Water-scarce Cities Research Articles

Sustainable Stormwater Management for Different Types of Water-Scarce Cities: Environmental Policy Effect of Sponge City Projects in China

With high-speed urbanization, ecological space is seriously shrinking, and lagging drainage facilities contradict the ecological needs of citizens. In particular, water-scarce cities are faced with frequent stormwater disasters, such as excessive accumulation of rainwater, peak runoff and water pollution, which threaten the safety of the urban water ecological environment. This paper combined the actual construction content of the sponge city project with a whole process policy evaluation framework to examine whether the projects solve these problems and to find different approaches to the results. Utilizing entropy fuzzy comprehensive evaluation provides a systematic standard for the evaluation system. The research shows that the sponge city project can achieve a good governance effect, including constructing a suitable scheme for urban hydrological characteristics, effectively improving the rainwater treatment level of different types of water-scarce cities, and alleviating the ecological contradiction of urban water environment. The stages of policy formulation, policy implementation and policy results achieve a good degree of completion. On one hand, sponge city projects transform the infrastructure at key locations, aiming at improving the rainwater interception capacity of the streets; on the other hand, restoring original natural waters improves the capacity of water conservation and forms a sustainable ecosystem between the city and nature.

Ecological Role of Small-scale Artificial Wetlands in Water-scarce Cities: A Case Study of Anyang City, Henan Province, China

Taking Anyang City, Henan Province, China, as an example, this paper mainly discusses the ecological role of artificial wetlands in water-scarce cities, elaborates the important ecological functions of artificial wetlands in urban ecosystems, and demonstrates the practical experience of artificial wetland renovation and sponge city construction through specific cases, such as the wetland redevelopment project of Magnuson Park in the United States.

Evaluating Losses from Water Scarcity and Benefits of Water Conservation Measures to Intercity Supply Chains in China.

The severe water scarcity in China poses significant economic risks to its agriculture, energy, and manufacturing sectors, which can have a cascading effect through the supply chains. Current research has assessed water scarcity losses for global countries and Chinese provinces by using the water scarcity risk (WSR) method. However, this method involves subjective functions and parameter settings, and it fails to capture the adaptive behaviors of economies to water scarcity, compromising the reliability of quantified water scarcity loss. There is a pressing need for a new method to assess losses related to water scarcity. Here, we develop an agent-based complex network model to estimate the inter-regional and intersectoral impacts of water scarcity on both cities and basins. Subsequently, we evaluate the supply chain-wide economic benefits of four different water conservation measures as stipulated by the 14th Five-Year Plan for the Construction of a Water-Saving Society. These measures include increasing the utilization rate of recycled water in water-scarce cities, reducing the national water consumption per industrial value-added, and implementing agricultural and residential water conservation measures. Results show that direct losses constitute only 9% of the total losses from water scarcity. Approximately 37% of the losses can be attributed to interregional impacts. Among the water-scarce cities, Qingdao, Lanzhou, Jinan, and Zhengzhou pose a significant threat to China's supply chains. Agricultural water conservation yields the highest amount of water savings and economic benefits, while residential water conservation provides the highest economic benefit per unit of water saved. The results provide insights into managing water scarcity, promoting cross-regional cooperation, and mitigating economic impacts.

Socio-hydrological impacts of rate design on water affordability during drought

Unaffordable water threatens water access in the United States, particularly for low-income households. In water-scarce cities, water shortages during drought necessitate either expensive infrastructure development or costly emergency measures to meet demand, which can in turn increase water rates. Rate design plays a key role in determining whether these costs threaten water affordability for low-income households, but water utilities are often constrained by local and state policy in their ability to set progressive rates. Therefore, new approaches to assess the impact of rates on water affordability within the local legal and hydrological context are needed in drought-prone regions. To address this gap, we design a socio-hydrological modeling framework that fuses legal analysis, behavioral economics, and water resource systems modeling to assess the impacts of rate design on household water affordability. We demonstrate this framework in an illustrative application in Santa Cruz, California, where droughts threaten water supplies and California Proposition 218 deters public water utilities in setting progressive rate design. Our results demonstrate that legal constraints reduce affordability during droughts by limiting drought surcharge rate structures. This framework can help utilities design rates to improve water affordability in their socio-hydrological context and illuminate the impacts of state policy on affordability outcomes.

