Abstract
The soil seepage is an important component for quantifying hydrological processes while remains unclear in high-altitude alpine meadows. The shallow soil seepage was continuously measured by an auto-logged micro-lysimeter (diameter = 30 cm, depth = 30 cm) from July 2018 to June 2019 in a piedmont summer pasture of alpine meadow on the Northeastern Qinghai-Tibetan Plateau. The results showed that all the shallow soil seepage events occurred during the non-frozen period from April to September and the accumulative amount was 106.8 mm, which consumed about 1/5 annual precipitation. The maximum and minimum monthly soil seepage was 30.7 mm in September and 1.0 mm in April, respectively. The binary Logistic model revealed that daily half-hour rainfall frequency (R2 = 0.37, individual explanatory power) and amount played significant roles in the daily soil seepage odds (R2 = 0.50). The best subsets regression analysis showed that the same-day rainfall amount (R2 = 0.59), the first 3-day rainfall frequency, and the first 4-day solar radiation accounted for 73% of variations in the daily soil seepage amount. Monthly soil seepage correlated with monthly rainfall frequency significantly (R2 = 0.74, p = 0.005). Our results highlighted that precipitation, including its amount and frequency, was the key determinant of the probability and amount of the shallow soil seepage in the piedmont summer pasture of alpine meadow. These findings would be helpful for improving predictions of the water budgets of piedmont alpine meadows.