The distribution and land use characteristics of alluvial fans in Lhasa River Basin in Tibet

Abstract

The land that is suitable for settlement or live is shortage in Lhasa River Basin (LRB). Alluvial fan is a candidate resource to suitable land in this situation. However, the basic information of alluvial fans, for example its distribution and land-use types, is little known. In this study, Google earth, ArcGIS and visual interpretation were used to get the outlines, areas, quantity and distribution of alluvial fans. Meanwhile, the land use, the distance from alluvial fans to roads, places (town and village) and rivers (including stream) are analyzed. The results show that there are 826 alluvial fans in LRB and the total area is 1166.03 km². The quantity of alluvial fans with area between 0.1 km2 and 1 km2 is 517, which is dominated in all. The quantity of alluvial fans is concentrated in the east of LRB, but that area is mainly distributed in the west. The area of Grassland is the largest in all land use types which is account for 68.70% of alluvial fans. Although cropland area is accounted by 2.16% of alluvial fans, it is accounted by 18.98% of the LRB's cropland area. The quantity of alluvial fans within in 5km distance to tertiary road, village, and river (including stream) are accounted of 93.70%, 53.63% and 77.38% respectively. Therefore, alluvial fans have played an import role in LRB, and may have huge utilization potential in the future.