Water Supply Security Research Articles

Reservoir Filling Up Problems in a Changing Climate: Insights From CryoSat‐2 Altimetry

AbstractRecent droughts have severely threatened water security in many regions worldwide. Reservoirs, designed to combat droughts and secure water supply partially, are reported failing to fill up to the total capacity due to severe droughts. How bad is climate affecting reservoir filling up on a global scale? This issue has not been studied. We present a big picture of reservoirs in crisis using satellite altimetry. Thanks to the unique characteristics of CryoSat‐2, 525 reservoirs worldwide were investigated during 2010–2022. Results show that most reservoirs (93%) are found not fully filled up at least once. About 21% of reservoirs, which are mainly located in the Southern Hemisphere, show a significant decline in water levels. Moreover, about 20% of reservoirs with larger level fluctuations (>3 m) are located in less developed economies, indicating informed operation rules are needed. Further analyses indicate reservoirs are largely affected by extreme climate events, such as ENSO.

Response of a source water quality through a heavy precipitation event: Nutrients, dissolved organic matter and their DBPs formation

To better understand the influence of heavy precipitation event on water supply security, the change of nutrients, dissolved organic matter (DOM) and their corresponding disinfection by-products (DBPs) generation in river were investigated through a heavy precipitation event. The results show that short-term sustained heavy precipitation causes additional load on the river. Significant temporal variations and increases in dissolved oxygen (DO), turbidity, dissolved organic carbon (DOC) and molecular weight of raw water were observed during the heavy precipitation, and dissolved organic nitrogen (DON) showed a remarkably decline with the continuation of precipitation. The molecular weight and aromaticity of DOM increased dramatically with the continuous superposition of precipitation and flow, and the proportion of hydrophobic fraction increased during the study period. Four different fluorescent components were identified, including humic-like (C1, C2 and C3), and protein-like fluorophore C4. Heavy precipitation events affected the mobilization of DOM, while the generation of DBPs increased by 4%–47% during the chlorination, and the elevated river level further increased the DBPs formation. In particular, the HOA fraction was the main contributor of DBPs (up to 70%). The risk of haloacetic acids (HAAs) generation caused by heavy rainfall was concentrated in the river runoff producing and regression periods for both hydrophobic and hydrophilic fractions of DOM. Humification index (HIX) was positively correlated with the yield level of TCM, DCAA, TCAA, and DCAN during chlorination. Chlorination disinfection of raw water during river runoff producing and regression period is likely to increase the haloacetonitriles formation potential (HANsFP), thus posing a vital threat to water supply safety, while chloramination disinfection may significantly relieve the threat. This study provides a theoretical basis for the direct/indirect link between short-term precipitation events and their impact on water quality.

Multimodal knowledge graph construction for risk identification in water diversion projects

The operation risks of water diversion projects involve numerous influencing factors, complex interrelationships, and heterogeneous data from multiple sources. This study presents a multimodal knowledge graph construction approach for water diversion projects, aiming to comprehend and identify the key risks associated with engineering operation and their propagation patterns. Utilizing term-masked pre-trained language models enhances comprehension of specialized terminology and identifies risk entities within the text. Employing high-order residual convolutional neural networks improves the processing capability for complex graph data, extracting risk information from images. Aggregating multimodal knowledge graphs based on the semantic relationships among entities and conditional probability to determine the coupled features of different risks. Employing complex network theory, analyze node degree and betweenness centrality to identify the diffusion effects and propagation levels of risks. The results indicate that the knowledge extraction accuracy of our method is high (with an average F1 score of 95.85%), enabling the qualitative analysis and quantitative calculation of operational risks in engineering. Relevant studies can effectively enhance the reliability of engineering safety management and reduce the impact of engineering risks on water supply security.

