PUBLIC PERCEPTION OF THE URBAN PLUVIAL FLOODS RISK—CASE STUDY OF POREČ (CROATIA)

Pluvial floods are rain-related floods that occur when water drainage is not fast enough due to heavy rainfall. One of the key components in the management of the urban pluvial flood risk (UPFR) is risk perception (RP). The objective of this paper was to define factors of RP based on the selected variables and to examine their reliability. Emphasis is placed on the contextualization of five factors related to cognition: awareness of the risk of pluvial floods (F1) and situation: anthropogenic causes of pluvial floods (F2), natural causes of pluvial floods (F3), consequences of pluvial floods in the future (F4), and preparedness for pluvial floods (F5). Furthermore, historical pluvial floods data were acquired from multiple sources and used to determine the distance of respondents' homes from frequently flooded places. The results showed that the questionnaire was consistent, i.e., factors are highly reliable. Significant differences were observed in the F2 regarding the gender of the respondents, and in the F4 regarding their age. Preparedness for the danger (F5) is the lowest perceived factor. Results from this study can facilitate communication between experts, decision-makers, and citizens

Comparison of GEOBIA classification algorithms based on Worldview-3 imagery in the extraction of coastal coniferous forest

Šume primorskih četinjača, sa svojom ekološkom, ekonomskom, estetskom i društvenom funkcijom, predstavljaju važan dio europskih šumskih zajednica. Osnovni cilj ovoga rada je usporediti najkorištenije GEOBIA (engl. Geographic Object-Based Image Analysis) klasifikacijske algoritme (engl. Random Trees – RT, Maximum Likelihood – ML, Support Vector Machine – SVM) s ciljem izdvajanja šuma primorskih četinjača na visoko-rezolucijskom WorldView-3 snimku unutar topografskog slijevnog područja naselja Split. Metodološki okvir istraživanja uključuje (1) izvođenje izoštrenog multispektralnog snimka (WV-3MS-a); (2) testiranje segmentacijskih korisničko-definiranih parametara; (3) dodavanje testnih uzoraka; (4) klasifikaciju segmentiranog modela; (5) procjenu točnosti klasifikacijskih algoritama, te (6) procjenu točnosti završnog modela. RT se prema korištenim pokazateljima (correctness – COR, completeness – COM i overall quality – OQ) pokazao kao najbolji algoritam. Iterativno postavljanje segmentacijskih parametara omogućilo je detekciju najprikladnijih vrijednosti za generiranje segmentacijskog modela. Utvrđeno je da sjene mogu uzrokovati značajne probleme ako se klasificiranje vrši na visoko-rezolucijskim snimkama. Modificiranim Cohen’s kappa coefficient (K) pokazateljem izračunata je točnost konačnog modela od 87,38%. WV-3MS se može smatrati kvalitetnim podatkom za detekciju šuma primorskih četinjača primjenom GEOBIA metode.With their ecological, economic, aesthetic, and social function, coniferous forests represent an important part of European forest communities. The main objective of this paper is to compare the most used GEOBIA (Geographic Object-Based Image Analysis) classification algorithms (Random Trees - RT, Maximum Likelihood - ML, Support Vector Machine - SVM) for the purposes of the coastal coniferous forest detection on a high-resolution WorldView-3 (WV-3) imagery on the topographic basin of the Split settlement (Figure 1). The methodological framework (Figure 2) includes: (1) derivation of a sharpened multispectral image (WV-3MS) (Figure 3); (2) testing of the user-defined parameters in segmentation process (Figure 4); (3) marking of test samples (signatures); (4) classification of a segmented model; (5) accuracy assessment of the classification algorithms, and (6) accuracy assessment of the final model. The developed ACP tool (Automated Classification Process) (Supplement figure 5) for speeding up the entire classification process, enabled the simultaneous generation of output results for three selected classification algorithms (RT, ML and SVM) (Figure 6). Metric indicators (correctness - COR, completeness - COM, and overall quality - OQ) have shown that RT is the most accurate classification algorithm for the coastal coniferous forest detection (Table 1; Figure 7). The iterative setting of segmentation parameters enabled the detection of the most optimal values &8203;&8203;for generating a segmentation model. It is found that shadows can cause significant problems if classification is done on high-resolution images (Figure 8). The solution may be to collect a larger number of samples in different areas for the purpose of more detailed class differentiation. The modified Cohen’s kappa coefficient (K) indicator shown the accuracy of the final model of 87.38% (Table 2; Figure 9). WV-3MS can be considered as very good data for the detection of coniferous forests using the GEOBIA method (Figure 10). According to this research, 31.36% of the Split topographic basin is covered by highly and extremely flammable vegetation