Driving factors for decoupling water resources ecological footprint and economic growth in water-deficient cities dominated by agriculture.

To explore the key factors and specific thresholds of water resources limiting economic development, and to provide technical support for water resources management in cities dominated by agriculture similar to Zhangjiakou. We used the Tapio elastic decoupling method to quantitatively evaluate the decoupling relationship between the water resources ecological footprint (WEF) and economic growth. Then the logarithmic mean Divisia index (LMDI) and mathematical statistics are used to identify the key factors and threshold effects. The results show a significant decreasing trend in the WEF and obvious spatial differences in Zhangjiakou between 2006 and 2015, with agricultural ecological footprint dominating all districts and counties (77.54 ± 14.35%). The changes in technological effect are a contributing factor to the decoupling between the WEF and the economy in Zhangjiakou, while the economic effect is the main restricting factor. In particular, there is a high correlation between the WEF and the number of water-saving irrigation machines and the total power of agricultural machinery. According to the findings, for water-scarce cities such as Zhangjiakou, where agriculture is the primary focus, it is suggested that increasing the number of agricultural machinery can effectively alleviate the problem of water scarcity constraining economic development.

Multimedia fate of sulfamethoxazole (SMX) in a water-scarce city by coupling fugacity model and HYDRUS-1D model

Increased concentrations of pharmaceutical and personal care products (PPCPs) have raised concerns about their impact on the ecological system and human health. To understand the environmental impact of PPCPs, we evaluated the fate of a typical PPCP of sulfamethoxazole (SMX) in a water-scarce city of Tianjin during 2013–2020 using a coupled model based on the dynamic fugacity model and HYDRUS-1D model. The results showed that the coupled model successfully simulated the reported SMX concentrations in the main fate media of water and soils, which accounted for 46.4 % and 53.0 % with equilibrium concentrations of 135–165 ng/L and 0.4–0.5 ng/g, respectively. The cross-media transfer flux results showed that advection was the prime input path for SMX in water, while degradation was the dominant output path. Wastewater irrigation and degradation were the main transfer processes of SMX in the soil. Moreover, human activities (i.e., emission loads) and climate (i.e., temperature and precipitation) change can significantly affect the concentrations and transfer rate of SMX in the media. These findings provide basic data and methods for the risk assessment of SMX in water-scarce regions.

Simulation Study on the Optimisation of Replenishment of Landscape Water with Reclaimed Water Based on Transparency.

Water-scarce cities have fewer surface water (SW) resources available for ecological use, causing landscape water to deteriorate due to water shortage and fail to perform their intended landscape functions. As a result, many cities use reclaimed water (RW) to replenish them. However, this could cause concern among the people, as RW usually has higher nutrient concentrations, which may stimulate algae growth and deteriorate the aesthetic senses of the receiving water bodies. In order to assess the feasibility of using RW for this purpose, this study used Xingqing Lake in Northwest China as insight into the effect of RW replenishment on the visual landscape quality of urban landscape water. Water transparency (measured by SD) is used as an intuitive indicator to reflect the comprehensive influence of suspended solids and algae growth on the water's aesthetic quality. Scenario analyses were carried out after calibrating and validating one-year data in MIKE 3 software with both SD and algae growth calculations, and the results showed that the low concentration of suspended matter in RW could compensate for the decrease in SD due to algal blooms caused by high concentrations of nitrogen and phosphorus, and the effect on SD is especially pronounced under conditions that are not conducive to algal growth, such as good flow conditions and low temperature. In addition, to meet a SD ≥ 70 mm, the total water inflow required can be significantly reduced with the optimal application of RW. It is also indicated that partial or complete utilization of RW to replace SW for replenishing the landscape water could be feasible from the viewpoint of landscape quality, at least for the landscape water investigated in this study. This can provide a method for the improvement to urban water management practices by using RW for replenishment in water-scarce cities.

