Ecological Engineering of Drawdown Wetlands Based on Water-level Fluctuation-Baijia Stream in the Three Gorges Reservoir as a Case Study

TheThreeGorgesReservoir(TGR)providesthebenefitsoffloodcontrol,electricitygenerationandimprovedtransportationalongtherivercorridor.Forthepurposeoffloodcontrol,thereservoirheightvariesbetween145mand175mabovesealevel,creatingareservoirlittoralzoneofabout350km2intotalareadistributedalongmorethan1200kmofshoreline.MostofthelittoralzoneisfloodedduringOctobertoMayandrelativelydryduringtheremainderoftheyear.WaterlevelregulationhascausedmarkedecologicalchangesinthelittoralzoneofTGR.ThelittoralzoneformedafterimpoundedbyTGRnotonlyisthecrucibletous,butalsotheecologicalopportunity.Thevegetationoflarge-scalehydro-fluctuationbeltisaveryvaluableresource,ifproperlyused,canturnharmintoadvantage.InviewofthecurrentstatusandexistingproblemsofthelittoralwetlandinTGR,weshouldfocusonutilizingresourcesofthelittoralwetlandeco-friendly.Basedontheneedsforthelittoralwetlandtransformintothemultifunctionalecologicaleconomicbenefitsuchasincreasingcarbonsources,biologicalproduction,andenvironmentalpurification,wemustdeveloptheecologicalengineeringmodelofsustainableutilizingthewetlandresourcesofthelittoralzone.InviewoftheenvironmentproblemsofTGRanditscharacteristicsofwaterlevelfluctuation,theecologicalengineeringfocusingonrestorationoflittoralwetlandshavebeencarriedoutsince2008.Theeco-logicalengineeringwasmainlyconductedatlittoralwetlandsinBaijiastreamofPengxiRiverofTGR,includingdike-pondsystem,submergencetolerancewetland-woodsandwaterfowlhabitatsrecreateprojects.Thedesignprincipleandprocessfortheecologicalengineeringoflittoralwetlandsrestorationundertheconditionoftheperiodicwaterlevelchangewasdescribedindetailsinthispaper.Effectsoftheecologicalengineeringandthebenefitstotheenvironmentswereassessed.Intheendofthearticleweproposedthattheecologicalengineeringfocusontherestorationoflittoralwetlands,alsoshouldconsideruti.