Assessment of the impacts of water resources allocation on the reliability, resilience and vulnerability of the water–energy–food–society (WEFS) nexus system

To ensure water, energy and food supply security in the future, examining resources shortage risks within the integrated management strategy of the water-energy-food-society (WEFS) nexus system under uncertainties is necessary. Reliability, resilience, and vulnerability (RRV) are the most popular criteria for quantifying risks. However, their current applications focus on individual systems and adopt constant resource shortage rate thresholds across different spatial scales. To consider the interconnections in the WEFS nexus system and reflect the spatial heterogeneities of resource shortage risks when estimating the RRV, this study proposed a framework for estimating the RRV of the WEFS nexus system under uncertainties through a WEFS nexus model integrating water resources allocation model. Water availability uncertainty was simulated using Monte Carlo simulation and inputted into the stochastic WEFS nexus model. The water, energy, and food shortage rates outputted from the WEFS nexus model were used to determine the RRV of the WEFS nexus system. The impacts of water resources allocation on the RRV of the WEFS nexus system were studied by investigating its response to different water resources allocation scenarios at the basin and operational zone scales. The results indicated that water resources allocation can effectively ensure water supply through reservoir operation and further decrease the shortage risk of water and food systems through its nexus. The vulnerability of the water system decreased from 15.87% to 6.71% and the RRV of the food system improved from 27.33%, 8.20%, and 13.15–69.84%, 26.17%, and 7.03%, respectively. The energy shortage risk increased with increasing energy demand, with a trade-off between water and energy systems, the RRV of which decreased from extremely low levels to 69.84%, 26.17%, and 7.03%. The water shortage risk exhibited spatial heterogeneities owing to the uneven distribution of the water regulating capacity. The water shortage risk significantly decreased in areas with sufficient water regulating capacity but remained high in areas with few water regulating capacity and further propagated from upstream to downstream through hydrologic connections. Even an insignificant water shortage can be found across the basin, risking water system and further the WEFS nexus system through its nexus. Our proposed framework for assessing the impacts of water resources allocation on the RRV of the WEFS nexus system can not only help understand the risk of the WEFS nexus system under uncertainties, but also contribute to the integrated planning and management of water, energy, and food.

When water policies derail livelihood aspirations: farmers’ agency in everyday politics in the Vietnamese Mekong Delta

ABSTRACT Development of water infrastructure is conventionally prioritised as a pre-emptive intervention policy to address water challenges. In the Vietnamese Mekong Delta, turning a river into a reservoir is touted as a ‘highly-modernist’ water management approach to secure the year-round supply of freshwater for agricultural production. This paper investigates how contested water-livelihood relations emerged from the building of the Ba Lai sluice scheme in Ben Tre Province, and how these processes demonstrate farmers’ agency in everyday politics in seeking solutions for livelihood sustainability. Drawing on a qualitative case study in Binh Dai District, we argue that, while the scheme successfully fulfils the state’s political intention in securing water supply for freshwater-based crop production in coastal zones, it generates contestation between the local government’s attempts to enforce freshwater policies and farmers’ agency in maintaining productive livelihoods. The findings suggest that power asymmetries are embedded within these water-livelihood relations. We find that seeking just solutions that have co-benefits for water management and livelihood sustainability should go beyond business-as-usual water politics by adequately recognising the agency of farmers in sustainable development. The case study offers lessons for navigating the sustainable future of water development projects in coastal deltas and beyond.

Engineering Approach to Assessing the Vulnerability of Water Abstraction

Variability in stream flow/discharge results in serious problems for engineers and difficulties in characterizing water systems under future climatic conditions. The management of water security in the engineering domain requires approaches aimed at minimizing the detrimental effects of the hydrological behavior of natural systems. Abstraction facilities must be strengthened to ensure sustainable supply and water security over time and at different scales. Several approaches and methodologies have been developed to translate water security into a framework that provides information on how to improve it. In this study, a scalar range idea is used to evaluate the sensitivity of a water resource system and cause–effect linkages define the vulnerability indicator as management-relevant information to address water security. This intuitively relates the extreme deviations of a particular streamflow to the average system response related to a particular hazard indicator. This determines the current stress in the operation of the abstraction facilities based on historical hydrometeorological changes, which is the basis for assessing future operational conditions and risks. This study uses streamflow extremes and averages as hazard-relevant indicators of water supply security. The results of the two case studies show that the applied approach fully appreciates the internal properties of water resource systems that affect the sensitivity/vulnerability of streamflow, as well as the derived streamflow vulnerability index and function. The obtained results were used to assess the vulnerability of water intake as well as the choice of safety factors and design parameters in accordance with the forecasted average annual and seasonal climate factors.

