engleski

Kostanjek landslide - Analyses of groundwater discharge as a basis for the new hydrological monitoring

Kostanjek landslide is the largest landslide in the Republic of Croatia. It is located in the western part of the City of Zagreb, in residential area at the base of the southwestern slope of Medvednica Mt. In the frame of the Japanese-Croatian five-year scientific joint-research project ‘Risk Identification and Land-Use Planning for Disaster Mitigation of Landslides and Floods in Croatia’ initial investigations related to hydrological conditions at the landslide area are undertaken in the period 2010-2011. The objectives of hydrological investigations are: study of influence of groundwater movements dynamics to sliding and identification of possible changes of groundwater level and discharge regime during the longer time period - from the end of the eighties and beginning of nineties of the last century. Through several series of simultaneous measurements of groundwater discharge in wider landslide area (tunnel in former marl quarry, spring in Bizek quarry, stream Dolje) during the first half of 2011, initial information necessary for planning of more detailed hydrological monitoring were gathered. It was found that the measured flow at the exit of the tunnel range within values which was already recorded twenty years ago, respectively between 4.8 and 10.9 l/s, and that during this period there were no significant change in the drainage function of the tunnel. It was also confirmed that the majority of flow rate in the tunnel appears as consequence of leakage from springs located in the upper part of the tunnel, while the increase of the flow of approximately 20% towards the tunnel exit is a consequence of further groundwater drainage, probably from the overlying deposits. Measurements in the Dolje stream showed that in all conditions the flow at the spring (Bizek quarry) is 22-26% higher than in the downstream profile, even in case when measurements are conducted immediately after the rainfall, when the difference was slightly smaller - about 10%. Results of simultaneous measurements present a good base for implementation of planned continuous groundwater discharge monitoring on wider influential area of the Kostanjek landslide.

Kostanjek landslide; hydrological conditions; discharge measuring

nije evidentirano