Spatial Analysis of Hydrological Characteristics of the Upper Reaches of Minjiang River Based on GIS Technology

Hydrological characteristics are not only the basis for water cycle and soil erosion research,but also can provide beneficial support to avoid geological and flood hazards.This research extracted river network information and watershed of upper Minjiang River Basin by GIS tools from digital evaluation model(DEM) with 90 m resolution,and analyzed drainage system density,longitudinal channel profiles of main channel and major tributaries quantitatively.Then we calculated runoff coefficient of the drainage basin from precipitation data of 21 rain-gauge station and runoff data of 8 hydrological station of upper Minjiang area from 1982 to 1987.The results indicate that: the runoff coefficient of Zhenjiangguan basin is the least one among all sub-basins,which is 0.55,the basin from Jiangsheba to Zipingpu hydrological station is the biggest one,which is 0.88,and the whole upper Minjiang River Basin is 0.77.The drainage density of upper reaches of Minjiang River is 0.172 km/km2,all sub-basin's drainage densities are between 0.165 and 0.177 km/km2.The channel slope of main stream is 9.7‰,the concave of longitudinal channel profiles and channel slope of the five tributaries which scatter from north to south in upper Minjiang River Basin decrease one after another,and main stream profile is affected by tectonic movement significantly.