Incorporating Future Climatic and Socioeconomic Variables in Water Demand Forecasting: A Case Study in Bangkok

With concerns relating to climate change, and its impacts on water supply, there is an increasing emphasis on water utilities to prepare for the anticipated changes so as to ensure sustainability in supply. Forecasting the water demand, which is done through a variety of techniques using diverse explanatory variables, is the primary requirement for any planning and management measure. However, hitherto, the use of future climatic variables in forecasting the water demand has largely been unexplored. To plug this knowledge gap, this study endeavored to forecast the water demand for the Metropolitan Waterworks Authority (MWA) in Thailand using future climatic and socioeconomic data. Accordingly, downscaled climate data from HadCM3 and extrapolated data of socioeconomic variables was used in the model development, using Artificial Neural Networks (ANN). The water demand was forecasted at two scales: annual and monthly, up to the year 2030, with good prediction accuracy (AAREs: 4.76 and 4.82 % respectively). Sensitivity analysis of the explanatory variables revealed that climatic variables have very little effect on the annual water demand. However, the monthly demand is significantly affected by climatic variables, and subsequently climate change, confirming the notion that climate change is a major constraint in ensuring water security for the future. Because the monthly water demand is used in designing storage components of the supply system, and planning inter-basin transfers if required, the results of this study provide the MWA with a useful reference for designing the water supply plan for the years ahead.     

Evaluation Criteria and Model for Risk Between Water Supply and Water Demand and its Application in Beijing

In China, studies on water supply and water demand balance have received much attention, but risk between water supply and water demand lacks the same focus. This paper presents evaluation criteria of risk between water supply and water demand, which includes threat, susceptibility, and vulnerability. A new quantitative definition of threat is given based on fuzzy probability; Susceptibility is proposed for evaluating the inherent state of the water resource systems; Vulnerability is qualitatively defined and computed in terms of economic losses. A model for risk evaluation is developed based on the maximum entropy principle and discriminant analysis. Risks in Beijing, used as a case study, are evaluated under different scenarios of inflow. The results show that all the risks in 2020 are first or second grade. After using reclaimed water and transferred water, the third grade and fourth grade risk account for 75 %, with 25 % of the first grade and second grade risk. Therefore, risks are still high in the situations of low precipitation periods.     

Quantifying the Urban Water Supply Impacts of Climate Change

The difference in timing between water supply and urban water demand necessitates water storage. Existing reservoirs were designed based upon hydrologic data from a given historical period, and, given recent evidence for climatic change, may be insufficient to meet demand under future climate change scenarios. The focus of this study is to present a generally applicable methodology to assess the ability of existing storage to meet urban water demand under present and projected future climatic scenarios, and to determine the effectiveness of storage capacity expansions. Uncertainties in climatic forcing and projected demand scenarios are considered explicitly by the models. The reservoir system in San Diego, California is used as a case study. We find that the climate change scenarios will be more costly to the city than scenarios using historical hydrologic parameters. The magnitude of the expected costs and the optimal investment policy are sensitive to projected population growth and the accuracy to which our model can predict spills.     

Reservoir volume optimization and performance evaluation of rooftop catchment systems in arid regions: A case study of Birjand,Iran

This study evaluated the performance of rooftop catchment systems in securing non-potable water supply in Birjand, located in an arid area in southeastern Iran. The rooftop catchment systems at seven study sites of different residential buildings were simulated for dry, normal, and wet water years, using 31-year rainfall records. The trial and error approach and mass diagram method were employed to optimize the volume of reservoirs in five different operation scenarios. Results showed that, during the dry water year from 2000 to 2001, for reservoirs with volumes of 200–20000 L, the proportion of days that could be secured for non-portable water supply was on average computed to be 16.4%–32.6% across all study sites. During the normal water year from 2009 to 2010 and the wet water year from 1995 to 1996, for reservoirs with volumes of 200–20000 L, the proportions were 20.8%–69.6% and 26.8%–80.3%, respectively. Therefore, a rooftop catchment system showed a high potential to meet a significant portion of non-potable water demand in the Birjand climatic region. Reservoir volume optimization using the mass diagram method produced results consistent with those obtained with the trial and error approach, except at sites #1, #2, and #5. At these sites, the trial and error approach performed better than the mass diagram method due to relatively high water consumption. It is concluded that the rooftop catchment system is applicable under the same climatic conditions as the study area, and it can be used as a drought mitigation strategy as well.     

