Journal of Water Resources Planning and Management

Environmental flow standards established according to a consensus-based, legislatively mandated process are being incorporated in the water rights permitting system for selected priority river systems in Texas. The flow standards for several of the rivers have been simulated as a part of a university research study using the new daily version of the Water Rights Analysis Package (WRAP) modeling system with modified input data sets from the Texas Commission on Environmental Quality (TCEQ) Water Availability Modeling (WAM) system. Metrics have been evaluated using time series of simulated streamflows and flow targets to characterize the engagement and attainment of the environmental flow standards. The metrics help determine the extent to which the standards are achieved within a river system water allocation simulation and enable the comparison of results between the different environmental flow regime components, different locations, and alternative river system development scenarios.

In 2000, the resilience and failure indices were introduced as a convenient and compact tool to express respectively water-distribution network (WDN) surplus and deficit in satisfying users’ demand, in terms of delivered power. In their original formulation, the mentioned indices, originally thought as WDN design tools, were developed only considering the demand-driven modeling approach, which would include pumps but not leakage. This paper extends the formulation of both indices and presents a generalized expression, more convenient for use when dealing with pressure-driven modeling and capable of including the effect of leakage. Following the original concept, the generalized indices were developed by calculating the power dissipated in the network as a function of the difference between the total power inserted through source nodes and pumps and the net delivered power, whereas the leakage-related power is considered as a loss similarly to the internally dissipated one. Applications to WDN analysis and design proved that using the new formulation in the presence of leakage and pressure-dependent consumptions yields better description of the delivered power excess, compared to the original demand-driven formulation and to another pressure-driven formulation present in the scientific literature.

Hydraulic head and mean annual streamflow, two main input parameters in hydropower resource assessment, are not measured at every point along the stream. Translation and interpolation are used to derive these parameters, resulting in uncertainties. This study estimates the uncertainties and their effects on model output parameters: the total potential power and the number of potential locations (stream-reach). These parameters are quantified through Monte Carlo simulation (MCS) linking with a geospatial merit matrix–based hydropower resource assessment (GMM-HRA) model. The methodology is applied to flat, mild, and steep terrains. Results show that the uncertainty associated with the hydraulic head is within 20% for mild and steep terrains, and the uncertainty associated with streamflow is around 16% for all three terrains. Output uncertainty increases as input uncertainty increases. However, output uncertainty is around 10–20% of the input uncertainty, demonstrating the robustness of the GMM-HRA model. Hydraulic head is more sensitive to output parameters in steep terrain than in flat and mild terrains. Mean annual streamflow is more sensitive to output parameters in flat terrain.

A water market is an effective way to increase water-use benefits. A preliminary market for irrigation water trading among villages has emerged in the arid area of northwestern China since 2008. This study conducts a quantitative evaluation of the water market at the Xiying irrigation district of the Shiyang River Basin in western China. Network analysis method is employed to assess trading activity and market centrality. The characters of case water market are compared with that of the United States and Australia to discuss the foundations and barriers for developing a mature water market in China. Results show that the case water market in China is undeveloped and is highly regulated by local government although water transactions continuously occur among villages for years. Insufficient incentives and high transaction cost are the key barriers in further developing the market. The indicators proposed in this study for market network analysis are useful for quantitatively evaluating the characters of a water rights market. The lessons derived from the assessment can guide water market development in China and other countries.

The water distribution system (WDS) reliability is the ability of a network to provide the required quantity of water to customers under uncertain system conditions. In this study, eight surrogate measures of WDS reliability were investigated: Two hydraulic reliability measures, two robustness measures, single failure reliability (SFRel) with three valve installation levels, and seismic reliability (SeisRel). The eight reliability measures were calculated for 16 study networks of various sizes (i.e., in terms of the number of nodes and links), numbers of sources, layouts, demand distributions, and topographies. The network characteristics (e.g., structural redundancy and overall pipe sizes) were quantified by using system characteristic indicators (SCI), and their correlations with the eight suggested reliability measures were analyzed. The following SCIs were considered: The average node degree, meshedness coefficient, total system demand, total system demand per source, length-weighted average pipe diameter, and total service area. Finally, univariate and multivariate linear reliability models were developed by fitting a linear regression line to the scatter plots of the reliability measures and SCIs.

