Présentations Colloques

Oral Presentation
8.10
Session 8.10: Recent developments in groundwater modeling and mathematical tools in Hydrogeology
Kukemilks Karlis
3D hydrogeological modeling of the Turaida castle mound under changing precipitation
In February 2002 three landslides occurred along the slopes of the Turaida castle mound, Central Latvia, causing damage to infrastructure and threatening the historical building. Several indications suggest that the landslides were caused by hydrogeological triggers- There was a lack of any elevated seismic activity and the landslides occurred at short intervals at different locations of the mound after an intensive snow melting. In the future more extreme precipitation events are expected in the study area, therefore the question arises whether this will result in elevated landslide activity.**To understand the hydrogeological landslide triggers, a high resolution 3D hydrogeological model of the castle mound was elaborated. Coupled flow of saturated, unsaturated, and fractured media under changing rain and snowmelt conditions was simulated using the HydroGeoSphere software. The hydraulic conductivities of the sediments were calibrated to fit the piezometer measurements using PEST code.**The hydrogeological model indicates the geological and climatic conditions, which cause the most critical groundwater heads for hillslope stability. **The geology of the study site is characterized by alternating Devonian clay and sandstone layers covered by glacial and anthropogenic deposits. Perched groundwater tables and springs discharging from fractures in sandstone layers can be observed.**The calibrated model confirms the geological evidence that perched groundwater tables can form in the study site. Moreover, the hydrogeological model can simulate different climatic scenarios, evaluate the influence of intensive rainfall events or snow melting on groundwater conditions and groundwater discharge from discrete fractures. This helps to determine the most critical hydrogeological scenarios for hillslope stability in the future which are useful for subsequent landslide risk mitigation in the Turaida castle mound.**
Germany