5.1 Dominant control of sediment fluxes: temperature or precipitation?
The seasonal variations in discharge and sediment load are jointly controlled by air temperature and summer rainfall (Figure 7). At the Ming Yong Glacier, fractures in the ice form crevasses, providing pathways for surface water to penetrate the glacier (Miles et al., 2020). In summer, elevated air temperatures increase the surface melting and generate snow-glacier meltwater (Lau et al., 2010). The meltwater can flow from the surface to base through glacier conduits (Eyles, 2006), leading to higher meltwater flow velocity and capacity. As a result, there is an increase in meltwater erosion and sediment export (Delaney & Adhikari, 2020; Mao & Carrillo, 2017). Concurrently, the intense rainfall in July from the Indian monsoon increases the rate of exposed slope erosion and can trigger landslides and rock avalanches, leading to the observed high sediment loads (Table S1) (Kirschbaum et al., 2020; Rosser, 2010). In other words, the discharge and suspended sediment load peaks observed in July can be explained by higher sediment accessibility, mobilization, and transport from the monsoon rainfall Conversely in winter, reduced snow/glacier melting and the decreased rainfall causes the deformation of the glacial conduits. Furthermore, accumulated snow shield the underlying crevasses (Carrillo & Mao, 2020; Gatesman, 2017), thereby weakening erosion and reducing the transport of sediments into the proglacial stream.(Table S1).