Drainage Density and Its Controlling Factors on the Eastern Margin of the Qinghai–Tibet Plateau
Hongshan Gao, Fenliang Liu, Tianqi Yan, Qin Lin, Zongmeng Li
Abstract
The drainage density ( D d ) is an important index to show fluvial geomorphology. The study on D d is helpful to understand the evolution of the whole hydrological and geomorphic process. Based on the Shuttle Radar Topography Mission 90-m digital elevation model, the drainage network of basins along the eastern margin of the Qinghai–Tibet Plateau is extracted using a terrain morphology-based method in ArcGIS 10.3, and D d is calculated. The spatial characteristics of D d are analyzed, and the relationship between D d and its influencing factors, e.g., the topography, precipitation, and vegetation coverage, is explored. Our results show that terrains with a plan curvature ≥3 can represent the channels in the study area. D d ranges from 2.5 to 0.1 km/km 2 , increases first, and then decreases from north to south on the eastern margin of the Qinghai–Tibet Plateau. D d decreases with increasing average slope and average local relief. On the low-relief planation surfaces, D d increases with increasing altitude, while on the rugged mountainous above planation surfaces, D d decreases rapidly with increasing altitude. D d first increased and then decreased with increasing mean annual precipitation (MAP) and normalized difference vegetation index (NDVI), and D d reaches a maximum in the West Qinling Mountains with a semi-arid environment, indicating that D d in different climatic regions of the eastern margin of the Qinghai–Tibet Plateau was mainly controlled by precipitation and vegetation.