4.1 Impact of stable snow on hydrological processes
In this study, we investigated the process of stable snow formation and
its distribution pattern in two major watersheds of the eastern Tibetan
Plateau-Kawasaki Plateau by means of the daily MODIS snowpack dataset,
showing that the distribution pattern of stable snow was different
between the Mamukau River Basin in the hilly plateau region and the
Hanliu River Basin in the alpine valley region; in the Mamukau River
Basin, the area of stable snow cover was larger in the spring, and the
area of stable snow cover was smaller in the winter. The long retention
time of the spring snowpack, its ablation rate is much smaller than that
in winter, and the large area of stable snowpack provides an adequate
water supply for the downstream rivers, similar to the role of glaciers
in recharging water resources in summer. It shows that the spring
snowmelt can effectively regulate the downstream river runoff, and the
water volume is more uniform; while the winter snow melt is fast, the
downstream river may rise significantly in a short period of time, but
the water volume fluctuates greatly, and the winter snowfall is small,
which may lead to some of the rivers in winter with small water volume
or ”cut-off”(López-Moreno et al. 2020); in the alpine valley area of the
Hanliu River Basin, the stable snowpack is mainly distributed in the
high altitude area, which is the main source of water supply. In the
Hanliu River basin in the alpine valley area, the stable snowpack is
mainly distributed in the high altitude areas. Due to the large vertical
difference, there are differences in the water and heat conditions in
different areas, and the melting of snow shows a situation of ”low first
and then high”, with the snow at low altitude melting faster and the
snow at middle and high altitudes melting later, which can play a role
in regulating river runoff to a certain extent. In winter, due to less
precipitation and faster ablation, this regulation may be less effective
than in spring, and in the later stages there may be a significant
reduction in the volume of water in the downstream rivers(Harpold et al.
2017).
Stable snowpack, as a stable material, is important for biochemical
cycling at regional and hemispheric scales. In the snowy season, the
stable snowpack can cache a large amount of snow, which makes the snow
and ice gradually melt and infiltrate into the soil, providing a stable
runoff supply for the snow melting season. Compared with the unstable
snowpack, the snowmelt runoff in the stable snowpack area in the spring
and summer snow melting seasons is more stable, which can effectively
prevent the spring and summer ice and snow flood disasters, and is of
great significance for the residents’ production and life and the water
supply of the city, and other water resources management. In addition,
stabilizing snowpack plays an important role in temperature regulation.
Due to its high albedo, snow can effectively reflect solar radiation and
reduce the ability of the ground to receive solar radiation. In this
study, the snowpack on the Western Sichuan Plateau was studied and
analyzed, and although the focus of this study was mainly on the Western
Sichuan Plateau, it is representative and exemplary as part of the
Tibetan Plateau. At the same time, snowpack, as one of the important
elements on a global scale, has a significant impact on climate change
and water allocation(Sturm et al. 2005). In-depth study of the formation
process and pattern of stable snowpack on the western Sichuan Plateau
can provide reference value for the study of stable snowpack in other
highland mountain areas and contribute to the understanding of global
stable snowpack. In addition, the study of the formation process and
stabilization pattern of the stable snowpack in the Western Sichuan
Plateau can provide insights into ecological environmental protection,
water resource management and disaster prevention on a global scale,
which is of great significance in promoting scientific research and
practice in this field.