Lessons learned from water-scarce cities: Proposed policies toward an integrated urban water management in Egypt

Water scarcity is one of the main challenges facing countries in arid or semi-arid zones. As an example, Egypt needs to deal with both insufficient quantity and quality of water for residents. Here, we propose actions and policies to promote an integrated water management approach to respond to water challenges in Egypt. Based on a literature review, we have selected a set of criteria concerning the environmental, economic, social, governmental, and physical dimensions of urban water management. We studied approaches from Peru, Namibia, and South Australia as these countries have similar climatic conditions and water issues and have made substantial advances toward sustainable water management. Key criteria are state or municipal ownership of water and related infrastructure, agreement on master plans for sustainable water management, improvement of water sanitation and overall infrastructure, and reduction of water demand. Participatory, and educational campaigns put water issues at the center of public debates. We evaluated which elements of water management approaches can be adapted and used in Egypt, which faces limited freshwater resources, and which faces a highly increasing population. Proposed actions included directing water fees to ecosystem projects, treatment of wastewater to be potable, participatory approaches that engage the community in water management, educational campaigns that lead to change of public perception and knowledge dissemination. We interviewed key stakeholders in the water sector in Egypt to validate our proposed approaches. The stakeholders supported knowledge dissemination, suggested using water fees in implementing environmental projects and criticized converting wastewater into drinking water. Finally, we drafted specific recommendations at the organizational and urban levels of water management. We recommended establishing a General Organization for Water Management to oversee water-related organizations and ministries. We also recommended prioritizing the economic conditions to support alleviation of water subsidy, increasing public awareness, and creating a public database for water knowledge. In addition, we recommended decentralized water management and water sensitive urban design. The value of these approaches is their applicability, with minor adaptations, to countries with similar or close climatic and socio-economic conditions to Egypt, such as the MENA region.

Comparative Economic and Life Cycle Analysis of Future Water Supply Mix Scenarios for Hong Kong – A Water Scarce City

Increasing urbanization and changes in climate have placed increasing stress on urban water supply systems. Policy makers have increasingly adopted alternative water supply sources, such as desalination and water reclamation to meet this challenge, however these technologies may increase the negative environmental impacts of the water supply system. These alternative sources are energy intensive, and more expensive to produce, which raises questions about their sustainability. In this study, a Life Cycle Assessment (LCA) and a economic portfolio choice model were used to determine the impacts of Hong Kong's long term water policy. The results of our study show that the current water policy will increase the carbon emissions of producing 1 m3 of freshwater by 11% to 1.65 kg CO2-Eq due to the addition of desalination. However, a fit-for-purpose water policy approach only increases emission by 4%, to 1.54 kg CO2-Eq, by instead relying on water reclamation to offset freshwater consumption. Impacts from increased energy consumption were mitigated by improved wastewater treatment, which reduced CH4 emissions. Although, ozone layer impacts increased due to higher NOx and N2O emissions, highlighting the need to consider emissions from wastewater treatment processes when evaluating water reclamation processes. Impacts to water prices were also minimized when reclaimed water was chosen over desalination, due to its lower unit production cost. By considering both cost and environmental impacts of such system level changes, decision makers can more accurately evaluate different water supply approaches for data-driven policymaking.

