The analysis of the flysch badlands inventory in central Istria, Croatia

The south-western part of Croatia, i.e. the area of central Istria (the research area, approximately 500 km2) is characterized by flysch complex with a great number of isolated relief landforms – badlands. The importance of badlands (areas with sparse or no vegetation) is in the fact that the sediment production from these areas is 8000 higher than from the areas with vegetation. In this paper the badland inventory for the area of research is presented with 5568 badlands (polygons) singled out with total badland area of 10.7 km2. Spatial analysis of the badland inventory showed that concentrated erosive channel flow at steep slope foot is the most important factor in the badland forming and development for the area of central Istria

Landslide inventory and characteristics, based on LiDAR scanning and optimised field investigations in the Kutina area, Croatia

This paper presents the preliminary results of analyses of landsliding processes derived from detailed LiDAR (Light Detection and Ranging) scans supported by field prospection on the south-western slopes of Mt. Moslavačka gora, in the wider Kutina area. This area is known for frequent landslides, but dedicated regional landslide research has not been previously undertaken. High resolution LiDAR scanning and orthophoto imaging enabled the production of a reliable landslide inventory, but also enabled research on landslide properties and the morphology of the area. Field mapping and prospection, sampling and borehole coring assisted in the collection of information about the material characteristics and specific features of typical landslides. In the research area, which covers more than 71 km2, more than 1200 very small landslides were detected. The majority of landslides were discovered in just several geological units indicating their high susceptibility: Pleistocene silts and sands with clayey interlayers, followed by M2 silty sands and gravels, and M7 sands. Nearly half of the landslides are estimated to be of recent and younger age, while other landslides may be considered as being historical implying a “long tradition” of landslide events in the research area. Preliminary terrain surface roughness analysis also supported the conclusion that the inventory contains landslides of several historical generations which are still detectable. In addition to slides (1123), this research also discovered numerous earthflow processes (143), which are more frequent in the predominantly sandy units. The landslides in this area are largely located on the banks of the gullies and are directly related to the action of water. Regarding that situation and the engineering properties of the encountered geological units, four types of bank instabilities can be differentiated: slides on top of rock masses; slides in firm soil mixtures; landslides in sands; landslides in predominantly coherent soil complexes

Specific aspects of engineering-geological models in Croatian karst terrain

The experiences of developing engineering geological models in karst areas for designing and construction purposes prove the necessity of considering at least three basic submodels: sedimentological, structural-tectonic and the weathering one. The research presented here deals with very important and frequently neglected segments in each of the submodels. Therefore, particular attention should be directed to: better understanding of carbonate sediment deposition, determination of environment and diagenetic processes, study of the 3D anisotropy of discontinuity frequency, and differentiation of weathering zones. The given data and examples elaborate and justify such an approach, which enables a more realistic detailed engineering model, more reliable evaluations of the engineering geological/geotechnical parameters and real site conditions

Engineering-geological and geotechnical properties of flysch formations in Kaštela region

Prikazuju se geološke i inženjerskogeološke značajke fliša u području Kaštela. Definirani su i opisani egzogenetski procesi koji karakteriziraju istraživano područje. Naslage fliša razdijeljene su prema morfološkom i sedimentološkom kriteriju što je omogućilo odvojeno sagledavanje njihovih inženjerskogeoloških značajki. Posebna pažnja usmjerena je definiranju inženjerskih značajki izdvojenih litoloških jedinica unutar fliša kojima su pridodane karakteristične GSI vrijednosti.Geological and engineering-geological properties of flysch in the region of Kaštela are presented. Exogenetic processes characterizing the area under study are defined and described. Flysch formations are classified according to morphological and sedimentological criteria, which has enabled a separate study of their engineering-geological properties. A particular attention is paid to the definition of engineering-geological properties of lithological units identified in the flysch and, in this context, typical GSI values are allocated to such units

UTJECAJ KISELIH KIŠA NA LITOTAMNIJSKI VAPNENAC NA GALERIJI KATEDRALE MARIJINOG UKAZANJA, ZAGREB, HRVATSKA

Urban, environmental pollution, caused by acid rains and damages of stone elements on Cathedral of Zagreb are described. On the surfaces of limestone elements that are in the »shade«, the black scabs have developed. The outher crusts, and inner powdery matter of the black scabs have been investigated by microscopy, and analyzed by means of x-ray. thermal and chemical analyses. They contain gypsum, calcite, soot, and sporadic fly ash.Opisani su zagađenje urbanog okoliša, sastojci kisele kiše i oštećenja kamenih elemenata galerije zagrebačke katedrale. Na površini vapnenačkih elemenata koji su u »sjeni« nastale su crne kraste. Vanjske kore i unutarnja praškasta tvar crnih krasta analizirane su mikroskopski, rendgenski, termički i kemijski. Sadrže gips, kalcit, čadu i ponekad lebdeći pepeo

