| The regional distribution of precipitation of Songhua River in 2000~2004 is derived from the records of precipitation of weather stations using PRISM (Parameter-elevation Regressions on Independent Slopes Model) and DEM (Digital Elevation Map) of 1km resolution based on the statistical results that respective rainfall has strong connection with its elevation in this paper. PRISM considered the weight of the distance from raster points to base stations and of the elevation changes from raster points to base stations. The precipitation in Songhua River was mapped in fine spatial resolution using GIS tools. Meanwhile calculations results are also given with methods of Kriging, Spline and Inverse Distance. Compared to these methods, PRISM shows good agreement with the ground measurement without appearing defects of them. Cross-validation is used for validating the application , relative error is mainly as the standard of validation ,absolute error is also obtained. With changing the resolution and the radius of study, Cases of lkm ,2km,10km and 20km of resolution and that of three kinds of radius are studied and errors of them are also calculated in this paper. The result of errors shows that cases of overestimates are more than that of underestimates in general. Errors bringing from changes of resolution are almost within 1%. All these show PRISM is suitable to Songhua River basin such area in mid-latitude without too high mountains. This method is brief and trustworthy, which can be enough applied to hydrological and other terrestrial study.
|
PDF Full Text Request