A Study on Spatial Variation of Water Security Risks for the Zhangjiakou Region

张家口市水资源安全风险空间分异研究

Zhangjiakou region is situated in an agro-pastoral ecotone with a fragile ecosystem. While it has limited surface water resources available and serious groundwater over-exploitation, the city is located in the water conservation zone for the Beijing-Tianjin-Hebei coordinated development area, so its water security is crucial for the entire Beijing-Tianjin-Hebei region. Therefore, it is of vital significance to determine the zoning management of water resources and decision-making according to the magnitude of water resource security risks. This study built an indicator system for water security risk assessment in line with the principles of scientific validity, comparability, operability, and data availability, and this system gives weights to these indicators using the AHP approach. County-level multi-source data for the study area, based on water resource zones, were collected by using mathematical statistics and 3 S technology. With normalized data and a weighting method the water security risks were calculated. The results showed large spatial variations of water security risks in Zhangjiakou on the scales of geomorphic and administrative units as well as river basins. High-risk areas are extensive in the Bashang Plateau, and extremely high risk values are found in the Baxia areas. On the watershed scale, high-risk areas are mainly distributed in the inland river basins and the Yongding River basin. The risk values of the Luanhe River, Chaobai River and Daqing River basins in the Zhangjiakou region tend to decrease from north to south. For the northern and western areas of the Bashang Plateau, the factor of "vulnerability of the disaster-prone environment" contributes the most to the water security risk level. Agricultural water use constrains industrial and ecological water use, but in the context of inadequate water resource endowments, the urban population concentration and industrial development are the main causes of water shortages and water pollution so they contribute more to water security risks. This study of the spatial variation of water security risks in Zhangjiakou can provide an important scientific reference for zone-based management and decision-making for reducing the water security risks in the farming-pastoral ecotone.

张家口市地处生态脆弱的农牧交错地带,地表水资源匮乏,地下水超采严重,可利用的地表水资源有限。同时,张家口市又处于京津冀协同发展中的水源涵养区,其水资源安全对于整个京津冀至关重要。根据水资源安全风险大小进行水资源分区管理和决策工作意义重大。本文在遵循科学性、可比性、可操作性和数据可获取性原则指导下,构建水资源安全风险评价指标体系,利用层次分析法求取指标权重,采用数理统计和3S技术空间分析获取张家口市基于水资源分区的以县域为单位的多源数据,进行数据归一化处理和加权水资源安全风险评价,结果表明:张家口市水资源安全风险在地貌单元与县域行政尺度上和在流域尺度上分异明显。坝上高风险区面积较大,但高风险极端值在坝下市辖区;流域尺度上水资源安全高风险区分布在内陆河流域和永定河流域,所辖的滦河流域、潮白河流域、大青河流域水资源安全风险值呈现由北向南降低的趋势。坝上偏西偏北区域,"孕灾环境脆弱性"对水资源安全风险的贡献率最大,坝下农区农业用水虽然会挤占其它产业发展和生态用水空间,在水资源禀赋不足的条件下,市辖区城市人口的集聚和工业经济的发展造成的水资源数量短缺和水环境污染所引发的水资源安全风险更大。张家口市水资源安全风险的空间分异研究,可为农牧交错带水资源安全风险分区管理和决策工作提供重要科学参考。