水是基础性自然资源和战略性经济资源，水资源短缺是中国基本国情，制约经济社会发展。污染排放导致的水质恶化进一步加剧区域的水资源短缺。水资源短缺影响本地经济生产活动，造成当地潜在直接经济损失风险，并通过供应链影响下游地区的经济活动，导致潜在间接经济损失风险。缓解水资源短缺、降低水资源短缺风险，是我国保障水安全的必然选择，对实现高质量和可持续发展具有重要意义。如何综合考虑污染排放、部门用水、水资源可用性和水生态健康等多要素，从更加精细化尺度剖析中国水资源短缺现状及城市间的水资源短缺风险转移情况，仍是当前研究的重点。本研究以中国为研究对象，耦合自然系统和社会经济系统展开水资源短缺风险评估研究。基于“水资源-水环境-水生态”，考虑部门用水、污染排放、可用水资源量和环境流量要求的时空异质性，在网格尺度上，分析2015年中国水资源短缺压力的空间分布及季节性特征。在此基础上，从经济损失视角出发，结合多区域投入产出表，在城市尺度上分析中国313个地区由于水资源短缺造成的本地直接潜在经济损失，以及受供应链影响引起其他地区的间接潜在经济损失。进而探讨在施加不同措施的情景下，各城市水资源短缺及其风险的变化情况，甄别有效的水资源管理政策。主要研究结果如下：

（1）中国直接蓝水足迹总量较大的地区主要位于经济发达和人口密集地区。从用水部门分析，农业直接蓝水足迹占比最高，位于新疆的喀什、阿克苏、塔城、昌吉、伊犁的农业直接蓝水足迹占比超过90%。此外，直接蓝水足迹总量较大的城市中，苏州、武汉、长沙和上海的工业直接蓝水足迹占比超过60%。8月中国直接蓝水足迹总量最高，达1073.85亿m³，主要集中在新疆西部、长三角和东南地区。中国直接灰水足迹整体呈现东南部高、西北低的空间分布趋势，主要集中分布在人口密集、经济发达、污染物流失系数较高的污染排放高值地区。直接灰水足迹的最大污染物是TN，主要来源是农业化肥（占42%）。因此，从防治角度应该关注农业和农村居民生活引起的面源污染问题，要特别重视TN带来的污染影响。水污染程度较高的城市，主要集中在水资源禀赋差，但人口较多或农业较为发达的华北地区和东北地区。基于城镇居民消费的蓝水和灰水足迹占比最大，蓝水和灰水足迹净流入地主要位于中部和东南沿海等较发达城市，净流出地主要分布在新疆和东北地区。

（2）仅考虑水量，中国面临水资源短缺压力的面积占11.80%，考虑水量水质，面临综合水资源短缺的面积扩大（15.12%），81%的城市面临缺水压力，主要位于东北、华北、长三角、新疆和东南沿海地区。仅考虑水量，地区面临基于水量的水资源短缺影响主要出现在春夏两季。其中，4月份遭受基于水量的水资源短缺影响的面积占比为14.30%。考虑水量水质，各月份面临基于水量-水质的水资源短缺压力的面积占比均上升，地区受基于水量-水质的水资源短缺影响主要出现在春夏两季，其中，4月份遭受水资源短缺影响的面积占比为16.74%。此外，中国超过一半人口（51.19%）处在基于水量-水质的水资源短缺地区。从消费角度看，基于水量的虚拟稀缺水使用量为5.7万亿m³，考虑水质后，基于水量-水质的虚拟稀缺水的使用被水污染放大了约2.6倍。313个地区基于水量-水质的虚拟稀缺水大于基于水量的虚拟稀缺水。其中，69%的城市基于水量-水质的虚拟稀缺水是其由基于水量的虚拟稀缺水的10倍及以上。这主要是因为各城市污染排放造成大量的灰水使用，具有较高的基于水量-水质的水压力指数。

（3）仅考虑水量，中国直接水资源短缺风险为2050亿元，考虑水量水质，中国直接综合水资源短缺风险扩大了16倍。可见，忽视社会经济活动污染排放导致的水质问题，会低估因当地水量短缺而造成的直接经济损失风险。农业、建筑业、化学产品制造业是缓解水量和水质型缺水工作的重点，应重视这些行业的用水强度提升及污染排放控制。中国跨区域贸易的基于水量-水质的虚拟水资源短缺风险为99513亿元，是基于水量的虚拟水资源短缺风险的17倍，污染排放导致的水体污染加剧了当地的直接水资源短缺风险对中国贸易体系的影响。其中，对下游地区部门风险传输最大的部门是农业、食品和烟草制造业、化学产品制造业、建筑业和纺织品制造业。受上游地区部门风险输入最大的部门是农业、化学产品制造业、食品和烟草业、金属冶炼和压延加工业、金融业。

