Search

The built environment significantly alters the rainfall-runoff response and associated transport of particulate matter (PM), chemicals, and pathogens in the urban water cycle. Urban water s...

Water distribution networks (WDNs) are systems of water distribution used in urban centers and industrial processes that require efficient design and operation, which may be achieved throug...

Leaks in water pipelines can create many problems, such as financial loss, environmental pollution, and public health hazards. Previous scholars and engineers have researched leak detection...

Turbulence is inherent in clarification basin systems; turbulence is challenging to quantify, yet directly impacting particulate matter (PM) separation. In computational fluid dynamic (CFD)...

In 2017, urban water retailers in California reported 364 million m3 in real water losses within their distribution systems, representing on average 7.12% of their total water delivered th...

Reliable forecasts of water demand that account for factors that drive demand are imperative to understanding future urban water needs. The effects of meteorological dynamics and sociocultu...

This case study uses a long short-term memory (LSTM)-based model to predict short-term urban water demands for the Hefei City of China. The performance of the LSTM-based model is compared with the autoregressive integrated moving average (ARIMA) model, the support vector regression (SVR) model, and the random forests (RF) model based on data with time resolutions ranging from 15 min to 24 h. Additionally, this paper investigates the performance of the LSTM-based model in predicting multiple successive data points. Results show that the LSTM-based model can offer predictions with improved accuracy than the other models when dealing with data with high time resolutions, data points with abrupt changes, and data with a relatively high uncertainty level. It is also observed that the LSTM-based model exhibits the best performance in predicting multiple successive water demands with high time resolutions. In addition, the inclusion of external parameters (e.g., temperature) cannot enhance the performance of the LSTM-based model, but it can improve ARIMAX's prediction ability (ARIMAX is the ARIMA with variables). These observations provide additional and improved evaluations regarding the LSTM-based models used for short-term urban water demand forecasting, thereby enabling their wider adoption in practical applications.

Demand forecasting for water resources is an essential planning element for cities to provide secure and sustainable water supplies. A common way of determining water demands is to identify...

New approaches are provided for urban water environment treatment projects (UWETP) with the development and application of the public-private partnership (PPP) model. However, an asymmetry ...

California has consistently altered natural water resources to provide water for its growing population and to support the fifth largest economy in the world. However, the old ways of copin...

Recent water crises showed that excluding community stakeholders in urban water system decision-making throughout can have an adverse effect on the entire community and decrease system resi...

Pumping systems are a topic of great relevance in the teaching of civil and environmental engineering courses related to urban water infrastructure. One key component of this teaching is th...

This paper estimates feasible water savings for a sample of nine urban water districts in California during the height of the 2012–2016 drought, just prior to the implementation of mandator...

Understanding air-pocket formation in closed conduits is important in urban water systems subject to rapid-filling conditions, such as in the case of stormwater sewers and tunnels during in...

Urban water governance is a framework for addressing critical issues in cities’ water resources by creating a more inclusive policy for sustainable transitions. Beyond the physical or direc...

Unit operations (UO) for urban water clarification are commonly implemented for management of particulate matter (PM), PM-associated chemicals, and microbial species, primarily through sedi...

North America’s water distribution systems are aging and incurring increased pipe breaks. These breaks pose a serious threat to urban drinking water security, leading to service interruptio...

Concerns over the impacts of urban growth have prompted the development and adoption of water-demand management strategies. Water and energy savings from increasingly efficient technologies...

Changing circumstances and the availability of new technologies are causing urban water systems to transition from managing system components in a separate and linear fashion to an integrat...

Water scarcity in arid and semiarid regions of the world is increasing rapidly due to multiple factors, exacerbating competition over alternative water uses. This is especially relevant in ...

Designing urban water infrastructure systems for environmental sustainability requires consideration of hydrologic performance design criteria and results from life cycle assessment (LCA). ...

Cities in developing countries frequently suffer from poor water quality. Thus, the ability to make informed decisions on the current state of urban water quality, as well as on rehabilitat...

Urban drainage networks are under constant pressure caused by a permanently changing environment. For proactive planning, management, and adaptation of urban water infrastructure, a robust ...

The Charles River Watershed Association, of Weston, Massachusetts, has an ambitious goal: transforming the ways in which urban areas manage drinking water, wastewater, and storm water. By seeking to integrate traditionally separate water systems, the association aims to maximize the recovery of resources from wastewater, restore the natural water cycle in developed areas, and revitalize the urban environment and its waterways.

The implementation of nodal demands in current transient modeling and analysis in the urban water distribution system (WDS) is usually based on steady-state conditions or empirical-based ap...

A comprehensive water-energy-carbon (WEC) nexus model for an urban water system (UWS) using system dynamics is proposed to assist municipalities, urban developers, and policy makers for nei...

