# The Influence of Glacier Mass Balance on River Runoff in the Typical Alpine Basin
## 3 Results
### Analysis of GSE and GMB Change Results  
The GSE in the Tailan River basin has shown a melting trend during different periods, with significant thinning of the majority of glacier tongues. Figure 7 shows that during the periods 2000-2009, 2009-2022, and 2000-2022, the glacier melting zones showed a significant thinning trend, while some accumulation zones showed thickening trends. The maximum thinning rate of glacier tongues was \(-\)2.4 m\(\cdot\)a\({}^{-1}\), and the average change rate of the overall glacier elevation ranged from \(-\)2.4 m\(\cdot\)a\({}^{-1}\) to 4.4 m\(\cdot\)a\({}^{-1}\). In Figure 7b, the GSE decreased in some tongue zones, while high altitude zones and some tongue zones displayed thickening trends, with the maximum increase rate of the GSE reaching 1.9 m\(\cdot\)a\({}^{-1}\). In Figure 7c, the maximum thinning rate of the GSE was \(-\)2.0 m\(\cdot\)a\({}^{-1}\), and the average change rate of the glaciers ranged from \(-\)2.0 m\(\cdot\)a\({}^{-1}\) to 1.3 m\(\cdot\)a\({}^{-1}\).  
The glacier zone with an altitude of 3000-5000 m was divided into altitude bands of 500 m, and the GMB at different altitudes was estimated, as shown in Table 6, indicating the average GSE and GMB at different altitudes. The average GSE changes and GMB were negative at different altitudes (excluding the GSE change and GMB change above 5000 m altitude from 2009-2022). From 2000-2009, 2009-2022, and 2000-2022, the GSE in the study area showed a significant decline during different periods, and the glaciers had a trend of accelerating, then slowing down, and then accelerating again in their retreat. The average elevation change rates in the entire study area were \(-\)0.29 \(\pm\) 0.14 m\(\cdot\)a\({}^{-1}\), \(-\)0.17 \(\pm\) 0.07 m\(\cdot\)a\({}^{-1}\), and \(-\)0.25 \(\pm\) 0.02 m\(\cdot\)a\({}^{-1}\), respectively. Using 850 \(\pm\) 60 kg\(\cdot\)m\({}^{-3}\) as the density conversion parameter, the average GMB in the Tailan River basin was calculated to be \(-\)0.34 \(\pm\) 0.05 m w.e.a\({}^{-1}\), \(-\)0.19 \(\pm\) 0.10 m w.e.a\({}^{-1}\), and \(-\)0.30 \(\pm\) 0.02 m w.e.a\({}^{-1}\), respectively.  
This paper compares and analyzes the GMB in the Tianshan area with other scholars' research. Based on the temperature index and accumulation model, [PERSON] et al. [71] reconstructed the annual, summer, and winter mean mass balance of Glacier No. 51 at Hasilegen Glacier in the eastern Tianshan Mountains from 1999 to 2015. The annual, summer, and winter mean mass balance of Glacier No. 51 were \(-\)0.37 m w.e.a\({}^{-1}\), \(-\)0.54 m w.e.a\({}^{-1}\), and 0.16 \(\pm\) 0.22 m w.e.a\({}^{-1}\), respectively. The results showed that temperature and annual precipitation were the main factors affecting the fluctuation of mass balance. [PERSON] et al. [72] used multiple remote-sensing data sources, such as MOD1C3 and TRMM3B43, and established a spatial distribution degree-day model to simulate the GMB in the north and south slope basins of the Tianshan Mountains. They obtained a mass loss  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Time** & \(\sigma_{Before}\) & \(\sigma_{Later}\) & _per_ \\ \hline
2000–2009 & 10.69 & 7.38 & 31 \\
2009–2022 & 10.54 & 7.90 & 25 \\
2000–2022 & 15.45 & 11.12 & 28 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Standard deviation of GSE change comparison before and after optimization.  
of \(-4.66\) mm w.e. and an annual change rate of \(-0.28\) mm w.e.a\({}^{-1}\) from 2000 to 2016. This study showed that glaciers in the Tianshan area have been in a negative GMB state since 2000 and confirmed the reliability of the estimated GMB in this paper.