（4）提高农业灌溉水有效利用率和降低工业用水强度的节水效果显著，是节水改进的首要目标。施加节水措施，水资源短缺缓解程度最大的是农业和工业较为发达且人口密集的城市。大量节水带来的经济效益很高，基于水量的直接水资源短缺风险较现状情景下降了21%，而基于水量-水质的虚拟水资源短缺风险较现状情景下降了3.22%，其中，48%发生在城市内部。施加污染治理措施带来更高的经济效益，基于水量-水质的直接水资源短缺风险及虚拟水资源短缺风险较现状情景均下降了22%。采取提升生态系统健康水平的措施，加剧了水资源短缺压力及伴随的经济损失风险。整体上，中国基于水量-水质的水压力指数上升0.27，缺水压力加剧最明显的地区分布在东北、长三角、云贵和东南沿海等部分地区。基于水量-水质的直接水资源短缺风险较现状情景提升了11.62%，虚拟水资源短缺风险提升了5.5%。为实现在保障水资源、保护水环境、维持水生态时，缓解水资源短缺及降低伴随风险的目标，因此，在提升生态健康的同时，施加节水和污染治理措施。研究发现，叠加污染治理措施的缓解效果更显著，中国基于水量-水质的直接水资源短缺风险较现状情景下降12.3%，但东北和南方地区仍面临缺水压力加剧的情况。同时叠加节水和污染治理措施，中国基于水量-水质的水压力指数下降0.07，基于水量-水质的直接水资源短缺风险较现状情景下降16%，但仍有部分城市面临缺水压力加剧的情况。因此，按照目前的规划目标施加措施，仍无法使得所有城市实现综合效益的提升。

研究发现，忽略水质会低估地区的水资源短缺程度及伴随的经济损失风险，提高水生态健康水平加剧了水资源短缺风险。因此，在维护水生态健康的同时，需要综合施加节水和污染治理措施，以缓解水资源短缺压力及风险。但是，按照十四五规划目标，全国所有城市仍难以在保障水资源、保护水环境、维持水生态的同时，缓解水资源短缺及降低伴随的经济损失风险。针对用水过多或污染排放过多的城市，应该制定更加严苛的水资源管理措施。

Water is a fundamental natural and strategic economic resource. China is facing a basic situation of water scarcity, which is an important bottleneck constraint on socioeconomic development. Water scarcity is further exacerbated by the problem of deteriorating water quality due to sectoral pollution discharges. Water scarcity affects local economic and production activities, resulting in a risk of potential direct local economic losses, and can affect economic activities in downstream areas through the supply chain, resulting in a risk of potential indirect economic losses. Mitigating water scarcity and reducing the risk of water scarcity is an inevitable choice to ensure water security in China, which is of great significance in realizing high-quality and sustainable development. How to analyze the water scarcity status and water scarcity risk transfer among cities at a more refined scale in China, taking into account pollution emission, sectoral water use, water resource availability, and water ecological health, is still the focus of current research. In this study, we conducted the water scarcity risk assessment and scenario simulation by coupling natural and socioeconomic systems. Based on water resource, water environment, and water ecology, we analyzed the spatial distribution and seasonal characteristics of water scarcity in China in 2015 considering the spatial and seasonal heterogeneity of water use, pollution emission, available water resources and environmental flow requirements. Then, we analyzed the direct and indirect water scarcity risk in 313 regions based on the multi-region input-output method from the perspective of economic loss. Finally, we explored the changes in water scarcity and related risk under scenarios of imposing different measures, and identifies specific effective water resources management policies. The main findings of this study are summarized below:

(1) Regions in China with a large total direct blue water footprint are mainly located in economically developed and densely populated areas. In terms of water use sectors, agriculture has the highest direct blue water footprint, with Kashgar, Aksu, Tacheng, Changji and Yili in Xinjiang accounting for more than 90% of the direct blue water footprint. In addition, among the cities with larger total direct blue water footprints, Suzhou, Wuhan, Changsha and Shanghai have an industrial direct blue water footprint of more than 60%. China's total direct blue water footprint was the highest in August at 107.385 billion m³, mainly concentrated in western Xinjiang, the Yangtze River Delta and southeastern China. The direct gray water footprint in China shows a spatial distribution trend of high in the southeast and low in the northwest, and is mainly concentrated in areas with high values of pollution discharge that are densely populated, economically developed, and have high pollutant loss coefficients. The largest pollutant in the direct gray water footprint is TN, and the main source is agricultural fertilizer (42%). Therefore, governments should pay attention to the problem of surface source pollution caused by agriculture and rural residents' life, as well as the pollution impact caused by TN from the perspectives of pollution prevention and control. In addition, cities with higher levels of water pollution are mainly concentrated in North China and Northeast China, which are poorly endowed with water resources but have larger populations or more developed agriculture. The blue and gray water footprints based on urban residents' consumption account for the largest share, and the net inflows of blue and gray water footprints are mainly located in the more developed cities in the central and southeastern coastal areas, while the net outflows are mainly distributed in Xinjiang and the northeastern region.