A Dynamic Model for Vulnerability Assessment of Regional Water Resources in Arid Areas: A Case Study of Bayingolin, China

Water scarcity is a common problem in many countries, especially those located in arid zones. The vulnerability of water resources due to climate change is an imperative research focus in the field of water resources management. In this study, a System Dynamics (SD) model was developed to simulate the water supply-and-demand process in Bayingolin, a prefecture in China, and to evaluate water resources vulnerability currently as well as in the future. The model was calibrated and validated using historical data. Three alternative scenarios were designed by changing parameters to test the vulnerability of water resources: i) increase the Wastewater Treatment Rate by 50 %; ii) decrease the Irrigation Water Demand per Hectare by 20 %; iii) increase Total Water Supply by 5 %. Results show that the baseline vulnerability of study region is high. The agricultural irrigation is the largest water use, and the water demand structure will change in future. Decreasing the irrigation water demand is the most suitable intervention to relatively reduce the vulnerability. Results also demonstrated that SD is a suitable method to explore management options for a complex water supply and demand system.     

Water Resources In Egypt: Future Challeges and Opportunities

Abstract

Water is one of the most important inputs for economic development. As the demand increases, so too does the importance of water. This is clearly the case in Egypt, where rainfall is rare and the governmentally enforced quota for withdrawal from the Nile River has not changed since 1959. The water demand has multiplied as a result of population growth, agricultural expansion, as well as industrial development and a rise in the standard of living. In this paper, a vision for the future water status in Egypt is presented. This vision is based on a perception of the current status of the available water resources. The water uses, the water use efficiency, the institutional and legislative frameworks of water management, and the strategies and policies to rationalize water use and to augment water supply are discussed. The local, regional and international governing and controlling factors of water utilization and management in Egypt are also analyzed and discussed. Three future water scenarios for year 2020, each reflecting alternate programs to develop the water systems and to rationalize the water uses, are presented. All scenarios showed that Egypt will suffer considerable water shortages in the near future. Recommendations to help overcome anticipated water challenges and to optimize the available opportunities are provided.     

Future Water Supply and Demand in the Okanagan Basin,British Columbia: A Scenario-Based Analysis of Multiple,Interacting Stressors

Surface water is critical for meeting water needs in British Columbia’s Okanagan Basin, but the timing and magnitude of its availability is being altered through climate and land use changes and growing water demand. Greater attention needs to be given to the multiple, interacting factors occurring and projected to occur in this region if water is going to be sustainably provisioned to human users and available for ecosystem needs. This study contributes to that goal by integrating information on physical, biological and social processes in order to project a range of possible changes to surface water availability resulting from land-use, climatic and demographic change, as well as from Mountain Pine Beetle infestation. An integrated water management model (Water Evaluation and Planning system, WEAP) was used to consider future scenarios for water supply and demand in both unregulated and reservoir-supported streams that supply the District of Peachland. Results demonstrate that anticipated future climate conditions will critically reduce streamflow relative to projected uses (societal demand and ecological flow requirements). The surficial storage systems currently in place were found unable to meet municipal and instream flow needs during “normal” precipitation years by the 2050s. Improvements may be found through demand reduction, especially in the near term. Beyond the implications for the District of Peachland, this work demonstrates a method of using an accessible modeling tool for integrating knowledge from the fields of climate science, forest hydrology, water systems management and stream ecology to aid in water and land management decision-making.     

