Risk Of Water Shortage Research Articles

Constrained CMIP6 projections indicate higher risks of future water shortages in Australia

Study RegionAustralia. Study FocusObservations and simulations both indicate a negative feedback between precipitation and temperature in arid environments, where low precipitation reduces the evaporative cooling effect, resulting in higher temperature. The negative sensitivity of temperature to precipitation is a key driver of the Australian land water cycle and an important source of uncertainty in climate model projections. Currently, the spread of projected future sensitivities of temperature to changes in precipitation remains substantial across models. To reduce this spread, we demonstrated the existence of a robust emergent relationship between historical wet season temperature sensitivity and future annual temperature sensitivity across all 36 CMIP6 (under emission scenarios SSP126 and SSP245) and 36 CMIP5 (under RCP26, RCP45 and RCP60) models. Combined with observations, we reduced the uncertainty of future temperature sensitivity projections. New Hydrological Insights for the RegionThe constrained results show that the uncertainties of future sensitivities of temperature to precipitation changes are reduced by 27.0–46.8 % (CMIP6) and 11.2–31.1 % (CMIP5). We reveal that the raw CMIP5 and CMIP6 projections both largely overestimate the future negative sensitivity of temperature to precipitation in Australia. These overestimated evaporative cooling effects suggest that future decreases in soil water and increases in drought frequency are also highly underestimated. In particular, the constrained results show an increase in total evaporation across Australia, which contrasts with the decreasing trend in the raw CMIP6 outputs.

Climate Change-Driven Hydrological Shifts in the Kon-Ha Thanh River Basin

Climate change is projected to bring substantial changes to hydroclimatic extremes, which will affect natural river regimes and have wide-ranging impacts on human health and ecosystems, particularly in Central Highland Vietnam. This study focuses on understanding and quantifying the projected impacts of climate change on streamflow in the Kon-Ha Thanh River basin, using the Soil and Water Assessment Tool (SWAT) between 2016 and 2099. The study examined projected changes in streamflow across three time periods (2016–2035, 2046–2065, and 2080–2029) under two scenarios, Representative Conversion Pathways (RCPs) 4.5 and 8.5. The model was developed and validated on a daily scale with the model performance, yielding good performance scores, including Coefficient of Determination (R2), Nash-Sutcliffe Efficiency (NSE), and Root Mean Squared Error (RMSE) values of 0.79, 0.77, and 50.96 m3/s, respectively. Our findings are (1) streamflow during the wet season is projected to increase by up to 150%, particularly in December, under RCP 8.5; (2) dry season flows are expected to decrease by over 10%, beginning in May, heightening the risk of water shortages during critical agricultural periods; and (3) shifts in the timing of flood and dry seasons are found toward 2099 that will require adaptive measures for water resource management. These findings provide a scientific foundation for incorporating climate change impacts into regional water management strategies and enhancing the resilience of local communities to future hydroclimatic challenges.

The Crisis in Oases: Research on Ecological Security and Sustainable Development in Arid Regions

Arid areas cover approximately 41% of Earth's land surface and support more than 38% of the global population. As an important part of drylands, oases are the main carriers of human production, socioeconomic activity, and the ecological environment. Oases typically sustain nearly all of an arid region's human population and produce nearly 95% of its gross domestic product. The ongoing intensification of global warming and human activities has resulted in water stress and water-related environmental problems in arid areas, along with land degradation and desertification. The risk of water shortage and natural disasters in these regions has also increased. The solution to mitigate these environmental issues and achieve ecological security and sustainable socioeconomic development is to accelerate the modernization of oasis ecological agriculture. This can be accomplished by coordinating the contradictions between agricultural, industrial, and domestic water use and ecological water use in arid areas, thereby improving the level of management in oases and strengthening their ability to cope with climate change.

