Hydrogeological pattern of groundwater flow of landslides in Cretaceous claystones based on long-term groundwater monitoring and hydrologging measurement

摘要

Long-term groundwater monitoring has been carried in the model locality of the landslide area at Treb-enice, situated in the northern part of the Czech Republic in Cretaceous claystones to marlstones. Primarily, long-term fluctuation of the groundwater and piezometric levels has been monitored. Monitoring of groundwater flow was carried out in selected wells also by the photometry logging method using a dilution technique of a marked liquid. On the basis of these results, the pattern of the groundwater flow through the landslide area was determined in lithologically homogeneous Cretaceous claystones to marlstones. Interpretation of monitoring results indicated that water flows preferentially through the zone of near-surface loosening of the claystone rock massif, in general parallel to the slope inclination between 8 and 10-m depth below ground level. This zone exhibits a higher permeability given by 1-2 orders of hydraulic conductivity compared with overlying strata and underlying rock in which this zone is closed. This verified pattern of groundwater flow has a significant effect on the stability of the sliding slope and it is one of the main factors affecting the evolution of landslides on the slopes formed by these rocks.