Development of a GIS-based Open Source Simulation Tool for Modelling General Avalanche and Debris Flows over Natural Topography

灾难性的颗粒和泥石流发生在世界各地的许多山区。雪崩、岩石或岩冰雪崩、泥石流、火山泥流和火山碎屑流只是其中的一些例子。要充分管理与这些现象有关的风险，就需要对这些过程所涉及的机制进行详细和可靠的分析。尽管在这个问题上已经做了大量的工作，并且确实存在一些复杂程度不同的基于物理的模型，但仍有一些问题尚未解决：(1)任意地形上的流动，粘性孔隙流体的作用或流动的两相性质，以及颗粒和/或流体夹带的作用尚未得到适当的解释。(2)到目前为止，还没有成功的尝试为这些复杂的模型构建易于处理的开源应用程序，而这对于使它们在大学和公共服务中提供给更广泛的用户群体至关重要。这一建议为这两个问题提供了一个有效、创新和统一的解决方案。因此，它关注的是快速的地球物理物质流动，包括雪崩和真正的两阶段泥石流，从一个已知的起始带通过沿自然山地地形的流动路径进入沉积带。对于起始带中给定数量的质量及其分布，我们感兴趣的是沿任意地形轨迹的运动和几何变形，包括沿轨迹的侵蚀和沉积过程以及沉积质量的最终分布。这也将包括动态演化的孔隙流体压力和/或固体和流体组分演化的影响。同样重要的重点应放在开发已开发模型的用户友好且可自由访问的应用程序上。这个应用程序将建立在GIS软件GRASS的基础上，GRASS是GNU通用公共许可证下的开源产品。新软件将使用物理模型测试和充分记录的质量流动事件进行评估。这些测试将涵盖广泛的过程和过程链，包括泥石流、碎片雪崩和雪或岩石雪崩。

Catastrophic granular and debris flows occur in many mountain areas all over the world. Snow avalanches, rock or rock-ice avalanches, debris flows, lahars and pyroclastic flows are only some examples. An adequate management of the risk related to these phenomena requires a detailed and reliable analysis of the mechanisms involved in such processes. Even though much work has been done on this subject, and a number of physically-based models with a varying degree of complexity do exist, some problems still remain unsolved: (1) Flow over arbitrary topography, the role of viscous pore fluid or two-phase nature of flow, and particle and/or fluid entrainment have not yet been accounted for in an appropriate way. (2) Until now, no successful attempts have been made to build easy-to-handle Open Source applications of these complex models, which would be essential to make them available to a broader group of users in universities and public services.This proposal offers an effective, innovative and unified solution to these two problems. It is therefore concerned with rapid geophysical mass flows, including avalanches and real two-phase debris flows, from a known initiation zone through the flow path along natural mountain topography into the deposition zone. For a given amount of mass and its distribution in the initiation zone, we are interested in the motion and geometric deformation along the track down the arbitrary topography, including the processes of erosion and deposition of mass along the track and the ultimate distribution of the deposited mass. This will also include the effect of dynamically evolving pore fluid pressure and/or evolution of the solid and the fluid components. An equally important focus shall be put onto the development of a user-friendly and freely accessible application of the developed model. This application will build upon the GIS software GRASS, which is available as an Open Source product under the GNU General Public License. The new software will be evaluated using physical model tests and well-documented mass flow events. These tests will cover a broad range of processes and process chains including debris flows, debris avalanches and avalanches of snow or rocks.