Quantifying the City-Scale Impacts of Impervious Surfaces on Groundwater Recharge Potential: An Urban Application of WRF–Hydro

Decades of urbanization have created sprawling, complex, and vulnerable cities, half of which are located in water-scarce areas. With the looming effects of climate change, including increasing droughts and water shortages, there is an urgent need to better understand how urbanization impacts the water cycle at city scale. Impervious surfaces disrupt the natural flow of water, affecting groundwater recharge in water-scarce cities, such as Los Angeles, looking to harness local water resources. In the face of growing water demand, informing on opportunities to maximize potential groundwater recharge can help increase cities’ resilience. WRF–Hydro, a physics-based hydrological modeling system, capable of resolving atmospheric, land surface, and hydrological processes at city scale, is adapted to represent urban impervious surfaces. The modified model is used to assess the hydrological implications of historical urbanization. Pre- and post-urban scenarios are used to quantify the impacts of impervious surfaces on the local water budget. Our results show that urbanization in LA has vastly decreased the potential for groundwater recharge, with up to half of the water inflow being redirected from infiltration in highly urbanized watersheds, while doubling surface runoff’s share of the city’s water budget, from ~15% to 30%. This study not only sheds light on the role of imperviousness on groundwater recharge in water-scarce cities, but also offers a robust and transferable tool for the management of urban land and water resources.

Household water use efficiency: Current trends, opportunities and constraints in Gaborone, Botswana

Sustainable management of household water demand requires understanding of the apportionment of indoor water use, which is affected by key determinants such as demographics, user behaviour, and the associated water use products (micro-components) that require careful consideration. These water use products include micro-components such as fixtures (e.g., toilets, showerheads, baths, basin, and kitchen taps) and appliances (e.g., washing machines and dishwashers). This study consequently investigates household water use efficiencies and cost implications of potential micro-component implementation in the water scarce city of Gaborone. In this regard, this study develops an approach that would eventually inform decision makers in establishing appropriate standards and/or policy strategies for effective implementation of water-saving schemes. This study applies a questionnaire survey method to collect both quantitative and qualitative data from households. Household demographics, income, water use capacities (i.e., flow rates and volumes) and user characteristics (frequency and duration) associated with micro-components were obtained. A regression analysis method is used to study the relationships between variables obtained from the household survey. Eventually, models that predict household water consumption and costs of different micro-component combinations for respective income groups are developed. Efficiency and cost criteria for evaluation of the effectiveness of water use efficiency initiatives and standards/policies have been presented. The results provide informative prospects of implementing water-saving schemes for different income groups considering appropriate standards. Water use efficiency in Gaborone is negative if the existing water use products are evaluated against SABS and USA standards. These results indicate inadequate uptake of efficient household water use products and present potential opportunities for water-saving initiatives and reduction of existing constraints.

Future global urban water scarcity and potential solutions

Urbanization and climate change are together exacerbating water scarcity—where water demand exceeds availability—for the world’s cities. We quantify global urban water scarcity in 2016 and 2050 under four socioeconomic and climate change scenarios, and explored potential solutions. Here we show the global urban population facing water scarcity is projected to increase from 933 million (one third of global urban population) in 2016 to 1.693–2.373 billion people (one third to nearly half of global urban population) in 2050, with India projected to be most severely affected in terms of growth in water-scarce urban population (increase of 153–422 million people). The number of large cities exposed to water scarcity is projected to increase from 193 to 193–284, including 10–20 megacities. More than two thirds of water-scarce cities can relieve water scarcity by infrastructure investment, but the potentially significant environmental trade-offs associated with large-scale water scarcity solutions must be guarded against.

Effects of the COVID-19 Pandemic on the Urban Water Cycle

The coronavirus disease 2019 (COVID-19) is a global crisis spreading to all countries. This study explains and documents the first-order effects of the new coronavirus on the urban water cycle. Urban water systems play an important role in public health because people rely so heavily on water services. Findings address short- and long-term changes in climate variables; availability and accessibility of clean water to prevent and control the spread of coronavirus in water-scarce cities; shifts in habits, behavior, and lifestyles of people and effects on water demand during lockdowns; and role of wastewater treatment in preventing the spread of coronavirus.

