Projected Water Demand Research Articles

Evaluation and Development of Drinking Water Supply System (SPAM) IKK Perbaungan Serdang Bedagai Regency

The purpose of this study was to analyze the evaluation and development of SPAM IKK perbaungan, Serdang Bedagai Regency, North Sumatra. The method used in this research were preliminary study, data collection, data analysis, discussion, conclusions, and suggestions. Data collection was divided into primary data consisting of the existing condition of SPAM IKK Perbaungan, while secondary data consists of pipeline network, service data, and population data. At the same time, the data analysis was in the form of population projections, water demand projections, and evaluation of SPAM based on technical and institutional aspects. The questionnaire results showed that over 60% of the population who are not PDAM customers are interested in becoming customers and agreed to pay connection fees. SPAM IKK Perbaungan would serve four villages, namely Simpang Tiga Pekan, Batang Terap, Citaman Jernih, and Kota Galuh, with populations of 9,118, 3,352, 7,184, and 4,896, respectively. The implementation was divided into two stages, namely Phase I in 2022-2027, which served Simpang Tiga Pekan, Batang Terap, and Citaman Jernih with total water demand of 33.51 L/s, then Phase II in 2028-2032, which added to serve Kota Galuh with a total water demand of 42.41 L/s.Keywords: Evaluation, Development, Drinking Water Supply System

Future Outlook of Fresh Water Supply and Demand in Selangor

Water is an essential resource for the well-being of humans as well as for ecosystems. In this regard, the increasing water scarcity areas has become one of the major problems faced by humanity. In Malaysia, Selangor is considered a water-stressed area due to the increase in water demand and limited suitable fresh water resources for treatment and distribution. The increase in population as well as urbanization and industrialization made the rivers in Selangor arguably the most polluted compared to other states. These situations result in a series of unscheduled water supply interruption over the years and negatively impact the majority of consumers. Projected water demand also indicates that the existing water supplies are not sufficient in the long run, therefore, it is deemed required to study the water demand and supply gap in Selangor to ensure the current water management is sustainable for the remote future. This paper mainly discusses on the current water production from Water Treatment Plants as well as projection of water demand which also foresee the future water deficit in Selangor. The method used in this study was based on review of secondary data acquired from available published report and website, while the assessment of water demand conducted comprise of calculation of projected population, projected domestic water demand, projected total water demand and water deficit up to year 2050. According to the result obtained, the existing water demand and supply in Selangor is 4,967 MLD, meanwhile, the projection of water demand in Selangor up to year 2050 is 7,011 MLD with the projected water deficit of 2,044 MLD. The findings of this paper are essential in water resources planning and management, particularly in terms of additional raw water supply that will be required to cater to the future water demand in Selangor.

Characterizing the relationship between urban sprawl and water demand in Dodoma Urban District, Tanzania: 1992–2029

ABSTRACT Rapid urban growth is making the planning of water resources increasingly uncertain, highlighting the need for plausible forecasts of water demand to achieve optimum allocation among competing uses. This study applies a population balance model and statistical modelling to investigate the relationship between water demand and urban sprawl in Dodoma Urban District in Tanzania. The findings revealed a positive but complex and non-linear relationship that is best characterized by a quadratic model: Predicted water demand (in million m3) = −1.206 + 0.285*(Urban growth in km2) – 0.002*(Urban growth in km2)squared. The model is a first step in characterizing the determinants of water demand for better planning and management of scarce water resources in a data-constrained but rapidly urbanizing region. We recommend striking a balance between desired future urban growth and projected water demand and prioritizing financial investments to develop alternative water supply sources.