Water distribution systems, as an urban infrastructure, have an indisputable role in the productivity of a society and the quality of life of its residents. It is necessary to develop policies for evaluation of the urban infrastructure performance and determining the proper time of maintenance and rehabilitation activities to increase system productivity and expand the system’s efficient performance time. In this paper, an algorithm is developed to evaluate the efficiency of urban water infrastructure performance, broken down into costs and benefits, and to determine the optimal time of water distribution network (WDN) rehabilitation using a probabilistic approach. The proposed algorithm is examined in a real water distribution network in Iran. Considering different break scenarios, the WDN’s performance within the projected performance period is simulated. The efficiency of the WDN is quantified using a reliability-based indicator, and costs and benefits of its performance are also evaluated. Bas...

Water-distribution operation is an essential part of an urban water-supply system to deliver high-quality water to consumers. Management of such an operation may involve deliberations of operation cost, system capacity, and environmental restriction, and is convoluted with many forms of uncertainties. In this paper, an integrated fuzzy programming and decision analysis (IFPDA) approach was proposed for a multilayer urban water-distribution system management under uncertainty. The system consisted of two water sources, four treatment plants, seven reservoirs, and seven consuming zones. Uncertain information associated with water demands, water-treatment capacities, water-transfer cost, and leakage rate was described by a trapezoidal-shaped fuzzy set and embedded into a fuzzy programming framework. The balance between the satisfaction degree of achieving the system objective and feasibility level of meeting the related constraints was analyzed by fuzzy inference procedures. The results indicate that...

The management improvement of irrigation networks is inevitable because of limited water resources and competition in various sectors of industry, agriculture, environment, and urban water consumption. Application of appropriate water delivery scheduling is one of the methods to improve irrigation management. Several delivery methods are practiced in irrigation networks according to water availability, type of network control system, and exiting capacities. One promising delivery method is the on-request system, which could be applied manually in irrigation networks. High performance of delivery methods arise from the determination of appropriate operation instructions. In previous studies, the Fuzzy SARSA learning (FSL) method was applied to determine operation instruction for on-request delivery in a canal of the Aghili irrigation network located in southwest Iran (SARSA is the definition of state, action, reward, state, action). In this work, the conventional manual operation on the same canal ...

Urban rainfall-runoff modeling is important to analyze the health of urban water systems. The Storm Water Management Model (SWMM) developed by the U.S. Environmental Protection Agency (USEP...

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-...

Water scarcity and aquatic environment deterioration have become increasingly serious problems in Urumqi, China. To alleviate the conflicts arising from competitive water users and retard the environment degradation, an optimization model was developed for regional water resources management under considering the dual total amount of water quantity and pollutant emissions control. Water allocation schemes and guarantee rates that combine diverse water sources and economic activities were obtained through the solutions of the proposed model. The interactions among water allocation schemes, various activities benefits, and pollutant emissions were analyzed synchronously. Policies for industrial structure adjustment and pollutants emission reduction were acquired through the analysis of the results. The modeling results can be valuable for water resources planning and justification of the existing industrial structure.

Urban water demand forecasting is key to municipal water supply management. Short-term urban water demands are influenced by weather conditions. Thus, short-term urban water demand forecasting could be improved by using accurate weather forecasting information. This study explores the potential of using an analog approach with a newly developed retrospective weather forecast (reforecast) of a numerical weather prediction (NWP) for improving short-term urban water demand forecasting. The analog method derives an analog ensemble forecast resampled from observed data (analogs) based on the reforecast of a NWP: the Global Ensemble Forecast System (GEFS). The probabilistic and ensemble mean forecasts generated from analogs of weekly total rainfall (WeekRain), number of rainy days in one week (RainDays), number of consecutive rainy days in one week (CosRainDays), number of hot days in one week (HotDays), and daily mean temperature of the first seven lead days (T) from the reforecast were evaluated using...

Rainwater harvesting (RWH) is being used more often today as a water supply and stormwater management green infrastructure (GI). In recent years, GIs in urban water engineering have gained attention due to their lower lifecycle costs—in both implementation and operation phases—rather than traditional gray approaches. The research described in the present paper compared implementation of RWH systems to gray approaches previously designed as a part of the long-term control plan (LTCP) for combined sewer overflow (CSO) control in Toledo, Ohio. RWH scenarios in this study were defined based on different system capacities and release policies, and then combined gray and green scenarios were analyzed according to their hydrologic performance and cost. This study employed long-term continuous hydrologic and hydraulic (H&H) simulations as well as lifecycle cost (LCC) analysis techniques. The results showed that greening the LTCP via RWH could improve the lifecycle cost-effectiveness by 48%. The captured r...