Development path for China's mega-large urban agglomerations based on the water-energy-food nexus

The Beijing-Tianjin-Hebei (BTH) mega-large urban agglomeration of China (CMUA) has significantly contributed to Chinese socioeconomic development. However, it faces severe shortages in the supply to meet the increasing demand of water, energy, and food resources (WEF). In order to safeguard the resource security of CMUA-BTH and the synergistic development of cities, and to compensate for the lack of dynamic analysis between urban agglomerations and WEF in previous studies. In this study, a coupled CMUA-WEF simulation model is developed based on the system dynamics approach. The model not only studies the three elements of WEF, supply and demand, but also conducts a comparative analysis of the three regions of BTH, and designs a total of four scenarios based on the possibility of future development, so as to facilitate the depiction of the trend of the WEF supply and demand system under different scenarios, and to provide theoretical basis for the government to formulate effective policy. The results show that: (1) Regarding demand, the aggregate demand for energy, food and water in the BTH will increase by about 3–5 times, 3 times, and 2 times, respectively, from 2000 to 2050, among which the total demand for energy will increase most significantly. In contrast, the variation of local resource supply side is small, which leads to the deterioration of resource security. (2) The risk of water shortage is the greatest in resource security, with less than 30% self-sufficiency in water security in all three regions. (3) Scenario analysis for CMUA-BTH indicates that “choking flow” (S3) yields more pronounced effects compared to “open source” (S2), and therefore adhering to the reduction of food waste, promoting energy-saving technologies, and intensifying water-saving measures can effectively reduce the risk of water shortages in the three regions. Optimal resource security in S4 increases Hebei's water pressure by 1.5%, alleviates Beijing's pressure by 7.3%, and the implementation of the Xiongan New Area and the new energy development policy can help realize the synergistic development of BTH and the inter-regional linkage.

An integrated adaptive allocation model for unified optimization of conventional and unconventional water resources based on fairness and efficiency

Unconventional water (UW) use has pros and cons, presenting the challenge of matching water utilization with regional water use characteristics. This study proposed the concept of amount-centered adaptive water allocation and built an integrated adaptive allocation model that includes conventional water (CW) and UW adaptability. The model consists of two modules. The first module introduces the regional composite index and inequality index to match CW and UW allocation amount with the sub-region’s characteristics. The second module defines the efficiency of CW and UW allocation, employs the Zero-Sum Gains Data Envelopment Analysis to find the solution set with the highest efficiency on the Pareto front, and further modifies it to reach the optimal allocation efficiency. Then the proposed model was applied to Jiangsu Province, China. Empirical and comparative analyses of the 54 weighting plans proved the validity and practicability of the model. The results showed: (1) The model tallies with the principles of fairness and efficiency and reduces the spatial heterogeneity of water shortage risk; (2) When available water supply decreases by over 20% due to future water-related emergency incidents, CW allocation would first reach its upper limit, while UW fails to effectively bridge the supply–demand gap; (3) Only by improving the maximum UW consumption by over 40% can the future risk of extreme water shortages be effectively addressed. The model proposed in this study has excellent practicality and application potential, providing a novel perspective for incorporating UW into the unified management of water resources.

Penggunaan CROPWAT 8.0 untuk Menentukan Kebutuhan Air Irigasi Tanaman Tomat pada Tanah Regosol di Kawasan Ternate Utara, Provinsi Maluku Utara

Tomato is an important crop in Ternate, North Maluku Province, Indonesia. This study aimed to determine the irrigation water requirements for tomato cultivation on Regosol soil in the North Ternate region using the CROPWAT 8.0 model. Climate data, crop data, and soil data were collected and processed using the CROPWAT 8.0 program. The results showed that the irrigation water requirements varied significantly between the rainy and dry seasons. During the rainy season, the total irrigation water requirement ranged from 60 to 107 mm, while in the dry season, it was much higher, ranging from 130 to 187 mm. This difference was primarily due to the low rainfall during the dry season. Simulations of planting at different periods showed relatively minor variations in crop water requirements, reflecting the stable weather conditions throughout the year in Ternate. The findings of this study can assist local tomato farmers in managing irrigation water more efficiently and effectively, thereby improving crop productivity and reducing the risk of water shortage.

