太湖流域水文连通性: 现状、研究进展与未来挑战

Hydrological connectivity research in Lake Taihu Basin:Status,progress and future challenges

水文连通性作为连接河湖水体间物质、能量及信息传递与交换的关键纽带,对水环境、水生态和生境状况具有联动与触发反馈作用,已成为水文学、水利学和生态学等诸多领域的研究热点.太湖流域作为全国典型的流域性密集平原河网区,在快速城镇化背景下,河湖水文连通关系变化剧烈并引起了一系列生态环境效应.本文以水文连通性概念与内涵为背景,对太湖流域水文连通性研究进行了综述.太湖流域水文连通性评价方法以图论法、景观格局指数及水文连通性函数等方法联合使用为主,且聚焦于区域尺度研究;演变过程按人类活动影响强度大致划分为自然水系形成阶段、古代人类活动影响阶段和现代人类活动影响阶段;气候变化和人类活动共同影响着太湖流域水文连通性变化,近百年来水利工程建设和城市化进程等人类活动的影响尤为剧烈;良好的水文连通性有利于汛期减轻流域洪涝灾害及非汛期保障水资源供给,但水文连通性的提高对水环境和水生态的效应由于涉及因素众多尚存在争议.针对当前研究现状和存在问题,提出(1)平原河网区水文连通性的定量表征与评估是水文连通性研究的前提;(2)定量解析流域水文连通性的驱动机制是水文连通性研究的重点;(3)深入跟踪大型引水调水工程对流域水文连通影响及其效应是一项长期任务;(4)兼顾环境生态效应的水利工程生态化改造研究,开展工程控制背景下的流域水文连通多目标优化调控,是实现太湖流域洪水调蓄、水资源供给、水环境净化、生物多样性维持等生态系统服务协同提升的重要途径.

Hydrological connectivity,the key bond in the transfer and exchange of material,energy and biological information between rivers and lakes,exerts coupling and feedback effects on the water quality,aquatic ecology and habitat conditions.Thus,it has become a hot spot in the fields of hydrology,hydraulics and ecology.The Lake Taihu Basin is a typical basin with a densely distributed river network in China.Due to rapid urbanisation and the construction of numerous hydraulic facilities in the area,the hydrological connections and interactions between rivers and lakes have been altered at an unprecedented rate,resulting in a series of ecological and environmental problems.In this study,the concept and connotation of hydrological connectivity were introduced based on a literature review,and the research progress of hydrological connectivity in the Lake Taihu Basin was systematically examined.The methods of evaluating hydrological connectivity in the Lake Taihu Basin are mainly based on graph theory,landscape pattern index and hydrological connectivity function,and focus on regional-scale research.According to the intensity of human activities,the evolution process of the river-lake network in the Lake Taihu Basin can be roughly divided into the naturally-formed stage,the ancient human-influenced stage and the modern human-influenced stage.Results showed that,in the past century,changes in the hydrological connectivity of the Lake Taihu Basin were influenced by climate change and human activities,especially human activities caused by water hydraulic facilities and urbanisation.Moreover,desirable hydrological connectivity is beneficial to flood mitigation in flood season and to water resources supply in the non-flood season,whereas the effects of improved hydrological connectivity on water quality and aquatic ecology remain controversial due to the involvement of various factors.Given the current research and existing problems observed in studies devoted to the hydrological connectivity of the Lake Taihu Basin,the prospects for future research are proposed as follows.First,the quantitative characterisation and assessment of hydrological connectivity is a premise for hydrological connectivity research.Second,the quantitative analysis of the driving mechanisms of the hydrological connectivity variations is a challenging topic in the research of hydrological connectivity.Third,tracking the impacts of the large-scale water diversion projects on the hydrological connectivity changes is a long-term task.Moreover,studies on the associated environmental and ecological effects of eco-hydraulic engineering transformation and the multi-objective optimisation of hydrological connectivity regulation in the context of engineering control are the ultimate approaches to achieve the synergetic optimisation of various ecosystem services,such as flood regulation,water supply,water purification,and biodiversity conservation in the Lake Taihu Basin.