Influence of Alpine Meadow Land Cover Differences on Precipitation-Runoff Processes on the Qinghai–Tibet Plateau, China

Abstract

How land cover differences affect runoff and sediment and their relationship with precipitation are largely unknown on the Qinghai–Tibet Plateau. This study was designed to examine precipitation-runoff processes using the runoff observation plots on the 30° slope surfaces. Three plots were selected with vegetative cover average of 30, 68, and 93%. Our results show that runoff with 30% land coverage is larger than those with 68 and 93%, under the same precipitation form and amount in an alpine meadow. The mean sediment per precipitation event is two to four times greater in an area with 30% vegetative cover compared with those in 68 and 93% vegetative cover. Both runoff and mean sediment yields increased with vegetative cover from 30 to 68 and 93%. The precipitation form also affects the runoff and sediment yield. Comparing sleet and rainfall, the runoff yield resulted from melted snow is maximal, but the sediment yield is minimal. Based on the runoff yields of precipitation, the runoff coefficients on a sloping surface of 30° with vegetative cover of 30, 68, and 93% are 5.3, 2.5, and 1.9%, respectively. Quadratic parabolic curves better describe the relationships of runoff and sediment with precipitation on the Qinghai–Tibet Plateau. Our results suggest that vegetation is a major control on runoff and sediment production in the permafrost region.