Spatial variation of runoff depth and sediment yield in relation to dominant Factors on the Tibetan Plateau

The riverine runoff and sediment are essential carriers for nutrients and pollutants delivery and are considered as important indicators of land degradation and environmental changes. With growing interest in environmental changes over the Tibetan Plateau, this study investigated mean annual runoff depth and sediment yield from eight headwater catchments in relation to dominant factors such as annual precipitation, air temperature, and glacier area ratio, etc. Results show that runoff depth (Q) is positively correlated with both precipitation (P) and temperature (T), indicating combined water supply from rainfall and meltwater, increase of which may exceed the evapotranspiration water loss caused by temperature raise. Sediment yield (S) shows an inverted parabolic relationship with precipitation and at the same time positive correlation with glacier area ratio (Ag). The variation in sediment yield with precipitation can be explained by the operation of two factors, i.e., rainfall erosive action that increases continuously with increase in precipitation, and vegetation protective action that is unity for zero precipitation and decreases with increases in precipitation.