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.