黃河源區(qū)典型草地水文循環(huán)研究.pdf

1、蘭州大學(xué)碩士學(xué)位論文黃河源區(qū)典型草地水文循環(huán)研究姓名：王軍德申請學(xué)位級別：碩士專業(yè)：水利工程、水文學(xué)及水資源指導(dǎo)教師：王根緒20060501蘭卅I大學(xué)砸：卜研究生學(xué)位論文AbstractHydrologicprocessincoldregionisalinkingmediumbetweenecologicalsystemandclimaticsystemHydrothermalconditiondirectlydeterminesthe

2、statusoftheecologicalenvironmentincoldregionThisstudyaimstoexplorewatercycleoftypicalgrasslandinsourceregionofYellowRiverFirstlyobtainedchangeofclimaticperiodsbyanalyzingairtemperatureandprecipitationofweatherstationloca

3、tedinthetownofDarifrom1956to2001Secondly，theinfiltrationandsoilmoistureinthetwotypicalwatershedswerestudiedbynumericalsimulationAlsotherelationshipbetweenenvironmentfactorsandsoilmoisturewerestudiedThemainconclusionsarea

4、sfollow：1Duringthepastnearly50years，theincreaserateofprecipitationandeVapotranspirationis0557mm／aand0132mm／asotheclimateofDarichangedfromdroughttomoistTheperiodoftemperatureis20a，15a，7aand5a，andtheperiodofprecipitationis

5、15～20aand7～8aAlsostudiedpotentialevapotraspirationbyFAO—penmanmonteithcombinedwithformerstudiesonsolarradiationovertheTibetanPlateauTheresultshowsthedecreasingrateoffloodingperiodandspringwinteris00467mm／aand01084mm／a2Th

6、esteadyinfiltrationrateisdifferentfordifferentvegetation，theratesare0，lmm／minand0017mm／minfortwowatershedsAtthebeginningofprecipitation，theinfiltrationrateofhighplantcoverissmallerthanlowplantcoverThebeginninginfiltratio

7、nrateofblackearthisbiggerKostiakovinfiltrationmodelisbetterformeadowgrasslandincoldregion，butforblackearthbeachHortoninfiltrationmodelisbetterFordifferentprecipitation—infiltrationprocesses，theresultsoftwomodelsarediffer

8、entTherunoffyieldsofmeadowandblackearthare1913—2921Land9313—15244L3Theseenvironmentalfactorsaredividedintofourmaincompositionfactorssuccessively：Factorofplant，factorofthevegetation，factorofslopeabovesealevelandthewindspe

9、edandtopographicalfactorTheorderofwatercontentoffourdifferentvegetationtype：ShrubforestBlackearthbeachDegradateonthemeadowSmallhighgrass，thesectionalchangeofthesoilmoisturehastwokindsofcharacteristics：thefirstisthefluctu

10、ationtypeincludinglighthighgrassanddegradatethegrass，thesecondisreducingtypeincludingshrubforestandblackearthbeach：Therelationbetweenthedifferentdepthsoilmoistureandtheheightabovesealevelobeytheunaryquadraticregressionmo

11、del，therelationbetweenthemoistureof60cmsoillayerandthetoplayersoil(10—30cm)andtheabsoluteheightabovesealevelisbetterthanothers，andthesoilmoistureanddependenceofheightabovesealevelarerelativelystrong；Changecharacteristico

12、fheightabovesealevelofthetypesoilmoistureofdifferentvegetation：Shrubforestandhighgrassvegetationtypesoilmoisturepresentthatthetrendreducesfirstandthenincreasesastheincreaseoftheheightabovesealevel；thetrendofthesoilmoistu

13、reofdegradationmeadowreducedwithitsdistributeincreaseofheightabovesealevel；Blackearthbeachsoilmoistureisreducedwithincreaseofheightabovesealeveldistributed；Accordingtotheorderofthegrassymarshlandofshrubforest，thegrassyma

14、rshland，notslightlydegradationdegree，slightlydegradationdegreeandblackearthbeach，thesoilmoisturesectionalchangeofdifferentdegradationdegreeappearssymmetricvariationtendencyonthesymmetricaxisthatisthenotslightlydegradatio