Speleogenesis and Hazards in Karst: Observing, Modeling, Predicting

碳酸盐岩和硫酸盐岩覆盖了地球陆地表面的10%以上。为世界25%的人口提供水的淡水石可以被水溶解。岩溶作用是控制岩溶区演化的重要因素。在喀斯特地貌中，水从地表消失，在下降的过程中，它被大气和土壤中的二氧化碳所富集。由此产生的弱碳酸能够溶解碳酸盐岩，无论是在岩石表面还是在岩石中的小裂缝内。通过方解石的化学溶解，裂缝和层面的扩大导致岩石渗透性的急剧增加，随着时间的推移，越来越多的水被捕获并通过扩大的裂缝和层面夹层携带到地下。岩溶系统的演化分不同的步骤进行：（i）最初，水主要从地表流向区域基准面，如河流。通过含水层的水流分散而缓慢。地表径流是岩溶地表演化的有效因素。(ii)随着时间的推移，化学溶解扩大了地下结构（裂缝，层面），次生孔隙度增加了许多倍，地下流动成为主导。扩大的裂缝变成了洞穴系统，有效地排干了集水区，水被迅速带到了大的岩溶泉。地表径流变得断断续续，并将稀疏。在这个项目中，岩溶作用是用一个数值模型，KARST 1工具，它描述了流动和演变的岩溶系统。数值算法将模拟喀斯特景观的典型特征，例如景观演变，包括侵蚀、扩散和剥蚀，以及扩大的裂缝和层面以及岩石基质中的流动和运输。将尝试生成特定的岩溶环境，如德国南部斯瓦比亚阿尔卑斯山的浅层和深层岩溶含水层，以及瑞士阿尔卑斯山的长洞穴系统等深层高山系统。

Carbonate and sulfate bedrocks cover more than 10% of the land surface of the Earth. The bedrocks, which provide water for 25% of the world’s population, can be dissolved by water. The dissolution process, termed karstification, largely controls the evolution of the karst region. In a karst landscape, water disappears from the surface, and on its way down it is enriched by carbon dioxide from the atmosphere and the soil. The resulting weak carbonic acid is able to dissolve carbonate rocks, both on the rock surface and within small fractures in the rock. The enlargement of fissures and bedding planes through chemical dissolution of calcite results in a dramatic increase in permeability of the rock, and with time more and more water is captured and carried subsurficially through enlarged fissures and bedding partings. The evolution of a karst system occurs in distinct steps: (i) Initially, water mainly runs off the surface towards a regional base level, e.g. a river. Flow through the aquifer is diffuse and slow. The evolution of the karst surface is effective due to the surface runoff. (ii) With time, the chemical dissolution has enlarged subsurface structures (fissures, bedding planes), and the secondary porosity increases manyfold, with subsurface flow becoming dominant. Enlarged fractures become cave systems, which efficiently drain the catchment, and water is rapidly carried to large karst springs. Surface runoff becomes episodic and will be sparse. In this project, karstification is simulated with a numerical model, the KARST 1 tool, which describes flow and evolution on and in the karst system. The numerical algorithm will simulate typical characteristics of a karst landscape, such as landscape evolution including erosion, diffusion, and denudation, as well as flow and transport in the enlarged fissures and bedding planes and the rock matrix. An attempt will be made to generate specific karst settings such as shallow and deep karst aquifers of the Swabian Alb in South Germany, but also deep alpine systems such as the long cave systems in the Swiss Alps.