Pressure standards assist in the design of water distribution systems and the assessment of their performance. Although exact thresholds are sometimes rather vague, unusually high and low pressures are widely understood to increase costs and put systems at risk from events like pipe bursts at the high-pressure end to the risk of contaminant intrusion or poor firefighting conditions at the low-pressure end. Interestingly, because the definition of what conditions constitute acceptable pressures differs around the world, a delivery pressure might be considered acceptable in some regions and unacceptable in others. But if a wider range of system conditions is considered, including transient events, an interesting question arises as to what exactly the standards might mean and how violations should be evaluated. Specifically, what kinds of pressure transgressions are most crucial to system performance and economics and what kinds are merely inconvenient? Certainly the issue of evaluating consequences is relevant, but it is also complex because some consequences are not easily attributed to specific system conditions. As this paper considers, the frequency, duration, and intensity of the pressure violation are all relevant, but so is the vulnerability of the system to those violations. Few of these issues have yet received adequate attention, but it is to raising such a discussion that this paper is aimed. There is no doubt that pressure standards can help to assess system performance and to trigger system evolution (i.e., operational and capital investments). But if the criteria themselves, and the means to evaluate them, are too vague, so will be the corrective outcomes.

A drinking water distribution system (DWDS) is a critical and a costly asset with a long lifetime. Drinking water demand is likely to change in the coming decades. Quantifying these changes involves large uncertainties. This paper proposes a stress test on the robustness of existing DWDS under changing drinking water demands. The stress test investigates the effects of extreme but plausible demand scenarios on the network performance. Two layouts, one conventional looped designed for fire flows and one designed as a self-cleaning, were tested. For 12 demand scenarios, diurnal patterns were simulated with the end-use model SIMDEUM. The performance of the network was evaluated on three criteria: (1) network pressure, (2) water quality, and (3) continuity of supply. Although the self-cleaning layout had higher head losses, it performed better regarding water quality than the conventional layout. Both networks are robust to the extremities of drinking water demands. The stress test is useful to quantify the performance range of the DWDS. For non-Dutch locations, the criteria and scenarios can be adapted to local conditions.

Particle swarm optimization (PSO) technique is applied in multiobjective irrigation planning environment, to the case study of Khadakwasla complex, India. The project consists of Khadakwasla irrigation project, Janai Sirsai lift irrigation scheme, and Purandar lift irrigation scheme. Objectives considered are net benefits, crop production, and labor employment on an annual basis. Uncertainty in the three objectives is tackled by a fuzzy approach and through hyperbolic and exponential membership functions. An irrigation planning scenario of 75% dependable inflow with groundwater and treated wastewater is analyzed (termed as 75WGWHM) and is the basis for formulating the multiobjective problem. Two additional scenarios, S1 with 75% dependable inflow without groundwater using a hyperbolic membership function and S2 with 75% dependable inflow with groundwater using an exponential membership function, are also explored and compared with 75WGWHM. It is observed from the results that hyperbolic membership function is superior to the exponential membership function for the present planning problem. In addition, sensitivity analysis on PSO parameters suggests that parameters are to be chosen with due care in order to achieve meaningful inferences that can be implemented practically.

The timing of significant shifts in urban water use is highly relevant to water managers, who can better manage demand with an understanding of historic change. This study employs breakpoint and decomposition analyses to explore changes in water use for three North Carolina municipalities between 1990 and 2014. Although water demands were on the rise in each city during the early 1990s, per capita demands began to trend downward in the middle-to-latter years of that decade. The timing of this shift correlates with declines in manufacturing water uses. Per capita demand then remained stable from 2002 until 2007, when rates for all three cities shifted downward once again. This second shift follows the coordination and institutionalization of drought responses at the state level. Only Raleigh experienced another significant decline, with the implementation of conservation pricing in 2010. Moreover, while total withdrawals have remained stable for the cities of Durham and Greensboro since the mid-to-late 1990s, Raleigh saw rapid growth until 2010, when water policies caused the withdrawal rate to drop markedly. In sum, these results suggest that past shifts in urban water use have resulted from the interaction of globalization, water stress, and cross-scale policies. Water managers may wish to consider how globalization and water stress shape demand, both directly and through policy adoption.