Journal of Water Resources Planning and Management

High flow pulses (or spells or freshes) play a crucial role in maintaining the ecological health of a river system. Impoundment of water in a reservoir and release or diversion of water for human water needs has significantly altered the magnitude and frequency of flow pulses in many river systems, often reducing river ecological health. A limited volume of water is sometimes available for release into the river to reintroduce pulses specifically aimed at meeting ecological requirements (environmental water). If aiming to achieve maximum environmental benefit, such releases from the reservoir should be timed to augment or piggyback natural unregulated catchment flow events. These decisions must be made in presence of uncertainty of near-future unregulated catchment inflows entering the river. Making flow release decisions under this uncertainty poses the risk of either not achieving the benefit of the environmental flow release because too little environmental water is released, or of causing flood damage because too much is released. To date, assessment of risks associated with piggybacking environmental flows have focused solely on the flooding risks. This paper considers assessment of trade-offs between environmental risks and flooding risks while making piggybacking decisions. The key contribution of the paper is a risk framework that allows for the assessment of both flooding and environmental risks when piggybacking of natural flow pulses occurs. The risk framework is used to assess rules or rules with varying levels of piggybacking on the trade-offs between environmental outcomes and flooding risks when releasing piggybacking flows under these rules for flow events under near-future forecast uncertainty. Spawning flows for a key fish species in the Yarra River in southeast Australia is used as a case study to compare three piggybacking rules.

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 proposes an approach for analyzing the effect of the cascade reservoir system operation under varying hydrologic conditions on transboundary cooperation, taking the Lancang–Mekong River as a case study. The results demonstrate that the economic gains from cooperation are greater than those from noncooperation, particularly in dry years. The systematic incremental benefits of cooperation increase with the exceedance percentage, $P$, of the flow duration curve, indicating that the dryer the basin, the more benefits cooperation can yield. The operation policies of the cascade reservoir system in China influence the spatial and temporal streamflow patterns in the downstream Mekong River and provide substantial economic benefits to downstream stakeholders in coalitions. When China participates in the cooperation, the cascade reservoirs release more water in dry seasons, leading to hydropower loss upstream, but extra gains at the system level. An interesting free-ride phenomenon in partial coalitions is observed, illustrating the unique character of the transboundary river basin system as a continuum. The shares of the benefit for each stakeholder vary with different cooperative game methods. It is also determined that stakeholders are unlikely to reach a consensus on the preferred solution to benefit sharing, but they will not depart from the grand cooperation if one of the three proposed cooperative game-theory solutions is really implemented.

Statistically downscaled global climate model (GCM) precipitation output is available for Philadelphia, but the temporal resolution is too low for direct use in model-based urban stormwater applications. Additionally, GCM output for Philadelphia does not accurately represent local storm intensities and durations. To address these limitations, this study presents an innovative approach employed by the Philadelphia Water Department (PWD) to transform GCM output into actionable science that can directly inform planning, design, and engineering applications, including hydrologic and hydraulic (H&H) modeling and intensity-duration-frequency curve development. This approach uses GCM output for current (1995–2015) and future (2080–2100) conditions under a certain greenhouse gas emission trajectory to develop delta change factors based on season and storm size. These factors are then used to create a plausible future hourly time series. A stochastic generator was also developed that utilizes the adjusted future time series to explore potential variability in projected precipitation patterns. The approach presented in this study is practical and transferable, addressing the need for actionable climate change information in the field of water resource management.

In recent studies about reliability analysis of water distribution systems (WDSs), different reliability indicators have been used to measure and compare the reliability of water networks. These indicators have been used as objective functions in WDS optimization design problems alongside network construction cost. In this research, it is shown that these prevalent indicators cannot completely model the ability of networks in the face of abnormal operational conditions such as nodal demand changes or pipe burst. Six well-known indicators were considered in reliability assessment of 20 different structures of five WDSs under a large number of abnormal operating conditions. Results show that some WDS structures, in spite of having higher reliability indicator values, are unable to adequately tolerate abnormal conditions. This deficiency may also result in removing some desirable water network structures in optimization procedures due to low values for reliability indicators. The research suggests a stochastic method, based on the correlation between the value of reliability indexes and the ability of WDS to operate in abnormal conditions, to find the best reliability indicator before the reliability analysis of each WDS.

This paper presents an ex ante analysis of a novel groundwater management reform being considered by irrigators in the Diamond Valley, Nevada. Groundwater extraction for irrigation in the valley has considerably exceeded the natural recharge rate since the 1960s. The area was recently declared a critical management area (CMA) by the State Engineer of Nevada, which will trigger curtailment of water rights unless other action halts unsustainable abstraction. We examined the likely impacts of a number of potential institutional structures that could be implemented as part of groundwater reform in the Diamond Valley. The major reform is a conversion from a priority-based curtailment of existing water rights to a shares-based system of gradually decreasing basinwide pumping allocations, an approach that offers some economic benefits to the region. The beneficial reforms, namely creation of a common market in which to trade rights and an ability to gradually, rather than suddenly, curtail rights, can be built into the existing priority-based rights structure. However, the conversion of rights to shares offers limited additional basinwide benefits, and mainly affects farmer profits through the redistribution of some profit from senior rights holders to junior rights holders. The redistributional nature of the institutional reform, paired with limited broader gains, may make it difficult to reach legal agreement regarding changes to established priority-based water rights institutions.

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 physical and economic outcomes in a comprehensive manner. This study develops a coupled agent–hydrologic model to both capture and provide insights into the dynamics and patterns of real-world water management using the midstream area of the Heihe River Basin in northern China as a case study. Water consumption patterns, economic efficiency, and environmental externalities of three different management schemes, namely an administered scheme (AS), a surface-water market scheme (SWMS), and a surface-water–groundwater market scheme (SGWMS) are evaluated. The results show that an agent’s (irrigation district) behaviors under market schemes are determined by the difference between equilibrium price and pumping cost, related to water table depth. The annual total benefits are improved under market schemes, especially in dry years. Negative environmental effects of the market schemes do occur but are not significant. The travel time of groundwater corresponds to a delay longer than 2 months in upper agents’ pumping influence on drawdown. In general, the proposed model application in this study addresses complex real-world management issues by presenting physically interpretable and verifiable outcomes, and therefore aids policymakers in decision making by providing a broader view of water management.

The authors document the development and testing of a new suite of hydrologic and hydraulic data for the customization of the new National Water Model (NWM) to the Great Lakes basin. The NWM was recently (August 2016) deployed operationally across the United States, including extensions across the international basins of the Columbia and Rio Grande Rivers. In its current configuration the NWM does not extend across the entire Great Lakes basin due to the challenges of reconciling data discontinuities along the United States–Canada border. The new hydrographic data set was developed by harmonizing data from existing sources across the Great Lakes basin, and by leveraging a strong binational partnership between US and Canadian federal agencies and research institutions. The completed hydrographic data set allows the NWM to be customized to the Great Lakes basin, and to be applied to water resources management problems including differentiating drivers behind long-term changes in Great Lakes water levels, forecasting water supplies for regional hydropower management, and understanding the physical processes along the Great Lakes coastline that govern the fate and transport of waterborne pollutants.