Petra Đomlija

Landslide Inventory in the Area of Dubračina River Basin (Croatia)

Systematic landslide mapping was performed for an area of 9.35 km2 of the geomorphological unit of hills in the Dubracina River Basin. Based on the visual interpretation of LiDAR imagery, supplemented by field reconnaissance mapping of damaged roads and structures, 48 landslides were identified. In this first phase of landslide inventory preparation for the area of the Dubracina River Basin, a preliminary landslide inventory map presents data on locations of all identified landslides. Three examples of identification of landslide contours are given to show different possibilities in visual interpretation of airborne LiDAR imagery.

The Croatian-Japanese SATREPS Joint Research Project on Landslides (IPL-161)

The Croatian-Japanese joint research Science and Technology Research Partnership for Sustainable Development (SATREPS) project ‘Risk Identification and Land-Use Planning for Disaster Mitigation of Landslides and Floods in Croatia’ was performed from 2009 to 2014. Key objectives of the project were landslides and floods hazard analysis and the development of guidelines for use in urban planning. This project is also designated as on-going IPL project 161. The aims of the working groups dealing with landslides were to establish a methodology of comprehensive real time monitoring at two most important landslides in Croatia based on the results of previous investigations and new in situ and laboratory testing and behavior analysis; laboratory soil testing and numerical modelling of static and dynamic landslide behavior; development of landslide inventories using direct sensing and remote sensing techniques followed by the development of methodologies of landslide hazard analysis and zonation in three pilot areas in Croatia. In this paper we will present the most important achievements of working groups related to landslide studies at the project pilot areas: two in Primorsko-Goranska County (the Rjecina River Basin and the Dubracina River Basin) and one in the City of Zagreb (a hilly area of Medvednica Mt.). The identification and mapping of existing landslides in the hilly area of Medvednica Mt., Dubracina River Basin and Rjecina River Basin so as establishment and results of the monitoring systems installed on the Grohovo Landslide and the Kostanjek Landslide will be described.

Landslide Risk Reduction in Croatia: Scientific research in the framework of the WCoE 2014- 2017, IPL 173, IPL 184, ICL ABN

In this paper scientific activities of the Croatian Landslide Group (CLG), World Centre of Excellence on Landslide Risk Reduction (WCoE) of the International Consortium on Landslide (ICL) for the period 2014–2017, are shortly described. The results of scientific research are presented through the fields of landslide science: landslide identification and mapping, landslide investigation and testing, landslide monitoring, landslide modelling and landslide stabilization and remediation. It is concluded that the resulting landslide inventory maps, regional empirical rainfall intensity-duration thresholds, kinematic landslide models and soil strength parameters, landslide movement prediction models, numerical models and simulations and behavior of geotechnical construction for landslide stabilization provide necessary information for landslide risk management in Croatia. Besides applied scientific research, the general objectives of ICL WCoE are achieved in the framework of two Croatian IPL Projects and regional ICL Adriatic-Balkan Network.

Diversity of Materials in Landslide Bodies in the Vinodol Valley, Croatia

Numerous landslides of different types present common hazardous phenomena in the Vinodol Valley (64.57 km2), situated near the City of Rijeka in coastal part of Croatia. During the previous and present geological investigations in the Vinodol Valley almost all landslide types were identified: falls, topples, slides and flows. The Vinodol Valley is characterized by irregular shape and a range of different landforms due to complex geological and geomorphological conditions. The inside of the valley is built of Paleogene siliciclastic (flysch) deposits, which is surrounded by the relatively steep carbonate borders composed of Upper and Cretaceous limestone. Along the most part of the NE border vertical rocky cliffs occur. The lower parts and the bottom of the valley (i.e., flysch deposits) are covered by heterogeneous Quaternary superficial deposits. In the Vinodol Valley more than 200 active and dormant landslides in soils were identified. Most of the active landslides are covered by dense forest vegetation. Original landslide topographies of dormant landslides are significantly modified by the anthropogenic agricultural activities. For this reason, the appropriate landslide identification and mapping method is the visual interpretation of the high-resolution LiDAR-derived imagery. Identified landslides are generally shallow to moderate shallow, with slip surface depth of several meters, and small to moderate small, with volumes in a range of 103–105 m3. Due to the diversity of geological conditions in the Vinodol Valley and the large number of identified landslides, the index and classification properties of soils from the landslide-forming materials were investigated. Soil samples were taken and laboratory tested according to the rules of the European Soil Classification System. In this paper, results of preliminary investigations of the relationship between the different types of landslides and the landslide-forming materials are presented.

Remedial Works on the Smrecje Landslide, Croatia

The Smrecje Landslide was occurred on the county road near the Gerovo village in Gorski Kotar region, Croatia, before more than 10 years. The landslide location is forming in clastic formations of shale, sandstone and marl rock masses from Triassic age. The landslide was overtaken 100 m long part of the road construction. The instability was evidenced in long term creep process with deformation increments associated with the seasonal water content variations in the clayey superficial deposit. Deformations on the pavement construction were reaching unacceptable values during 2008 that caused necessity of complete landslide remediation. Field investigations were executed and the remediation measures were designed. Field investigations were included investigation drilling, soil and rock mass samples taken, geophysical measurements using seismic refraction and geoelectrical tomography techniques so as engineering geological surface mapping. In the paper we will present description of the Smrecje landslide, results of the conducted field investigations, so as designed remediation measures. Based on the remediation design, the remediation works were constructed in the spring 2009.