Bathymetric Survey of the St. Anthony Channel (Croatia) Using Multibeam Echosounders (MBES)—A New Methodological Semi-Automatic Approach of Point Cloud Post-Processing

Multibeam echosounders (MBES) have become a valuable tool for underwater floor mapping. However, MBES data are often loaded with different measurement errors. This study presents a new user-friendly and methodological semi-automatic approach of point cloud post-processing error removal. The St. Anthony Channel (Croatia) was selected as the research area because it is regarded as one of the most demanding sea or river passages in the world and it is protected as a significant landscape by the Šibenik-Knin County. The two main objectives of this study, conducted within the Interreg Italy–Croatia PEPSEA project, were to: (a) propose a methodological framework that would enable the easier and user-friendly identification and removal of the errors in MBES data; (b) create a high-resolution integral model (MBES and UAV data) of the St. Anthony Channel for maritime safety and tourism promotion purposes. A hydrographic survey of the channel was carried out using WASSP S3 MBES while UAV photogrammetry was performed using Matrice 210 RTK V2. The proposed semi-automatic post-processing of the MBES acquired point cloud was completed in the Open Source CloudCompare software following five steps in which various point filtering methods were used. The reduction percentage in points after the denoising process was 14.11%. Our results provided: (a) a new user-friendly methodological framework for MBES point filtering; (b) a detailed bathymetric map of the St. Anthony Channel with a spatial resolution of 50 cm; and (c) the first integral (MBES and UAV) high-resolution model of the St. Anthony Channel. The generated models can primarily be used for maritime safety and tourism promotion purposes. In future research, ground-truthing methods (e.g., ROVs) will be used to validate the generated models

Mapping of marine litter on the seafloor using WASSP S3 multibeam echo sounder and Chasing M2 ROV

Marine litter is a growing threat to the marine environment. Mapping of marine litter is becoming increasingly important to detect its potential hotspots and prevent their spread. In this paper, the applicability of the multibeam echo sounder (MBES) WASSP S3 and remotely operated underwater vehicle (ROV) Chasing M2 was tested in the detection and mapping of marine litter on the seafloor within the wider area of the St. Ante Channel (Šibenik, Croatia). Also, the precision assessment of WASSP S3 was tested at different cruising speeds. Results have shown that Chasing M2 can be used effectively for the initial detection of marine debris in shallow waters. However, if the underwater navigation and positioning system and auxiliary measurement scales are not used, the ROV has limited capabilities in deriving morphometric parameters of marine litter on the seafloor. This was determined by comparing the 3D model of a tire which was derived using video photogrammetry captured with ROV and the 3D model of a tire which was produced using a hand-held 3D scanner. Furthermore, the results have shown the WASSP S3 is not suitable for identifying marine litter smaller than 1 m at depths up to 10 m. The MBES WASSP S3 can detect marine litter that has a minimum area of 100 * 100 cm and a height of around 40 cm at depths up to 10 m. The results pointed to the need for caution when choosing an adequate sensor to detect and map marine litter on the seafloor. In addition, MBES interval measurements have shown that WASSP S3 precision is in the centimeter range (<10 cm) at different cruising speeds. The obtained results have helped to establish the guidelines for the integrated use of MBES, ROV, and UAV in the detection of marine litter on the seafloor

Geospatial technologies in modeling and promotion of protected areas on the example of lake Zmajevo oko