Thermal stratification characteristics and cooling water shortage risks for pumped storage reservoir–green data centers under extreme climates

Utilizing the thermal stratification of reservoirs to obtain cold water for cooling green data centers (GDCs) is a new mode of energy conservation and emission reduction. However, global warming is expected to alter this phenomenon in deep reservoirs and thus may affect the digitalization process. While the frequency and intensity of extreme climate (EC) events are increasing under a changing climate, the impacts of these highly destructive events on thermal stratification and the related cascading effects on GDC cold-water supplies are still unclear. A two-lateral-dimensional thermohydrodynamic model was established to determine the characteristics of reservoir thermal stratification changes and its potential water environment impacts based on the heat extreme experienced by the Jinshuitan Reservoir, a large, pumped storage power station (PSPS) with a GDC in southeastern China. Fourteen different PSPS inlet/outlet schemes under 2 climate scenarios were designed, and two new indexes, namely, the risk index of cold-water shortage and the index of thermal stratification, were proposed to explore the impact of extreme climates on GDC water extraction. The results showed that compared to the present climate conditions, the reservoir experienced stronger thermal stratification with a 20.6 % average increase in thermal stability, a longer thermal stratification duration with a transitional trend from seasonal to permanent stratification, and a thinner cold-water layer with a 15-m average decrease. Changes in the thermal stratification of reservoirs under EC conditions will benefit some species, such as diatoms (except for early July and the period from mid-August to early October), green algae and cyanobacteria and the migration of warm-water fish, but adversely impact dissolved oxygen, diatoms and cold-water fish. Furthermore, the risk of cold-water shortages under EC conditions was consistently greater than that under average climate (AC) conditions (traditional assessment) when the elevation of pumped storage intake/outlet was less than 145 m. According to the traditional assessment method, the intake/outlet elevation of pumped storage reservoirs resulted in a 60.27 % increase in the risk of cold-water shortages during climate extremes. Furthermore, the demand for green cold-water withdrawal and optimal pumped storage power generation benefits were met when the PSPS intake/outlet elevation was 145 m. Beyond solving this specific case, this study elucidates the importance of linking the thermal stratification and data center of cold-water withdrawal to ECs. These findings provide new insights for increasing climate change resilience.

Climate variability impacts on runoff projection in the 21st century based on the applicability assessment of multiple GCMs: A case study of the Lushi Basin, China

In this study, we initiatively employed the improved Secure Hash Algorithm (SHA) to evaluate and compare the competencies of multiple Coupled Model Intercomparison Project Phase Six (CMIP6) General Circulation Models (GCMs). The selected GCM outputs were bias-corrected by the non-parametric quantile mapping (QM) method. The calibrated and validated data were then used to run the XAJ (Xin’anjiang) model to assess long-term climate variation impacts on runoff under four Shared Socioeconomic Pathways (SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5), where the results were compared with the baseline period (1976–2000). Overall, the CNRM-CM6-1-HR, FIO-ESM-2–0, INM-CM5-0 and NorESM2-MM models reconstructed better spatio-temporal evolutionary trends related to historical precipitation and evaporation, and were applied as selected GCMs for reliable runoff projection applications. The intensification amplitudes of precipitation and evaporation produced by selected GCMs gradually spread from SSP1-2.6 to SSP5-8.5 throughout the 21st century. Compared to the baseline period (257 m3/s), the extreme streamflow during the wet periods is likely to increase for SSP5-8.5 (288 ∼ 298 m3/s), SSP3-7.0 (276 ∼ 294 m3/s), and SSP2-4.5 (222 ∼ 280 m3/s), whereas SSP1-2.6 decreases to varying degrees (178 ∼ 255 m3/s). Meanwhile, during the dry periods, the extreme streamflow is projected to decrease by 28 ∼ 73 m3/s (SSP5-8.5), 32 ∼ 38 m3/s (SSP3-7.0), 8 ∼ 31 m3/s (SSP2-4.5), and 5 ∼ 33 m3/s (SSP1-2.6) from historical levels (62 m3/s). The overwhelming majority of increasing trends in the wet periods and vastly decreasing trends in the dry seasons indicate that the basin will face some floods and water shortage risks in the mid to late 21st century. The findings broaden the efficacious applications of SHA in the performance selection of GCMs and QM method in bias correction. The conclusions provide a reference for flood and drought mitigation planning and water resources policymaking in the Yellow River Basin.

