Soil water sources and its implications on vegetation restoration in the Three-river Headwaters Region during different ablation periods

Abstract

Abstract. Under climate warming, effective restoration and protection of the ecological environment could happen by timely supplementing soil water. So it is crucial to understand the spatial-temporal changes in soil water sources. Two thousand six hundred samples of soil water, precipitation, river water, ground ice, supra-permafrost water, and glacier snow meltwater have been collected from June, August, and September 2020 to quantify the soil water sources in the Three-River Headwater Region under different ablation periods. Results indicated that precipitation, ground ice, and snow meltwater accounted for approximately 72 %, 20 %, and 8 % of soil water during the early ablation period. Snow is completely melted in the heavy and the end of the ablation period, and precipitation contributed to about 90 % and 94 % of soil water, respectively. These recharges also vary markedly with altitude and vegetation type. Various factors influence soil water sources, including temperature, precipitation, vegetation, evapotranspiration, and the freeze-thaw cycle. However, soil water loss will further exacerbate vegetation degradation and pose a significant threat to the ecological security of the “Chinese water tower.” So there is an urgent need to monitor soil water, warn of vegetation degradation associated with soil moisture loss, and identify reasonable water-soil conservation and vegetation restoration patterns.