Proučavanje prirodne baštine uvelike ovisi o njenoj očuvanosti jer globalne klimatske promjene, prirodne katastrofe, masovni turizam, terorizam te ljudski nemar uvelike utječu na promjene u krajoliku, a samim time i na zaštićena područja. Posljednjih desetljeća geoprostorne tehnologije je zahvatio proces ubrzanog razvoja. One su omogućile dokumentaciju trenutnog stanja i izradu modela visoke kvalitete u svrhu očuvanja i promocije zaštićenih područja. Područje istraživanja ovog diplomskog rada bilo je jezero Zmajevo oko kod Rogoznice. Cilj istraživanja bio je utvrditi preciznost integralnog mjernog sustava kombinacija RTK GPS i višesnopnog dubinomjera s obzirom na to da je isti prvi put korišten u Republici Hrvatskoj te dobiti informacije o osnovnim karakteristikama jezera (površina, volumen, dubina). Također, jedan od ciljeva je bio kartirati te klasificirati dno jezera kao i utvrditi podvodne tunele. Aerofotogrametrijom, za koju je korištena bespilotna letjelica Phantom 4 Pro opremljena fotoaparatom visoke razlučivosti, obuhvaćeno je vodno lice jezera i šire obalno područje u tampon zoni od 100 m. Batimetrijskom izmjerom, za koju se po prvi put u RH koristio integralni mjerni sustav kombinacija višesnopnog dubinomjera WASSP S3 i Hemisphere V320 GNSS pametne antene, obuhvaćeno je dno jezera. Integralni mjerni sustav s operativnom frekvencijom od 160 kHz u potpunosti je omogućio kartiranje dna te deset bočnih tunela (pukotina). U završnoj fazi istraživanja, podaci prikupljeni objema metodama su spojeni te je izrađen integralni model jezera visoke kvalitete. Na temelju 2.5D i 3D modela izračunati su volumen, površina i duljina obalne linije jezera. Točnost modela dobivenog aerofotogrametrijom iznosi < 5 cm. Vertikalna preciznost, nefiltriranih podataka, integralnog mjernog sustava iznosi 6,8 cm, a horizontalna 11,8 cm. U programu Lumion izrađena je virtualna šetnja jezerom u svrhu promocije, a pomoću 3D printera Prusa i3 MK3 ispisan je i fizički model jezera koji može poslužiti kao suvenir. Prikupljeni podaci visoke kvalitete predstavljaju temelj za buduća istraživanja na ovom zaštićenom području.The study of natural heritage largely depends on its preservation because global climate change, natural disasters, mass tourism, terrorism and human negligence greatly affect changes in the landscape, and thus protected areas. In recent decades, geospatial technologies have been affected by a process of rapid development. They enabled the documentation of the current situation and the development of high quality models for the purpose of preserving and promoting protected areas. The research area of this graduation thesis was Lake Zmajevo oko near Rogoznica. The objective of the research was to determine the accuracy of the integrated measuring system of combinations of RTK GPS and multi-beam depth sounder, given that it was used for the first time in the Republic of Croatia and to obtain information on the basic characteristics of the lake (area, volume, depth). Also, one of the objectives was to map and classify the bottom of the lake as well as to identify underwater tunnels. Aerial photogrammetry used by the Phantom 4 Pro UAV equipped with a high-resolution camera covered the water surface of the lake and the wider coastal area in the buffer zone of 100 m. The bathymetric survey, for which, for the first time in the Republic of Croatia, an integrated measuring system of combinations of the WASSP S3 multi-beam depth sounder and the Hemisphere V320 GNSS smart antenna was used, covered the bottom of the lake. An integrated measuring system with an operating frequency of 160 kHz has fully enabled the mapping of the bottom and ten side tunnels (cracks). In the final phase of the research, the data collected by both methods were combined and an integrated model of a high quality lake was developed. Based on the 2.5D and 3D models, the volume, area, and length of the lake shoreline were calculated. The accuracy of the model obtained by aerial photogrammetry is < 5 cm. The vertical precision of unfiltered data of the integral measuring system is 6.8 cm, and the horizontal is 11.8 cm. In the Lumion software, a virtual walk through the lake was made for the purpose of promoting. A physical model of the lake, which can serve as a souvenir, was printed by the help of the 3D printer Prusa i3 MK3. The collected high quality data are the basis for future research in this protected area

