Research on Spatial Distribution of Annual Precipitation in Shaanxi Province Based on GIS

Based on annual precipitation data of Shaanxi and its surrounding areas by trend surface analysis and stepwise regression analysis,a prediction model for macroscopic geographical factors and precipitation was established and it acquired 100m×100m spatial distribution of precipitation by micro-topography correction.The result indicated that there was great difference of precipitation distribution of Shaanxi.The precipitation in Qinba mountain area in South Shaanxi was 1700mm,that in sandy area in Northern Shaanxi was only 300mm.The distribution of precipitation showed an obvious descending trend from south to north in Shaanxi,and there was more precipitation in mountain area than in river valley and basin area.The different types of agricultural area such as paddy field,dry land and irrigation district were formed.