A Water Shortage Risk Assessment Model Based on Kernel Density Estimation and Copulas

Accurate assessment and prediction of water shortage risk are essential prerequisites for the rational allocation and risk management of water resources. However, previous water shortage risk assessment models based on copulas have strict requirements for data distribution, making them unsuitable for extreme conditions such as insufficient data volume and indeterminate distribution shapes. These limitations restrict the applicability of the models and result in lower evaluation accuracy. To address these issues, this paper proposes a water shortage risk assessment model based on kernel density estimation (KDE) and copula functions. This approach not only enhances the robustness and stability of the model but also improves its prediction accuracy. The methodology involves initially utilizing kernel density estimation to quantify the random uncertainties in water supply and demand based on historical statistical data, thereby calculating their respective marginal probability distributions. Subsequently, copula functions are employed to quantify the coupled interdependence between water supply and demand based on these marginal probability distributions, thereby computing the joint probability distribution. Ultimately, the water shortage risk is evaluated based on potential loss rates and occurrence probabilities. This proposed model is applied to assess the water shortage risk of the Yuxi water receiving area in the Central Yunnan Water Diversion Project, and compared with existing models through experimental contrasts. The experimental results demonstrate that the model exhibits evident advantages in terms of robustness, stability, and evaluation accuracy, with a rejection rate of 0 for the null hypothesis of edge probability fitting and a smaller deviation in joint probability fitting compared to the most outstanding model in the field. These findings indicate that the model presented in this paper is capable of adapting to non-ideal scenarios and extreme climatic conditions for water shortage risk assessment, providing reliable prediction outcomes even under extreme circumstances. Therefore, it can serve as a valuable reference and source of inspiration for related engineering applications and technical research.

A warming-induced glacier reduction causes lower streamflow in the upper Tarim River Basin

Study areaThree headwater basins of the Tarim River Study focusThis study built upon existing knowledge by incorporating threshold melting temperatures into the Spatial Processes in Hydrology (SPHY) model and decomposing the streamflow changes into individual runoff components. Additional glacier retreat rate data were used to calibrate the improved SPHY, which provides better constrained estimates of glacier response to climate change. We employed bias-corrected simulations from Coupled Model Intercomparison Project Phase 6 (CMIP6) models to drive the improved SPHY under four future scenarios (SSP1–2.6, SSP2–4.5, SSP3–7.0, and SSP5–8.5). New hydrological insights for the regionModeling results show accelerated glacier melt in the future, with glacier volume at the end of this century projected to be less than 20% of the current level under SSP5–8.5. Furthermore, future streamflow is expected to decrease, most notably in the Karakash River basin under the SSP1–2.6 scenario. The reduction in streamflow, mainly during the summer months, results from decreased glacier melt runoff, which cannot be offset by increased rainfall runoff. Additionally, the implementation of climate change mitigation measures could delay glacier loss, but the dominant component of runoff would still shift from current glacier melt to future rainfall. Plain language summaryGlobal warming accelerates the hydrological cycle, altering the temporal and spatial patterns of streamflow, especially in cold regions, such as the Tarim River Basin. Understanding future streamflow changes is important for the economic development and ecological protection of this region, which will help to manage the risk of water shortages and to plan engineering works to mitigate water shortage crises. We therefore used state-of-the-art climate simulation to project future streamflow changes over three basins of the Upper Tarim River. We found that under all future scenarios, runoff will decrease in these basins. This decrease is mainly due to glacier retreat and cannot be mitigated by anticipated increases in rainfall in the future.

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.

An ordered multi-objective fuzzy stochastic approach to sustainable water resources management: a case study from Taiyuan City, China

Abstract The uncertainty of socioeconomic development and climate change poses challenges to the sustainable management of water resources in Taiyuan, China. The study proposes a type-2 fuzzy chance-constrained ordered multi-objective fractional programming (T2FCC-ORMOFP) model to address the allocation of water under uncertainties. The model incorporates type-2 fuzzy programming and chance-constrained programming into an overall framework to handle multiple uncertainties under multi-level and multi-objective conflicts, while using fractional programming to reflect the marginal benefits of the system. It prioritizes the principles of optimal, fair, and stable distribution by the upper-level governing authorities, while considering the social and economic environmental benefits of lower-level decision-making. The optimal water allocation scenarios were obtained under different hydrological guarantee rates, violation levels of water supply constraints, and net economic benefits of type-2 fuzzy numbers for 2030. Additionally, groundwater is replaced by reclaimed water in varying proportions for flexible water supply. The results show that the water demand in Taiyuan cannot be ignored, and the risk of water shortage is more sensitive for the agricultural and industrial sectors. The recycled water substitution strategy can optimize the water supply structure and improve social and economic benefits (9–12%). Also T2FCC-ORMOFP can improve overall efficiency (20%) compared with a single-level model.

