Speleogenesis and Hazards in Karst: Observing, Modeling, Predicting

碳酸盐和硫酸盐基岩覆盖了地球陆地表面的10%以上。基岩为世界上25%的人口提供水，可以被水溶解。岩溶作用在很大程度上控制着岩溶区的演化。在喀斯特地貌中，水从地表消失，在向下流动的过程中，大气和土壤中的二氧化碳使其变得更加丰富。生成的弱碳酸能够在岩石表面和岩石中的小裂隙中溶解碳酸盐岩石。方解石的化学溶解导致裂隙和层面的扩大，导致岩石渗透率的急剧增加，随着时间的推移，越来越多的水被捕获并通过扩大的裂隙和层理裂隙带到地下。岩溶系统的演化是以不同的步骤进行的：(I)最初，水主要从地表流向区域基准面，例如河流。通过含水层的水流是扩散的，速度很慢。地表径流对岩溶面的演化是有效的。(2)随着时间的推移，化学溶蚀作用扩大了地下结构(裂隙、层理)，次生孔隙度成倍增加，地下流动占主导地位。扩大的裂缝形成洞穴系统，有效地排干了集水区，水迅速被输送到大型岩溶泉水中。地表径流变得时断时续，而且将变得稀少。在这个项目中，岩溶作用是用一个数值模型--CAST1工具模拟的，它描述了岩溶系统上和内部的流动和演化。该数值算法将模拟喀斯特地貌的典型特征，如地貌演变，包括侵蚀、扩散和剥蚀，以及扩大的裂隙、层面和岩石基质中的流动和运移。将尝试产生特定的岩溶环境，如德国南部斯瓦比安阿尔布的浅层和深层岩溶含水层，但也将产生深层高山系统，如瑞士阿尔卑斯山的长洞系统。

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.