## 5 Results and Discussions
### Numerical Stability Analysis for Increased Lake Water Level  
The stability of the moraine sediment dams labelled AB, CD, and EF, as illustrated in Figure 1, was analysed. The moraine sediment dam AB, positioned towards the north of the lake, is strategically located near the lake's discharge site. This placement has resulted in an excavation approximately in the middle of the dam, which plays a crucial role in maintaining a relatively static water level in the lake. The other two dams, CD and EF, are situated at the western and eastern edges of the lake, respectively. Among the three dams, dam AB exhibits notably higher cohesion (c) values compared to dams CD and EF. Cohesion is a critical parameter in assessing the shear strength of soil and influences the stability of the dam structures. The higher cohesion observed in dam AB suggests that its materials have a greater internal strength, which enhances the dam's resistance to shear forces and potential failure. This increased cohesion can be attributed to variations in the \begin{table}
\begin{tabular}{l l l l l} \hline
**Parameter** & **Symbol** & **Unit** & **Silty Sand (Loose)** & **Silty Sand (Dense)** \\ \hline Material model & Model & - & M-C & M-C \\ \hline \multicolumn{5}{c}{AB section} \\ \hline Total unit weight & \(\gamma_{\text{unsat}}\) & \(\text{kN}/\text{m}^{3}\) & 17 & 19 \\ \hline Saturate unit weight & \(\gamma_{\text{sat}}\) & \(\text{kN}/\text{m}^{3}\) & 20 & 22 \\ \hline Young’s modulus & E & MPa & 15,000 & 30,000 \\ \hline Friction angle & \(\phi\) & 0 & 10 & 18 \\ \hline Cohesion & c & \(\text{kN}/\text{m}^{2}\) & 65 & 125 \\ \hline Dilatancy & \(\psi\) & Degree & - & 6 \\ \hline Poisson’s ratio & \(\
u\) & - & 0.38 & 0.32 \\ \hline Permeability & k & m/day & 0.0018 & 0.00096 \\ \hline \multicolumn{5}{c}{CD section} \\ \hline Total unit weight & \(\gamma_{\text{unsat}}\) & \(\text{kN}/\text{m}^{3}\) & 19 & 21 \\ \hline Saturate unit weight & \(\gamma_{\text{sat}}\) & \(\text{kN}/\text{m}^{3}\) & 22 & 23 \\ \hline Young’s modulus & E & MPa & 8 & 14 \\ \hline Friction angle & \(\phi\) & 0 & 12 & 20 \\ \hline Cohesion & c & \(\text{kN}/\text{m}^{2}\) & 35 kPa & 105 kPa \\ \hline Dilatancy & \(\psi\) & Degree & - & 8 \\ \hline Poisson’s ratio & \(\
u\) & - & 0.42 & 0.34 \\ \hline Permeability & K & m/day & 0.00236 & 0.000864 \\ \hline \multicolumn{5}{c}{EF section} \\ \hline Total unit weight & \(\gamma_{\text{unsat}}\) & \(\text{kN}/\text{m}^{3}\) & 16 & 20 \\ \hline Saturate unit weight & \(\gamma_{\text{sat}}\) & \(\text{kN}/\text{m}^{3}\) & 19 & 22 \\ \hline Young’s modulus & E & MPa & 10 & 28 \\ \hline Friction angle & \(\Phi\) & 0 & 12 & 24 \\ \hline Cohesion & c & \(\text{kN}/\text{m}^{2}\) & 47.5 kPa & 115 kPa \\ \hline Dilatancy & \(\psi\) & Degree & - & 8 \\ \hline Poisson’s ratio & \(\
u\) & - & 0.30 & 0.24 \\ \hline Permeability & k & m/day & 0.00138 & 0.00090 \\ \hline \end{tabular}
\end{table} 
Table 1: Material properties of moraine sediment dams at the AB, CD, and EF sections. sediment composition, consolidation due to traffic load, or soil characteristics at the dam AB site. In contrast, the lower cohesion values in dams CD and EF indicate that these dams may have relatively weaker internal bonding among the sediment particles, potentially affecting their stability under load. The differences in material properties among the dams are crucial for understanding their stability and performance, particularly in scenarios involving rising water levels or other stress factors. To assess the stability of three moraine sediment dams, designated AB, CD, and EF, and to evaluate the consequences of their potential failure due to rising water levels in Gurudongmar Lake, the non-linear finite element software PLAXIS 2D 8.6 was utilised. This widely recognised programme is extensively used by geotechnical engineers to analyse the stability of earth structures and slope stability.