A MUNICIPAL WATER DEMAND MODEL FOR THE CONTERMINOUS UNITED STATES1

With the increasing Federal role in all aspects of water resource planning, the need for a planning model to enable calculations of projected Municipal Water requirements has become evident. This study represents an initial effort at developing an econometric model of Municipal Water requirements which (1) incorporates variables (or proxies) reflecting the various factors affecting water demand (i.e., demographic, social, industrial), and (2) requires only readily available, published data for its use. This model permits determinations of the water requirements of 488 cities grouped into 19 geographic regions or “Pseudo States.” Separate regression functions have been fitted to the cities within each of the 19 regions. Derivation of the exact functions for each region entailed a cross section stepwise regression analysis in which some 18 different variables were examined. KEY WORDS: planning model; econometric model; initial effort; municipal water     

Factors affecting the variability of household water use in Melbourne,Australia

This study investigates the variability of household water use in Melbourne with the aim of improving the current understanding of factors affecting residential water use. This understanding is critical to predicting household water demand, particularly at an appropriate spatial and temporal resolution to support Integrated Urban Water Management based planning and to improve the understanding on how different household water demands respond to demand management strategies. The study used two sets of data each collected from 837 households under significantly different water use conditions in the years 2003 and 2011. Data from each household consist of the household characteristics and quarterly metre readings. Ordinary Least Square regression analysis followed by detailed analysis of each factor was used to identify key factors affecting household water use. The variables studied are household size, typology of dwelling, appliance efficiency, presence of children under 12 years, presence of children aged between 12 and 18 years, tenancy, dwelling age, presence of swimming pool, evaporative cooler, and dishwasher. All of them except presence of children aged between 12 and 18 years, tenancy and dwelling age were identified as variables that contribute to the variability of household water use in Melbourne. The study also found that the explanatory capacity of these variables increases with decreasing water use. This paper also discusses the significance of the explanatory variables, their impact and how they vary over the seasons and years. The variables found in this study can be used to inform improved prediction and modelling of residential water demand. The paper also explores other possible drivers to explain residential water use in light of the moderate explanatory capacity of the variables selected for this study thus, provides useful insights into future research into water demand modelling.     

RESIDENTIAL WATER CONSERVATION: CASA DEL AGUA1

ABSTRACT: A single-family residence in Tucson, Arizona, was retrofitted with water-conserving fixtures, rainwater harvesting, and graywater reuse systems. During a four-year study, efficient use of water was shown to significantly decrease demand for domestic water at the house without reducing the residents' quality of life. The use of municipal water was reduced by 66 percent to 148 gallons per day (gpd) and total household use was reduced by 27 percent to 245 gpd. Graywater reuse averaged approximately 77 gpd or 32 percent of the total household water use. Evaporative cooling required about 15 gpd. Water use for toilet flushing was only 9 gallons per capita per day (gpcd) or 14 percent of interior water use.     

WATER CONSERVATION IN CASABLANCA,MOROCCO1

ABSTRACT: This study examines water consumption characteristics in Casablanca and analyzes approaches for sustainable water demand management. Research procedures involve the development and estimation of water demand models for the residential/commercial, industrial, and institutional sectors; forecasts of water demand to 2010; and simulation of the effects of a complex of water conservation methods on the forecasted demands. The results indicate that residential/commercial water demand is weakly responsive to price changes (elasticity =?0.448) while institutional water demand is slightly more responsive (elasticity =?0.648). The conservation approaches used in the simulations included public education, plumbing code revisions to require use of water conservation devices, leak detection and repair, pricing policy, metering, and pressure reduction. The results indicate that considerable saving in water use can be attained through a comprehensive water demand management program.     

WATER SUPPLY OPTIONS IN A NEW MEXICO WATER PLANNING REGION1

ABSTRACT: The population in the Jemez y Sangre Water Planning Region of New Mexico has reached the point at which the demand for water exceeds available supplies, particularly when precipitation is below average, as has frequently occurred in recent years. The desire to develop a sustainable water supply that relies on renewable supplies in wet years and preserves the water in storage for times of drought motivated a diverse set of stakeholders in the region to participate in regional water planning. The planning effort culminated in development of the Jemez y Sangre Regional Water Plan, which was adopted by municipal and county governments in the region. The plan assesses and compares water supply and demand in the region and recommends alternatives for protecting and restoring the existing water supply and addressing the pending gap between supply and demand anticipated by the year 2060. To convey to decision makers the alternatives available to solve the future water shortage, option charts were developed to portray the amount of water that could be obtained or conserved through their implementation. The option charts show that the projected gap between supply and demand cannot be met through one alternative only, but will require a combination of alternatives.     

