Index of nibbled degrees and approximation degrees shows the landform development and the developmental stages of drainage system within a watershed area. 溝沿線(xiàn)對流域邊界的逼近度指標，從流域尺度反映流域地貌系統發(fā)育階段。
Yulin District and Hengshan County were taken as the cases, and ecological security index system was constructed to assess the security levels of the two regions. 選擇了榆林市和橫山縣兩個(gè)行政單元，針對區域特征，構建了不同尺度上的生態(tài)安全指標體系，利用層次分析法，對不同尺度上生態(tài)安全的空間分異進(jìn)行了研究。