Ecosystem Service Impacts of Urban Water Supply and Demand Management

Utilities face the challenge of enhancing long-term water security while minimising undesirable economic, social and environmental impacts of supply and demand management options. This paper provides an example of how the ecosystem services concept can be used to enumerate and organise broad impacts of water supply options. A case study of Adelaide, South Australia, is used to examine costs and benefits associated with different sources of water and source-water mix scenarios. Ecosystem service impacts are estimated using estimates from the literature. Seven water supply and demand management options are considered for Adelaide: 1) the River Murray, 2) Mt. Lofty Ranges catchments, 3) wastewater reuse, 4) desalination, 5) stormwater harvesting, 6) groundwater and 7) water conservation. The largest costs are associated with sourcing water from conservation measures such as water restrictions on outdoor watering estimated at $1.87/kL. Salinity damage costs associated with residential uses are estimated at up to $1.54/kL. Salinity damage costs of wastewater reuse were estimated at $1.16/kL. The largest benefit is coastal amenity services associated with stormwater harvesting and treatment estimated at $1.03/kL. Results show that there is a trade-off between financial costs and ecosystem services impacts with source-water mix scenarios with the highest ecosystem services cost having the lowest financial O&M cost and vice versa. This highlights the importance of taking ecosystem services into account when evaluating water supply options.     

Analysis and Modelling of Stormwater Volume Control Performance of Rainwater Harvesting Systems in Four Climatic Zones of China

Rainwater harvesting has been widely used to alleviate urban water scarcity and waterlogging problems. In this study, a water balance model is developed to continuously simulate the long-term (57 to 65 years) stormwater capture efficiency of rainwater harvesting systems for three water demand scenarios at four cities across four climatic zones of China. The impacts of the “yield after spillage” (YAS) and “yield before spillage” (YBS) operating algorithms, climatic conditions, and storage and demand fractions on stormwater capture efficiency of rainwater harvesting systems are analyzed. The YAS algorithm, compared with the YBS, results in more conservative estimations of stormwater capture efficiency of rainwater harvesting systems with relatively small storage tanks (e.g., ≤50 m³). The difference between stormwater capture efficiency calculated using the YBS and YAS algorithms can be remedied by increasing storage capacity and reduced by decreasing water demand rates. Higher stormwater capture efficiency can be achieved for rainwater harvesting systems with higher storage and demand fractions and located in regions with less rainfall. However, the lager variations in annual rainfall in arid zones may lead to unstable stormwater management performance of rainwater harvesting systems. The impacts of storage and demand fractions on stormwater capture efficiency of rainwater harvesting systems are interactive and dependent on climatic conditions. Based on the relationships among storage capacity, contributing area, water demand, and stormwater capture efficiency of rainwater harvesting systems, easy-to-use equations are proposed for the hydrologic design of rainwater harvesting systems to meet specific stormwater control requirements at the four cities.     

Least Economic Cost Regional Water Supply Planning – Optimising Infrastructure Investments and Demand Management for South East England’s 17.6 Million People

This paper presents a deterministic capacity expansion optimisation model designed for large regional or national water supply systems. The annual model selects, sizes and schedules new options to meet predicted demands at minimum cost over a multi-year time horizon. Options include: supply-side schemes, demand management (water conservation) measures and bulk transfers. The problem is formulated as a mixed integer linear programming (MILP) optimisation model. Capital, operating, carbon, social and environmental costs of proposed discrete schemes are considered. User-defined annual water saving profiles for demand management schemes are allowed. Multiple water demand scenarios are considered simultaneously to ensure the supply–demand balance is preserved across high demand conditions and that variable costs are accurately assessed. A wide range of supplementary constraints are formulated to consider the interdependencies between schemes (pre-requisite, mutual exclusivity, etc.). A two-step optimisation scheme is introduced to prevent the infeasibilities that inevitably appear in real applications. The model was developed for and used by the ‘Water Resources in the South East’ stakeholder group to select which of the 316 available supply schemes (including imports) and 511 demand management options (considering 272 interdependencies) are to be activated to serve the inhabitants of South East of England. Selected schemes are scheduled and sized over a 25 year planning horizon. The model shows demand management options can play a significant role in the region’s water supply and should be considered alongside new supplies and regional transfers. Considering demand management schemes reduced overall total discounted economic costs by 10 % and removed two large reservoirs from the least-cost plan. This case-study optimisation model was built using a generalised data management software platform and solved using a mixed integer linear programme.     