WATER PRICE RESPONSIVENESS OF COMMERCIAL ESTABLISHMENTS1

ABSTRACT: Pricing policy in water allocation has become of more concern as some areas find water is indeed a scarce resource. Demand estimates, where the quantity purchased-value in use relationships are of concern, have been made in other studies for residential, industrial, and agricultural uses in many areas of the country. The price-quantity relations for water use in commercial firms are estimated and discussed for several different types of stores in this study. A derived demand model is used to estimate commercial demand in the Miami, Florida, area. The price elasticity was generally low (inelastic) for all groups studied except for department stores. This group was found to have an elastic demand for water at all prices above $0.93 per thousand gallons purchased per month, where the mean price for this part of the sample was $1.24. The major implication of the study is that commercial establishments may be responsive to price changes over the long run, much as has already been shown for other types of user groups in other studies.     

Impacts of Multiple Stresses on Water Demand and Supply Across the Southeastern United States1

Abstract: Assessment of long‐term impacts of projected changes in climate, population, and land use and land cover on regional water resource is critical to the sustainable development of the southeastern United States. The objective of this study was to fully budget annual water availability for water supply (precipitation ? evapotranspiration + groundwater supply + return flow) and demand from commercial, domestic, industrial, irrigation, livestock, mining, and thermoelectric uses. The Water Supply Stress Index and Water Supply Stress Index Ratio were developed to evaluate water stress conditions over time and across the 666 eight‐digit Hydrologic Unit Code basins in the 13 southeastern states. Predictions from two Global Circulation Models (CGC1 and HadCM2Sul), one land use change model, and one human population model, were integrated to project future water supply stress in 2020. We found that population increase greatly stressed water supply in metropolitan areas located in the Piedmont region and Florida. Predicted land use and land cover changes will have little effect on water quantity and water supply‐water demand relationship. In contrast, climate changes had the most pronounced effects on regional water supply and demand, especially in western Texas where water stress was historically highest in the study region. The simulation system developed by this study is useful for water resource planners to address water shortage problems such as those experienced during 2007 in the study region. Future studies should focus on refining the water supply term to include flow exchanges between watersheds and constraints of water quality and environmental flows to water availability for human use.     

MUNICIPAL UTILIZATION OF WATER DEMAND MANAGEMENT: THE ONTARIO EXPERIENCE1

ABSTRACT: Managing the demand for municipal water supply has become a viable alternative or supplement to traditional supply management responses. Though senior governments in Canada are committed to the concept, there is a lack of knowledge concerning the level of use of the demand management concept and little promotion of water conservation. This paper assesses the extent of the use of this concept as it applies to municipal water supply across southern Ontario and examines factors that influence the variation in use of water conservation strategies. Information from 219 municipalities revealed that the concept is not in wide use in southern Ontario and that existing variation can be partially explained by the extent of problems experienced and the population size served by the municipal water supply system. Suggestions for increasing municipal use of the demand management concept are offered.     

Residential Water Demand Management: Lessons from Aurora,Colorado1

Abstract: Residential water demand is a function of several factors, some of which are within the control of water utilities (e.g., price, water restrictions, rebate programs) and some of which are not (e.g., climate and weather, demographic characteristics). In this study of Aurora, Colorado, factors influencing residential water demand are reviewed during a turbulent drought period (2000‐2005). Findings expand the understanding of residential demand in at least three salient ways: first, by documenting that pricing and outdoor water restriction policies interact with each other ensuring that total water savings are not additive of each program operating independently; second, by showing that the effectiveness of pricing and restrictions policies varies among different classes of customers (i.e., low, middle, and high volume water users) and between predrought and drought periods; and third, in demonstrating that real‐time information about consumptive use (via the Water Smart Reader) helps customers reach water‐use targets.     

