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Alluvial (torrential) fans, especially those created from debris-flow activity, often endanger built environments and human life. It is well known that these kinds of territories where human activities are favored are characterized by increasing instability and related hydrological risk therefore, treating the problem of its assessment and management is becoming strongly relevant. The aim of this study was to analyze and model the geomorphological aspects and the physical processes of alluvial fans in relation to the environmental characteristics of the territory for classification and prediction purposes. The main geomorphometric parameters capable of describing complex properties, such as relative fan position depending on the neighborhood, which can affect their formation or shape, or properties delineating specific parts of fans, were identified and evaluated through digital elevation model (DEM) data. Five machine learning (ML) methods, including a hybrid Euler graph ML method, were compared to analyze the geomorphometric parameters and physical characteristics of alluvial fans. The results obtained in 14 case studies of Slovenian torrential fans, validated with data of the empirical model proposed by Bertrand et al. (2013), confirm the validity of the developed method and the possibility to identify alluvial fans that can be considered as debris-flow prone.

Debris flows can transport large amounts of material and therefore present a significant threat to infrastructure and human life. In this research, we used tree-ring width analyses to quantify the response of trees to three debris flow events in NW Slovenia (Javoršček, Srpenica) and W Slovenia (Nikova) for which we know the time of origin. We attempted to date these and similar tree responses in the past and compared the patterns between different tree species. Altogether, we sampled 147 trees across a range of tree species (Fagus sylvatica, Pinus sylvestris, Fraxinus excelsior, Fraxinus ornus, Acer pseudoplatanus, Picea abies, Juglans regia, Acer campestre, Tilia cordata and Ostrya carpinifolia), including reference trees that were outside the debris flow fan. For 91 trees, we constructed tree-ring chronologies and used pointer-year analysis to identify years that had abnormal growth. For the remaining trees (mostly Ostrya carpinifolia, Tilia cordata and Acer pseudoplatanus), we either could not accurately distinguish tree rings or two samples from a single tree showed significantly different growth patterns. The growth patterns of Fagus sylvatica and Picea abies following debris flow events showed a weak response at the Javoršček site and no clear responses at the other two sites. Tree species responded similarly at the same locations. Due to the lack of a clear response pattern, we were not able to reconstruct past debris flows. Drobirski tokovi s sposobnostjo prenašanja večjih količin materiala so nevarni za infrastrukturo in življenje ljudi. Z analizo širine lesnih branik smo v raziskavi poskušali prepoznati odziv dreves na vpliv treh drobirskih tokov v SZ Sloveniji (Srpenica, Javoršček) in Z Sloveniji (Nikova) z znanim časom nastanka, na podlagi spremembe širine branike datirati podobne drobirske tokove v preteklosti in primerjati odzive različnih drevesnih vrst. Na treh lokacijah smo vzorčili skupno 147 dreves različnih drevesnih vrst (Fagus sylvatica, Pinus sylvestris, Fraxinus excelsior, Fraxinus ornus, Acer pseudoplatanus, Picea abies, Juglans regia, Acer campestre, Tilia cordata in Ostrya carpinifolia), vključno z referenčnimi drevesi, ki niso bila izpostavljena delovanju dejavnika. Pri 91 drevesih smo uspešno izdelali drevesne kronologije in z uporabo metode značilnih let ugotovili leta, ki so pri posameznih drevesnih vrstah ter na posameznih lokacijah glede na širno branike kazala zelo različne trende rasti. Pri drugih drevesih vrstah (večinoma Ostrya carpinifolia, Tilia cordata in Acer pseudoplatanus) nam ni uspelo razbrati vseh branik, oz. sta bili po dve zaporedji širin branik istega drevesa različni. V analizi rasti za prvo leto po dogodku smo šibak odziv na vpliv drobirskih tokov zaznali na lokaciji pod Javorščkom, ne pa tudi v Srpenici in Nikovi. Različne drevesne vrste so se na istih lokacijah odzvale podobno. Ker smo zaznali odziv le na eni lokaciji, nismo mogli rekonstruirati drobirskih tokov po posameznih lokacijah v preteklosti.