陕北地区供用水结构变化及需水量预测

陕北地区水资源短缺,随着能源化工基地的建设,供需矛盾日益尖锐.本文通过分析陕北地区的水资源及其可利用量分布规律,以及1980-2010年间的供用水结构变化规律,根据省市相关规划目标及行业用水标准,预测了该地区未来水平年的需水量.结果是陕北地区2020年和2030年的需水量分别为19.95亿m3和27.65亿m3.因此现阶段16亿m3的水资源可利用量不能满足陕北地区的未来需水要求.     

Assessment of Future Water Scarcity at Different Spatial and Temporal Scales of the Brahmaputra River Basin

Climate change is one of the main driving forces that affect both the temporal and spatial variability of water availability. Besides climatic change, current demographic trends, economic development and related land use changes have direct impact on increasing demand for freshwater resources. Taken together, the net effect of these supply and demand changes has led to a growing water scarcity in major international river basins. The Brahmaputra River Basin is one of the most vulnerable areas in the world, as it is subject to combined effect of climate change and development pressures. A robust assessment of water scarcity considering both climatic and socio-economic changes is therefore vital for policy makers of the basin. In this study, we analyze future water scarcity of the Brahmaputra Basin in a geographically and temporally detailed manner, incorporating several novel approaches: (i) the application of consistent set of scenarios to estimate future water scarcity; (ii) estimation of water demand in terms of both water withdrawals and consumptive water use; (iii) comparison of water demand and availability on different temporal scales i.e., yearly, seasonal and monthly rather than only annual basis. (iv) assessment of groundwater recharge affected by climate change together with future demands for groundwater abstraction. Although the Brahmaputra Basin is one of the water abundant regions of the world, our analysis illustrates that during dry season water scarcity for the Basin will become more severe in the coming decades, which requires special attention to the decision makers of the authority.     

Modeling the Effects of Conservation,Demographics, Price,and Climate on Urban Water Demand in Los Angeles,California

With a service area population exceeding four million people and with close to 90 % of the water supply being imported from sources outside the city, the Los Angeles water system is subject to multiple stressors, including climate change and population growth. The influence of various factors on water demand in Los Angeles was evaluated through development and application of multiple linear regression models for residential, commercial, industrial, and governmental water demand categories from 1970 to 2014 in the service area of the Los Angeles Department of Water and Power. Performance of the models in describing historical water demand was compared using the coefficient of determination, mean average percent error, and normalized root mean square error. Overall, the results of the linear regression models demonstrated that each water demand category is affected by different parameters. However, price and population were found to have the most significant impact on all categories. The seasonality of residential water demand was well described with the model based on monthly data, with precipitation and temperature being highly significant factors. Fitting of the residential data furthermore revealed that price and conservation have significantly counteracted the impact of population growth on water demand.     

