基于河湖地质过程的武汉市湖泊的成因划分

Genetic Classification of Lakes in Wuhan Based on River and Lake Geological Process

武汉市位于长江中游,长江与汉江在此交汇,城区河网纵横,湖泊众多,素有"江城"和"百湖之市"之称.湖泊对于武汉城市的可持续发展及宜居城市建设有着特别重要的意义.关于武汉市的湖泊前人曾开展了大量的研究,但对于湖泊的成因则研究较少.湖泊的成因不仅对武汉市近代地质环境演化具有重要意义,同时也是湖泊保护的基础科学问题.在地质地貌调查上,通过江湖古地理演变分析,结合历史文献记录等综合研究,认为武汉湖泊的形成与河流地质作用过程密切相关,据此将武汉市湖泊的成因类型划分为:河道遗迹湖(又分河道废弃湖和河道洲滩夹湖)、河堤溃口湖、河间洼地湖和沟谷壅塞湖四种类型.分析了各类湖泊的特征、地貌分布及形成过程.其中沟谷壅塞湖是现存湖泊的主要类型,其形成演化与区域气候变化背景下的河海相互作用密切相关,分别经历了湖盆形成期(20~14 ka)、湖泊形成期(14~7 ka)和湖泊发展期(7 ka以来)3个阶段.此外,武汉的城市与湖泊经历了由"湖中城"到"城中湖"的发展历程,围湖造地是武汉市最重要人为改造自然工程,依湖泊类型的不同采取了不同的围湖发展方式,汉口地区以河间洼地湖为主,主要以"筑堤-排水-造地"填湖发展;武昌和汉阳地区以沟谷壅塞湖为主,采取的是"堵塞湖汊造地"的环湖发展方式.在未来的城市建设中,有计划地实施湖-湖连通和河-湖连通工程是十分必要的.

Wuhan is located on the confluence of the Yangtze and Han river in the middle reaches of the Yangtze River.Wuhan is known as"River City"and"City with hundreds of lakes"because of dense river network and numerous lakes in Wuhan.The lakes in Wuhan are of great significance to the sustainable development of Wuhan and the construction of livable city.Many studies have been carried out on the lakes in Wuhan,but few on factors controlling formation of the lakes.The study of genesis of lakes is not only great significance to the Wuhan’s modern geoenvironmental evolution but also is a basic scientific issue of lake protection.Based on geological and geomorphic survey,a comprehensive study was carried out on the evolution of river and lake palaeogeography and the historical literature records and so on.The results suggest that the formation of the lakes in Wuhan is closely related to river geological process.And the lakes in Wuhan can be divided into four types based on cause of lake formation:Oxbow lakes(also called abandoned channel lake and lake bounded by a channel and a shoal),bank burst lake,interfluvial depression lake and valley barrier lake.Based on the characteristics,geomorphic distribution and formation process of all types of lakes,we suggest that valley barrier lake is the main type of lakes inWuhan and that its formation and evolution are closely related to the interaction between river and sea controlled by climate change.The valley barrier lakes have experienced three stages:lake basin formation(20-14 ka),lake formation(14-7 ka)and lake development(since 7 ka).In addition,Wuhan has experienced the development process from"the lakes encircling a city"to"the city surrounding lakes".The reclamation of the lakes is the most important man-made natural reconstruction project in Wuhan,which is also the main cause of the tension between man and land at present.The major lakes in Hankou area are interfluvial depression lake.The mode of filling development of these lakes is"DikeDraining-Land".The lakes in Wuchang and Hanyang areas are dominated by valley barrier lakes.The mode of lake surrounding development of these lake is"Lake branches filling and Land forming".