Study On The Regional Surface Water Cycle Of The Yangtze Basin (Baohe Basin) Based On The Technique GIS & RS

Based on the technique GIS and RS, the paper studies the regional surface watercycle (SWC) of the Yangtze basin by model VIC-3L with focusing on Baohe basin.The main results are as followed:1) Different height, latitude, slope and other factors would lead to non-uniformspatial distribution of some climate variables. In fact, even step-to-step interpolationperformed multiple times for error correction could not truly reflect the littletemperature topographic effect. For this reason, Gaussian weighted method is adoptedfor interpolation before step-by-step correction for the space distribution oftemperatures to improve greatly the accuracy of spatial interpolation. SIA combinedwith statistical regression could decrease precipitation space interpolation error.2) ArcGIS is used to pick up the parameters of hydrological models. Thecomparison showes that what resulting from ArcGIS, such as slope aspect, slopegradient, flow direction, flow velocity in the river basin, river basin and river system'sborder, are consistent with the results from DEM.3) The remote sensing data of the leaf area index (LAI) could reflect the seasonalvariation of the real LAI, and the ground vegetation types acquired by remote sensingimaged the land cover, which has similarities with distribution of ground vegetationtypes. The simulation results are improved after adding the remote sensing data,particularly the flow into the estuary when the remote sensing data were applied in theresearch of simulation of surface water cycle (SWC).4) In the process of SWC, the ground vegetation types, soil humidity andprophase soil humidity, landscape and precipitation have effect on the surface runoff,even on the water surface cycle. The simulation of spatial distribution, which is aboutrespective average components of ground surface balance from 1979 to 1984 andfrom1992 to 2001 in Baohe basin, show that the transpiration of vegetation is moresignificant comparing with the earth's surface soil during evaporation process. Thesimulation of ground runoffs distribution points out that the spatial difference of soilwater is in accordance with the real situation, and the simulation results of grid timeseries show that the surface runoff has an annual period oscillation, which iscoincident with the results from the climate and hydrological data.5) The simulations of Baohe basin regional SWC show that there are on error of21.82% of flow rate while using uniformity farmland vegetation and on error of-14.23% of flow rate while using traditional vegetation with less than actual flow rate,the lowest error is 1.43% when the non-uniformity farmland vegetation is applied inthe simulation. So the paper points out that the non-uniformity of land surface effectsSWC, which leads to the changes of river's flow rate.