Analysis of basin morphologic characteristics and their influence on the water yield of mountain watersheds upstream of the xiongan new area, north china

Abstract

In this study, based on the DEM, we extracted the drainage networks and watersheds of the Daqing Riverwith ArcGIS, investigated the basin characteristicsandthe differences in their spatial distributions and analyzed the relations of the drainagedensity with some surface conditions and how the drainagedensityinfluenced the water yield. The results suggested a power function between the mainstream length and drainage area, showing that withthe increase in basin area, the basins became longer.The result of the power function between the relief and drainage area with negative exponent values means the relief changed more slowly with increasing basin area.The values of the circularity ratio andelongation ratio indicatethat the basin shape of the mountain watersheds in theDaqing River was narrow and predisposed to flooding during periods of heavy rainfall. The orders of the streams in the mountain watersheds ranged from five to seven.The average bifurcation ratio of those nine mountainous watersheds reveals the order of the u+1 rivers in each basin of the Daqing River was on average 4 times larger than that of order u rivers. The drainage density (Dd) was high in the north and low in the south of the Daqing River. Rainfall wasnegatively correlated with drainage density, but the correlation between them was notsignifi-cant atthe 0.05 level. Drainages developed in places with poor vegetation cover.The drainages in the southwest, north and west developed considerably, while drainages in the east and southeast did not develop much. Yet, the available data showed the impact of the watershed area, elongation ratio and drainage density on the water yield was not significant. In contrast, there was a significant positive correlation between channel slope and the water yield modulus. The hypsometric integrals and the relation between drainage density and hypsometric integral suggest that the landform evolution of the mountain basins alongthe Daqing Riverwerein the old stage with no furtherincrease trend of drainage density in the future.