Multi-objective cooperative optimization of reservoir scheduling and water resources allocation for inter-basin water transfer project based on multi-stage coupling model

The efficient coupling of a water allocation model with a reservoir operation model is key to maximizing the benefits of inter-basin water transfer (IBWT) projects. Most existing studies of IBWT operations and management do not account for matching water transfer and demand, and instead seek to optimize either the water allocation model or the reservoir scheduling model. In this paper, we propose a multi-stage joint optimization framework for reservoir scheduling and water allocation models that considers the key operation indicators of the project in the water source area and the multi-dimensional objectives in the receiving area. We derived a functional relationship that balances considerations regarding water, the economy, and ecology (WEE) in the receiving area and applied it to the water allocation model. The reservoir operation model was developed by considering the multiple benefits of water transfer and power generation in the water resource area. To reduce the complexity of the model and the tightness of its coupling, the model was divided into multiple stages of optimization and solved using the Multi-objective Evolutionary Algorithm Based on Decomposition (MOEA/D) algorithm. The results showed the allocation schemes of water resources influenced the competition between the economic and ecological benefits. Using the WEE model, a more reasonable water transfer and allocation method can be selected according to different development needs. As such, the water shortage rate of each user in the receiving area is kept below 8%, and there is significant improvement in all indicators compared with the conventional scheme. In addition, this model enables the reservoir group to achieve a power generation capacity of more than 5.64 kWh with the goal of meeting the water transfer demand, maintaining the reservoir empty rate at about 10%, and reducing the risk of water shortages. Our study can serve as a reference for effectively addressing the challenges associated with IBWT projects, and it can inform socioeconomic development in receiving areas while optimizing water transmission and allocation.

An assessment tool to improve rural groundwater access: Integrating hydrogeological modelling with socio-technical factors

Sustainable exploitation of groundwater resources for drinking water provision in rural communities in sub-Sahara Africa remains elusive due to the limited knowledge of these hydrogeological systems. This is exacerbated by poor maintenance of existing infrastructure, limited technical capacity, the socio-economic characteristics of the area and poor governance. Assessing the likelihood of a given individual user experiencing water shortage calls for an interdisciplinary approach. After a preliminary multifactorial analysis incorporating a range of variables from technical to societal, it was found that most of the overall risk of water shortage for an individual household could be attributed to three factors; (1) Proximity, specified as the distance to the closest supply well (determined by geographical parameters), (2) Availability of good quality water in the wells (determined by hydrogeological understanding and modelling), and (3) Sustainability (determined by socio-technical and socio-economic parameters). In the latter case, a distinction was made between hardware functionality- the water point's performance considering a sufficient yield and reliability through time- and software functionality, based on a combination of socioeconomic data from surveys and analysed using Multiple Factor Analysis (MFA). All three factors are eventually mapped onto indicators in the range of [0–1] and then represented in a Geographical Information System based on the partition of the entire spatial domain (e.g., counties, villages, and neighbourhoods). The three indicators are then combined in a final index based on the product of the three factors, thus mapping time-dependent overall risk and allowing the assessment of temporal risk-evolution scenarios. The methodology is applied to Kwale County, Kenya, where community handpumps and groundwater points comprise the main water supply system. Apart from mapping the present situation, the methodology is finally used to assess the impact of future climate scenarios.

Can climate knowledge enable Warragamba Dam, Sydney, Australia to be used to manage flood risk?

