I.　Basic　water　and　rainfall　information　in　the　Taihu　Basin

　　The　Taihu　Basin　belongs　to　a　subtropical　monsoon　climate　zone.　There　are　four　distinctive　seasons,　abundant　rainfall　and　adequate　heat　here.　In　winter,　the　invasion　of　continental　cold　air　mass　brings　about　prevailing　north　wind　prevails,　and　the　climate　is　cold　and　dry.　In　summer,　controlled　by　marine　air　mass,　southeast　wind　prevails　and　the　climate　is　hot　and　wet.

　　The　average　temperature　over　years　in　the　Taihu　Basin　is　15-17℃,　featuring　higher　temperature　in　the　south　and　lower　in　the　north.　The　average　rainfall　whose　spatial　distribution　gradually　decreases　from　southwest　to　northeast　is　1177㎜　over　years.　Inter-annual　variability　of　precipitation　changes　significantly　and　the　distribution　of　yearly　rainfall　is　uneven,　influenced　by　the　changes　in　monsoon　strength.

　　There　are　three　distinct　rainy　seasons　annually　in　the　Taihu　Basin.　Spring　rain,　from　March　to　May,　features　many　rainy　days　that　account　for　about　30%　of　the　annual　rainy　days.　The　Meiyu　period,　from　June　to　July,　features　abundant　rainfall,　accounting　for　about　20%-30%　of　the　annual　precipitation.　The　Meiyu　period　usually　lasts　23　days,　there　are　greater　changes　in　number　of　days　and　precipitation.　For　example,　the　Meiyu　period　lasted　only　3　days　and　the　precipitation　was　48㎜　in　1958,　whereas　in　1954,　the　Meiyu　period　lasted　59　days　and　the　precipitation　was　400㎜,　which　was　9.6　times　that　of　1958.　During　the　Meiyu　period　which　ranges　long　spell　land　large　area,　the　total　amount　of　precipitation　is　large,　thus　it　may　result　in　increased　likelihood　of　basin-wide　floods.　Typhoon,　with　a　comparatively　shorter　period　from　August　to　October,　has　greater　precipitation　intensity　and　often　leads　to　serious　regional　floods,　such　as　the　Typhoon　No.　6214　on　the　5^thof　September　in　1962,　during　which　the　precipitation　of　Suzhou　2　days　reached　439㎜.

　　The　Meiyu　period　and　typhoon　rain　are　the　main　causes　for　the　floods　in　the　Taihu　Basin.

II.　Governance　of　the　Taihu　Basin　Project

　　The　Taihu　Basin　witnessed　big　basin-wide　floods　in　1931,　1954,　1991　and　1999.　With　the　rapid　development　and　high　centralization　of　the　economy　and　society,　the　consequence　financial　loss　continued　to　increase.

　　In　accordance　with　the　planning　of　water　conservancy　in　the　basin,　the　first　round　of　comprehensive　regulation　began　in　1991.　Altogether　11　key　projects　have　been　built　in　the　basin,　i.e.,　Wangyu　River,　Taipu　River,　Hang-Jia-Hu　South　Discharge,　Hang-Jia-Hu　North　Exhaust　Passage,　Lake　Levee,　West　Cited　Discharge,　Red　Flag　Pond,　Tiaoxi　Flood　Protection　in　East　and　West,　Expanding　the　Highway　of　River　Port　and　Xietang,　Wuchengxi　Cited　Discharge,　Huangpu　River　Upstream　Flood　Control.　Combined　with　the　existing　water　projects　in　the　basin,　the　Taihu　Basin　has　initially　formed　a　project　system　through　which　the　flood　flows　northwards　into　the　Yangtze　River,　eastwards　into　the　Huangpu　River　and　southwards　into　the　Hangzhou　Bay.　The　system　makes　full　use　of　the　regulation　and　storage　in　Taihu　---　storage　and　discharge　coordinated,　but　the　main　purpose　is　to　discharge.　In　addition,　the　whole　system　has　initially　had　some　basic　conditions,　such　as　flood　control,　optimal　allocation　of　water　resources,　and　reasonable　dispatch.

　　On　the　basis　of　Comprehensive　Planning　for　Flood　Control　in　the　the　Taihu　Basin　and　the　integrated　regulation　of　water　environment　program,　such　subsequent　projects　are　to　be　implemented　in　the　Taihu　Basin　as　subsequent　Project　Around　the　Lake　Levee,　subsequent　Project　in　Wangyu　River,　subsequent　Project　in　Taipu　River,　Extension　Project　in　Xinmeng　River,　Dredging　Project　in　the　East　of　Taihu　and　Flood　Discharge　Project　in　Wusong　River,　Expanding　Project　of　South　Discharge　in　Hang-Jia-Hu　District,　Extension　Project　in　Xingou　River,　subsequent　Project　of　Flood　Control　in　the　East　and　West　of　Tiaoxi,　Sluice　Project　in　the　Estuary　of　Huangpu　River　etc..　On　completion,　all　the　projects　are　to　be　combined　with　regional　key　projects　and　urban　flood　control　projects　to　further　enhance　flood　control　capacity　in　the　Taihu　Basin.

III.　The　main　problems　of　flood　control　in　the　basin

　　At　present,　the　problems　of　flood　control　work　in　the　Taihu　Basin　mainly　lie　in　four　aspects.　First,　the　overall　flood　control　standard　in　the　basin　is　low,　which　is　incompatible　with　regional　economic　and　social　development.　Second,　the　capacity　of　flood　discharge　in　the　basin　is　insufficient　and　the　conflict　between　flood　control　and　flood　discharge　is　serious,　which　lead　to　increased　difficulty　of　coordination　between　basin　and　region,　and　between　flood　control　and　water　supply.　Third,　there　exist　vulnerable　spots　in　the　key　flood　control　projects,　which　affect　their　overall　functioning.　Fourth,　underlying　surface　in　the　basin　has　undergone　great　change,　which　makes　the　flood　control　and　disaster　reduction　more　difficult.