天水地区位于甘肃省东南部。其北部的黄土高原,以黄土梁峁和黄土沟壑为主。海拔1200—2000米之间。中部的北秦岭,山脉重叠,沟谷幽邃,海拔2500—3800米,相对高差500—800米,为长江、黄河两流域的分水岭,南部是徽成盆地和南秦岭山地,盆地海拔千米上下;山地断层比较发育,地貌结构是山高谷狭,多陡崖峭壁,海拔1800-2400米,相对高差500-800米。

Using satellite and aerial photos,maps in large scale and others the parameter variables for classification of soil types are chosen.By the cluster analysis of"matching coefficients"a soil type map in Tianshui District is made and the areas of each kind of soil types are measured. The remote data from satellite are a spectrum record,it is not directly connected with the earth surface covered by soil.But because of close soil relation with the surface complex,the statistical analysis on the basis of comprehensive information,as a method,have great potentialities for application, Since grey scale of one part compare with another only on same a picture, it is the question not researched in this paper whether measurement of colour grey scale of soil image will result in dispersal of light density.