2.2 The extraction of alluvial fans
The alluvial fans were drawled by visual interoperation in Google Earth
Pro (7.3.3.7692). The standard about visual interoperation was the three
obvious characteristics of alluvial fans formed by flooding process in
LRB: (1) fan-shaped landform, (2) braided flow channels, and (3) none
consistent flow, as shown Fig2.. According those characteristics, the
outline data is got in Google Earth Pro. Then added outline to ArcGIS to
get the data about area, position and distribution of alluvial fans.