Reservoir Sediment Management and Downstream River Impacts for Sustainable Water Resources—Case Study of Shihmen Reservoir

Sustainable water resources of reservoirs depend on preserving the valuable storage capacity. Sediment management is a crucial task in reservoir operations. Extreme floods caused by typhoon events have brought a massive amount of sediments from the watershed of Shihmen Reservoir in Taiwan. In the case study of Shihmen Reservoir, the primary purpose of the sediment management strategies is to minimize sediment deposition and recover reservoir capacity. Two assessment indexes, the capacity–inflow ratio (CIR) and the capacity–sediment ratio (CSR) are investigated to provide a feasible assessment of desilting techniques. Three desilting projects have been planned and implemented in progress, including one modified power plant penstock and two desilting tunnels. Without effective sediment management strategies, the projected storage capacity may drop to 32.9% of the initial storage capacity in the next fifty years. On the other hand, if sediment management is implemented as per the project schedule, 70.3% of the initial storage capacity may be retained, enabling the provision of sustainable water supplies to meet projected water demands. In investigating the impacts caused by the desilting operations, the floodwater level and riverbed variations along the downstream river of the dam are simulated by the hydromorphological model. From simulated results, the downstream river morphology may adjust toward the equilibrium state under the long-term desilting operations of Shihmen Reservoir. Although relatively high sediment concentration is released during the desilting operation, it decays gradually along the downstream river. In addition, riverbed deposition does not significantly affect the floodwater level caused by the increment of riverbed elevation in desilting operations.

Analysis of River Basin Management in Madagascar and Lessons Learned from Japan

River basins in Madagascar are prone to water scarcity and conflicts of use, which are projected to worsen due to climate change. Therefore, effective integrated water resources management (IWRM) is key. This review examines the current condition of IWRM in Madagascar, evaluates its sustainability, and compares it with the one in Japan. The effects of climate change were analyzed using Aqueduct data. Madagascar has established an IWRM legal framework aligned with the Sustainable Development Goals; however, its application remains limited. For Japan, it was useful to establish IWRM for floods, water utilization, and environmental conservation. This study analyzes the future projections of water availability and demand for the 12 major river basins of Madagascar. Climate change will reduce water availability; the West and the East will experience water stress; the demand will be higher in the highlands, with less water available in the south. The proposed framework and Japan’s experience in river basin management can contribute to solving those problems. The findings of this study serve to enhance the knowledge on IWRM and the impact of climate change in Madagascar; they also suggest actions to be taken by the Malagasy government.

GMS-MODFLOW application in the investigation of groundwater potential in Concepcion, Tarlac, Philippines

This study used GMS-Modflow to investigate the ten-year groundwater potential in Concepcion, Tarlac. This region in Central Luzon, Philippines, with limited surface water, depends on groundwater as its primary freshwater source. The water demand projection estimated an increase of 38.5% from 2020 to 2030; hence, higher groundwater abstraction is perceived in the next ten years. To deviate from the risk associated with reliance on groundwater, this study, through GMS-MODFLOW, developed a groundwater model to mimic the aquifer’s current condition and investigated its behavior in response to future spatial and temporal variables. The simulation results generally showed a sustainable groundwater supply in Concepcion, Tarlac, for the next ten years, with no significant decline in hydraulic heads.

Projected water demand by 2050 in South Gobi region of Mongolia

The South Gobi region (including Umnugovi, Dundgovi and Dornogovi aimags - provinces) of Mongolia is becoming a leading region of the nation’s economic and social development. Water resources play an important role in ensuring sustainable economic development of the South Gobi region. In the South Gobi region, lack of proven groundwater resources, data on water extraction and consumption makes it difficult to accurately identify risks and to manage limited resources for sustainable development. Based on the available historical data between 2015 and 2019 on water resources and water use, the water demand in this region has been projected up to the year 2050 on the basis of dynamic modelling of water management, including major stakeholders, country’s sustainable economic development vision up to the year 2050, and the impact of climate change. The model predicts continued increasing demand for mining, agricultural, industrial and social services and rural water demands, while gradual decline for the livestock water demand was projected after the gradual increase in the first half of the period. Basing on the system dynamic modelling of water management, it can be said that the groundwater resources of the South Gobi region may not be able to meet the above needs after 2037. Economically feasible measures and managements to prevent the risk of water scarcity before water shortage happens are proposed based on the results of the model.

