The whole research area includes two major topographies-alluvial fan and alluvial plain.Furthermore, the alluvial fan can be divided into the tip part, the middle part, and the rim part.

• 整个研究区包含了冲积扇与冲积平原两大地形区，其中，冲积扇又可分为近扇顶地区、扇央地区与扇端地区。