# The Influence of Glacier Mass Balance on River Runoff in the Typical Alpine Basin
## 4 Discussions
### Influence of Topographic Factors on GSE Change
#### 4.2.2 Influence of Slope and Aspect on GSE Change  
Aspect slope was also an important factor of glacier melt [76]. To investigate the relationship between GSE change and terrain factors (slope and aspect) in the Tailan River basin, the average elevation change for glaciers was calculated for each 1\({}^{\circ}\) slope. Figure 10 shows a strong positive correlation (R\({}^{2}\) = 0.99) between the average GSE change and slope. The average GSE change increases with increasing slope, with negative values when the slope is less than 49\({}^{\circ}\) and positive values when the slope is greater than 49\({}^{\circ}\). It is believed that, as the glacier slope increases and the area of receiving sunlight decreases, compared to areas with lower slopes, glaciers with a steeper slope usually have a slower melting rate. The negative value of the GSE change becomes positive, showing an accumulation phenomenon, which is consistent with the pattern of GSE and altitude change.  
The average GSE change was calculated for every 10\({}^{\circ}\) interval. Figure 11 shows that glaciers with an aspect ranging between 0-100\({}^{\circ}\) and 160\({}^{\circ}\)-360\({}^{\circ}\) were thinning. To understand the distribution of glacier melt, the study area was divided into eight zones based on aspect orientation [23], with (0\({}^{\circ}\)-22.5\({}^{\circ}\), 337.5\({}^{\circ}\)-360\({}^{\circ}\)) representing the north, (22.5\({}^{\circ}\)-67.5\({}^{\circ}\))  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Study Area** & **Time** & \
\begin{tabular}{c} **Altitude** \\ **(m)** \\ \end{tabular} &
\begin{tabular}{c} **Mean** \\ **(m\(\cdot\)a\({}^{-1}\))** \\ \end{tabular} & **Paper** \\ \hline Mont Blanc & 2003–2014 & (1500, 4870) & 0.2–0.3 & [73] \\ Tanggula Mountain & 2000–2020 & (5000, 7120) & \(-\)0.76 \(\pm\) 0.05 & [74] \\ Geladandong Mountain & 2012–2018 & (4933, 6555) & \(-\)0.55 \(\pm\) 0.11 & [75] \\ Tianshan & 2000–2016 & (2500, 7530) & \(-\)0.28 \(\pm\) 0.20 & [9] \\  & 2000–2009 & & \(-\)0.29 \(\pm\) 0.14 & \\ Tailan River basin & 2009–2022 & (944, 7392) & \(-\)0.17 \(\pm\) 0.07 & Research \\  & 2000–2022 & & \(-\)0.25 \(\pm\) 0.02 & \\ \hline \hline \end{tabular}
\end{table}
Table 7: Comparison of typical monitoring GSE.  
Figure 10: The relationship between glacier elevation and slope.  
representing the northeast, (67.5\({}^{\circ}\)-112.5\({}^{\circ}\)) representing the east, (112.5\({}^{\circ}\)-157.5\({}^{\circ}\)) representing the southeast, (157.5\({}^{\circ}\)-202.5\({}^{\circ}\)) representing the south, (202.5\({}^{\circ}\)-247.5\({}^{\circ}\)) representing the southwest, (247.5\({}^{\circ}\)-292.5\({}^{\circ}\)) representing the west, and (292.5\({}^{\circ}\)-337.5\({}^{\circ}\)) representing the northwest. The findings revealed that glaciers facing north had the greatest thinning rate. Glaciers in the study area are located at different altitudes, and a comparison revealed that glaciers facing north are mostly situated at lower altitudes. Glaciers in the lower-altitude zones exhibit rapid melting, while those in higher-altitude zones show slow melting or even accumulation.