Perhitungan Kebutuhan Air Bersih dan Perencanaan Kebutuhan Infrastruktur Perpipaan PDAM di Kel Sako, Sako Baru, Sialang dan Sukamaju Kec. Sako Kota Palembang

The service of clean water in urban areas is very important to be given special attention. PDAM Tirta Musi The Sako Kenten Service Unit serves 4 sub-districts in Sako sub-district, including Sako, Sako Baru, Sialang, and Sukamaju. As the area grows, the population also increases. It is estimated that in 2029 the total population in Sako sub-district will reach 106,273 people. Meanwhile, for now the population which only reaches 93,326 people, it is felt that there is a shortage of clean water supply from PDAM. Based on the results of surveys and interviews, information was obtained that the availability of clean water from PDAM in the Sako area is only 6,000 liters per month on average. This is not enough for the population. It becomes a big task for PDAM Tirta Musi to prepare it by building an adequate pipeline network. Another problem is the existing piping system does not support the flow with such a large discharge, so it requires a network using the latest material, namely using HDPE pipes. The use of this material was chosen because HDPE does not require much connection and the pipe is stronger than PVC pipe. After carrying out the survey and calculation of the RAB, it was found that the need for a new network system reached Rp. 53,756,600,000, - in order to meet service standards for 80% of the population in Sako District. Keywords : PDAM Tirta Musi, Projection of water demand, Pipeline Network Budget Plan

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

AbstractEnsuring 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.

STUDI KELAYAKAN WADUK CIKAWARI 2A DAN 5A DALAM RANGKA PEMENUHAN KEBUTUHAN AIR KOTA BANDUNG

The water need in the Northern area of Bandung City was predicted to be 2.49 m3/s in 2040. The government responded to this issue by planning the construction of several reservoirs in the Cikapundung watershed. A previous study suggested three potential locations, i.e., Cikukang 2, Cikawari 2A, and Cikawari 5A reservoir. Since Cikawari 2A and Cikawari 5A are located on the same Cikawari river, three construction alternatives, i.e., a single reservoir of Cikawari 2A, a single reservoir of Cikawari 5A, and cascade reservoir Cikawari 2A+5A are proposed. Each alternative has its own advantages and limitations, thus evaluation of the best construction alternative needs to be carried out. The evaluation was conducted based on their reliable service in supplying water to Bandung City. This evaluation was analyzed by comparing the projected water demand following population growth and water availability derived from the rainfall-runoff model, NRECA. The analysis was conducted using two variations of dam height and reservoir capacity for each alternative. Based on the analysis results, the single reservoir of Cikawari 2A with 45 m of dam’s height was chosen as the most suitable alternative. It can supply 0.56 m3/s of water and provide water for 30.4% of the citizens in 2020, and decrease to 30.15% in 2040. However, it was also found that the reservoir could only supply 0.44 m3/s of water during the dry period. These results showed that the construction of the reservoir itself could not meet the total water demand. Therefore, another alternative is required to closing the gap in water demand.Keywords: Cikapundung watershed, water supply, Cikawari reservoir, reservoir simulation, service reliability

The Future Challenge: Water Demand Forecasting

Palembang has abundant water sources; the city of Palembang is traversed by one of the longest rivers in Indonesia, the Musi River. However, population growth is increasing over time, as is the need for clean water. Projections of the amount of clean water demand in the future are needed; apart from anticipating water shortages, water demand projections are required to construct clean water facilities and infrastructure. This research was conducted using statistical calculations to calculate the population in the next ten years. The population of Palembang in 2030 is projected to increase to1,898,221 inhabitants. The results of this population projection are used in calculating the total water demand in 2030. The total water demand is obtained from the calculation of domestic, non-domestic, fire hydrant, and water loss needs. In 2030, the total amount of water needed is 6,816 L / second.

Modeling of water demand management in an arid area: case of Bechar city

Bechar city is located in arid climate of the Algerian Sahara, with an average annual rainfall of about 72 mm. There are two sources to ensure the water supply of the town of Bechar; the first comes from a watershed made up of eight non-renewable boreholes, and the second comes from the Djorf Torba dam, located about 45 km to the west. The pressure on water demand in the highland region depends on many factors, namely: demographic, social, climatic and economic. This study is based on the application of a water evaluation and planning computer tool on the city of Bechar. Which allows us to analyze the supply–demand balance in the water and assess the impact of different scenarios on the study area for manage the water resource and the projected water demand for the different sectors (drinking water, industrial water and agriculture) until 2060.

