The effects of different factors on soil water infiltration properties in High Mountain Asia: A meta-analysis

Abstract

High Mountain Asia (HMA) surrounding the Tibetan Plateau (TP) is a critical gathering place for water resources. Investigating soil water infiltration properties in HMA is a vital component of comprehending the hydrological cycle processes in this region. Despite some experimental studies having analyzed the soil water infiltration properties under specific conditions in HMA, a systematic quantitative anlysis of this region's soil water infiltration properties remains lacking. To investigate the effect of soil water infiltration properties under different factors in HMA, we conducted a literature review and meta-analysis based on experimental data from the literature. Our study employed the initial infiltration rate (IIR), steady infiltration rate (SIR), and average infiltration rate (AIR) as response variables to quantify the variations in soil water infiltration properties under diverse conditions. Results revealed that (1) the most significant negative effect on soil water infiltration rates was due to slope (IIR: −48.31 %, SIR: −36.87 %, AIR: −51.81 %). The subgroup analysis indicated that the negative effect of slope on the three infiltration rates was more pronounced as the slope gradient increased. (2) The positive and negative effects of different vegetation types on soil water infiltration rates were significantly different. Among them, the trees + shrub group exhibited the most prominent positive effect on IIR and SIR (IIR: +206.49 %, SIR: +153.45 %). Conversely, the widely distributed alpine meadow in HMA had a significant negative effect on IIR (−39.35 %). (3) Contrary to conventional soil infiltration experiments, the increase of initial soil moisture (SM) in HMA had a positive effect on IIR and AIR (IIR: +13.88 %, AIR: +23.37 %). Considering the study of macropore flow, this may be related to soil texture and vegetation growth. (4) As the values of each soil physicochemical property increased, there was a significant positive effect of increasing non-capillary porosity (NCP) and soil organic carbon content (SOC) on AIR (NCP: +31.00 %, SOC: +47.70 %). At the same time, we found that soil water infiltration studies in HMA are subject to spatial and quantitative limitations. Considering the importance of soil water infiltration in HMA, we recommend more comprehensive studies of soil water infiltration in HMA. Such studies would provide a vital theoretical foundation for enhancing the HMA soil infiltration model and improving the terrestrial hydrological cycle process in the region.