A conceptual model for glacial lake bathymetric distribution

Abstract. The formation and expansion of glacial lakes worldwide due to global warming and glacier retreat have been well documented in the past few decades. Thousands of glacial lake outburst floods (GLOFs) originating from moraine-dammed and ice-dammed lakes were reported, causing devastating impacts on downstream lives and properties. Detailed glacial lake bathymetry surveys are essential for accurate GLOF simulation and risk assessment. However, these bathymetry surveys are still scarce as glacial lakes located in remote and high-altitude environments hamper a comprehensive investigation. We developed a conceptual model for glacial lake bathymetric distribution using a semi-automatic simulation procedure. The basic idea is that the statistical glacial lake volume-area curves conform to a power-law relationship indicating that the idealized geometric shape of the glacial lake basin should be hemispheres or cones. First, by reviewing the evolution of various types of glacial lakes, we identified 10 standard conceptual models to describe the shape of lake basins. Second, we defined a general conceptual model to depict the continuum transitions between different standard conceptual models for those specific glacial lakes that lie between two standard conceptual models. Third, we nested the conceptual model into the actual glacial lake basin to construct the water depth contours and interpolate the glacial lake bathymetric distribution. We applied the conceptual model to simulate three typical glacial lakes in the Tibetan Plateau with in-situ bathymetric surveys to verify the algorithm's applicability. The results show a high consistency in the point-to-point comparisons of the measured and simulated water depths with a total volume difference of approximately ±10 %. The conceptual model has significant implications for understanding glacial lake evolution and modeling GLOFs in the future.