Geospatial technologies in modeling and promotion of protected areas on the example of lake Zmajevo oko

Proučavanje prirodne baštine uvelike ovisi o njenoj očuvanosti jer globalne klimatske promjene, prirodne katastrofe, masovni turizam, terorizam te ljudski nemar uvelike utječu na promjene u krajoliku, a samim time i na zaštićena područja. Posljednjih desetljeća geoprostorne tehnologije je zahvatio proces ubrzanog razvoja. One su omogućile dokumentaciju trenutnog stanja i izradu modela visoke kvalitete u svrhu očuvanja i promocije zaštićenih područja. Područje istraživanja ovog diplomskog rada bilo je jezero Zmajevo oko kod Rogoznice. Cilj istraživanja bio je utvrditi preciznost integralnog mjernog sustava kombinacija RTK GPS i višesnopnog dubinomjera s obzirom na to da je isti prvi put korišten u Republici Hrvatskoj te dobiti informacije o osnovnim karakteristikama jezera (površina, volumen, dubina). Također, jedan od ciljeva je bio kartirati te klasificirati dno jezera kao i utvrditi podvodne tunele. Aerofotogrametrijom, za koju je korištena bespilotna letjelica Phantom 4 Pro opremljena fotoaparatom visoke razlučivosti, obuhvaćeno je vodno lice jezera i šire obalno područje u tampon zoni od 100 m. Batimetrijskom izmjerom, za koju se po prvi put u RH koristio integralni mjerni sustav kombinacija višesnopnog dubinomjera WASSP S3 i Hemisphere V320 GNSS pametne antene, obuhvaćeno je dno jezera. Integralni mjerni sustav s operativnom frekvencijom od 160 kHz u potpunosti je omogućio kartiranje dna te deset bočnih tunela (pukotina). U završnoj fazi istraživanja, podaci prikupljeni objema metodama su spojeni te je izrađen integralni model jezera visoke kvalitete. Na temelju 2.5D i 3D modela izračunati su volumen, površina i duljina obalne linije jezera. Točnost modela dobivenog aerofotogrametrijom iznosi < 5 cm. Vertikalna preciznost, nefiltriranih podataka, integralnog mjernog sustava iznosi 6,8 cm, a horizontalna 11,8 cm. U programu Lumion izrađena je virtualna šetnja jezerom u svrhu promocije, a pomoću 3D printera Prusa i3 MK3 ispisan je i fizički model jezera koji može poslužiti kao suvenir. Prikupljeni podaci visoke kvalitete predstavljaju temelj za buduća istraživanja na ovom zaštićenom području.The study of natural heritage largely depends on its preservation because global climate change, natural disasters, mass tourism, terrorism and human negligence greatly affect changes in the landscape, and thus protected areas. In recent decades, geospatial technologies have been affected by a process of rapid development. They enabled the documentation of the current situation and the development of high quality models for the purpose of preserving and promoting protected areas. The research area of this graduation thesis was Lake Zmajevo oko near Rogoznica. The objective of the research was to determine the accuracy of the integrated measuring system of combinations of RTK GPS and multi-beam depth sounder, given that it was used for the first time in the Republic of Croatia and to obtain information on the basic characteristics of the lake (area, volume, depth). Also, one of the objectives was to map and classify the bottom of the lake as well as to identify underwater tunnels. Aerial photogrammetry used by the Phantom 4 Pro UAV equipped with a high-resolution camera covered the water surface of the lake and the wider coastal area in the buffer zone of 100 m. The bathymetric survey, for which, for the first time in the Republic of Croatia, an integrated measuring system of combinations of the WASSP S3 multi-beam depth sounder and the Hemisphere V320 GNSS smart antenna was used, covered the bottom of the lake. An integrated measuring system with an operating frequency of 160 kHz has fully enabled the mapping of the bottom and ten side tunnels (cracks). In the final phase of the research, the data collected by both methods were combined and an integrated model of a high quality lake was developed. Based on the 2.5D and 3D models, the volume, area, and length of the lake shoreline were calculated. The accuracy of the model obtained by aerial photogrammetry is < 5 cm. The vertical precision of unfiltered data of the integral measuring system is 6.8 cm, and the horizontal is 11.8 cm. In the Lumion software, a virtual walk through the lake was made for the purpose of promoting. A physical model of the lake, which can serve as a souvenir, was printed by the help of the 3D printer Prusa i3 MK3. The collected high quality data are the basis for future research in this protected area

