Responses of soil water dynamics to precipitation events in an alpine meadow ecosystem of the Qinghai Lake Basin based on high‐precision lysimeter measurements

Abstract

AbstractIn high‐altitude cold areas, how precipitation and freeze–thaw processes affect soil water dynamics is not well understood due to a lack of high real‐time resolution measurements. This study measured soil water balance components with a high‐precision lysimeter in an alpine meadow ecosystem in the Qinghai Lake watershed from June 30, 2020, to June 30, 2021. The results showed that the total precipitation (TP), evapotranspiration (ET), soil water storage change (ΔS) and the vertical water flow (WF) of this ecosystem were 705.18, 633.21, 72.58 and −0.60 mm, respectively, during the study period. Continuous wet days with precipitation events larger than 10.00 mm led to percolation, while continuous dry days with strong ET caused an upward WF. Pearson correlation analysis suggests that a larger instantaneous precipitation intensity may be more conducive to an increase in shallow soil moisture (R2 > 0.72, p < 0.05). Furthermore, the TP thresholds in the complete thawing period inducing the soil water response in the mattic epipedon layer (0–20 cm) and organic layer (20–40 cm) were 3.24 mm and 16.61 mm, respectively. The difference in the average response time of soil water to a single precipitation event between the mattic epipedon layer and organic layer was 5.52 ± 3.65 h. These results deepen the understanding of the temporal pattern of water flux in alpine meadow ecosystems on the Tibetan Plateau.