooperation remains difficult to determine. This paper prop...