1Geography, Engineering and Environment, Northumbria University, Newcastle upon Tyne, UK
2School of Geography, Queen Mary, University of London, London, UK
3Department of Geography and Earth Sciences, Aberystwyth University, Aberystwyth, Wales, UK
4Reynolds International Ltd, Suite 2, Broncoed House, Broncoed Business Park, Mold, UK
5HR Wallingford Ltd, Howberry Park, Wallingford, Oxfordshire, UK
6CH2M HILL, 304 Bridgewater Place, Warrington, Cheshire, UK
Received: 09 May 2014 – Discussion started: 13 Jun 2014
Abstract. The instability of moraine-dammed proglacial lakes creates the potential for catastrophic glacial lake outburst floods (GLOFs) in high-mountain regions. In this research, we use a unique combination of numerical dam-breach and two-dimensional hydrodynamic modelling, employed within a generalised likelihood uncertainty estimation (GLUE) framework, to quantify predictive uncertainty in model outputs associated with a reconstruction of the Dig Tsho failure in Nepal. Monte Carlo analysis was used to sample the model parameter space, and morphological descriptors of the moraine breach were used to evaluate model performance. Multiple breach scenarios were produced by differing parameter ensembles associated with a range of breach initiation mechanisms, including overtopping waves and mechanical failure of the dam face. The material roughness coefficient was found to exert a dominant influence over model performance. The downstream routing of scenario-specific breach hydrographs revealed significant differences in the timing and extent of inundation. A GLUE-based methodology for constructing probabilistic maps of inundation extent, flow depth, and hazard is presented and provides a useful tool for communicating uncertainty in GLOF hazard assessment.
Revised: 08 Feb 2015 – Accepted: 16 Feb 2015 – Published: 16 Mar 2015
Westoby, M. J., Brasington, J., Glasser, N. F., Hambrey, M. J., Reynolds, J. M., Hassan, M. A. A. M., and Lowe, A.: Numerical modelling of glacial lake outburst floods using physically based dam-breach models, Earth Surf. Dynam., 3, 171-199, doi:10.5194/esurf-3-171-2015, 2015.