3.4 The distance of alluvial fans to road, place and river
Fig.10 shows the trend of the quantity and area proportion of alluvial
fans with the distance to different grade road. For primary road, theRq1 is 29.66%, and the Rd1 is 21.83%. When the distance is not more than 5km,Rq and Rd are dramatically
increasing. The Rq5 reach 75.91%, and the area
proportion is 89.87 %.
Furthermore, for tertiary road, the regulation is same with primary
road. Rq1 , Rd1and Rq5 ,Rd5 are 66.71%, 44.97% and 93.70%, 97.50%
respectively. Therefore, the great majority alluvial fans are adjacent
to road with distance not more than 5km.
Fig.11 shows the trend of the quantity and area proportion of alluvial
fans with the distance to towns and villages. TtheRq1 andRd1 to towns just are 1.94% and 1.59%, even theRq5 and Rd5 are 34.62%
and 36.30%. After the distance recaching 10 km, theRq and Rd exceed 50%.
That means the majority of alluvial fans are mainly distributed in the
regions with the distance to town over 5km. However, theRq5 and Rd5 to village are
53.63% and 46.14%, reflecting about half of alluvial fans are near
with villages.
Fig.12 shows the trend of the quantity and area proportion of alluvial
fans with the distance to river. The Rq1 andRd1 are 23.66% and 21.83%, and theRq5 and Rd5 have been
61.86% and 77.38%. That can reflect the majority alluvial fans have a
near distance to water resources.