Journal of Water Resources Planning and Management

This paper describes a simulation-optimization model aimed at helping water utilities determine the best way to operate large-scale multisource water-supply systems. The operation of water systems is optimized taking into account the principal planning objectives defined for interventions that include reducing operating costs, satisfying demand, delivering water of appropriate quality, and not prompting the use of emergency sources. The model allows that these planning objectives may not be completely fulfilled in critical circumstances (e.g., droughts) when goals have to be prioritized by the water utilities. The model is a highly nonlinear programming problem and is solved with the general algebraic modeling system (GAMS), using the MINOS algorithm (GAMS/MINOS). The application of the model to the multimunicipal urban water-supply system of the Algarve shows its capabilities for optimizing the operation considering economic and noneconomic goals included in the objective function and to cope with future shortages in critical circumstances by improving the conjunctive use of the different water sources with interannual planning time horizons.

Climate change has made environmental impact a factor of growing importance in decision making for municipalities. Increasingly, the environmental impacts of expanding and operating a water distribution system (WDS) are considered alongside the cost and hydraulic design. This paper presents a nondominated sorting genetic algorithm (NSGA-II) that minimizes capital costs, annual pumping energy use, and environmental impacts in WDS design that adheres to hydraulic constraints. A previously developed environmental impact (EI) index is included in the environmental objective function of the optimization program. The EI index normalizes and aggregates multiple environmental measures evaluated with an economic input-output life-cycle assessment (EIO-LCA) model. The EIO-LCA-based NSGA-II was applied to the Anytown network. Annual pumping energy use was found to dominate the EI index while capital cost and the EI index were inversely related, and the annual pumping energy use and the EI index followed a near linear relationship. The location and shape of the Pareto fronts were sensitive to demand and roughness coefficient (C-factor) adjustments with greater sensitivity observed for changes in demand than changes in the C-factor.

The usefulness of transient models depends on their predictive ability. Consequently, their results should ideally be validated with field data. Despite numerous theoretical developments in the area of surge analysis, comparisons between field and modeled data for large distribution systems (DSs) are scarce. Transient low-pressure events at a water treatment plant (WTP) resulted in negative pressures at numerous locations in the DS. Three distinct surge events were measured in a full-scale DS and modeled with transient analysis software. The simulated pressure profiles were compared with field data collected from 9–12 sites within the DS. The objective was to apply a commercial transient analysis algorithm to a large and detailed network model ($\approx 15,000\mathrm{nodes}/\mathrm{pipes}$) to estimate transient pressure variations within the network. Results showed similar trends for the three low-pressure events analyzed: the modeled pressures matched reasonably well with the measured pressures, as long as they remained positive. Whenever the pressures reached negative values, the simulated amplitude was larger than that of the recorded pressures. Modeling parameters and factors that might explain such results were tentatively investigated. The importance of field data in understanding and confirming the model outputs is highlighted.

Contamination source identification involves the characterization of the contaminant source based on observations that stream from a set of sensors in a water distribution system (WDS). The streaming data can be processed adaptively to provide an estimate of the source characteristics at any time once the contamination event is detected. In this paper, an adaptive dynamic optimization technique (ADOPT) is proposed for providing a real-time response to a contamination event. A new multiple population–based search that uses an evolutionary algorithm (EA) is investigated. To address nonuniqueness in the initial stages of the search and prevent premature convergence of the EA to an incorrect solution, the multiple populations are designed to maintain a set of alternative solutions that represent various nonunique solutions. As more observations are added, the EA solutions not only migrate to better solution states but the number of solutions decreases as the degree of nonuniqueness diminishes. This new algorithm adaptively converges to the solutions that best match the available observations. The use of the developed method is demonstrated for two WDS networks.

A simple yet effective approach is developed on the basis of dynamic programming (DP) as a means of objectively selecting and prioritizing sewerage projects within available funds and system capacity. The methodology consists of two DP models: a collection system model with an embedded benefit assessment technique to identify areas for wastewater collection; and a transportation system model to select routes of wastewater conveyance. Unlike conventional benefit analysis, benefits in this approach are defined as changes in adverse environmental, public health, and other noneconomic consequences as a result of sewerage provisions. The approach is a useful decision tool for planning sewerage system expansion. The models are used to identify “best” sewerage expansion plans for Ensenada, Baja California, Mexico. Sixteen potential areas for sewerage expansion and three existing plants with additional wastewater treatment capacity are considered.

Water pricing is one of the water-demand management tools advocated to improve water allocation, water-use efficiency, equity, and sustainability. Often, however, little attention is paid to farmers’ cooperation, which is necessary for introducing efficient irrigation water pricing. This paper studies the price sensitivity of the preferences for water-pricing methods in a broader water-rights system perspective in the Krishna River basin in India. We applied a choice experiment to investigate farmers’ preferences for and the efficiency of a given pricing method based on willingness to pay estimates. The results indicate that farmers never prefer the existing area pricing system. At higher price levels, farmers would chose volumetric pricing followed by quota pricing, whereas at low price levels quota pricing is preferred. Price sensitivity of farmer preferences for volumetric pricing is high. Since water prices are expected to rise in the future as Indian water policies intend to eventually recover the full costs of irrigation water, volumetric-based pricing methods will probably be the most acceptable solution from the farmers’ perspective.

Drought indexes (DIs) have commonly been used to quantify drought conditions around the world. Most DIs are developed for specific regions and, therefore, may not be directly applicable to other regions because of the inherent complexity of drought phenomena, different hydroclimatic conditions, and different catchment characteristics. A few studies in which the suitability of some of the existing DIs was evaluated for different parts of the world have been cited in the literature. However, no such study has been conducted in Australia, where droughts are more frequent than elsewhere in the world. In this paper, five DIs, namely, percent of normal (PN), deciles, Standardized Precipitation Index (SPI), Surface Water Supply Index (SWSI), and Aggregated Drought Index (ADI) were evaluated for the Yarra River catchment in Victoria, Australia. The evaluation was conducted to determine how well these indexes modeled historical droughts. Five decision criteria, namely, robustness, tractability, sophistication, transparency, and extendability, were used to compare the performance of these DIs. The results showed that the ADI was superior to other indexes for drought management within the Yarra River catchment.

An integrated hydrologic-economic-institutional water model was developed for the Rio Yaqui Basin, located in northwest Mexico, with the objective of assessing the impacts on agricultural economic benefits from strategies for allocating environmental flow. This paper focuses on the creation of simulation models that estimate the agricultural net benefits under different environmental flow scenarios and surface water allocation strategies. The results illustrate a trade-off between interannual variability of environmental flows and variability in agricultural benefits, corresponding to economic risk, for three allocation strategies. Results also show that environmental flow allocations affect groundwater levels through impacts on surface-ground water interactions.

In this paper, the reliability of a transient test-based technique as a powerful tool in the management of real supply pipe systems is shown. The pressure signal acquired during the first phase of the single completed test has been analyzed on the basis of extensive research activity performed in the previous years in the field of transient test-based techniques and refined on the basis of numerical and laboratory tests. Specifically, the wavelet transform, which allows the automatic detection of singularities in noisy pressure signals, and a Lagrangian model, which evaluates the causes of discontinuities, are efficiently coupled for analyzing the pressure signal acquired in the described pipe system. As a result, the topology of such a system has been checked, and its functioning conditions have been determined. Moreover, the unwanted status of an in-line valve—certified by the manager as fully open but actually partially closed—has been pointed out.