Chemical Characteristics and Genetic Analysis of Karst Groundwater in the Beijing Xishan Area

As an important water supply source in Beijing， karst groundwater has played an irreplaceable role in the security of urban water supply and ecological environment protection in the past 70 years. The Xishan karst groundwater system， located in the upper reaches of western Beijing， belongs to ecological conservation areas. There are several centralized water supply fields in this area. In this study， the Xishan karst groundwater system was taken as the research object. A total of 120 karst groundwater samples in this area were investigated by using statistical analysis， ion ratio， and principal component analysis （PCA） methods to explore the spatial distribution characteristics and formation mechanism of groundwater hydrochemistry. The research results showed that： ① the groundwater quality of the Xishan system was generally good， with the characteristics of neutral pH and low salinity. A total of 84.17% of the water samples were classified as hard water. The chemical type of groundwater was mainly HCO3-Ca·Mg. ② The chemical composition of groundwater was mainly affected by the water-rock interaction， and the weathering source of rock was mainly the dissolution of carbonate. ③ The results of principal component analysis showed that 34.41% of the chemistry formation of groundwater could be explained by carbonate dissolution， 27.33% by rock salt and evaporate dissolution， 11.76% by aquifer sediment dissolution， and 10.30% by domestic sewage discharge. From the recharge area to the runoff area and then to the discharge area， the TH and TDS gradually increased. Coal mining drainage and human activities were the main factors that caused groundwater degradation and variable hydrochemical types in the piedmont. In the future， it is necessary to further strengthen environmental governance， control point and non-point source pollution， and continuously monitor key areas to provide scientific support for ecological and environmental protection.

Effects of chloride on corrosion scale compositions and heavy metal release in drinking water distribution systems

Variations in water chemistry may lead to the release of harmful heavy metals in drinking water distribution systems (DWDSs). In this study, the effects of chloride on the release of heavy metals such as Fe, Mn, As, Cr, Mo, V, Sr, and Co were examined using steel and cast iron pipe loops. After chloride was added, the relative contents of goethite (α-FeOOH), lepidocrocite (γ-FeOOH), and siderite (FeCO3) in pipe scales increased, but the contents of magnetite (Fe3O4) decreased. The most prevalent compounds were α-FeOOH and γ-FeOOH. When the chloride levels were increased, the effluent concentrations of Fe, Mn, As, Cr, Mo, V, Sr, and Co significantly increased. These heavy metals were released presumably because of the destabilization and dissolution of corrosion scales induced by chloride and adsorption site competition. Strong positive correlations were also observed between Fe&Mn, Fe/Mn&As, Fe/Mn&Cr, Fe/Mn&Mo, Fe/Mn&V, Fe/Mn&Sr, and Fe/Mn&Co, indicating the co-release of Fe, Mn, and other metals. This study may be helpful for the potential strategies on avoidance of heavy metal release and improvement of water supply security.

RT-CLAD: Artificial Intelligence-Based Real-Time Chironomid Larva Detection in Drinking Water Treatment Plants.