Dams that serve a dual purpose of water supply and flood mitigation operate to maintain a defined full supply level of water that balances the two conflicting requirements. To optimize the use of available storage space, the full supply level may be adjusted to reflect changing risks of future water shortages and future flood inflows based on known seasonal variations and current observations. The Warragamba Dam in eastern Australia is located upstream of the populated Hawkesbury-Nepean valley which has one of the largest flood exposures in the country. However, the operating protocol of the reservoir does not include provisions to reduce the full supply level of the dam for flood mitigation. Large scale climate indicators that are known to influence the hydroclimate of this region may potentially contain useful information to inform the dual use of this reservoir, but their utility for this purpose has not been studied. Here we explore whether current observations of large-scale climate along with antecedent catchment conditions can be used to estimate the probability of large inflows into the reservoir in the next 3- and 6 months, to aid flood management. We find that the predictors have a substantial influence on the probability of large inflows. The probability differences during opposite predictor phases vary by season and range from 30% to 70%. Our results indicate that considering current climate information to inform dual use of the Warragamba dam has merit.

Pervasive Permafrost Thaw Exacerbates Future Risk of Water Shortage Across the Tibetan Plateau

AbstractRivers originating from the Tibetan Plateau (TP) provide water to more than 1 billion people living downstream. Almost 40% of the TP is currently underlain by permafrost, which serves as both an ice reserve and a flow barrier and is expected to degrade drastically in a warming climate. The hydrological impacts of permafrost thaw across the TP, however, remain poorly understood. Here, we quantify the permafrost change on the TP over 1980–2100 and evaluate its hydrological impacts using a physically‐based cryospheric‐hydrological model at a high spatial resolution. Using the ensemble mean of 38 models from the Coupled Model Intercomparison Project Phase 6 (CMIP6), the near‐surface permafrost area and the total ground ice storage are projected to decrease by 86.4% and 61.6% during 2020–2100 under a high‐emission scenario, respectively. The lowering of the permafrost table and removal of permafrost as a flow barrier would enhance infiltration and raise subsurface storage capacity. The diminished water supply from ground ice melt and enhanced subsurface storage capacity could jointly reduce annual runoff and lead to exacerbated regional water shortage when facing future droughts. If the most severe 10‐year drought in the historical period occurs again in the future, the annual river runoff will further decrease by 9.7% and 11.3% compared with the historical dry period due to vanishing cryosphere in the source area of Yellow and Yangtze River. Our findings highlight the importance to get prepared for the additional water shortage risks caused by pervasive permafrost thaw in future water resources management across the TP.

Changes in the supply and demand potentials of China's glacier water resources in the 21st century: Spatiotemporal mismatches and combined effects

China's glacier water resources (GWRs) are not only indispensable suppliers of fresh water for humans living in large domestic areas but also affect the water supply to downstream neighbouring countries. Therefore, it is crucial to systematically evaluate the spatiotemporal (mis-) matches between the supply and demand potentials of China's GWRs and the combined supply and demand effects in the 21st century to enable regional sustainable development. To facilitate such research, in this study, we first regionalized the importance of China's GWRs in terms of the supply potential and downstream human dependence to reveal the spatial (mis-) matches between supply and demand potentials. Then, changes in the service potential of glacier meltwater and in population dynamics, as well as their temporal (mis-) matches and associated opportunities and risks, were further assessed at the river basin scale. The results showed that GWR plays an important role in 4 of 16 macroscale glacier-fed basins (i.e., Tarim, Junggar, Ili, and Zangxi) and 11 of 37 subbasins within the China region due to higher supply potential and demand potential in those basins. The importance of China's GWRs increases dramatically when taking the demand potential of downstream countries into account, especially in the Ganges and Indus river basins. The peaks in meltwater runoff from the most glacierized basins of the eastern Tianshan Mountains, eastern Qilian Mountains, and southeastern Tibetan Plateau of China occur slightly earlier than the projected peak population (around 2030) under the mid-range Shared Socioeconomic Pathway (SSP245), leading to a compound risk in terms of decreasing meltwater supply and increasing human dependence at the end of the 2020s. However, the peak meltwater is expected to occur later than the peak population in the Tarim, Qiangtang Plateau, and Qaidam basins. The opportunities offered by the increase in meltwater can relieve the water resource pressure for those populations under water-stressed conditions. Greater attention should also be paid to water shortage risks in the transboundary river basins, especially in the Indus and Ganges basins, because the peak meltwater within China is generally expected to occur sooner than the projected peak population of downstream countries. This study provides an effective planning and decision-making basis for the full utilization of China's GWRs and adaptation when glacier runoff declines.