Assessing Future Water Demand and Associated Energy Input with Plausible Scenarios for Water Service Providers (WSPs) in Sub-Saharan Africa

This study examined the current state of water demand and associated energy input for water supply against a projected increase in water demand in sub-Saharan Africa. Three plausible scenarios, namely, Current State Extends (CSE), Current State Improves (CSI) and Current State Deteriorates (CSD) were developed and applied using nine quantifiable indicators for water demand projections and the associated impact on energy input for water supply for five Water Service Providers (WSPs) in Kenya to demonstrate the feasibility of the approach based on real data in sub-Saharan Africa. Currently, the daily per capita water-use in the service area of four of the five WSPs was below minimum daily requirement of 50 L/p/d. Further, non-revenue water losses were up to three times higher than the regulated benchmark (range 26–63%). Calculations showed a leakage reduction potential of up to 70% and energy savings of up to 12 MWh/a. The projected water demand is expected to increase by at least twelve times the current demand to achieve universal coverage and an average daily per capita consumption of 120 L/p/d for the urban population by 2030. Consequently, the energy input could increase almost twelve-folds with the CSI scenario or up to fifty-folds with the CSE scenario for WSPs where desalination or additional groundwater abstraction is proposed. The approach used can be applied for other WSPs which are experiencing a similar evolution of their water supply and demand drivers in sub-Saharan Africa. WSPs in the sub-region should explore aggressive strategies to jointly address persistent water losses and associated energy input. This would reduce the current water supply-demand gap and minimize the energy input that will be associated with exploring additional water sources that are typically energy intensive.

Uncertainties in agricultural water supply under climate change: Aidoghmoush basin, Iran

The planning of future supplies of agricultural water is beset by uncertainties stemming from inaccuracies in general circulation models, assumed greenhouse gases emissions scenarios (GHGESs), imperfect models employed for estimating reservoir inflows and approximate methods for estimating agricultural water demand. The uncertainty of providing agricultural water under climate change was assessed, relying on simulations involving baseline (1971–2000) and future periods (2040–2069 and 2070–2099). Climatic variables were simulated using six atmosphere–ocean general circulation models (AOGCMs) driven by GHGESs A2 and B2 in the Aidoghmoush basin, Iran. Projection of reservoir inflow was performed using the IHACRES model and artificial neural network (ANNs). Agricultural water demand was calculated using the FAO–Penman–Monteith and Hargreaves-Samani (HS) methods. Eight modelling scenarios were considered based on combinations of AOGCMs, GHGESs, reservoir inflow and agricultural water demand projections. Reservoir operation rules were calculated with a particle swarm optimisation algorithm. The results show that agricultural water demand will increase in future periods compared with the baseline period. The operation rule derived from the combination of the HS and ANN models (under GHGES A2) showed the best performance in 2040–2069 by achieving the highest reliability (93%) of water supply. The operation rule derived from the combination of HS and ANN models (under GHGES B2) achieved the highest reliability (95%) of water supply in 2070–2099. The results provide adjusted reservoir operation rules under uncertainty caused by climate change and related impacts on water resources management.

Assessment and reform of greywater reuse policies and practice: a case study from Sharjah, United Arab Emirates

Abstract This article presents an assessment of one of the earliest greywater reuse (GWR) experiences in Sharjah, United Arab Emirates (UAE). In 2003, the Sharjah Electricity and Water Authority (SEWA) imposed a compulsory GWR program on various categories of new buildings in the city. However, implementation of the program faced significant resistance and setbacks and remained limited to about 200 buildings, representing less than 2% water savings. In the analysis presented in this study, the need for GWR was assessed through analyzing SEWA's water supply and demand projections, conducting a 12-month water use survey of 285,000 Sharjah residents from about 140 nationalities, and identifying the areas in the city with intense water use. In addition, analysis and reforms of the various aspects of SEWA's GWR reuse policies and practice were presented and discussed. Reforming the policy to increase GWR to about 10% water savings can lead to significant reductions in desalinated water consumption and wastewater generation and consequently significant reductions in desalination cost (35 million USD/y), energy consumption (225,840 MWh/year) and CO2 emissions (120 ton/year). The case study presented in the article can serve as a reference to guide GWR policies and practice, especially for local authorities in developing countries.

