Journal of Water Resources Planning and Management

Forum papers are thought-provoking opinion pieces or essays founded in fact, sometimes containing speculation, on a civil engineering topic of general interest and relevance to the readership of the journal. The views expressed in this Forum article do not necessarily reflect the views of ASCE or the Editorial Board of the journal.

It has been widely theorized that water age may be a useful indicator of the quality of water within drinking water distribution networks. However, there is limited evidence of model simulation results being related to empirical water quality (WQ) data to substantiate the theory. This paper presents the findings of investigations designed to determine if there was an observable relationship between mean water ages calculated using a WQ simulation model, and measured WQ in two live distribution networks. The age of water in all pipes was calculated using Aquis hydraulic and WQ modeling software. Historic regulatory WQ data was examined to determine if there was a relationship between general WQ and calculated water age within the networks. A more detailed study was then undertaken in one network by translating model locations that were representative of the spread of water age into real-world locations. WQ samples were taken intensively from these sites and analyzed for a range of aesthetic, physical, chemical, and bacteriological parameters indicative of general WQ. Some relationship between the calculated mean age of water and the general WQ in the network was demonstrated. Analysis that considered calculated water age and associated WQ along unperturbed flow routes through the network produced a stronger relationship. Given that regulatory WQ within the study networks as reported to the Drinking Water Inspectorate (DWI) was 99.9 percent compliant, this relationship was deemed noteworthy.

This paper empirically analyzes the efficiency of urban water utilities using state-of-the-art methodology combining data envelopment analysis (DEA) and a two-stage double bootstrap procedure. In the first stage, robust efficiency estimates are obtained with an improved DEA analysis. In the second stage, a truncated regression model and a double bootstrap procedure are used to estimate the effect of a set of environmental variables on unbiased DEA estimates. The findings suggest that the efficiency scores obtained after bias correction are significantly different to the original efficiency estimates. The results also show the existence of a significant relation between efficiency and several environmental variables including the proportion of water sourced from groundwater, customer density, and residential consumption.

Following an increased emphasis on watershed management by the U.S. Environmental Protection Agency (EPA) in the 1990s, the Kentucky Division of Water (KDOW) developed and implemented a watershed-management framework process for the state of Kentucky in 1997. The Kentucky Water Resources Research Institute (KWWRI) coordinated the first implementation of the framework process in the Kentucky River basin beginning in 2000. After an evaluation of the program that followed the completion of the first five-year cycle of the framework, the KWRRI made significant changes to the framework so as to incorporate greater stakeholder involvement and to place a greater focus on the development and implementation of watershed plans at a local level. This paper provides a summary of the watershed activities in the Kentucky River basin over the past 15 years and evaluates the lessons learned during that process. It is hoped that these observations will be useful to other agencies and organizations that are engaged in watershed-management activities, either at the state or local level.

Evidence from ecological studies suggests that the alteration of river flows downstream of reservoirs can threaten native aquatic ecosystems and the services they offer. Innovative revisions to water management practices are required to improve the health of aquatic species while maintaining the benefits from current infrastructure projects. The impacts of individual reservoir operations on ecosystem vitality are often masked by the uncoordinated and compounding influences of several impoundments upstream, undermining the examination of environmental impacts from particular reservoirs in a large watershed system. This paper presents a large-scale optimization model that investigates the value of coordinated reservoir management practices for ecological benefits in a large watershed with several major reservoir systems operating for a range of management objectives. An application of the model is presented for the Connecticut River watershed, the largest river basin in New England and one of the most impounded rivers in the United States. The model can examine trade-offs between the maintenance of ecologically acceptable, daily streamflows at key locations throughout the watershed and traditional reservoir objectives, including flood risk reduction, municipal and riparian water supply, hydropower production, and recreation. The ecological streamflow targets are designed specifically for the basin’s ecology in a collaborative process engaging regional experts and constitute a unique and innovative component of the modeling approach. This study focuses on the re-operation of a network of federal flood control dams for the restoration of environmental flows. Results suggest that coordinated changes to current flood control reservoir operations can restore aspects of the natural hydrologic flow regime necessary for ecosystem persistence without significantly reducing current flood risk reduction capabilities.

In this study, an inexact fuzzy chance-constrained nonlinear programming (IFCCNP) method was developed for agriculture water resources management under multiple uncertainties. It improved upon the previous stochastic programming methods, and could reflect uncertainties expressed as probability distributions, fuzzy sets, intervals, and their combinations. By using the integration of above programming to represent the multiple uncertain parameters, the IFCCNP can generate results that are more reliable reflecting practical problem than the previous methods. The developed model is then applied to a case study of agriculture water resources management system where many crops and their planting stages are considered under different precipitation years for demonstrating its applicability. The results indicate that comprehensive solutions have been obtained. Through analysis under different precipitation levels, it provides bases for identifying desired agriculture water resources management plans with reasonable benefit and irrigation schedules under crops and their planting stages. IFCCNP is applicable to practical problems to address the crop water allocation under the precipitation variation and sustainable development with multiple uncertainties. Decision alternatives can be generated for decision makers through the proposed approach under typical years.

Changes in air temperature and precipitation that are due to climate change can affect operational objectives and hydropower production of reservoirs. This study uses a stochastic conceptual snowmelt-runoff model to generate inflow ensembles for a wide range of potential temperature and precipitation scenarios as a means of testing which types of climate changes could adversely affect hydropower production. The method is applied to a case study of the Dworshak Reservoir on the North Fork of the Clearwater River in central Idaho. Reservoir operations in response to the climate-change ensemble scenarios were simulated using a decision support system operations model according to current operating criteria and guidelines. The magnitude and timing of hydropower generation resulting from each temperature- and precipitation-change scenario were examined, assuming no change from historical reservoir operations. Results showed that lower precipitation and higher temperature created less runoff and therefore less hydropower generation. However, increased precipitation and decreased temperature scenarios showed limited increases in hydropower production due to turbine capacity and other operational constraints. Firm hydropower production from Dworshak steadily decreased with increasing mean annual temperature and steadily increased with increasing mean annual precipitation. Timing of spring hydropower production shifted to earlier spring and winter with increasing temperature. Because these simulations did not adapt reservoir operations from historical procedures, they are not intended to be realistic predictions of changes in hydropower generation in the future. Rather, the results demonstrate how the approach can provide guidance about which types of hydrograph changes, such as shifts in inflow timing, might warrant changes in reservoir operations.

Pressure reducing valves (PRVs) are often used to manage pressure and reduce losses in water distribution systems (WDS). Different approaches are available in the literature on how to locate and set the PRVs in order to maximize their effectiveness and minimize water losses. The available methodologies minimize the mean square difference between the actual and the target pressure at each node. Since the excess head can be used also to generate hydropower by using turbines and/or pumps as turbines (PATs), a different objective function could be suggested to maximize energy production. Consequently, a comprehensive analysis will be developed in the paper which highlights the differences between the preexisting approach and the suggested one, in terms of device location, pressure reduction, and recoverable energy. Numerical simulations showed that minimizing pressure may also affect the production of energy, while maximizing the energy production itself could be an attractive alternative, leading to higher generation and only a slight increase of the average node pressure.