The presence of chironomid larvae in tap water has sparked public concern regarding the water supply system in South Korea. Despite ongoing efforts to establish a safe water supply system, entirely preventing larval occurrences remains a significant challenge. Therefore, we developed a real-time chironomid larva detection system (RT-CLAD) based on deep learning technology, which was implemented in drinking water treatment plants. The acquisition of larval images was facilitated by a multi-spectral camera with a wide spectral range, enabling the capture of unique wavelet bands associated with larvae. Three state-of-the-art deep learning algorithms, namely the convolutional neural network (CNN), you only look once (YOLO), and residual neural network (ResNet), renowned for their exceptional performance in object detection tasks, were employed. Following a comparative analysis of these algorithms, the most accurate and rapid model was selected for RT-CLAD. To achieve the efficient and accurate detection of larvae, the original images were transformed into a specific wavelet format, followed by preprocessing to minimize data size. Consequently, the CNN, YOLO, and ResNet algorithms successfully detected larvae with 100% accuracy. In comparison to YOLO and ResNet, the CNN algorithm demonstrated greater efficiency because of its faster processing and simpler architecture. We anticipate that our RT-CLAD will address larva detection challenges in water treatment plants, thereby enhancing water supply security.

Spatial suitability between water supply pressure and waterworks water supply capacity in the Guangdong-Hong Kong-Macau Greater Bay Area: Spatial-temporal evolution pattern, driving mechanism and Implications

The Guangdong-Hong Kong-Macao Greater Bay Area (GHMGBA) is one of the four major bay areas in the world. However, the mismatch between water resource distribution and spatial layout of population and productivity poses great challenge to water supply security of the GHMGBA. Evaluating the spatial suitability of water supply pressure (WSP) and waterworks water supply capacity (WSC) is essential to the spatial equilibrium allocation of water resources and water supply security in the GHMGBA. Therefore, the current study first investigated the spatial-temporal evolution pattern of WSP and waterworks WSC using the standard deviational ellipse and Exploratory Spatial Data Analysis (ESDA) methods, the spatial suitability of WSP and waterworks WSC was further evaluated using the coupling coordination degree model, and the driving mechanism of such spatial suitability was finally revealed using the dynamic spatial Durbin model. The results show that the WSP respectively forms high and low value aggregations in the eastern and western parts of the Pearl River estuary; the area with high waterworks WSC is mainly located in the northern part, the high-high cluster areas are in the eastern part of Zhaoqing and the western part of Huizhou, and the low-low cluster areas are mainly in Guangzhou-Foshan, Shenzhen-Hong Kong and Zhuhai-Macao. The coupling coordination of WSP and waterworks WSC was in an overall imbalance state. The eastern and western parts of the Pearl River estuary are slightly unbalanced or with better level. Demand-driven and economic efficiency have significant effects under spatial and economic proximity weights, government guidance has a significant positive effect, while market orientation has an insignificant positive effect; environmental pollution and resource allocation have a significant negative effect under geographical proximity weight, and environmental pollution has a stronger negative effect on spatial suitability. Finally, policy recommendations were proposed to improve the spatial suitability of WSP and waterworks WSC of the GHMGBA.

Potential storage augmentation impacts on hydropower production, irrigation water supply and environmental flows in the Indus Basin in Pakistan

Study regionIndus River basin, Pakistan Study focusThe study assesses the implications on irrigation water reliability, hydropower production and environmental flows to the Indus Delta resulting from the implementation of large new storages on the Indus River. These large dams have the potential to impact water supply security of the Indus Basin Irrigation System which operates with a priority of maximising irrigation supply via the 1991 Water Apportionment Accord. Implementation of the Accord under future scenarios involving new large dams is open to interpretation. This study uses the daily time step Indus River System Model to simulate the potential impact of these new large dams on hydropower production, irrigation water supply and flows to the Indus Delta under different Accord interpretations. New insights for the regionPakistan possesses significant potential for increasing hydropower production from the Indus River through the construction of new reservoirs, which could raise the nationwide share of electricity generated from hydropower from 29% to 44–53%. This study demonstrates that augmenting storage capacity can yield threefold benefits – improved end-of-system environmental flows, more reliable irrigation supply for the Rabi season, and increased hydropower production. Additionally, this modelling approach can be instrumental in strengthening the existing water governance arrangements when considering the construction of new dams, thereby improving the health of the Indus delta ecosystem through the construction of dam construction.

