Water

2018
Qin, Yue, Lena Höglund-Isaksson, Edward Byers, Kuishuang Feng, Fabian Wagner, Wei Peng, and Denise L. Mauzerall+. “Air quality-carbon-water synergies and trade-offs in China's natural gas industry.” Nature Sustainability 1 (2018): 505-511.Abstract
Both energy production and consumption can simultaneously affect regional air quality, local water stress and the global climate. Identifying the air quality–carbon–water interactions due to both energy sources and end-uses is important for capturing potential co-benefits while avoiding unintended consequences when designing sustainable energy transition pathways. Here, we examine the air quality–carbon–water interdependencies of China’s six major natural gas sources and three end-use gasfor-coal substitution strategies in 2020. We find that replacing coal with gas sources other than coal-based synthetic natural gas (SNG) generally offers national air quality–carbon–water co-benefits. However, SNG achieves air quality benefits while increasing carbon emissions and water demand, particularly in regions that already suffer from high per capita carbon emissions and severe water scarcity. Depending on end-uses, non-SNG gas-for-coal substitution results in enormous variations in air quality, carbon and water improvements, with notable air quality–carbon synergies but air quality–water trade-offs. This indicates that more attention is needed to determine in which end-uses natural gas should be deployed to achieve the desired environmental improvements. Assessing air quality–carbon–water impacts across local, regional and global administrative levels is crucial for designing and balancing the co-benefits of sustainable energy development and deployment policies at all scales.
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Peng, Wei, Fabian Wagner, M. V. Ramana, Haibo Zhai, Mitchell J. Small, Carole Dalin, Xin Zhang, and Denise L. Mauzerall+. “Managing China's coal power plants to address multiple environmental objectives.” Nature Sustainability 1 (2018): 693-701.Abstract
China needs to manage its coal-dominated power system to curb carbon emissions, as well as to address local environmental priorities such as air pollution and water stress. Here we examine three province-level scenarios for 2030 that represent various electricity demand and low-carbon infrastructure development pathways. For each scenario, we optimize coal power generation strategies to minimize the sum of national total coal power generation cost, inter-regional transmission cost and air pollution and water costs. We consider existing environmental regulations on coal power plants, as well as varying prices for air pollutant emissions and water to monetize the environmental costs. Comparing 2030 to 2015, we find lower CO2 emissions only in the scenarios with substantial renewable generation or low projected electricity demand. Meanwhile, in all three 2030 scenarios, we observe lower air pollution and water impacts than were recorded in 2015 when current regulations and prices for air pollutant emissions and water are imposed on coal power plants. Increasing the price of air pollutant emissions or water alone can lead to a tradeoff between these two objectives, mainly driven by differences between air pollution-oriented and water-oriented transmission system designs that influence where coal power plants will be built and retired.
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2015
Dalin, Carole, Huanguang Qiu, Naota Hanasaki, Denise L. Mauzerall, and Ignacio Rodriguez-Iturbe. “Balancing water resource conservation and food security in China.” Proceeding of the National Academy of Science (2015).Abstract
China’s economic growth is expected to continue into the next decades, accompanied by sustained urbanization and industrialization. The associated increase in demand for land, water resources, and rich foods will deepen the challenge of sustainably feeding the population and balancing agricultural and environmental policies. We combine a hydrologic model with an economic model to project China’s future food trade patterns and embedded water resources by 2030 and to analyze the effects of targeted irrigation reductions on this system, notably on national agricultural water consumption and food self-sufficiency. We simulate interprovincial and international food trade with a general equilibrium welfare model and a linear programming optimization, and we obtain province-level estimates of commodities’ virtual water content with a hydrologic model. We find that reducing irrigated land in regions highly dependent on scarce river flow and nonrenewable groundwater resources, such as Inner Mongolia and the greater Beijing area, can improve the efficiency of agriculture and trade regarding water resources. It can also avoid significant consumption of irrigation water across China (up to 14.8 km3 /y, reduction by 14%), while incurring relatively small decreases in national food self-sufficiency (e.g., by 3% for wheat). Other researchers found that a national, rather than local, water policy would have similar effects on food production but would only reduce irrigation water consumption by 5%.
