Karst aquifers form the most significant groundwater reserve in Switzerland. 18% of the drinking water is exploited from these aquifers. In spite of this significance, they are poorly documented as concepts and tools dedicated to their systematic characterisation did not exist. As a consequence karst aquifer documentation was of variable quality and precision, but generally quite low in Switzerland. Management strategies were therefore often arbitrary and far from optimal. Insufficient knowledge of karst systems and the absence of methods to improve this situation made the implementation of more adequate management very difficult. During the last 15 years the needs for better documentation increased as new types of projects (e.g. windmills) were carried out. Researchers at the Swiss Institute for Speleology and Karst Studies (SISKA) worked on various cases and realised that the scientific background was available to design a clear workflow for setting up a model of karst hydrogeological systems.
Within the scope of the Swisskarst project, SISKA therefore developed a systematic and pragmatic approach to characterise karst aquifers and systems. This approach, called “KARSYS”, provides concrete 3D models of the aquifers which can directly be used for the management of karst groundwater. These models address three basic questions: (1) Where does the water emerging at a karst spring come from? (2) Which underground routes does it flow through? (3) What are the groundwater reserves and where are they located? This approach was developed in order to be applicable with a reasonable effort. Results must also be usable for further refinement such as flow modelling.
The main outcome of a KARSYS application is a 3D conceptual hydrogeological model of the study area, including a characterisation of aquifers and flow systems. As practitioners often prefer to use maps and profiles, four standard documents have been developed to synthetise and visualise the results of the approach: (1) a karst hydrogeological map based on a standardised mapping process, (2) an identity card of the system which gathers the main characteristics of the systems, (3) an interactive and ready-to-use 3D model of the system and (4) a list of literature on the investigated system. Depending on further application, other outputs may be derived from the approach in order to address any specific question. As the KARSYS approach is systematic and iterative, most of these outputs are automatically processed and regularly updated with the integration of new data and/or the correction of previous ones. The four documents provide a set of normalised and reproducible indicators which can be directly compared for all the documented systems.
The approach and by extension the project provides useful indications for the exploitation and the management of karst groundwater, such as for geothermal or hydropower energy production or for the prevention of natural hazards, or even for the assessment of civil engineering projects in karst environments. KARSYS was already utilised for a large number of applied questions, according to various demands of water authorities and users for the period 2010-2013. This induces a constant improvement of the approach and of its outputs. Concerning academic research, the approach pro-vides a consistent base to any hydrodynamic simulation of the system.
Towards a sustainable management of karst waters in Switzerland (SWISSKARST)