Taking the spatio-temporal effects of climate change into account for Life Cycle Assessment of prospective scenarios to secure water supplies in agricultural areas

To cope with climate change, agricultural territories are forced to implement adaptation strategies, including the implementation of irrigation infrastructures. These strategies are deployed over a long term, and their environmental performance may vary in time and space due to climate change. Environmental assessment methods that include spatio-temporal dynamics must be developed to identify long term “no-regret” scenarios. This study proposes an innovative approach based on the coupling between a crop model, i.e. AquaCrop, and the Territorial-Life Cycle Assessment (T-LCA) framework. Results are exemplified and discussed, with comparison of scenarios with or without irrigation, between 1981 and 2099, at six contrasting locations in terms of climate and soil conditions for the Shared Socioeconomic Pathways 5-8.5 scenario developed by the Intergovernmental Panel on Climate Change. The assessments report that climate change can affect the eco-efficiency of irrigated perimeters over time. Moreover, climate change may alter the conclusions of the comparison of scenarios with or without irrigation infrastructure at a given location. Additionally, a sensitivity analysis is performed on key parameters of the study highlighting the importance of the electricity mix. Finally, spatio-temporal dynamics need to be considered to assess the environmental performance of long-term land planning scenarios and account for environmental effects such as climate change.

Nature-based alternative-water landscapes for water security and green space health

Abstract This paper is concerned with highlighting and learning from Alternative-Water Urban Landscapes (AWULs) from around the world. Such systems contribute to issues such as water security and greenspace health. Nature-based methods for treating alternative-water can provide for secure water supplies in local landscapes and a wide range of social and environmental co-benefits. However, such treatment methods have raised concerns about efficacy, safety, public opinion, and cost, which have often led to a reliance on centralised, and high-energy and chemical treatment methods. To move forward, more understanding about AWULs is required. The aim of this research is to reveal principles for the design of nature-based AWULs. A framework for the analysis of AWULs was developed from relevant literature works. The framework comprised two sets of criteria based on conservative and innovative aspirations for the AWUL design. A search of AWUL and landscape literature revealed 26 precedents as suitable. These were then analysed using the two sets of criteria which revealed three key outcomes. These included making use of free-water surface flow landscape-based treatment, large AWUL footprints and, partial decentralisation. These findings helped to fashion a set of design principles to guide and encourage adoption of nature-based AWUL by implementers.

A Comparison of Maximum Permissible Concentrations for Pesticides in Brazilian Water Supply

Abstract Pesticides have been used for a long time in agriculture to prevent the growth of undesired organisms. However, depending on the type of production (i.e., conventional, organic, and regenerative), they might not be applied. Adequate types and uses of pesticides should not cause any damage to any non-target species or environments due to the exposure to it, especially if all farming operations have been done properly. Reversely, when pesticides are applied in inappropriate time, amount or technique, they may cause several impacts, among which is water contamination. Brazil stands out worldwide for its agricultural potential, but it is exposed to risks concerning the water supply security to its population. The current study is a comparison of the Maximum Permissible Concentrations (MPC) for pesticides in potable water supply in Brazil with the values set in the United States, Canada, European Union countries, Japan, and the guidelines issued by the World Health Organization. The regulations of each country were used, as well as the trading, consumption and agricultural production data. The Brazilian regulation is the one accounting for the largest number of pesticides. However, their MPC is 5,000 times more permissible than that from the European Union for the herbicide known as glyphosate, 300 times than that for 2,4-d and 20 times than that for atrazine. Finally, it was possible to observe the relevance of revising the regulation and public policies in place to minimize the indiscriminate use of pesticides in Brazil and adapt these compounds to the standards in a global level.

