Collaborative research: Development of sliding laws for glacier-flow and landscape-evolution models

通过这个项目，建立了预测冰川和冰盖滑动速度(即滑动规律)所需的数学关系。现有滑动定律形式的可变性增加了冰川流动计算机模型结果的主要不确定性。这些计算机模型是用于评估下个世纪冰川损耗和由此导致的海平面上升以及研究冰川对岩石侵蚀的主要工具。这项工作通过从冰川床的实际地形中得出滑动定律，并将冰川内外碎屑的摩擦阻力纳入其中，改进了滑动定律。因此，这项研究有可能改进对冰川流动模型的预测和对其不确定性的评估。现场和实验室测量与3D流动建模相结合，目标是完全限定可能的滑动行为范围。加拿大和瑞士的冰川消退暴露出的冰床地形是以高分辨率测量的，并进行了统计描述。此外，滑动的摩擦阻力也是在实验室实验中测量的，在实验中，含有碎屑的冰在岩床上滑动。这两组测量用于冰川滑动的数值模拟，得出了滑动速度、床面应力、床面地形、冰中碎屑浓度以及将冰和岩石分开的饱和水沉积物的面积范围之间的关系。

With this project, mathematical relationships needed to predict the sliding speeds of glaciers and ice sheets (that is, sliding laws) are developed. Variability of the forms of existing sliding laws adds major uncertainty to the results of computer models of glacier flow. These computer models are the principal tools used to both assess glacier wastage and resultant sea-level rise over the next century and to study rock erosion by glaciers. This work improves sliding laws by deriving them from the actual topography of glacier beds and incorporating the frictional resistance of debris within and underneath glaciers. Thus, this study has the potential to improve predictions of glacier-flow models and assessments of their uncertainty.Field and laboratory measurements are combined with 3D flow modeling, with the goal of fully bracketing the range of sliding behavior possible. The topography of glacier beds exposed by receding glaciers in Canada and Switzerland is measured at high resolution and statistically described. Also, frictional resistance to slip is measured in laboratory experiments in which ice containing debris is slid over a rock bed. These two sets of measurements are used in numerical simulations of glacier sliding that yield relationships among sliding speed, stresses at the bed, bed topography, debris concentration in ice, and areal extent of water-saturated sediment dividing ice from rock.