A method based on iterations
3D Geological model. A usefull overview..
In association with the fact files, a 3D geological model of each karst system is proposed. This geometric view of the aquifer system is a meaningful way to approach locations, dimensions and circulations of the karst water.
Implementing and defining the model is seen like the basic step of the first karst system conceptualization. In order to answer technical question occurring in the model, a further iteration of the model will be driven to enhance the precision of the limits and the contents of the karst system.
The geological model is based on:
- Relief data elevation
- Geological data: lithology and stratigraphy
- Structural information: folds, faults, overlap…
- Hydraulic data: springs location, cave observations, borehole logs, dye tracer tests…
3D geological models are available by localization on the Interactive map. They may although be found by canton on this list .
In order to manipulate the pdf3D a dedicated tab is there proposed.
Late 2010, the canton Vaud was the first canton to be modeled. The cantons of Freibourg and Bern started to be modeled in 2011. The modeling of the other cantons will follow.
The geological 3D model is a step by step construction (Beuchire case study, Jura)
Behavior of the water in the karst system
The evaluation the potential energy of a perched karst aquifer or estimate the overflowing stage of a temporary spring requires numerical simulations of the karst systems.
The KARSYS method provides the geological model which forms the basis for understanding and reproducing the water behavior in low water stage as well as in high water stage according to (i) the recharge process on the catchment area and (ii) the interactions between adjacent water bodies depending on the water level.
Springs discharge fluctuations, meteorological data and relief elevation models are the basis necessary information to simulate the hydrological karst system behavior. Precise simulations improve the understanding of karst systems and contribute to the sustainable management of groundwater resources.
Simulations are wide range applied:
- Groundwater resources and reserves volume evaluation;
- Natural hazard evaluation;
- Hydroelectric potential evaluation;
- Geothermic potential evaluation;
- And many others.
Relevance of the karst system 3D model is tested by simulation. This model of karst aquifer response to rainfall is adapted to the observations of usual discharges and high water peaks. This model should make it possible to understand better the hydraulic behaviour of the springs.
Thanks to the model estimation of the impacts of various regional climate change scenarios on the response of the springs will be tested. According to the variability of the considered scenarios, the model would be able to predict the spring response to extreme conditions induced by trends of the Global Climate Change. Appropriated preventive measures could then be taken in concordance to the simulation results.
Example 1: the Flims case study.
Simulation of behavior of the Prau Pultè spring, the Tunnel spring and the lag Tiert spring, which feed the Cauma lake, have been undertaken, in order to understand the fluctuations of the lake table since the Flims tunnel drilling. The aim of the study is to restore as well as possible the situation before the driling.
Complex behavior of the Cauma lake (Flims case study)
Simulated fluctuations of the Cauma lake feet the mesured signal...
Example 2: The HydroVaud project.
The project was to evaluate the hydroelectrical and geothermic potential of 57 karst systems distributed in Jura and Alps area of the Vaud canton. Hydrological simulations take into account hydraulic potential of perched aquifers and specific discharges of the associated springs or drains.
The results are translated in power production units (MW).
Hydroelectric potential of Vaud Jura karst sytems in MW