Engineering properties of marine sediments in Mali Ston Bay (Croatia) based on “Mainland-Pelješac” bridge investigations

The complete geological characteristics of the wider area of the Pelješac peninsula are presented: lithostratigraphical, structural/tectonic and seismotectonic. The main accent is put on engineering geological characteristics of clastic sediments in Mali Ston Bay encountered during investigations for implementation project of the “Mainland-Pelješac” bridge. The bridge large proportions with 2404 m in length and with 14 pylons under the sea, requested thorough and expensive in-situ and laboratory investigations which enabled development of detailed and reliable engineering model of quaternary clastic sediments at the explored site. The results clearly indicate three different engineering units which are predominantly classified according to the obvious difference in consistency: Unit A – very soft and soft soil; Unit B – soft to firm soil and Unit C – firm soil. Because of great soil total thickness, locally over 100 m, its generally poor engineering properties and great seismicity of the area the foundation surroundings are unfavorable. The mentioned units which are classified according to its engineering properties also tightly correspond to the deposition environments which represent much wider area than just exploration site. Therefore authors presume presence of units A, B and C in wider area with similar geological situations like proximities of the Zrmanja, Krka, and Cetina deltas. </p

Identification of rockfall source areas using the seed cell concept and bivariate susceptibility modelling

The objective of this research was to prepare a rockfall susceptibility map. Explorations were conducted in the Dubračina River basin (Croatia). The input data included a geological map, an orthophoto and a 1-m digital terrain model (DTM). After a talus inventory was prepared, the seed cell concept was applied to define the rockfall source areas. The contributing factors (predictors) of rockfalls were evaluated by the chi-squared test. The analysis confirmed the following predictors: CORINE land cover, lithology, slope, aspect, distance from a spring, distance from a road, distance from a fault, distance from a stream, and distance from the rock-soil geological boundary. A matrix pairwise comparison of the predictor ratings was used to define the most significant contributing factors. The predictors that affected the susceptibility map in the share of 86.3% were the slope (61.6%), lithology (13.4%), CORINE land cover (6.2%), and distance from the rock-soil geological boundary (5.1%). Two susceptibility maps were prepared: one using all nine contributing factors and another using the four most significant factors. The analysis showed that both maps were good, with the same areas under the receiver operating characteristic (ROC) curves. The map prepared with only four contributing factors can be considered a better map due to its more precise spatial definition of critical areas. It can be concluded that geological map, 1-m DTM and orthophoto provide enough data to prepare reliable rockfall susceptibility map. The application of the bivariate statistical zonation method called the “frequency ratio method” was proven to be successful. This research demonstrates that the application of the seed cell concept can be useful to speed up the process of rockfall source area detections in large research regions

THE INFLUENCE OF ACID RAINS ON THE LITHOTHAMNIAN LIMESTONE ON THE GALLERY OF THE MARY'S ASCENSION CATHEDRAL, ZAGREB, CROATIA

Urban, environmental pollution, caused by acid rains and damages of stone elements on Cathedral of Zagreb are described. On the surfaces of limestone elements that are in the »shade«, the black scabs have developed. The outher crusts, and inner powdery matter of the black scabs have been investigated by microscopy, and analyzed by means of x-ray. thermal and chemical analyses. They contain gypsum, calcite, soot, and sporadic fly ash

Modulus of elasticity for grain-supported carbonates — determination and estimation for preliminary engineering purposes

The determination and estimation of elastic behaviour are essential in engineering practise, especially in quarrying, mining, construction, and all engineering professions that perform operations dealing with rock materials. Young’s modulus, or modulus of elasticity, is the most important property describing the deformability of rock material. In this paper, grain-supported carbonates from Croatia are described and their elastic modulus and significant physical and mechanical properties are determined. The analysis of the collected data was performed in the R statistical environment. Estimation models based on multiple linear regression and the regression tree model were created. The methodology of model development and evaluation in R environment is described in detail. According to the more stringent coefficients (RMSECV and adjusted R2) used to evaluate the success of the estimation, simple regression tree models were found to perform well for the preliminary estimation, while more complex models based on Bagging performed very well