Arsenic Contamination in Indian Groundwater: From Origin to Mitigation Approaches for a Sustainable Future

The presence of arsenic in Indian groundwater poses a significant threat to both the ecosystem and public health. This review paper comprehensively addresses the topic, encompassing the underlying causes and potential solutions. Health consequences examines the serious health risks of drinking water contaminated with arsenic. Arsenic’s complex geochemical processes of mobilization, transport, and distribution in groundwater are investigated. Mathematical models, geographical analysis, and data-driven modeling are discussed in the context of Indian groundwater. A comprehensive assessment of removal methodologies and the various factors influencing the mobility of arsenic is addressed. It was documented that community water purifiers and plants have successfully eliminated approximately 90% of arsenic, and the implementation of rainwater collection systems has also enhanced the overall quality of water. This review aims to address existing knowledge gaps and assess various strategies aimed at ensuring a more secure and sustainable water supply for the regions in question. The ultimate goal is to enhance the overall well-being of the population and protect the integrity of local ecosystems.

Health Impacts of the 2023 Flood in Pakistan: A Comprehensive Case Study on Skin-related Ailments and Waterborne Diseases

The devastating flood that struck Pakistan in 2023 had profound ramifications for public health, leading to a surge in waterborne illnesses and skin-related ailments among the affected populace. This thorough case study delves into the post-flood health consequences, with a specific focus on the emergence of skin rashes, allergies, burns, and heat strokes as formidable challenges. The report underscores the urgent necessity for swift, well-coordinated medical interventions during disasters to effectively alleviate the repercussions on vulnerable communities. The following recommendations could be used to prevent future diseaster situation. Effective management of post-flood scenarios demands meticulous risk assessment and mitigation strategies [2]. Vital to this process is the cultivation of community resilience, achieved through strengthening local capacities, fostering awareness, and promoting community engagement [6]. Integrated water management strategies are imperative to thwart waterborne diseases in the aftermath of floods, encompassing enhanced sanitation infrastructure, secure water supply, and health education [7]. Climate change adaptation must be seamlessly integrated into disaster response plans to tackle the escalating frequency and intensity of floods [10]. Leveraging medical relief and telemedicine, including mobile clinics, can bridge gaps in healthcare access during disasters [9]. These innovations facilitate remote medical consultations and essential healthcare delivery. Recognizing the toll floods take on mental well-being, access to psychosocial support services is paramount [8]. Cross-border collaboration heightens disaster response and recovery [3]. Resource and expertise sharing enhances healthcare interventions in the aftermath of trans-boundary floods. Early warning systems are pivotal in preventing casualties and mitigating health impacts [5]. To ensure equitable outcomes, disaster management must prioritize vulnerable groups such as the elderly and children, tailoring interventions to their distinct needs [1].

Will extreme drought impact the reservoir water quality? A 30-year observational study

Climate change affects the security of the global water supply. However, only a few studies on the effects of drought on water quality in Asia have been published. In 2021, Taiwan faced its most severe water crisis in the past 56 years. The Te-Chi reservoir, situated at an elevation exceeding 1420 m, stands out as significantly affected by hydrologic variability. Overcoming geographical challenges, we captured an exceptional climatic period to sample and analyze water quality. Subsequently, we investigated multivariate long-term water quality data incorporating climate and hydrological information to evaluate the effect of climate change on the reservoir. The results showed the annual average temperature had risen by about 1.4 °C while total annual rainfall declined over the past 18 years. 30-year water quality data from 1993 to 2022 was analyzed to examined the long-term water quality change. There was an observed upward trend in the electrical conductivity of the reservoir water. The concentration of dissolved oxygen showed a decreasing trend, which may be attributed to the increase of temperature due to climate change. Besides, as the water level dropped during the drought, we found that the concentration of total phosphorus, total nitrogen and electrical conductivity in Te-Chi reservoir tended to increase, while the transparency of the water decreased. Consequently, we further explored the potential pollution sources during extreme drought by multivariate statistical methods, such as Pearson’s correlations, principal component analysis, and factor analysis. We found that four varimax rotated principal components collectively explain 82% of the variation in water quality data of the Te-Chi reservoir with the reservoir water level, signifying their representativeness in interpreting the monitoring data. We also assessed the contribution of each factor to specific water parameters, which can aid in better management of water resources during such challenging conditions. In conclusion, this study provides evidence and raises awareness on the effect of climate change by long-term water quality data with multiple parameters. The water quality components in the reservoir are affected by extreme weather, which is predicted to occur more frequently in the future and thus could affect energy scarcity, public health and food safety for sustainable reservoir operation. The study underscores adaptive management, mitigation strategies and the future research direction.

