Distribution and land use characteristics of alluvial fans in the Lhasa River Basin,Tibet

In Lhasa River Basin (LRB),land suitable for settlement or living is experiencing a shortage of resources.Alluvial fans have the potential to alleviate this problem.However,basic information,such as the distribution and land use types of alluvial fans,is rarely studied.In this study,Google Earth,ArcGIS and visual interpretation were used to obtain the outlines,areas,quantities and distribution of alluvial fans.Meanwhile,to show the utilisation potential of alluvial fans,we analysed the land use,their distance from the roads,places (town and village) and rivers.The results showed 826 alluvial fans exist in LRB,with a total area of 1166.03 km2.The number of alluvial fans with areas between 0.1 and 1 km2 is 517,ac-counting for 62.59％ of the total number of alluvial fans.Grassland is the dominant land use type,accounting for 68.70％ of the total area of alluvial fans.The cropland area accounted for 2.16％ of alluvial fans and accounted for 18.98％ of the total cropland area in LRB.Exactly 93.70％,53.63％ and 61.86％ of the total number of alluvial fans were located within 5 km from the tertiary road,village,and river,respectively.To sum up,our survey results showed that alluvial fans are important land resources in LRB and may have huge utilisation potential.