Seasonal Variation of Rainy and Dry Season Per Capita Water Consumption in Freetown City Sierra Leone

Ensuring a sustainable urban water supply for developing/low-income countries requires an understanding of the factors affecting water consumption and technical evidence of individual consumption which can be used to design an improved water demand projection. This paper compared dry and rainy season water sources available for consumption and the end-use volume by each person in the different income groups. The study used a questionnaire survey to gather household data for a total of 398 households, which was analysed to develop the relationship between per capita water consumption characteristics: Socio-economic status, demographics, water use behaviour around indoor and outdoor water use activities. In the per capita water consumption patterns of Freetown, a seasonal variation was found: In the rainy season, per capita water consumption was found to be about 7% higher than the consumption for the full sample, whilst in the dry season, per capita water consumption was almost 14% lower than the full survey. The statistical analysis of the data shows that the average per capita water consumption for both households increases with income for informal slum-, low-, middle- and high-income households without piped connection (73, 78, 94 and 112 L/capita/day) and with connection (91, 97, 113 and 133 L/capita/day), respectively. The collected data have been used to develop 20 statistical models using the multiple linear stepwise regression method for selecting the best predictor variable from the data set. It can be seen from the values that the strongest significant relationships of per capita consumption are with the number of occupants (R = −0.728) in the household and time spent to fetch water for use (R = −0.711). Furthermore, the results reveal that the highest fraction of end use is showering (18%), then bathing (16%), followed by toilet use (14%). This is not in agreement with many developing countries where toilet use represents the largest component of indoor end use.

Projection of irrigation water demand based on the simulation of synthetic crop coefficients and climate change

Abstract. In the context of major changes (climate, demography, economy, etc.), the southern Mediterranean area faces serious challenges with intrinsically low, irregular, and continuously decreasing water resources. In some regions, the proper growth both in terms of cropping density and surface area of irrigated areas is so significant that it needs to be included in future scenarios. A method for estimating the future evolution of irrigation water requirements is proposed and tested in the Tensift watershed, Morocco. Monthly synthetic crop coefficients (Kc) of the different irrigated areas were obtained from a time series of remote sensing observations. An empirical model using the synthetic Kc and rainfall was developed and fitted to the actual data for each of the different irrigated areas within the study area. The model consists of a system of equations that takes into account the monthly trend of Kc, the impact of yearly rainfall, and the saturation of Kc due to the presence of tree crops. The impact of precipitation change is included in the Kc estimate and the water budget. The anthropogenic impact is included in the equations for Kc. The impact of temperature change is only included in the reference evapotranspiration, with no impact on the Kc cycle. The model appears to be reliable with an average r2 of 0.69 for the observation period (2000–2016). However, different subsampling tests of the number of calibration years showed that the performance is degraded when the size of the training dataset is reduced. When subsampling the training dataset to one-third of the 16 available years, r2 was reduced to 0.45. This score has been interpreted as the level of reliability that could be expected for two time periods after the full training years (thus near to 2050). The model has been used to reinterpret a local water management plan and to incorporate two downscaled climate change scenarios (RCP4.5 and RCP8.5). The examination of irrigation water requirements until 2050 revealed that the difference between the two climate scenarios was very small (< 2 %), while the two agricultural scenarios were strongly contrasted both spatially and in terms of their impact on water resources. The approach is generic and can be refined by incorporating irrigation efficiencies.

A Review of Water Demand Framework for River Basin in Southeast Asia

Water demands are the most referred indicators for water distribution system operators to regulate production and storage of potable water. Many regional in Southeast Asia are greatly dependent on freshwater resources, which most of the time comes from large rivers basin, with starting point in high mountains and the flowing water which distribute into many parts in particular region for daily activities. Hence, understanding the projection of water demand by the reservoir that are formed by constructing dams across rivers need to be done which can contribute to water demand framework for river basin. Evaluation on consideration and estimation between water withdrawal and water availability can provide the quantity of water loss. This paper presents a review of water demand projection for different reservoir in river basin across Southeast Asia.