(2) Just considering water quantity, the area facing water stress in China accounts for 11.80%. Considering both water quantity and water quality, the area facing water stress accounts for 15.12%, and 81% of cities facing water stress are mainly located in Northeast China, North China, the Yangtze River Delta, Xinjiang, and Southeast China's coastal region, and the number of cities facing extreme water stress increases by 99. Just considering water quantity, regions facing water stress mainly appear in spring and summer. In April, 14.30% of the area was affected by water stress based on water quantity. Considering both water quantity and quality, the percentage of area faced water stress rises in all months. The area faced water stress based on water quantity and quality mainly occurs in spring and summer, of which, the percentage of area in April is 16.74%. In addition, more than half of China's population (51.19%) located in areas facing water stress based on water quantity and quality. From the perspective of consumption, the virtual scarcity water based on water quantity is 5.7 trillion m³, and the virtual scarcity water based on water quantity and quality is amplified by water pollution by about 2.6 times. 313 regions have more virtual scarcity water based on water quantity and quality than that based on water quantity. Among them, 69% of the cities have a virtual scarcity of water based on water quantity and quality, which is 10 times more than that just based on water quantity. This is mainly due to the large graywater use in the cities due to sectoral polluting discharges and higher water stress index based on water quantity and quality.

(3) Just considering water quantity, the direct water scarcity risk in China is 205 billion CNY, while the direct water scarcity risk considering both water quantity and quality expands by 16 times. Results show that ignoring water quality problems caused by pollution discharges from socio-economic activities will underestimate the direct economic losses due to local water quantity shortages. Agriculture, construction, and chemical product manufacturing are the focus of efforts to mitigate water stress based on water quantity and quality, so that attention should be paid to water intensity improvement and pollution discharge control in these sectors. The virtual water scarcity risk based on water quantity and quality in China is 9,951.3 billion CNY, which is 17 times higher than that just based on water quantity. Water pollution caused by polluting discharges exacerbates the impact of local direct water scarcity risk on China's trading system. Among the sectors with the largest transmission of risk to downstream regional sectors are agriculture, food and tobacco manufacturing, chemical product manufacturing, construction, and textile manufacturing. The sectors most exposed to sectoral risk inputs from upstream regions are agriculture, chemical product manufacturing, food and tobacco, metal smelting and rolling, and finance.

(4) Increasing the effective utilization of irrigation water in agriculture and reducing the intensity of water use in industry are the primary targets for water saving improvements, which have significant water saving effects. Water scarcity is mitigated to the greatest extent by the application of water conservation measures in cities with more developed and densely populated agriculture and industry. The economic benefits of substantial water savings are high, with the direct water scarcity risk based on water quantity decreasing by 21% from quo scenario and the virtual water scarcity risk based on water quantity and quality decreasing by 3.22% from quo scenario, with 48% of this occurring in the inner cities. The economic benefits of implementing pollution control measures are higher, with the direct water scarcity risk and the virtual water scarcity risk based on both water quantity and quality decreasing by 22% from quo scenario. However, improving ecosystem health measures exacerbate water stress and the associated economic loss risk. Overall, China's water stress index based on water quantity and quality rises by 0.27, with the most pronounced intensification of water stress distributed in Northeast, Yangtze River Delta, Yunnan-Guizhou, and Southeast coastal regions. The direct water scarcity risk based on both water quantity and quality has increased by 11.62% from quo scenario, and the virtual water scarcity risk has increased by 5.5%. In order to achieve the goal of mitigating water scarcity and reducing the accompanying economic risks when safeguarding water resources, protecting water environment and maintaining water ecology, water conservation and pollution control measures are therefore imposed while enhancing ecological health. This study found that the mitigation effect of overlapping pollution control measures is more significant, with China's direct water scarcity risk based on water quantity and quality decreasing by 12.3% compared to quo scenario, but the northeastern and southern regions are still facing increased water stress. By combining water conservation and pollution control measures, considering both water quantity and quality, the water stress index in China decreases by 0.07, and the direct water scarcity risk decreases by 16% compared to quo scenario, but some cities still face increased water stress. Therefore, the imposition of measures in accordance with the current planning targets will still not allow all cities to realize the comprehensive benefits.

This study found that neglecting water quality underestimates the extent of water scarcity and associated economic loss risk. Improving the water ecosystem health will exacerbate the water scarcity risk, so that governments need to impose the water conservation and pollution control measures in parallel to alleviate the water stress and water scarcity risk. However, according to the targets of 14th Five-Year Plan, it’s still difficult for all cities to safeguard water resources, protect the water environment, and maintain water ecology while mitigating water scarcity and minimizing related economic losses risk. More stringent water management measures should be implemented in cities that with much water utilization and pollution discharge.