Low impact development (LID) strategies are being encouraged in many communities as an approach to reduce potential adverse impacts of development on receiving streams. Many questions exist regarding how well various LID strategies perform in different settings, just as similar questions have been raised regarding performance of traditional stormwater best management practices (BMPs). Whereas historical focus on BMP performance has been water quality concentrations or loads, characterization of volume reduction benefits for both conventional and LID practices is increasingly an objective of researchers and stormwater managers. More than a decade ago, Urban Water Resources Research Council (UWRRC) members worked to develop a set of standardized monitoring and reporting protocols for traditional BMPs and to establish a master database for the purpose of evaluating BMP performance and the factors affecting performance. This effort culminated in the International Stormwater BMP Database (www.bmpdatabase.org),...

The research team evaluates whether a proportional hazards model can successfully be applied to a water distribution piping network located in a complex urban area in order to identify which risk factors play a role in the failure of urban water pipes, to what extent, and, for each pipe, to forecast the number of future breaks. Risk factors can be inherent to the pipe (material, diameter, length, date of installation, break history) or reflecting environmental conditions (traffic, water zone, proximity to subways, highways.) Long Island City, an area of New York City with 220 miles of water pipes and 20 years of break data (1982–2002) constitutes the case study. Various conditions of applicability pertaining to the stratification of the data based on material, break frequency, and history are examined.

A methodology is presented for the reliability assessment of urban water distribution networks (UWDN) on the basis of component analysis, network topology, and—most importantly—survival ana...

This paper explores the potential and limitations for southern California water markets using an economic-engineering network flow optimization model, CALVIN. CALVIN is used to estimate how a market would affect overall southern California water use, to preliminarily assess the economic benefit of more flexible water allocation policies, and to explore the characteristics of an ideal market. Results from CALVIN suggest substantial economic and reliability benefits exist for implementing water market or other transfer mechanisms, and these benefits could be achieved with relatively little reallocation of agricultural water. An ideal water market in southern California would reduce more costly urban water shortages, reducing the demand for increased imports from outside of southern California. Additionally, substantial economic benefits could accrue from expanding some conveyance and storage facilities, particularly the Colorado River Aqueduct and conjunctive use storage capacity.

An efficient and equitable method for determination of impact fees for urban water systems is presented. A fair allocation of costs is based on n-person cooperative game theory designed to allocate costs by zones, user classes, and/or demand types. The least-cost solution of each alternative is found using an intelligent search method reported elsewhere. The proposed method is demonstrated on a small water system, and the results are compared with other cost allocation methods.

The management of wet-weather flow (WWF) is necessary to maintain the quality of urban water resources. Throughout history, strategies have been implemented to control WWF for many reasons, including flood and water quality control, aesthetic improvement, waste removal, and others. A comprehensive literature review has been conducted to determine past strategies and to revisit the historical developments of WWF management. Understanding these past strategies and the development of WWF-management systems over time will aid current and future generations in their WWF-management efforts. This paper summarizes the historical literature review, highlighting the development of WWF management from ancient times to the present. The relationship between past developments, the current state, and the future of WWF management is addressed by identifying several lessons learned.

Water resources planners and managers are continually faced with decisions to be made under uncertainty. In planning problems such as water supply, flood control, and ground-water remediation, the trade-offs among expected cost, cost variability, and system performance and reliability must be assessed amidst inherent variability and imperfect information. Robust optimization (RO) is introduced as a framework for evaluating these trade-offs and controlling the effects of uncertainty in water resources screening models. Upon the introduction of scenarios, which represent realizations of the random parameters in the model, two types of robustness are defined: a policy is optimality-robust if it remains optimal or nearly optimal for all scenarios, and feasibility-robust if it remains feasible or nearly feasible for all scenarios. Applications to urban water transfer planning and ground-water quality management are presented, with optimality robustness related to cost variability and feasibility robustness rel...

Water rationing is a common, but little studied, technique for managing urban water supplies during drought. This paper reviews a wide range of approaches for implementing water rationing for urban drought management. These rationing approaches are assessed in terms of practical and theoretical performance. The paper then examines the potential benefits of allowing drought water rations to be transferable or marketable. Transferable rights have become a common suggestion for allocating scarce resources for a wide range of water-quantity and water-quality problems. Although attractive in terms of economic theories of resource allocation, transferable drought water rations often will be uneconomical for small transactions, due to likely high costs of completing transactions. However, transferable drought water rations might be useful for allocating scarce water among large industrial, commercial, and institutional users and among residential users with very different water demands. The equity effects of tra...

Increasing use of distributed, physically based urban storm water management models requires urban water managers to acquire, maintain, and utilize the extensive, spatially referenced data bases ne...