4.3 The utilization potential of alluvial fans
The distances between alluvial fans and road, human settlement and water
system are important factors effecting the utilization potential of
alluvial fans. The transport network density of Tibet is lowest among
all the provinces of China (Jin et al., 2010), which indicates that
transport roads are sparse in LRB. However, the quantity percentage of
alluvial fans distanced to primary road and tertiary road not more than
5 km are 79.51% and 99.72% (Fig.10), so the most of alluvial fans are
easy to access. LRB has a typical semi-arid frigid climate (Lin et al.,
2008), so water resource is an important factor for regional
development. The quantity percentage of alluvial fans distanced to river
not more than 5km reach 61.86% in this semi-arid basin (Fig.12). It’s
showed the majority of alluvial fans will be appropriate for
agricultural or residential development from the water perspective.
There is a situation should be focused that some rivers located between
roads and alluvial fans. For the utilization, those rivers have two
functions, of providing water resource and cutting the accessibility to
alluvial fans in this situation. In order to adequately use those
alluvial fans, some bridges could be built in the future.
The area of grassland and bare land in alluvial fans is 802.59
km2, and the area of alluvial fans which is occupied
by grassland not less than 50% (A50%grassland) even
reach to 903.17 km². The land-use degree of grassland and bare land is
lower than cropland and imperious area (Zhuang & Liu, 1997). So those
two types of alluvial fans, A50%grassland and
A50%grassland A30%bare land, should be
more utilization potential based on reasonable explorations. Besides,
the utilization potential of the alluvial fans located in the west and
south of LRB should be focused. There are many
A50%grassland (Fig.8), and near rivers in the west
(Fig.1). Therefore, alluvial fans in Damshung may be more protentional
in the future. The Chenguan is an urban area of Lhasa city which is
capital of Tibet located in the south of LRB. And the government
residences of Tolung Dechen, Chushur and Taktse are near with Chenguan.
Therefore, the south of LRB especially near Chenguan should be more
needed for available land than another region. There are alluvial fans
with 243 km²in the region, meanwhile some bare land are located in those
alluvial fans. So, the alluvial fans in this part may be utilized
adequately the future.