3.1 The quantity of alluvial fans
The quantity of alluvial fans with different size is provided in Fig.3.
As a whole, there are 826 alluvial fans in LRB. The number of
2nd size (0.1
km²<area≤1 km²) is the most in all the sizes with a number of 517, and
it’s proportion is 62.59%. And then, the number of
3rd size (1 km²<area≤10 km²)is the second with a
number of 205. The number of 4th (area>10 km²) is 17,
just only accounted for 2.06% in the total alluvial fans. That means
the alluvial fans with area less than 1 km²are dominated, and with area
more than 10 km²are in LRB.
Furthermore, the alluvial fans are ranked by area from small to large,
and there is an exponential relationship (the equation:
y=3.93e0.067x, R2=0.92) between
accumulating area with quantity of alluvial fans, which is showed in
Fig4. It is found that the accumulating area of alluvial fans is 83.39
km2, when the quantity accounting for 50% of total
quantity of alluvial fans. Furthermore, the quantity of alluvial fans is
746.27, when the area accounting for 50% of total area with 1166.03
km2, which indicates that the area is occupied by 26
large-size alluvial fans (4th).