How does hybrid environmental governance work? Examining water rights trading in China (2000–2019)

Intensifying competition for water induces the growth of water markets in several countries for sharing water between rural communities and cities. While there is a growing recognition that adoption of market mechanisms in environmental governance relies on the state and different institutional arrangements, much less is known about how the interconnections among the state, market-tools, and the community work in practice. In China's distinctive political system, the central government has adopted a ‘Two-Hands’ approach (两手发力) to water governance – a combination of strong central regulation and infrastructure development on the one hand, and adoption of market principles on the other to improve water reallocation. A recent study has explored the policy evolution underpinning this transition. However, no studies have systematically examined the implementation of the Two-Hands approach to reveal the underlying institutional hybrid patterns in environmental governance. This study fills this research gap by employing a Fuzzy Set Qualitative Comparative Analysis (fsQCA) to analyze how the interplay of the central government, market, and local governance shapes water rights trading patterns. A total of 29 water-scarce cities using water rights trading with 385 transactions were investigated for the period between 2000 and 2019 by combining evidence from fsQCA and qualitative case-studies. The implications drawn from interpreting the results are as follows: (1) the central government shapes the development of the market and its transactions but this is expressed in multiple ways through pilot projects and the national water exchange platform; (2) establishing water markets and investing in water infrastructure are mutually reinforcing, rather than mutually exclusive; and (3) local governments employ different property rights arrangements to adapt water markets in China's centralized politically institutional context.

Spatiotemporal variations of agricultural water footprint and socioeconomic matching evaluation from the perspective of ecological function zone

The water footprint theory has provided an effective approach for evaluating the utilization of freshwater resources in agricultural production. However, there are few studies have explored the dynamic coupling relationship between water footprint and socioeconomic factors, especially from the perspective of regional ecological features. Therefore, the water footprint method was used to investigate the dynamic evolution of agricultural water consumption from 2005 to 2015 in Zhangjiakou, an extremely water-scarce city which is divided into six ecological zones (I, II, III, IV, V, and VI). Then mathematical models such as the Gini coefficient were first employed to evaluate the spatiotemporal matching characteristics of agricultural water footprint and socioeconomic factors. The results show that: (1) The agricultural water footprint increased by 1.69 × 109 m3 in Zhangjiakou, of which the animal products water footprint increased by 1.59 × 109 m3, accounting for 94%. (2) Cereals had always been the major contributors to crop water footprint, with an increasing contribution rate from 49% to 54%. Milk and egg products were the main drivers for the increasing water footprint of animal products, with a total contribution rate increased from 46% to 55%. Meanwhile, the spatial differentiation was significant. The contribution rate of the cereal water footprint was less than 50% in counties of high-altitude ecological zones I, II and IV in 2015, while it was higher than 50% in counties of low-altitude ecological zones III, V and VI. (3) The per unit area water footprint in counties of the ecological zone III was much higher than the average level, while per capita water footprint and per unit output value water footprint were far below it, indicating agricultural structure optimization requires a comprehensive consideration of multiple socioeconomic factors. This study is expected to provide policy-makers with scientific guidance that is conducive to agricultural water conservation and ecological zone planning.

Restoration of Urban Water Environment Landscape System and SWMM Technology Integration in Water-Scarce Cities

Economic development has led to a rapid increase in urban water consumption. The number of cities with water shortages nationwide is increasing. The establishment of a water resource circulation system is conducive to solving the urban water shortage. This study aims to investigate the restoration of the urban water environment landscape system and the integration of SWMM technology in cities with scarce water resources. For this objective, the meteorological situation of a city with water shortage in central China was used to establish the surface water hydrological model of Teaneck Creek. By establishing a data collection system at each meteorological point of the city, the USEPA SWMM model was implemented to simulate the movement of the urban sub-base system. The relationship model between the surface water flow and groundwater flow was established, and then the relationship between vegetation and soil was determined to formulate a plan for the restoration of a benign and environmentally friendly urban water environment landscape system. The established model can solve the urban water shortage problem. The results showed that the developed model was increased the utilization rate of water resources by about 20% and the urban greening rate by about 15%. The system will bring China a sustainable and eco-friendly urbanization process, which is of guiding significance for the production and development of cities with water shortages in China.

