The least square method is applied to study the deformation tendency and calculate the meanannualrate of deformation.
用最小二乘法拟合了库区地壳形变多年的变化趋势，计算了多年平均形变速率。
2
The annualmean increase rate of sandy desertification is 0.37 percent from 1940s to 1990s, which forebodes a increasing trend of sandy desertification in Hexi corridor.