Water-energy nexus in a desalination-based water sector: the impact of electricity load shedding programs

Reliance on water production by desalination as a solution to water scarcity is growing worldwide. High energy demands of seawater desalination raise new challenges for both water and energy management and highlight the importance of understanding the operational dependencies of the water sector on energy supplies. This study provides an in-depth analysis of the impact of the water-energy nexus in a desalination-based water sector, using Israel as a case study. Being large energy consumers, desalination plants are part of the Electricity Load Shedding Program (ELSP), which government energy regulators invoke in times of energy shortage. We focus on the interdependency between the two sectors as manifested at the time of ELSP utilization during an extreme heat wave. We show that energy shedding compensation is 6 to 14 times greater than the economic loss to the desalination plant from no water production, creating an obvious economic incentive to participate in ELSPs. However, this imbalance has a substantial negative impact on the water sector, which may compromise the level of service. Our evaluation concludes that the government authorities regulating water and energy need an official mechanism and policy for joint management strategies that can ensure economic efficiency and reduce the risk of power and water shortages during extreme events.

The role of root zone soil moisture return on vegetation green-up: A comparison of two degrading permafrost sites

The effects of permafrost degradation on ecological changes have attracted more and more attention, but the underlying interactive mechanisms are still not well understood. From a unique angle of view, this study focuses on the linkage between the freezing-induced root zone soil moisture return (SMR) and vegetation green-up along with climate warming and permafrost degradation. Using 7-year soil-weather monitoring data in the high-altitude and high-latitude permafrost regions, we investigated the changes of root zone SMR in two degrading permafrost sites. Results demonstrate that, as one important water source for vegetation green-up, the ratio of root zone SMR to the soil moisture storage after final thawed, Rsmr, could reach 22.8 % and 10.5 % at the two sites, respectively. In contrast to the negligible change at the high-latitude permafrost site, a rapid increase rate of 7.7 % per decade in Rsmr was found at the high-altitude permafrost site over the monitoring period of 2012–2018. Generally, vegetation green-up definitely benefited from the enrichment of soil moisture storage, but their sensitivities to climate warming and permafrost degradation were different at the two sites. The increase of Rsmr effectively buffered the shrinking trend of soil water availability of the root zone both over the pre-freezing and the green-up period at the high-altitude permafrost site. The changing role of root zone SMR might be threatened during the vegetation green-up in the longer future. Whereas, there would be no water shortage risk for the foreseeable future at the high-latitude permafrost site. Overall, this study emphasized the importance of SMR in enhancing soil water availability for vegetation green-up under the background of quick climate warming and permafrost degradation.

Urbanization and the Emerging Water Crisis: Identifying Water Scarcity and Environmental Risk with Multiple Applications in Urban Agglomerations in Western China

Urbanization and climate change have combined to exacerbate water shortages in cities worldwide. While rapid urbanization is faced with the risk of water resource shortage, there are few studies on the impact of water resource shortage and the ecological environment in mega-regions. Taking the three major urban agglomerations in Western China as an example, the spatial–temporal agglomeration pattern and driving force for the risk of water shortage are analyzed. First, a new comprehensive index system for environmental risks of water resources has been established, which can be used to assess spatial changes in water resource shortage risks. Secondly, the relationship between water resource shortage and the urban agglomeration effect is discussed in regards to water resource vulnerability, exposure, and recoverability. The results showed: (1) From 2000 to 2018, the risk of total water shortage in 12 provinces (cities) in Western China decreased from 3.42 to 2.59; the risk of total water shortage in the Guanzhong Plain urban agglomeration dropped the fastest, with an average annual decline rate of 10.57%. (2) Water resource shortage in different cities of the three major urban agglomerations is out of sync in time and space; the risk level of water shortage is high in the north and low in the south. (3) Geological environmental change is an important influencing factor of water resource shortage; the negative impact of industrial water use on the risk of water shortage is the largest, with a contribution of 24.9%. In addition, this paper also puts forward policy suggestions to alleviate the risks of water shortage in the urbanization process in the western region. This research can provide a scientific basis for the sustainable development of urban water resources.