Scenario-Based GLOF Modelling and Flood Routing Analysis for the Gurudongmar Lake Complex, Eastern Himalayas

The Gurudongmar Lake Complex has been analyzed through five Glacial Lake Outburst Flood (GLOF) scenarios to assess potential dam breach impacts and downstream flood routing along the upper Tista River (see Excel Datasheet). Scenarios 1 to 3 simulate individual dam breaches at GL-1, GL-2, and GL-3, respectively, each with three breach magnitudes: 20%, 50%, and 80% of dam height (denoted as A, B, and C). These scenarios evaluate the standalone hazard posed by each lake. Scenarios 4 and 5 explore compound breach events involving upstream and downstream lake combinations. Scenario 4 models GL-2 breaching in conjunction with GL-1, while Scenario 5 involves simultaneous failure of GL-3 and GL-1. Each compound scenario includes the same three breach magnitudes for the upstream lake, combined with GL-1 breaching. These configurations help assess cascading effects and the amplified flood hazard resulting from multiple lake failures. Scenario 6, which considers the breaching of GL-4 in combination with GL-3 and GL-1, was not included in the study due to the very small area and volume of GL-4. It is unlikely to exert any significant hydrological influence on the larger downstream lakes. The model results include routed GLOF hydrographs at key locations along the upper Tista River: GL-1 outlet (0 km), Gaigong (16 km), Thangu Valley (32 km), Kunga (47 km), Lachen (54 km), and Chungthang town (74 km). These hydrographs help assess the progression and attenuation of flood waves under different breach scenarios, supporting hazard evaluation and early warning planning. This dataset is part of the research study: Chowdhury, A., Begam, S., Kroczek, T., Vilímek, V., Sharma, M.C., De, S.K., 2025. Erosional dam breach modelling for multi-glacial lake outburst process and downstream flood exposure assessment in the Eastern Himalayas. J. Hydrol. 649, 1–21. https://doi.org/10.1016/j.jhydrol.2024.132417.