甘肃省各流域降水量的GIS模块插值估计与改进

Catchment precipitation estimation with GIS modules and its improvements in Gansu Province

考虑了我国西部流域降水量的主要因素,应用GIS插值模块及其改进方法以甘肃省为例对不同流域单元区年平均降水量进行插值估计,并进行了分析对比。改进方法是:根据气象台站海拔高度面与数字高程模型DEM(Digital Elevation Model)之间的海拔高度差,并以流域地形坡面、不同流域单元降水的垂直变化率为参数,引入ArcGis的Spline、IDW、Kriging 3个模块进行插值。结果表明:与气象站降水量统计值相比,这不仅更有效地表达降水量空间分布变异程度,而且通过调整参数和反复验证可有效地提高插值精度,以弥补西部流域气象台站稀少所造成的数据空白,避免某些方法或模型(如PRISM)对上述流域降水模拟估计值偏小的不足。

In this paper, considering the main factors of watershed precipitation in the west China, GIS interpolation modules and their improvements have been used to evaluate annual mean precipitation of different watershed units in Gansu. The obtained results have been analyzed and compared. The improvement was based on the hight difference between the DEM and the elevation surface of the meteorological stations, the vertical changing rate of precipitation and the relief facets of watersheds as well. Spline, IDW and Kringing modules have been introduced to the interpolation. The results showed that this approach can certainly enhance estimation precision via parameter adjustment and repeated verifications, and can efficiently present spatial variations of precipitation. Therefore, it is useful to overcome insufficiencies of parameters the PRISM required and its underestimations, which may result from the scarcity of meteorological stations and the great relief variations in the west China.