Revisiting snowmelt dynamics and its impact on soil moisture and vegetation in mid-high latitude watershed over four decades

Snowmelt is a critical water supply that affects the environmental security and sustainable development. However, the dynamic contributions of climatic factors to snowmelt and their impacts on soil moisture (SM) and vegetation growth remain unclear. In this study, by combining changes in spring snowmelt (snow water equivalent), climatic factors (precipitation and temperature), SM, and vegetation growth (normalized difference vegetation index [NDVI]) during 1982–2018, the spatiotemporal patterns in snowmelt and its mutual effects on SM and NDVI in a mid-high latitude watershed (Mongolia) were investigated. The results showed that spring snowmelt has decreased (-0.54 m/yr, p < 0.05) in Mongolia, with cold season temperature and precipitation identified as key influencing factors. The negative association between cold season temperature and snowmelt is intensifying (-0.0010 mm/yr, p > 0.05), while the positive influence of cold season precipitation is weakening (-0.0004 mm/yr, p > 0.05). Additionally, snowmelt provides 30 % of SM, and rising spring temperatures, along with reduced snowmelt, is the main reasons for SM decline (0.001 m³/m³/yr, p < 0.05). The negative impact of spring temperature on SM is growing (-0.0029 %/yr, p < 0.05), while snowmelt's positive contribution is diminishing (-0.0011 %/yr, p < 0.05). Furthermore, spring temperature has the strongest direct effect (positive) on vegetation, while SM exerts the greatest total influence (positive). Snowmelt indirectly affects (positive) vegetation through its role in SM. Despite vegetation increased in 60.5 % of the area, the declining trends in SM and snowmelt, alongside the reduced contribution of SM to vegetation (-0.0028/yr, p < 0.05), suggest an increased risk of future drought. Overall, this study provides new insights into the dynamics and interrelationships between snowmelt, SM, and vegetation in mid-to-high latitude regions, offering valuable implications for sustainable development decision-making.