水资源管理“三条红线”约束下的城镇化水平阈值分析——以张掖市为例

水资源与城镇化的关系问题是水科学研究的热点,二者之间存在着复杂的交织关系。论文选取典型干旱区城市张掖市为研究对象,以最严格水资源管理制度为约束条件,基于水资源约束下的城镇化水平阈值计算思路,引入节水量和灰水足迹测算方法改进了传统水量水质双要素水资源承载力计算模型,并在此基础上统筹可供水量、可节水量及水功能区纳污能力构建了水资源管理“三条红线”约束下的城镇化水平阈值计算模型;通过分析张掖市城镇化水平与水资源开发利用的历史数据并进行情景模拟,对2020年和2030年张掖市城镇化水平阈值做出了预测。结果表明：1）在水资源开发利用红线约束下,到2030年张掖市可利用水资源量为23.02×10⁸ m³,与现状基本一致,且以当前的水资源开发利用水平,水量承载能力难以支撑政府未来规划中的城镇化进程与经济增长的用水需求;2）严格遵照用水效率控制红线中所规定的用水定额标准时,张掖市将有望改善水量承载能力不足问题,且到2030年时,水量承载城镇人口能力可达331.91×10⁴人,其中水量承载能力提升主要得益于农业部门节水;3）在水功能区限制纳污红线的约束下,2030年张掖市水质可承载能力上限为62.47×10⁴人,仅为规划城镇人口数量的78%,水质可承载能力对城镇化进程形成了强烈的约束作用,约束力主要来自于城镇区域氨氮排放;4）在水资源管理“三条红线”约束下,到2030年时张掖市城镇化水平阈值上限为48.05%。

Threshold Analysis of Urbanization with the Constraint of “Three Red Lines” on Water Resources Management: A Case Study of Zhangye City

The relationship between the water resources and urbanization is a hot spot in water science research. There is a complex intertwined relationship between water resources and urbanization. This paper selects a typical city in arid region, Zhangye City, as the research subject and takes the strictest water resources management system as constraint condition to analyze the influence of the most significant management system of the water resources on the process of urbanization. Based on the constraint on water resources, it brings in water-saving quantity and grey water footprint to improve the double-factor method for calculating water resources carrying capacity based on water quantity and water quality. A model for calculating the threshold of the urbanization level with the constraint of “Three Red Lines” on water resources management is established. Meanwhile, the paper predicates the urbanization level thresholds of Zhangye City in 2020 and 2030 via scenario simulation and analyzes the historical data of urban development, water resources and water utilization in Zhangye City. The results show as follows. Firstly, the available water resources in Zhangye City is 23.02×10⁸ m³ by 2030 in total under the red lines of water resources development and utilization, which is basically the same as the current situation. In current situation of water resources utilization, the water carrying capacity is difficult to support the water demand in the process of urbanization and economic growth. Secondly, when strictly following the red line control of the water quota standard, the shortage of water carrying capacity in Zhangye City is expected to be alleviated, and the water quantity carrying capacity can provide 331.91×10⁴ urban residents with living water by 2030. The increase in water carrying capacity is mainly due to the water saving in the agricultural sector. Thirdly, with the red line on water resources pollution, the upper limit of the water quality carrying capacity in Zhangye City is 62.47×10⁴ people by 2030, which is only 78% of the planned urban population. The carrying capacity of water quality becomes a strong constraint during the process of urbanization and the ammonia emissions in urban areas are the main factors. Lastly, with the constraint of “Three Red Lines” on water resources management, the upper limit of urbanization level in Zhangye City is 48.05% by 2030. In the future development, Zhangye City should put emphasis on strengthening the agricultural saving and sewage treatment to improve the carrying capacity of the water quantity and water quality.