Pluvial Flash Flood Hazard and Risk Mapping in Croatia: Case Study in the Gospić Catchment

Since the beginning of the 21st Century, Europe has been affected by destructive floods. European Union Member States have an obligation to develop flood hazard and flood risk maps as support to the Flood Risk Management Plan (FRMP). The main objective of this study is to propose a methodological framework for hazard and risk assessment of pluvial flash floods in Croatia at the catchment level, which can be integrated into the FRMP. Therefore, a methodology based on the source–pathway–consequence approach for flood risk assessment is presented, which complies with the EU Floods Directive. This integrated and comprehensive methodology is based on high-resolution open data available for EU Member States. Three scenarios are defined for a low, medium, and high probability, defined by design storms of different durations. The proposed methodology consists of flood hazard analysis, vulnerability assessment, and risk analysis. Pluvial flash flood hazards are analyzed using a 2D hydrologic–hydraulic model. The flood vulnerability assessment consists of a GIS analysis to identify receptors potentially at risk of flooding and an assessment of susceptibility to potential flood damage using depth–damage curves. Flood risk is assessed both qualitatively in terms of risk levels and quantitatively in terms of direct damages expressed in monetary terms. The developed methodology was applied and tested in a case study in the Gospić catchment in Croatia, which surrounds a small rural town frequently affected by pluvial flash floods

A New Systematic Framework for Optimization of Multi-Temporal Terrestrial LiDAR Surveys over Complex Gully Morphology

Terrestrial LiDAR scanning (TLS) has in preceding years emerged as one of the most accurate and reliable geospatial methods for the creation of very-high resolution (VHR) models over gullies and other complex geomorphic features. Rough terrain morphology and rapid erosion induced spatio-temporal changes (STCs) can lead to significant challenges in multi-temporal field TLS surveys. In this study, we present a newly developed systematic framework for the optimization of multi-temporal terrestrial LiDAR surveys through the implementation of thorough systematic pre-survey planning and field preparation phases. The developed systematic framework is aimed at increase of accuracy and repeatability of multi-temporal TLS surveys, where optimal TLS positions are determined based on visibility analysis. The whole process of selection of optimal TLS positions was automated with the developed TLS positioning tool (TPT), which allows the user to adjust the parameters of visibility analysis to local terrain characteristics and the specifications of available terrestrial laser scanners. Application and validation of the developed framework were carried out over the gully Santiš (1226.97 m2), located at Pag Island (Croatia). Eight optimal TLS positions were determined by the TPT tool, from which planned coverage included almost 97% of the whole gully area and 99.10% of complex gully headcut morphology. In order to validate the performance of the applied framework, multi-temporal TLS surveys were carried out over the gully Santiš in December 2019 and 2020 using the Faro Focus M70 TLS. Field multi-temporal TLS surveys have confirmed the accuracy and reliability of the developed systematic framework, where very-high coverage (>95%) was achieved. Shadowing effects within the complex overhangs in the gully headcut and deeply incised sub-channels were successfully minimalized, thus allowing accurate detection and quantification of erosion induced STCs. Detection of intensive erosion induced STCs within the observed one-year period was carried out for the chosen part of the gully headcut. Most of the detected STCs were related to the mass collapse and gradual uphill retreat of the headcut, where in total 2.42 m2 of soil has been eroded. The developed optimization framework has significantly facilitated the implementation of multi-temporal TLS surveys, raising both their accuracy and repeatability. Therefore, it has great potential for further application over gullies and other complex geomorphic features where accurate multi-temporal TLS surveys are required for monitoring and detection of different STCs

A New Systematic Framework for Optimization of Multi-Temporal Terrestrial LiDAR Surveys over Complex Gully Morphology

