Wastewater treatment and reuse are important means of addressing water scarcity and protecting the aquatic environment in urban areas. However, it comes at the cost of energy consumption and greenhouse gas emissions. However, the issues of governance and provincial-scale research have largely been ignored in current urban wastewater treatment and reuse studies. This paper summarizes the current status of 175 wastewater treatment plants (WWTPs) in Beijing, explores energy-intensive processes, energy consumption ratios, and the overall energy intensity of WWTPs, and maps the structure of urban wastewater treatment and reuse governance. The results indicate that most WWTPs in Beijing are medium or small in scale, treating wastewater at less than 200 thousand tons/day. Then, five energy-intensive subprocesses are identified, and their energy consumption ratios vary with treatment technologies and management factors, which calls for individual WWTP analysis and plant-specific strategies. The energy intensity of WWTPs in Beijing varies with treatment capacity and membrane bioreactor treatment technology used. Large-scale WWTPs employing MBR technology have a higher average energy intensity. Furthermore, the current coordination group and the four-layer policy system provide sufficient executive power and promote efficiency in departmental collaborations. Finally, inconsistent data, reductions in energy consumption, and the normalization of the governance structure are discussed, and policy suggestions are proposed.

Achieving sustainable water resources management objectives can work in tandem with poverty reduction efforts. This study evidenced the strong social hydrological linkages that exist in Cambodia, which allowed for presenting a broader understanding of water resources challenges to better formulate and connect policies at the local and national levels. Models are often not developed with household- or community-level input, but rather with national- or coarse-level datasets. The method used in this study consisted of linking qualitative and quantitative social analysis with a previously developed technical water planning model. The results from the social inequalities analysis were examined for three water use types: domestic, rice production, and fishing in three parts of the watershed, namely, upstream, midstream, and downstream. Knowledge generated from the social analysis was used to refine previous water planning modeling. The model results indicate that without household data to consider social inequalities, the technical analysis for the Stung Chinit watershed was largely underrepresenting the shortages in irrigation supply seen by groups in the most downstream sections of the irrigation system. Without adding social considerations into the model, new policies or water infrastructure development suggested by the model could reinforce existing inequalities.

The interlinkages between water for irrigation and for fish habitat are complex. This is particularly true in the Stung Chinit, a tributary to one of the most robust fisheries in the world, where livelihoods rely heavily on rice production and fishing and there is pressure to increase rice production with increased irrigation. This study assesses the tradeoffs between various management options and irrigation strategies in the Stung Chinit watershed under multiple projections of climate change. Due to the relative demands for instream flows and rice, if dry season rice is widely promoted, flows will be severely impacted. However, implementing a flow requirement protects these flows, while only causing minor shortages to rice when planted once or twice per year. These shortages may be alleviated with improved cooperation, management and shifting rice irrigation practices. While climate change will lead to warming temperatures and potentially higher demands for irrigation, the larger threat to rice and ecosystems appears to be water management (or lack thereof). This study suggests that there is sufficient water in the system to expand the irrigated area by 10%, grow rice twice per year and protect downstream flows under climate change; however, well-coordinated management is required to achieve this.

A climatically driven, water system modeling framework that captures a full range of interacting components at necessary spatiotemporal scales was developed for the Southwestern United States, including a detailed representation of California’s water supply and demand network, within the Water Evaluation and Planning (WEAP) system. Credibility of the model as a tool for water-energy analysis was garnered through evaluation of the historic regional water balances, including metrics of water supply, water use, groundwater storage, environmental requirements, and the energy use associated with water. The ability of the model to address policy-relevant questions was demonstrated by evaluating the impacts of a future 30-year drought scenario that included a realistic 2°C warming trend through 2050. With drought, the total energy used to supply water decreases by about 3% compared to the historic use, and warming alone reduces overall energy use by a modest 1% due to overall reductions in water delivery. The strongest signal of persistent warming expresses itself in groundwater storage, which decreases by an additional 9% beyond the impact of drought alone. A water conservation scenario was used to demonstrate the response of the water sector to the types of conservation strategies being pursued at local and state levels, with conservation reducing water use by about 10% and energy use by 3% relative to historic levels. Such measures overcome the warming trend, but it is demonstrated that persistent drought challenges groundwater conservation strategies and reductions in energy use by the water sector, leading to further overdraft of aquifers and increased energy use.

Rwanda’s economy is inextricably linked to its water supply, with agriculture employing nearly 70% of its population and making up half of the country’s export revenue. It aspire to become an upper-middle-income country by 2035, and a high-income country by 2050. But rising temperatures and more prolonged dry spells threaten crop production and strain water supply. Rwanda’s Vision 2050 policy details the country’s long-term goals and provides the planning blueprint to guide Rwanda’s development. But such growth, coupled with climate change, will profoundly affect its water supply and demands. Gaining a clearer understanding of the changing water supply and demand, as well as the nexus between water, energy, and food production, is critical to Rwanda’s success. The Water Resources Group (2030 WRG) is a public-private-civil society partnership hosted by the World Bank to help governments balance water security with longterm development and economic growth. The recently established Rwanda Water Resources Board (RWB), the Ministry of Agriculture and Animal Resources, and Ministry of Environment tasked the 2030 WRG in 2020 with performing a Hydro-Economic and Climate Change Analysis (HECCA), with the following directives: 1. Conduct a strategic assessment of the water sector that demonstrates how water and the economy are inter-linked; 2. Recommend concrete actions toward sustainable water resources management; and 3. Support a dialogue to identify and align joint initiatives among sectors, both public and private, towards sustainable water resources management, and enable long-term economic growth through 2050.