三峡工程蓄水对洞庭湖水情的影响格局及其作用机制

J．LakeSci．(湖泊科学)，2012，24(2):178-184http://www．jlakes．org．E-mail:jlakes@niglas．ac．cn2012byJournalofLakeSciences三峡工程蓄水对洞庭湖水情的影响格局及其作用机制*赖锡军，姜加虎，黄群(中国科学院南京地理与湖泊研究所湖泊与环境国家重点实验室，南京210008)摘要:三峡工程建成投入运行后，汛末蓄水将使坝下河湖水情发生变化，长江中下游秋季来水减少成为常态．为客观分析三峡蓄水对洞庭湖水情的影响分量、空间格局及其作用机制，选取三峡工程典型的蓄水过程，运用长江中游江湖耦合水动力学模型计算了因上游来水变化引起的洞庭湖水情时空变化．结果表明:1)三峡汛末蓄水对洞庭湖水位影响具有明显的“北高南低，东强西弱”的格局，即东洞庭湖最为显著、南洞庭湖东部和西洞庭湖北部次之，南洞庭湖西部和西洞庭湖南部最小．2)洲滩湿地受蓄水影响最明显的主要为东洞庭湖、南洞庭湖和湖泊洪道两侧的条带状洲滩．3)三峡蓄水对洞庭湖水位的影响机制有二:长江干流水位快速消落加速湖泊水体下泄以及削减长江三口分流补给湖泊的水量．关键词:三峡工程;蓄水;水情;淹水历时;水动力学模型;洞庭湖PatternofimpoundmenteffectsandinfluencingmechanismofThreeGorgesProjectonwaterregimeofLakeDongtingLAIXijun，JIANGJiahu＆HUANGQun(StateKeyLaboratoryofLakeScienceandEnvironment，NanjingInstituteofGeographyandLimnology，ChineseAcademyofSciences，Nanjing210008，P．R．China)Abstract:WiththeoperationofThreeGorgesProject(TGP)，waterregimeofriversandlakesdownstreamofthedamchangedwiththereservoirregulation．TheloweringofwaterlevelbecomesnormalafterfloodseasoncomparedwiththeyearsbeforeTGP．Here，thewaterstorageofTGPin2006wasselectedasacasetoquantitativelyinvestigatetheeffectsofTGPonwaterregimeofLakeDongting．WeappliedthecoupledhydrodynamicanalysismodelforthemiddleYangtzeRivertocomputethevariationofwaterregimeinducedbythewaterstorage．Duringimpoundment，thereductionofthewaterlevelanddischargeare1．32mand466m3/s，re-spectively，atChenglingji，theoutletofLakeDongting．ThebottomlandsinsidetheLakeDongtingareexposedaheadoftimeandthelakeareawithover5inundationdaysreachto287km2．Resultsalsoindicatethat:1)theimpactofTGPonwaterregimevar-iedwithlocations:eastLakeDongtingtakesthefirstplace，theeastofSouthLakeDongtingandthenorthofWestLakeDongtingsecond，andthewestofSouthLakeDongtingandthesouthofWestLakeDongtingthird．2)Thebottomlandswhichstronglyaffect-edbytheimpoundmentaremainlylocatedatEastLakeDongting，SouthLakeDongtingandthebothsidesoffloodways．3)Twoinfluencingmechanismsonwaterregimeareidentified:oneistheincreaseofthelakedischargeinducedbytherapiddrawdownofthemainstreamoftheYangtzeRiver;theothe