## 1 Introduction  
In recent years, the future of Himalayan glaciers has been a subject of intense debate [1] due to their significance in shaping the water resource outlook of the Indian subcontinent [2] and the risks posed by glacial lake outburst floods (GLOFs) [3]. Glacial lakes are a widespread phenomenon in glaciated regions globally [4, 5, 6]. When these lakes are impacted by ice or rock masses, overtopping or breaching of their natural dams can occur, leading to GLOFs that pose significant risks to downstream infrastructure and communities [7, 8]. GLOFs have caused substantial economic losses and fatalities worldwide [7, 8, 9, 10]. GLOFs typically involve a mixture of water and sediment that can travel distances ranging from tens to over 100 km at velocities exceeding tens of kilometres per hour, posing a serious threat to downstream settlements due to their high discharge magnitude and long runout distances [11]. Such cascading events are frequent in glacial valleys, where steep topography, rapidly retreating glaciers, and slope degradation expose unstable ground, potentially leading to new mass movement zones. These events result in a loss of life and property in downstream regions. Infrastructure, including hydroelectric facilities, has been severely damaged by floodwaters [7; 12; 13; 14], while roads, bridges, and buildings have been swept away or demolished [10]. Debris flows, commonly triggered by GLOFs, pose significant hazards. [PERSON] et al. [15] have used predictive modelling to highlight a concerning trend for the future, identifying around 5000 over-deepenings in Himalayan glacier beds that have the potential to evolve into significant glacial lakes. It has been reported that around three million people in India are at risk of exposure to GLOFs [16]. As mountain communities increasingly settle at higher elevations, the threat posed by GLOFs is expected to grow. The retreat of glaciers due to climate change is contributing to the formation of new glacial lakes and the expansion of existing ones [17; 18; 19]. As glaciers recede, they leave behind voids that progressively fill with meltwater, resulting in the formation of numerous glacial lakes [20]. This transformation involves melting glacier tongues that are gradually replaced by expanding water bodies. Under the changing climate realities, the issue of GLOFs is of major concern for the people of Sikkim. A recent example of a devastating GLOF in Sikkim includes the South Lhonak Lake overtopping on [21], which caused a huge loss of life and property in Sikkim and West Bengal in India and in parts of Bangladesh. Downstream flood risks from natural dams are fundamentally tied to the dam's ability to retain the impounded water. This capability can be compromised through several mechanisms, like overtopping due to extreme wave events, catastrophic structural failures, or accelerated erosive processes. In some cases, these failures may occur sequentially, resulting in a two-phase outburst flood Moraine-dammed glacial lakes are particularly vulnerable to such failures, as both overtopping and structural collapse can occur in these settings [22]. Moraine dams, which are formed from accumulated debris and sediment, are prone to failure under specific conditions. The likelihood of dam failure is influenced by several factors: (1) a small width-to-height (DWH) ratio of the dam, which implies a relatively steep and narrow structure; (2) high potential energy of the impounded water, which increases the force exerted on the dam; and (3) low internal cohesion within the moraine structure, which compromises the dam's stability [18; 22]. Geomorphological aspects, such as the moraine's volume, shape, and slope stability, also play critical roles. Moraines with a low DWH ratio are especially susceptible to failure due to their less stable geometry.