Participatory Optimization Scenario for Water Resources Management: A Case from Jordan

Participatory optimization scenario process was developed for water resources management of the Zarqa River Basin in Jordan. The basin was selected to represent a case study of semi-arid area in the Mediterranean because of its entire range of prototypical water management problems. The nature of the institutional framework, the severity of the water related problems and concentration of population in the basin have required the need for stakeholders’ involvement in the optimization process. The paper demonstrates a Water Resources Model (WRM) consisting of integrated cascade of modules, embedded in a framework of a participatory approach in water resources optimization. The system includes baseline scenario, identification of constrains and instruments, the optimization scenario and analysis of results. In a participatory approach, stakeholders identified the optimization criteria (constraints) and the management interventions (instruments). Constraints were set to securing high supply/demand ratio of 0.98 and improving reliability of supply to 75 %, while specific eight instruments were suggested and manipulated by the model to achieve the above criteria. The results of the WRM optimization scenario showed that the specified constraints were met so that the supply/demand ratio increased from 0.90 to 0.996 and the reliability of supply improved from 58 % to 84 %. The benefit/cost ratio, water shortfall, and the economic efficiency had responded effectively. The model proved its efficiency in using the full featured basin characteristics towards baseline and optimization scenarios with the support of stakeholders in simulating the basin behavior over time using the model parameters.     

Using Information-Gap Decision Theory for Water Resources Planning Under Severe Uncertainty

Water resource managers are required to develop comprehensive water resources plans based on severely uncertain information of the effects of climate change on local hydrology and future socio-economic changes on localised demand. In England and Wales, current water resources planning methodologies include a headroom estimation process separate from water resource simulation modelling. This process quantifies uncertainty based on only one point of an assumed range of deviations from the expected climate and projected demand 25 years into the future. This paper utilises an integrated method based on Information-Gap decision theory to quantitatively assess the robustness of various supply side and demand side management options over a broad range of plausible futures. Findings show that beyond the uncertainty range explored with the headroom method, a preference reversal can occur, i.e. some management options that underperform at lower uncertainties, outperform at higher levels of uncertainty. This study also shows that when 50 % or more of the population adopts demand side management, efficiency related measures and innovative options such as rainwater collection can perform equally well or better than some supply side options The additional use of Multi-Criteria Decision Analysis shifts the focus away from reservoir expansion options, that perform best in regards to water availability, to combined strategies that include innovative demand side management actions of rainwater collection and greywater reuse as well efficiency measures and additional regional transfers. This paper illustrates how an Information-Gap based approach can offer a comprehensive picture of potential supply/demand futures and a rich variety of information to support adaptive management of water systems under severe uncertainty.     

Water Demand Forecasting in Umm Al-Quwain (UAE) Using the IWR-MAIN Specify Forecasting Model

IWR-MAIN software is used in this paper to forecast water demand in the Emirate of Umm Al-Quwain (UAQ), located in the northern part of the United Arab Emirates (UAE), for the next twenty 5 years. Two different databases are used. The first one provides average yearly water consumptions since 1980, while the second provides more detailed monthly water consumptions from 2000. The correlation between three different independent variables and water consumption is studied. These variables are population of UAQ, average temperature, and average rainfall. Results show that population is the most significant variable that affects water consumption in Umm Al-Quwain. Several calibration simulations are performed and each simulation is divided into two periods. In the first period the software “Statistical Package for the Social Sciences” (SPSS) is used to determine the correlation coefficients between the independent variables and actual water consumptions. These coefficients are used in IWR-MAIN over the second period to calculate values of water demand which are compared against actual water consumptions. Model calibration indicates that starting the calibration in 1999 in database one and 2006 in database 2 minimizes differences between actual and simulated water demands. Therefore, these simulations were used as the bases for several forecasting scenarios of water demand in Umm Al-Quwain. Results of one of these scenarios show that 50% increase in water demand is expected by the year 2015 and double of the current demand will be needed before 2025. In another forecasting scenario, it was found that by considering the expected increase in the income level, the water demand will increase by 40% in one decade. A new technique of using IWR-MAIN to separate estimates of metered demand, unmetered demand, and unaccounted water (losses) is also presented in this paper. Finally, results of a fourth scenario indicate that water demand in Umm Al-Quwain will be highly affected by the expected high migration rate due to the anticipated new developments in the emirate.     

