## 5 Discussion  
In terms of long-term glacier dynamics, changes in surface velocity are primarily influenced by variations in climate and topographic conditions. Since topography generally remains constant, the glacier velocity overextended period is mainly affected by climate. The impact of climate on velocity is reflected in the seasonal variations in temperature, precipitation, and snowfall, which alter the glacier's mass balance, thermal state, and hydrological characteristics.  
As summer arrives and temperatures rise, ice deformation accelerates, particularly through ice creep. Studies have shown [20; 31; 32; 33] that debris-laden ice deforms easily; at 2 \({}^{\circ}\)C, deformation-induced velocity within a 0.35 m debris layer can reach about 60% of the glacier's surface velocity. Rising temperatures also reduce ice viscosity and increase plasticity, thereby accelerating glacier flow. Both temperature and precipitation influence velocity by altering the glacier's hydrological characteristics. Temperature increases lead to meltwater production, infiltrating the glacier bed and raising subglacial water pressure. According to the hydraulic leverage principle, this pressure facilitates glacier sliding, regardless of bedrock smoothness, and affects basal till deformation, further accelerating glacier motion.  
The wedge-shaped pattern of glacier flow indicates that a higher mass balance gradient requires greater flow velocity to maintain the equilibrium. Both temperature and snowfall influence glacier velocity by altering the mass balance gradient. In summer, meltwater reduces the overall accumulation and shear stress, slowing the velocity. However, the impact of temperature on other factors often outweighs the reduction in the mass balance gradient, resulting in higher summer velocities. During intense ablation, glaciers retreat, accumulation decreases significantly, basal shear stress drops sharply, and velocity slows. If other factors cannot compensate, summer velocity may decrease. Conversely, in exceptionally snowy winters, increased accumulation thickens the ice, raises the basal shear stress, and can cause a sudden increase in velocity.  
Topography affects surface velocity at specific time points by influencing forces such as friction, gravity, and internal pressure. Overall, glacier velocity over time is influenced by multiple climate-related factors that interact dynamically, leading to fluctuations. At any given time, variations in velocity across regions are also shaped by topographical differences.  
Figure 8: The flow velocity change in each sample when the elevation rises by one meter.  
Figure 9 shows the wedge pattern of glacier flow [34]. The upstream material accumulation thickening and the downstream material loss thinning of the levering glacier occur during the quiet period. This requires a large glacier flow rate to maintain the material budget of the ice body. A similar effect of temperature and snowfall on glacier flow is to change the mass balance gradient of the glacier. In summer, glacial meltwater reduces the total glacier accumulation, decreases the glacier shear stress, and reduces the glacier flow velocity. If the effect of temperature on glacier viscosity, water pressure, and other factors is greater than the effect of decreasing the mass balance gradient, the glacier will show a phenomenon of a higher summer flow velocity. When strong ablation is encountered, the glacier retreats, the accumulation is greatly reduced, the bottom shear stress is sharply reduced, and the glacier flow speed is slow. Other factors are not enough to compensate for this effect, and the phenomenon of summer flow speed reduction will occur. Similarly, in the unusually snowy winter, a huge amount of glaciers accumulate, the ice layer becomes thicker, the shear stress of the bottom surface increases, and the glacier flow velocity may also suddenly increase.