Assessing economic impacts of future GLOFs in Nepal’s Everest region under different SSP scenarios using three-dimensional simulations

Abstract. This study investigates simulated glacial lake outburst floods (GLOFs) at five glacial lakes in the Everest region of Nepal using the three-dimensional model OpenFOAM. It presents the evolution of GLOF characteristics in the 21^st century considering different moraine breach scenarios and two Shared Socioeconomic Pathways scenarios. The results demonstrate that in low-magnitude scenarios, the five lakes generate GLOFs that inundate between 0.35 and 2.23 km² of agricultural land with an average water depth of 0.9 to 3.58 meters. These GLOFs reach distances of 59 to 84 km, affect 30 to 88 km of roads, and inundate 183 to 1,699 buildings with 1.2 to 4.9 m of water. In higher scenarios, GLOFs can extend over 100 km and also affect larger settlements in the foothills. Between 80 and 100 km of roads, between 735 and 1,989 houses and between 0.85 and 3.52 km² of agricultural land could be inundated, with average water depths of up to 10 meters. The high precision of the 3D flood modeling, with detailed simulations of turbulence and viscosity, provides valuable insights into 21^st-century GLOF evolution, supporting more accurate risk assessments and effective adaptation strategies.