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2014
Dalin, Carole, Naota Hanasak, Huanguang Qiu, Denise L. Mauzerall, and Ignacio Rodriguez-Iturbe. “Water resources transfers through Chinese interprovincial and foreign food trade.” Proceedings of the National Academy of Sciences 111, no. 27 (2014).Abstract
China’s water resources are under increasing pressure from socioeconomic development, diet shifts, and climate change. Agriculture still concentrates most of the national water withdrawal. Moreover, a spatial mismatch in water and arable land availability—with abundant agricultural land and little water resources in the north—increases water scarcity and results in virtual water transfers from drier to wetter regions through agricultural trade. We use a general equilibrium welfare model and linear programming optimization to model interprovincial food trade in China. We combine these trade flows with province-level estimates of commodities’ virtual water content to build China’s domestic and foreign virtual water trade network. We observe large variations in agricultural water-use efficiency among provinces. In addition, some provinces particularly rely on irrigation vs. rainwater. We analyze the virtual water flow patterns and the corresponding water savings. We find that this interprovincial network is highly connected and the flow distribution is relatively homogeneous. A significant share of water flows is from international imports (20%), which are dominated by soy (93%). We find that China’s domestic food trade is efficient in terms of rainwater but inefficient regarding irrigation, meaning that dry, irrigation-intensive provinces tend to export to wetter, less irrigation-intensive ones. Importantly, when incorporating foreign imports, China’s soy trade switches from an inefficient system to a particularly efficient one for saving water resources (20 km3 /y irrigation water savings, 41 km3 /y total). Finally, we identify specific provinces (e.g., Inner Mongolia) and products (e.g., corn) that show high potential for irrigation productivity improvements.
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2013
Konar, M., Z. Hussein, N. Hanasak, D. L. Mauzerall, and I. Rodriguez-Iturbe. “Virtual water trade flows and savings under climate change.” Hydrol. Earth Syst. Sci. Discuss. 10 (2013): 67-101. Publisher's VersionAbstract
The international trade of food commodities links water and food systems, with important implications for both water and food security. The embodied water resources associated with food trade are referred to as “virtual water trade”. We present the first 5 study of the impact of climate change on global virtual water trade flows and associated savings for the year 2030. In order to project virtual water trade under climate change, it is essential to obtain projections of both bilateral crop trade and the wateruse efficiency of crops in each country of production. We use the Global Trade Analysis Project (GTAP) to estimate bilateral crop trade flows under changes in agricultural pro10 ductivity. We use the H08 global hydrologic model to estimate the water-use efficiency of each crop in each country of production and to transform crop flows into virtual water flows. We find that the total volume of virtual water trade is likely to go down under climate change. However, the staple food trade is projected to save more water across most climate impact scenarios, largely because the wheat trade re-organizes into a 15 more water-efficient structure. These findings indicate that trade may be an adaptation measure to climate change with ramifications for policy.
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2010
Zhang, J., DL Mauzerall, T Zhu, S Liang, M Ezzati, and J Remais. “Environmental health in China: challenges to achieving clean air and safe water.” The Lancet 375 (2010): 1110–19.Abstract
Environmental risk factors, especially air and water pollution, are a major source of morbidity and mortality in China. Biomass fuel and coal are burned for cooking and heating in almost all rural and many urban households, resulting in severe indoor air pollution that contributes greatly to the burden of disease. Many communities lack access to safe drinking water and sanitation, and thus the risk of waterborne disease in many regions is high. At the same time, China is rapidly industrialising with associated increases in energy use and industrial waste. Although economic growth from industrialisation has improved health and quality of life indicators, it has also increased the release of chemical toxins into the environment and the rate of environmental disasters, with severe eff ects on health. Air quality in China’s cities is among the worst in the world, and industrial water pollution has become a widespread health hazard. Moreover, emissions of climate-warming greenhouse gases from energy use are rapidly increasing. Global climate change will inevitably intensify China’s environmental health troubles, with potentially catastrophic outcomes from major shifts in temperature and precipitation. Facing the overlap of traditional, modern, and emerging environmental dilemmas, China has committed substantial resources to environmental improvement. The country has the opportunity to address its national environmental health challenges and to assume a central role in the international eff ort to improve the global environment.
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