Permafrost, a unique geological phenomenon found in the Qinghai-Xizang Plateau and other high-altitude cold regions, significantly influences the generation of runoff and hydrological processes in frozen watersheds. Its ability to retain water differentiates these processes from those in non-frozen landscapes.

A comprehensive understanding of permafrost dynamics and its effects on hydrology is crucial for advancing water resource studies in alpine regions.

A research team at the Northwest Institute of Eco-Environment and Resources of the Chinese Academy of Sciences (CAS) has quantitatively assessed the hydrological connections between soil water in the permafrost active layer, water above the frozen layer, and surface runoff, utilizing long-term data collected from multiple sites across the Qinghai-Xizang Plateau.

Their findings were published in Hydrology and Earth System Science and Catena.

The results show that the freeze-thaw changes of permafrost active layer have a direct impact on the water interaction and transformation relationship of "precipitation - soil water - permafrost water - surface runoff" in the basin. This impact varies depending on the underlying surfaces of alpine vegetation.

It is found that there is a high correlation between suprapermafrost groundwater and river runoff processes. Statistical analysis of observational data from typical small watersheds revealed that suprapermafrost groundwater contributes 57% to 65.8% of the variability in river runoff. This finding highlights the critical role of permafrost water in the hydrological cycle of the basin.

Notably, the research found a strong correlation between suprapermafrost groundwater and river runoff processes. Statistical analysis of observational data from several small watersheds revealed that suprapermafrost groundwater accounts for 57% to 65.8% of the variability in river runoff, underscoring the critical role that permafrost water plays in the overall hydrological cycle of the basin.

The study also found that landscape zones such as cold deserts, glaciers, and alpine meadows are the most important runoff-generating areas in the northwestern alpine permafrost watersheds. For example, more than 95% of the annual runoff in the upper Shule River originates from glaciers, alpine meadows and cold desert landscapes.

Simulation results indicate that permafrost degradation will significantly impact watershed runoff. Specifically, permafrost degradation will reduce flood runoff and increase dry season runoff to some extent, with variations depending on the type of landscape.

This study not only revealed the influence of freeze-thaw changes in the active layer of permafrost on the hydrological processes of the basin, but also quantified the significant contribution of frozen layer water to changes in river runoff. These insights provide a new scientific basis for the effective management of water resources in the region.