Numerically simulating alpine landscapes: The geomorphologic consequences of incorporating glacial erosion in surface process models

A numerical model that simulates the evolution of glaciated mountain landscapes is presented. By employing a popular, sliding based, glacial erosion model, many common glacial landforms are created. The numerical model builds on earlier work as it is fully two-dimensional and employs the first order forcing on mountain evolution. These forcings include tectonic uplift, isostasy, hillslope processes, fluvial processes, and glacial processes. A climate-dependent model of ice dynamics is employed to determine ice coverage and ice flux. Two simulations are presented; one with generic model parameters, and a second with parameters that correspond to conditions in the Southern Alps of New Zealand. Landforms that are produced by the model include climate climate-dependent elevation lowering, similar to what might be expected by a "glacial buzz-saw", valley overdeepening, terminal moraines, and valley retreat. The model also predicts that current rates of sedimentation are higher than the long-term average, and that several tens of thousands of years are required for the landscape to adjust to a change in the dominant erosional forcing. Therefore, glaciated orogens are unlikely to achieve topographic steady state over Milankovitch timescales.