Changing climate drives future streamflow declines and challenges in meeting water demand across the southwestern United States

Society and the environment in the arid southwestern United States depend on reliable water availability, yet current water use outpaces supply. Water demand is projected to grow in the future and climate change is expected to reduce supply. To adapt, water managers need robust estimates of future regional water supply to support management decisions. To address this need, we estimate future streamflow in seven water resource regions in the southwestern U.S. using a new SPAtially Referenced Regressions On Watershed attributes (SPARROW) streamflow model. We present streamflow projections corresponding to input data from seven climate models and two greenhouse gas Representative Concentration Pathways (RCP4.5 and 8.5) for three, thirty-year intervals centered on the 2030s, 2050s, and 2080s, and for a historical thirty year interval centered on the 1990s. Across water resource regions, about half of the RCP4.5 models (51%) and two thirds of the RCP8.5 models (67%) indicate decreases in streamflow in the 2080s relative to the historical period. Models project maximum decreases in streamflow of 36–80% in all water resource regions for all periods and RCPs relative to historical streamflow, and maximum streamflow decreases of up to 20–45% in the 2080s at sites along the Colorado River used for measuring compliance with interstate and international water agreements. Headwaters are projected to experience the greatest declines, with substantial downstream implications. Among these estimates, the streamflows from models forced with RCP8.5 tend to be lower than those forced with RCP4.5. Not all climate models, times, and RCPs project widespread streamflow declines. The most ubiquitous streamflow increases are projected to occur in the 2030s under RCP4.5. Later time periods and enhanced greenhouse gas forcings indicate smaller regions of streamflow increase and lower accumulated streamflows, suggesting that limiting or reducing greenhouse gas concentrations could support future water availability. Although some possible streamflow increases are promising, the modest and spatially limited increases in streamflow projected for later time periods are still unlikely to be sufficient to meet the projected water demand. These results inform the likelihood of future water agreement compliance, and support developing strategies to balance water supply and demand.

Evaluation of water supply alternatives for Istanbul using forecasting and multi-criteria decision making methods

Water scarcity is one of the most serious problems of the future due to increasing urbanization and water demand. Urban water planners need to balance increasing water demand with water resources that are under increasing pressure due to climate change and water pollution. Decision makers are forced to select the most appropriate water management alternative with respect to multiple, conflicting criteria based on short and long term projections of water demand in the future. In this paper, we consider water management in Istanbul, a megacity with a population of 15 million. PurposeThe purpose of this paper is to develop a method combining demand forecasting with multi-criteria decision making (MCDM) methods to evaluate five different water supply alternatives with respect to seven criteria using opinions of experts and stakeholders from different sectors. MethodologyTo combine forecasting with MCDM, we design a data collection method in which we share our demand forecasts with our experts. For demand forecasting, we compare Holt-Winters, Seasonal Autoregressive Integrated Moving Average (S-ARIMA), and feedforward Artificial Neural Network (ANN) models and select S-ARIMA as the best forecasting model for monthly water consumption data. Generated demand projections are shared with experts from different sectors and collected data is evaluated with Fuzzy Theory using two distinct MCDM models: Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) and Preference Ranking Organization Method for Enrichment Evaluations (PROMETHEE). Also our analyses are complemented with two sensitivity analyses. FindingsOur results indicate that greywater reuse is the best alternative to satisfy the growing water demand of the city whereas all experts find desalination and inter-basin water transfer as the least attractive solutions. In addition, we adopt the PROMETHEE GDSS procedure to obtain a GAIA plane indicating consensus among experts. Furthermore, we find that our results are moderately sensitive to the number of experts and they are insensitive to changes in experts’ evaluations. NoveltyTo the best of our knowledge, our study is the first one incorporating water demand and supply management concepts into the evaluation of alternatives. From a methodological perspective, water demand projections have never been used in an MCDM study in the literature. Also, this paper contributes to the literature with a mathematical construction of consensus and Monte Carlo simulations for the sufficiency of experts consulted in a study.