Assessment of the interconnection demand of the river-lake system in the Lake Taihu basin

Abstract

水系连通需求分析是河湖水系连通战略研究的重要内容.水系连通需求指人类社会经济发展对水资源调配、防洪排涝、改善生态环境等方面的需求及对河湖水系健康的维护,它源于水系能够提供各种水生态系统服务功能的生态学特性.通过分析水系连通需求、水生态系统服务功能和水系连通工程之间的内在关系,认为水系连通需求评价可转化为对水生态系统服务功能的评价.运用水当量评价方法,建立了河湖水系连通需求评价的方法体系,并以河网地区的典型代表——太湖为例,定量评价了太湖在水资源调配、调蓄洪水、水环境净化和维持生境等方面的连通需求.结果表明,太湖水系年均连通需求最大的是净化入湖废污水需水量,其次为水资源调配需水量,而太湖调蓄洪水的需求减少;湖水自身净化需水量较大,且为一次性需水.水环境净化的需求需要通过降低污染物入湖量,进行湖泊生态修复等主要措施以及引清水增加环境容量这一辅助连通措施共同完成.水系连通需求的定量评价可为水系连通战略及工程的规划设计提供理论基础.;River-lake system interconnection demand is one of the key elements among the research of river-lake system interconnection strategy.It reflects the demand of the social-economic development on water diversion,flood regulation,eco-environment improvement and the maintenance of the health of river-lake system.It is based on the inherent ecological properties that a drainage system can provide various water ecosystem services to a river-lake system.Since the river system,river system interconnection demand, the water ecosystem services,and river system interconnection engineering are closely interconnected,the methods which have been adequately studied for assessing the water ecosystem services can be applied to the assessment of river system interconnection demand.So methodologies for evaluation of river system interconnection demand are established by applying the water equivalent method.With a long historical practices of river system interconnection in Lake Taihu watershed,which is a typical and emergent floodplain river network area in eastern China,demanding on Lake Taihu river system interconnection is assessed in this study.The main demand includes water resource diversion,flood regulation,water purification,and habitat sustainment.Purification water demand per year of retained pollutants in the lake is 2.85×10¹⁰ m³/a,ranked the first place.Water resource diversion demand is 3.0×10⁹-4.2×10⁹ m³/a,ranked the second place,while the demand of flood regulation of the lake is decreased by 7.2×10⁸-10.7×10⁸ m³/a.Purification demand of the water from the lake is 8.14×10⁹ m³,and is consumed once only;the habitat maintenance water demand is 3.58×10⁹ m³.The results show that water environment improvement demand is tremendous.To ease the stress,countermeasures such as control of the pollutant entering into the lake,desilting and dredging the lake,and ecological restoration of the lake water need to be applied firstly,then the diversion of clean water as an assisting way.There are different corresponding interconnection ways for each demand,and it is necessary to confirm the ratio of each interconnection project.