Rainwater harvesting potentials for a water-scarce city in Bangladesh

The potential for a rainwater harvesting (RWH) system to supplement the water supply in Chittagong city, Bangladesh, was assessed. Two years were selected for the analysis (2006 and 2020); the projected rainfall for 2020 was evaluated using the Statistical Downscaling Model. Data on projected runoff, land use changes, population growth and catchment areas were also accumulated. The whole city was divided into 22 sub-basins and 176 354 building rooftops were studied for RWH opportunities. Using the weighted linear combination method in a geographic information system environment, potential rooftops and zones were identified for 2006 and 2020. The results showed that the areas with a high RWH potentiality index could supplement water demand by up to 13.03% and 29.68% in 2006 and 2020, respectively. With proper data, this novel approach for a decision support system can be applied to investigate RWH potential in any urban area.

Analyzing the effects of institutional capacity on sustainable water governance

Sustainable management of water resources is becoming increasingly important in the face of challenges from urbanization, climate change, globalization, and other societal changes. Hong Kong, a water scarce city, is particularly in need of sustainable water management. In this paper, we focus on the key players in Hong Kong’s water management and assess their capacities to pick up signals, balance interests, implement policies, and learn and adapt from 1999 to 2018. We find that while the socio-economic and environmental contexts have changed, their capacities to pick up signals and balance interests have remained relatively flat, although they were responsive to public outcry especially over drinking water contamination. Their main attention has been focused on implementation and technical solutions, forgoing opportunities to collaborate with intermediaries in preparing for water stressed scenarios. Thus, we advocate for capacity building and bringing the public and communities into the governance structure for the pursuit of water sustainability in Hong Kong.

Assessing Water Security in Water-Scarce Cities: Applying the Integrated Urban Water Security Index (IUWSI) in Madaba, Jordan

Water security is a major concern for water-scarce cities that face dynamic water challenges due to limited water supply, climate change and increasing water demand. Framing urban water security is challenging due to the complexity and uncertainties of the definitions and assessment frameworks concerning urban water security. Several studies have assessed water security by granting priority indicators equal weight without considering or adapting to the local conditions. This study develops a new urban water security assessment framework with application to the water-scarce city of Madaba, Jordan. The study applies the new assessment framework on the study area and measures urban water security using the integrated urban water security index (IUWSI) and the analytic hierarchy process (AHP) as a decision management tool to prioritise and distinguish indicators that affect the four dimensions of urban water security: drinking water, ecosystems, climate change and water-related hazards, and socioeconomic aspects (DECS). The integrated urban water security index (IUWSI) highlights the state of water security and intervention strategies in Madaba. The study reveals that urban water security in Madaba is satisfactory to meet basic needs, with shortcomings in some aspects of the DECS. However, Madaba faces poor security in terms of managing climate- and water-related risks. The IUWSI framework assists with a rational and evidence-based decision-making process, which is important for enhancing water resources management in water-scarce cities.

Estimation of fuel potential of faecal sludge in a water scarce city, a case study of Jaipur Urban, India

Abstract Non-sewer sanitation systems are widely implemented for treatment and management of faecal sludge (FS) and septage in developing nations. India became an open defecation free (ODF) country in 2019, with more than 90 million toilets at rural and urban level constructed to achieve this ODF status. Government of India also initiated a faecal sludge and septage management (FSSM) policy in 2017. This paper highlights the policy vision for the state of Rajasthan and predicts options for a safely managed sanitation system through exploring the fuel potential of faecal sludge generated in the city. The intended study is an attempt to valorize faecal sludge into a marketable product through determining the heat capacity of dried faecal sludge from different sources such as pit toilets, septic tanks etc. In the present work in urban Jaipur, which is already a water scarce city, various onsite sanitation systems were targeted to collect FS samples from different locations. It was observed that the FS generated has a high heating value of 13.96 MJ/kg, with total solids ranges from 7 to 9%. For a pragmatic resource recovery option, the experimental data observed is validated with a literature review.