Optimizing Deficit Irrigation Scheduling Under Shallow Groundwater Conditions in Lower Reaches of Amu Darya River Basin

Water demand for irrigated agriculture is increasing against limited availability of fresh water resources in the lower reaches of the Amu Darya River e.g., Khorezm region of Uzbekistan. Future scenarios predict that Khorezm region will receive fewer water supplies due to climate change, transboundary conflicts and hence farmers have to achieve their yield targets with less water. We conducted a study and used AquaCrop model to develop the optimum and deficit irrigation schedule under shallow groundwater conditions (1.0–1.2 m) in the study region. Cotton being a strategic crop in the region was used for simulations. Capillary rise substantially contributes to crop-water requirements and is the key characteristic of the regional soils. However, AquaCrop does not simulate capillary rise contribution, thereby HYDRUS-1D model was used in this study for the quantification of capillary rise contribution. Alongside optimal irrigation schedule for cotton, deficit strategies were also derived in two ways: proportional reduction from each irrigation event (scenario-A) throughout the growth period as well as reduced water supply at specific crop growth stages (scenario-B). For scenario-A, 20, 40, 50 and 60 % of optimal water was deducted from each irrigation quota whereas for scenario-B irrigation events were knocked out at different crop growth stages (stage 1(emergence), stage 2 (vegetative), stage 3 (flowering) and stage 4 (yield formation and ripening)). For scenario-A, 0, 14, 30 and 48 % of yield reduction was observed respectively. During stress at the late crop development stage, a reduced water supply of 12 % resulted in a yield increase of 8 %. Conversely, during stress at the earlier crop development stage, yield loss was 17–18 %. During water stress at the late ripening stage, no yield loss was observed. Results of this study provide guidelines for policy makers to adopt irrigation schedule depending upon availability of irrigation water.     

Water balance modelling of alternate water sources at the household scale

Alternate water sources are being implemented in urban areas to augment scheme water supplied by a water utility to homes. These sources include residential wells, rainwater tanks and greywater systems. Greater water efficiency can be achieved when these systems are designed to match a water source to a given demand based on both water quantity and quality parameters. In this way the use of an alternate water source can be maximised and the use of the high quality scheme water minimised. This paper examines the use of multiple alternate water sources sequentially to supply the same demand point potentially optimising the use of all available water sources. It also allows correct sizing of such water systems and their components to reduce scheme water demand. A decision support tool based on water balance modelling was developed that considers such water options at the household scale. Application of this tool to eight scenarios for both large and small house lots shows that using alternate water sources individually can result in significant scheme water savings. However by integrating these sources additional scheme water saving can be made.     

Water demand versus supply in Saudi Arabia: current and future challenges

Saudi Arabia is facing a chronic water-shortage problem. Demand far exceeds the sustainable yield of both conventional and non-conventional water resources. The resulting demand–supply gap is being bridged through groundwater depletion. In this paper, demand–supply gaps for the coming 20 years are projected under three scenarios: optimistic, moderate and pessimistic. Future sustainable water yields are calculated and allocated to projected water demand in the domestic, industrial and agricultural sectors. The study shows that Saudi Arabia will not be able to bridge the demand–supply gap in the near future. Intensive water demand management measures are needed in all sectors to minimize future demand–supply gaps, especially focused on the largest water consumer: the agricultural sector.     

Influences Of Past And Future Climates On The Great Lakes Region Of North America

ABSTRACT

The paper examines the impact of climate on water resources, focussing on the Great Lakes region of North America. Following a discussion of the prevailing interactions between climate and hydrology the potential impacts of atmospheric warming as a result of increased CQ concentration are examined. Using the results of several investigations based on global circulation models, significant impacts are described in electricity demand, residential heating and cooling, power generation, shipping, agriculture, recreation, and municipal water use. In view of the considerable uncertainty involved in forecasting future climatic conditions, resource managers examining the future should consider a range of future climatic conditions and impacts.