Runoff coefficient characteristics and its dominant influencing factors in a riparian grassland in the Qinghai Lake watershed, NE Qinghai-Tibet Plateau

Abstract

The runoff coefficient is useful for understanding the flood frequency controls in particular hydrologic or climatic regime, especially in the alpine riparian grassland. This study firstly investigated the runoff coefficient characteristics and dominant influencing factors of a riparian grassland in the Qinghai Lake watershed, NE Qinghai-Tibet Plateau. Results showed that the riparian grassland had a low runoff coefficient of 0.71 % in the Qinghai Lake watershed. Results showed that rainfall depth and the 10-min maximum rainfall intensity were the dominant controls on runoff coefficient. The runoff coefficient and rainfall depth had a positively linear relationship. No significant relationship was found between the runoff coefficient and rainfall intensity in the study area. However, the 10-min maximum rainfall intensity significantly influenced the runoff coefficient. The antecedent soil moisture influenced the soil water infiltration. Moreover, the runoff coefficient and antecedent soil moisture had no significant relationship. The investigation of the influencing factors on runoff coefficient would help understand the hydrological processes in the alpine riparian grassland.