Impact of Climate Change on Reservoir Operation during the Dry Season in the Pearl River Basin

Climate change has far-reaching impacts that have created new challenges for water resource management. As an important measure to coordinate the relationship between society, economy, and environment, reservoir scheduling can reduce the future impact of climate change. It is, therefore, important to investigate the impacts of scheduling on reservoir operation. In this study, a reservoir system in the Pearl River Basin was selected to explore these impacts. Results show that the basin temperature significantly and abruptly increased in 2000, and precipitation and streamflow changed abruptly in 1983 and 1992. Historically, climate change has increased power generation, increased the risks to water supply security and ecological protection, and altered the relationship between power generation and ecological protection objectives. Based on 28 global climate models, the rank scoring method, Delta statistical downscaling, and the SWAT model, three emission scenarios (RCP2.6, RCP4.5, and RCP8.5) in CMCC-CM were evaluated to assess the climate change impact. In the future, the temperature will continue to exhibit an increasing trend, and the amount and distribution of streamflow will be altered. Although climate change will increase power generation in the dry season, it will also bring about new challenges for ecological protection and water supply security. Accordingly, the Datengxia Reservoir operating rules may require significant amendments.

Cape Town residents’ willingness to pay for a secure and ‘green’ water supply

The City of Cape Town experienced a serious drought between 2016 and 2018 which led to severe water shortages and concerns for the environment. This study took advantage of a period of unprecedented levels of awareness about water security in order to investigate households’ willingness to pay (WTP) for reliable water supply and their WTP to avoid environmental damages in securing this supply. Increasing the supply of water from dams and groundwater will ultimately impact on aquatic ecosystems, but alternatives are more expensive. We surveyed 248 households from 105 suburbs and used contingent valuation methods to investigate WTP for both secure and less damaging or ‘greener’ ways of supplying water. Depending on income level, households were willing to pay 63–127% more for their normal levels of consumption in order to have security of supply, and a further 35–68% more to ensure its environmental sustainability. Based on the relationship between WTP for 7 income categories, the overall WTP for secure water supply under non-drought conditions amounted to some 2.8 billion ZAR/year, which is about 90% higher than pre-drought revenues. Aggregate WTP for securing this supply using options that ensured the protection of the region’s rivers and estuaries was 3.3 billion ZAR. These results have an important bearing on water investment and pricing decisions over the longer term.

Type-2 fuzzy chance-constrained linear fractional programming model for a water resource management system: A case study of Taiyuan city, China

Abstract Uncertainties arising from extreme climate events and human activities pose a challenge to the efficient allocation of water resources. In this study, a type-2 fuzzy chance-constrained linear fractional programming (T2F-CCLFP) is developed to support the water resource management system under uncertainty by incorporating type-2 fuzzy sets, chance-constrained programming, and fractional programming into a comprehensive multi-objective optimization framework. The model enables the trade-off between economic, social, and environmental sustainability and provides water supply solutions associated with different levels of fuzzy uncertainty and risk of violating constraints. The T2F-CCLFP model is applied to Taiyuan, Shanxi Province, China, to support its water resource management. Results reveal that: (i) the industrial structure is transitioning toward diverse industries from energy and heavy industry dominance; (ii) external water transfer will be the major water-supply sources for the city in the future, accounting for 55 and 50% of the total water supply in 2025 and 2030, respectively; (iii) the water-supply security of the city is enhanced by provoking the utilization of reclaimed water (the annual growth rate is 13.9%). The results are helpful for managers in adjusting the current industry structure, enhancing water supply security, and contributing to the sustainable development of socio-economic and water systems.