Terrestrial LiDAR scanning (TLS) has in preceding years emerged as one of the most accurate and reliable geospatial methods for the creation of very-high resolution (VHR) models over gullies and other complex geomorphic features. Rough terrain morphology and rapid erosion induced spatio-temporal changes (STCs) can lead to significant challenges in multi-temporal field TLS surveys. In this study, we present a newly developed systematic framework for the optimization of multi-temporal terrestrial LiDAR surveys through the implementation of thorough systematic pre-survey planning and field preparation phases. The developed systematic framework is aimed at increase of accuracy and repeatability of multi-temporal TLS surveys, where optimal TLS positions are determined based on visibility analysis. The whole process of selection of optimal TLS positions was automated with the developed TLS positioning tool (TPT), which allows the user to adjust the parameters of visibility analysis to local terrain characteristics and the specifications of available terrestrial laser scanners. Application and validation of the developed framework were carried out over the gully Santi&scaron; (1226.97 m2), located at Pag Island (Croatia). Eight optimal TLS positions were determined by the TPT tool, from which planned coverage included almost 97% of the whole gully area and 99.10% of complex gully headcut morphology. In order to validate the performance of the applied framework, multi-temporal TLS surveys were carried out over the gully Santi&scaron; in December 2019 and 2020 using the Faro Focus M70 TLS. Field multi-temporal TLS surveys have confirmed the accuracy and reliability of the developed systematic framework, where very-high coverage (&gt;95%) was achieved. Shadowing effects within the complex overhangs in the gully headcut and deeply incised sub-channels were successfully minimalized, thus allowing accurate detection and quantification of erosion induced STCs. Detection of intensive erosion induced STCs within the observed one-year period was carried out for the chosen part of the gully headcut. Most of the detected STCs were related to the mass collapse and gradual uphill retreat of the headcut, where in total 2.42 m2 of soil has been eroded. The developed optimization framework has significantly facilitated the implementation of multi-temporal TLS surveys, raising both their accuracy and repeatability. Therefore, it has great potential for further application over gullies and other complex geomorphic features where accurate multi-temporal TLS surveys are required for monitoring and detection of different STCs

Long-Term Assessment of Spatio-Temporal Landuse/Landcover Changes (LUCCs) of O&scaron;ljak Island (Croatia) Using Multi-Temporal Data&mdash;Invasion of Aleppo Pine

The karst landscapes of the Mediterranean are regarded as some of the most vulnerable, fragile, and complex systems in the world. They hold a particularly interesting group of small islands with a distinctive, recognizable landscape. The Republic of Croatia (HR), which has one of the most indented coasts in the world, is particularly known for them. In this paper, we analyzed the spatio-temporal changes (STCs) in the landscape of O&scaron;ljak Island, the smallest inhabited island in HR. Landuse/landcover change (LUCC) analysis has been conducted from 1944 to 2021. The methodology included the acquisition of multi-temporal data, data harmonization, production of landuse/landcover (LU/LC) maps, selection of optimal environmental indicators (EIs), and simulation modeling. In total, eleven comparable LU/LC models have been produced, with moderate accuracy. STCs have been quantified using the nine EIs. The dominant processes that influenced the changes in the O&scaron;ljak landscape have been identified. The results have shown that, in recent decades, O&scaron;ljak has undergone a landscape transformation which was manifested through (a) pronounced expansion of Aleppo pine; (b) deagrarianization, which led to secondary succession; and (c) urban sprawl, which led to the transformation of the functional landscape. The most significant of the detected changes is the afforestation of the Aleppo pine. Namely, in a 77-year span, the Aleppo pine has expanded intensively to an area of 11.736 ha, created a simulation model for 2025, and pointed to the possibility of the continued expansion of Aleppo pine. Specific guidelines for the management of this new transformed landscape have been proposed. This research provides a user-friendly methodological framework that can efficiently monitor LUCCs of a smaller area in the case when geospatial data are scarce and satellite imagery of coarser resolution cannot be used. Moreover, it gives an insight into the availability and quality of multi-temporal data for the HR