The Impacts of Water Conservation Strategies on Water Use: Four Case Studies1

Tsai, Yushiou, Sara Cohen, and Richard M. Vogel, 2011. The Impacts of Water Conservation Strategies on Water Use: Four Case Studies. Journal of the American Water Resources Association (JAWRA) 47(4):687‐701. DOI: 10.1111/j.1752‐1688.2011.00534.x Abstract: We assessed impacts on water use achieved by implementation of controlled experiments relating to four water conservation strategies in four towns within the Ipswich watershed in Massachusetts. The strategies included (1) installation of weather‐sensitive irrigation controller switches (WSICS) in residences and municipal athletic fields; (2) installation of rainwater harvesting systems in residences; (3) two outreach programs: (a) free home indoor water use audits and water fixture retrofit kits and (b) rebates for low‐water‐demand toilets and washing machines; and (4) soil amendments to improve soil moisture retention at a municipal athletic field. The goals of this study are to summarize the effectiveness of the four water conservation strategies and to introduce nonparametric statistical methods for evaluating the effectiveness of these conservation strategies in reducing water use. It was found that (1) the municipal WSICS significantly reduced water use; (2) residences with high irrigation demand were more likely than low water users to experience a substantial demand decrease when equipped with the WSICS; (3) rainwater harvesting provided substantial rainwater use, but these volumes were small relative to total domestic water use and relative to the natural fluctuations in domestic water use; (4) both the audits/retrofit and rebate programs resulted in significant water savings; and (5) a modeling approach showed potential water savings from soil amendments in ball fields.     

STATISTICAL ANALYSIS OF WATER CONSUMPTION1

The purpose of this study was to determine the degree of influence of various factors on municipal water consumption in Illinois. For the collection of basic data, questionnaires were sent to all public water works of incorporated towns. The questionnaire was designed to obtain information on factors which may have any effect on water use. The effects of the different parameters on water consumption were based on several correlation and regression combinations of predictands and predictors. It was found that in the Chicago region the percent of services and water used for commercial and industrial purposes and the age of the water works were the most important parameters influencing water consumption (gallons per capita per day) when pumpage is metered at the water works as well as at the customers. For the State, excluding the Chicago region, percent of public water use, persons per service, population and commercial and industrial water use were the most important parameters. It has been recommended that similar statistical analysis be conducted periodically to establish a trend or law of change from the influencing parameters.     

Assessing energy use and greenhouse gas emission savings from compact housing: a small-town case study

Data from the US Department of Energy show that single-family detached homes consume about 17% more energy per year than attached homes and roughly double that of units in large multi-family structures. While greater use of these compact housing types could reduce a community's energy use and greenhouse gas (GHG) emissions, most local climate action plans (CAPs) do not quantify those potential savings. This article describes how the climate action planning process in the Town of Blacksburg, Virginia has addressed residential sector GHG emissions and demonstrates a methodology applied in that community for estimating potential GHG reductions from compact housing. It finds that in an aggressive compact housing scenario GHG emissions from new housing could be decreased by as much as 36%, without factoring in additional energy conservation or efficiency measures. The article concludes with a discussion of the opportunities and challenges related to implementing compact housing in future residential development.     

A REGIONAL APPROACH TO PROJECT EVALUATION1

ABSTRACT. Water and related land resource planning has generally been characterized by project evaluation in isolation. Feasible alternatives have been ignored because the economic analysis did not include the interdependence of such subregional and regional variables as factor and product prices and production possibilities. This paper presents an economic framework, consistent with a regional development objective and an efficiency criterion, for proposing and evaluating resource projects. Subregional and regional derived demand curves for water are developed under alternative assumptions of subregional competition, regional market restraints, and yield and price uncertainty. The derivation of water demand curves using the proposed regional framework as compared to sub regional isolation has the desirable properties of (1) a marginal analysis that is more flexible over time is substituted for a static average analysis; (2) range estimates incorporating probabilities are substituted for point estimates; (3) approximations to functional demand curves are substituted for “needs”; and (4) fewer resources are required to meet a regional market restraint.     

Water Supply Planning Considering Uncertainties in Future Water Demand and Climate: A Case Study in an Illinois Watershed

Ensuring an adequate, reliable, clean, and affordable water supply for citizens and industries requires informed, long-range water supply planning, which is critically important for water security. A balance between water supply and demand must be considered for a long-term plan. However, water demand projections are often highly uncertain. Climate change could impact the hydrologic processes, and consequently, threaten water supply. Thus, understanding the uncertainties in future water demand and climate is critical for developing a sound water supply plan. In Illinois, regional water supply planning attempts to explore the impacts of future water demand and climate on water supply using scenario analyses and hydrologic modeling. This study is aimed at developing a water supply planning framework that considers both future water demand and climate change impacts. This framework is based on the Soil and Water Assessment Tool to simulate the watershed hydrology and conduct scenario analyses that consider the uncertainties in both future water demand and climate as well as their impacts on water supply. The framework was applied to water supply planning efforts in the Kankakee River watershed. The Kankakee River watershed model was calibrated and validated to observed streamflow records at four long-term United States Geological Survey streamflow gages. Because of the many model parameters involved, the calibration process was automated and was followed by a manual refinement, resulting in good model performance. Long-range water demand projections were prepared by the Illinois State Water Survey. Six future water demand scenarios were established based on a suite of assumptions. Climate scenarios were obtained from the Coupled Model Intercomparison Projection Phase 5 datasets. Three representative concentration pathways (RCPs), RCP2.6, RCP4.5, and RCP8.5, are used in the study. The scenario simulation results demonstrated that climate change appears to have a greater impact on water availability in the study area than water demand. The framework developed in this study can also be used to explore the impacts of uncertainties of water demand and climate on water supply and can be extended to other regions and watersheds.     

