Lake volume and potential hazards of moraine-dammed glacial lakes – a case study of Bienong Co, southeastern Tibetan Plateau

Abstract. The existence of glacial lakes in the southeastern Tibetan Plateau (SETP) is a potential hazard to downstream regions, as outburst such has result disastrous lake floods (GLOFs). In present study, we conducted comprehensive investigation Bienong Co, moraine-dammed SETP. First, basin morphology was determined, and volume estimated, showing that maximum depth ∼181 m ∼102.3×106 m3. These scenarios included possibility GLOFs being triggered by ice avalanches (Scenarios A1–3) from mother glacier or landslides lateral moraines B1–3 C1–3). Avalanche volumes nine trigger were obtained Rapid Mass Movement Simulation (RAMMS) modeling results. Next, Basic Environment for Computation Environmental Flow Natural Hazard (BASEMENT) model used simulate generation propagation avalanche-induced displacement waves lake. With model, overtopping flows erosion on moraine dam subsequent also simulated. results indicate avalanche scenario may cause largest mass entering lake, resulting wave up 25.2 amplitude (Scenario A3) near dam. Landslide with smaller waves. Scenarios A1, A2, A3 released water 24.1×106, 25.3×106, 26.4×106 m3, respectively. Corresponding peak discharges at are 4996, 7817, 13 078 m3 s−1, high dam, breach widths 295, 339, 368 m, respectively, generally similar approximately 19 m. landslide scenarios, only generated B3 C3 depths 6.5 7.9 153 169 According our simulations, A1–3 all flow through 18 settlements 20 h, threatening more than half them. Both produce first eight h have relatively small impact Comparisons area, depth, which bathymetry data available show Co deepest known same surface area Plateau. This study could provide new insight into SETP be valuable reference GLOF disaster prevention local government.