GeoTwinn: Twinning of the European Geological Surveys

oai:repozitorij.hgi-cgs.hr:hgi_6The GeoTwinn is the Horizon 2020 Twinning project funded by European Commission and is fully entitled: Strengthening research in the Croatian Geological Survey: Geoscience-Twinning to develop state-of-the-art subsurface modelling capability and scientific impact. The project twins the Croatian Geological Survey (HGI-CGS) with two world-leading geoscience research institutions: the Geological Survey of Denmark and Greenland (GEUS) and the British Geological Survey of the United Kingdom Research and Innovation (BGS-UKRI). The Project has started in October 2018, and is coordinated by HGI-CGS. The major aims of the project are: to significantly strengthen HGI-CGS’s research potential and capability, networking between scientists and institutions, and also development of ideas and new projects proposals. During three years of implementation, HGI-CGS experts will have the opportunity to collaborate with eminent sci-entists from other two partnering institutions. HGI-CGS will also benefit from a range of research tools, technologies, software and methods at the disposal of GEUS and BGS-UKRI. Almost thirty scientists from HGI-CGS will participate in the training programme which includes intensive training, consultations, and application of gained knowledge on test areas/data. The program involves short term visits, two-way scientific exchanges and workshops which will support HGI-CGS to strengthen research and capabilities in four important geoscience subject areas (Fig. 1): (1) 3D geological surveying and modelling (WP1) – to em-bed state-of-the-art geological surveying, interpretation and modelling. In the first activity, modern digital geological workflow and subsurface modelling capabilities including 3D virtual reconnaissance will be introduced. Also, digital field data capture, geological databases and 3D geological modelling are introduced. The second activity will reinforce these 3D visualisation and modelling skills by applying them to pilot areas using deep seismic reflection and borehole data. (2) advanced groundwater flow and contaminant transport modelling (WP2) – to understand, simulate and predict the movement of groundwater and contaminants in the subsurface. It comprises two activities, the first of which deals with strengthening HGI-CGS’s capacity to undertake cutting-edge numerical groundwater flow in porous aquifers, incorporating the robust assessment of uncertainty. The second activity deals with groundwater flow in the karst aquifers of Dinaric karst region of Croatia using advanced statistical time-series analysis methods. It will also introduce research methods to identify and analyse emerging groundwater contaminants. (3) identification and analysis of geohazards (WP3) – to introduce cutting-edge remote sensing methods for hazardous geological processes detection, monitoring and analysis. Training also includes the interpretation and visualisation of stereo imagery, processing of satellite imagery, INSAR interferometry and satellite detection of small-scale movements. The project also contains training on heuristic, statistical and geostatistical techniques to enable production of landslide susceptibility mapping. (4) geothermal energy (WP4) – scientific exchanges and training that will lead to new research into geological controls on subsurface heat flow and geochemical processes operating in hydrothermal systems. HGI-CGS staff will attend training on sampling and analytical methods of noble and dissolved gases from hydro-thermal systems. The training is also directed toward interpretation of hydrochemical data and geochemical modelling of hydrothermal systems. Second segment of the training develops fluid and heat flow modelling capability through numerical modelling of geothermal systems.The project will increase the research capacity, excellence and skill of the coordinating partner whilst fostering a network of both early career and more experienced researchers who can collaborate to produce high quality and impactful results: • a step-change in the excellence and impact of the re-search published HGI-CGS staff; • raise the reputation and the research profile of HGI-CGS scientists for novel research; • enhance research and innovation related to environmental issues, including the need for a shift to a low-carbon economy, climate change adaptation and risk management, and environmental protection and resource efficiency; • write successful bids into EU and other research grant schemes; • develop and enhance network of collaborators across the European Union; • form partnerships between the participating organisations, that outlast the project. Whilst the project focuses on supporting HGI-CGS to achieve a step-change in its research capacity, and the research profile of its scientists, it also offers significant benefits to GEUS and BGS-UKRI. By exposing GEUS and BGS-UKRI staff to a diverse range of geological set-tings within Croatia, particular environmental challenges, and to a different, large group of stakeholders, partnering institutions will also increase their level of expertise and knowledge