基于EBM模型的长江经济带工业用水效率时空差异及影响因素分析

工业化进程的加快使得工业水资源需求不断增加，工业废水排放量也越来越大，如何提高工业用水效率从而缓解水资源压力成为日益严峻的问题。本文选取工业用水量、工业就业人数、工业固定资本和工业废水治理费用作为投入指标，以工业增加值与工业废水排放量作为期望与非期望产出指标。首先利用EBM模型计算长江经济带2008—2017年工业用水效率，其次利用泰尔指数来分析工业用水效率的区域差距，最后利用面板Tobit模型来分析影响不同地区工业用水效率的驱动因素。结果显示，近年来长江经济带的工业用水效率呈波动下降趋势，不同地区效率差异明显；经济发展水平、工业化程度、技术水平、水资源禀赋和政府环境管制力度对长江经济带的工业用水效率都有一定影响，但存在地区差异。     

THE ACCURACY OF WATER USE FORECASTS: EVALUATION AND IMPLICATIONS1

ABSTRACT: Forecasts of 1980 river basin water use presented in the reports of the 1960 Senate Select Committee on National Water Resources and in the Water Resources Council's First National Water Assessment of 1968 were compared to estimates of actual use in 1980 to assess the accuracy of efforts to forecast future water use. Results show that the majority of the forecasts were substantially in error. In general, the First National Assessment forecasts erred by a smaller margin, but tended to repeat the regional patterns of overestimation (underestimation) exhibited in the Senate Select Committee forecasts. Moreover, forecasts of the two groups that came within 20 percent of the 1980 withdrawals, in general were accurate, not because of superior prediction, but because of offsetting errors in forecast components. This performance leads us to conclude that water use forecasts, regardless of the time-frame or the forecast method employed, are likely to always be highly inaccurate. Accordingly, if such forecasting efforts are to be of value in contemporary water resources planning, forecasters should direct their attention toward methods which will illuminate the determinants of the demand for water.     

RESIDENTIAL WATER DEMAND IN METRO MANILA1

ABSTRACT: An econometric demand function is estimated for residential water use in Metropolitan Manila. Regression results using annual time series data from 1970 to 1981 show that residential water consumption responds to changes in economic variables. Residential demand showed an income (household) elasticity of 0.542 and a combined price elasticity of -0.287. Implications for planning and management are discussed.     

WATER SUPPLY AND URBAN GROWTH PLANNING: A PARTNERSHIP1

ABSTRACT As urban expansion outstrips water supplies, the usual solution is to build pipelines to bring in water from sources farther afield. Such water supplies may act as either a leader of urban development or as a follower. In either case, this engineering approach to the provision of water has fostered less than optimal utilization of regional water and land resources for urban growth. More efficient utilization of these resources is achieved when water supply development and urban growth planning are conjoint activities. Water supply planners and land use planners, working together, are able to generate and evaluate the full range of urban development options, including water demand management through conservation. Preferred regional growth plans are achieved using the best mix of water supply and urban growth. The result is a reduced rate of water supply development and a reduction of urban expansion on prime lands. This partnership approach is demonstrated for the Calgary Region under two levels of water conservation.     

WATER DEMAND AT WESTERN U.S. RECREATION DEVELOPMENTS1

Although the volume of potable water used at recreation developments is minor relative to total regional water use, very high quality is required and the source is often of limited capacity, such as a mountain spring or small local aquifer. Frequent confrontations between developers and regulatory agencies result from claims by developers that water demand will be very small while regulators tend to treat such developments the same as municipal residence. Almost no published data base exists for resolving such conflicts. Included here are: 1) Water use measurements of various peak period durations (seasonal, monthly, daily, and instantaneous) at several types of recreational developments in Utah and Wyoming (mountain cabins, both ski- and water-based condominiums, and recreation vehicle campgrounds), 2) statistical (frequency) analysis of the data and a comparison with municipal demands in the same region, and 3) analysis of occupancy rates at the various categories of developments.