V disertaciji je obravnavana problematika ocenjevanja nevarnosti zaradi delovanja drobirskih tokov na hudourniških vršajih. Glavni poudarek raziskave je problematika, ki se je v preteklih raziskavah izkazala za težavno in sicer gre za klasifikacijo hudourniških območij, iz katere bi bilo razvidno ali je izbrano hudourniško območje nagnjeno k delovanju drobirskih tokov. Na izbranem nevarnem območju pa ocenjevanje magnitude potencialnega drobirskega toka in določeni deli postopka matematičnega modeliranja gibanja drobirskih tokov, predvsem povezani z reološkimi karakteristikami mešanice in vplivom topografskih podatkov o terenu, ki so osnova za izdelavo modela. Disertacija se v prvem delu osredotoča na določanje parametrov hudourniških območij in analizo različnih metod za njihovo klasificiranje. Na podlagi analize večih metod je predlagana klasifikacija na nevarna, prehodna in nenevarna hudourniška območja, ki je predstavljena na izbranem testnem območju. V analizo smo vključili v tujini in Sloveniji razvite metode in orodja s tega področja. V drugem delu disertacije je poudarek na ocenjevanju magnitude potencialnega drobirskega toka z modelom LS-Rapid, ki je uporabljen na hudourniškem območju Bele, kjer je prikazana uporaba modela za določanje nestabilnih območij na nivoju celotnega hudourniškega območja. Uporaba modela za ocenjevanje količine sproženega materiala pa je prikazana na primeru plazu Stože, kjer je izvedena analiza plazu, ki se je sprožil novembra 2000. Za določanje parametrov modela LS-Rapid, ki jih za potencialne zemeljske plazove ni možno natančno določiti, smo podali napotke o določanju mejnih vrednosti, ki so uporabne za modeliranje potencialnih zemeljskih plazov. Zaradi modeliranja gibanja drobirskih tokov na hudourniških vršajih so bile za potrebe določanja reoloških karakteristik drobirskega materiala izvedene raziskave v geomehanskem laboratoriju na vzorcih materiala, ki smo ga odvzeli na izvornem mestu plazu Stože. Na podlagi testiranja smo podali navodila, kako za model Flo-2D določati reološke karakteristike potencialnih drobirskih tokov. Prikazana je tudi analiza vpliva različnih topografskih podatkov na rezultate modeliranja gibanja drobirskih tokov. Uporabljeni so bili tako komercialni kot tudi javni topografski podatki predvsem uporabni so se izkazali najnovejši LiDAR-ski podatki. Na podlagi lastnih rezultatov in predlogov je na koncu disertacije podan predlog metodologije za ocenjevanje nevarnosti zaradi delovanja drobirskih tokov na hudourniških vršajih in usmeritve za nadaljnje delo. PhD thesis deals with debris flow hazard assessment on torrential fans. Its main focus is on the known problems pointed out with the already performed research, such as is the way of preliminary classification of torrential catchments to determine those, which are prone to trigger debris flows, furthermore, how to estimate magnitudes of potential debris flows triggered in these torrential catchments, and finally, open questions with regard to debris-flow mathematical modeling on torrential fans, especially their rheological characteristics to be used in mathematical models and how topography influences modelling results. In the first part, we focus on geomorphological parameters of torrential catchments and various methods for classification of torrential catchments prone to debris-flow triggering. Based on analysis of the selected methods, a new classification method was proposed for classification of debris-flow prone catchments, transitional catchments and catchments with no debris- flow hazard. This new method was then tested in selected torrential catchments in Slovenia. For debris-flow magnitude assessment, we applied the LS-Rapid triggering model. With its application in the Bela torrential catchment (NW Slovenia), we could identify several active landslides and potentially unstable areas, which could under unfavorable conditions turn into active landslides and trigger debris flows. A detailed study and debris-flow modeling was then carried out on the Stože landslide (NW Slovenia), which was triggered in November 2000. For debris-flow model parameters, which cannot be determined with sufficient reliability without analyzing soil samples in detail in a geomechanical laboratory, we proposed an estimation of their limit values, which can be used for potential landslide modeling. Soil samples were taken from the Stože landslide source area for testing in a geomechanical laboratory. In this way, rheological properties of a potential debris flow could be determined, and then used in debris-flow mathematical routing model on a torrential fan. Based on our own laboratory study, and additionally testing of the Flo-2D model, we proposed instructions how to assess potential debris-flow rheological characteristics. Furthermore, with the Flo-2D model we tested the influence of different topographical datasets on debris-flow modeling results. We applied different publicly available topographical data and commercial LiDAR data to develop DEM with different resolutions. The debris-flow modeling results, obtained by using new public available LiDAR based data and the Flo-2D model, turned out to be very /plausible. Finally, we comprise single steps described in previous sections into a new methodology for debris-flow hazard assessment on torrential fans, culminating in the debris-flow hazard mapping. The PhD thesis ends up with some recommendations for further research in this field.

V diplomski nalogi je predstavljen pojav hudourniških poplav in njihova razlika v primerjavi z ostalimi poplavami. Do poplav običajno pride ob močnih ali dalj časa trajajočih padavinah. V zadnjih letih so taki padavinski dogodki precej pogosti in ljudje se soočamo z vprašanji o podnebnih spremembah, ki bi lahko povzročile vedno večje število naravnih nesreč. V Sloveniji so hudourniške poplave poznan pojav, saj je Slovenija dežela, ki leži v povirnih delih mnogih vodotokov. Predvsem v severozahodnem hribovitem delu Slovenije, kjer letno pade največ padavin, so pogoste hudourniške poplave in erozija. Hudourniške poplave običajno spremljajo še ostali procesi kot so hribinski plazovi, hudourniška erozija in blatni ter drobirski tokovi. Omenjeni procesi imajo velik vpliv tudi na končno škodo, ki jo običajno precej povečajo. Zaradi zelo hitrega pojava in kratkega časovnega trajanja hudourniških poplav je pomemben dejavnik pri zmanjšanju škode pravočasno in čim bolj točno napovedovanje le teh. Za kvalitetno napovedovanje pa je potrebno usklajevanje več dejavnikov. V zadnjih letih se skupaj z razvojem tehnologije vedno bolj uporabljajo tehnike daljinskega zaznavanja, ki so precej doprinesle h kvalitetnim poplavnim napovedim. V diplomskem delu so opisani tudi različni protipoplavni ukrepi, ki se uporabljajo za zmanjšanje posledic in škode, ki jih hudourniške poplave pustijo za sabo. Z ustreznimi zakonskimi predpisi o graditvi objektov na poplavno ogroženih območjih, večjim številom vremenskih merilnih postaj, radarskimi in satelitskimi opazovanji in kvalitetnimi vodogradbenimi ukrepi lahko dosežemo hitrejše napovedovanje in ukrepanje ob hudourniških poplavah. The thesis presents flash floods phenomenon and the differences between flash floods and other types of floods. Flooding is usually caused by intense or long-lasting rainfall event. These kinds of events are more often in the last years and climate changes could cause even more natural disasters. Flash floods are quite known phenomenon in Slovenia which is situated in many upper parts of river basins. Flash floods and erosion are most common in northwestern hilly landscape of Slovenia where is also measured the biggest amount of annual precipitation. Flash floods are often accompanied by landslides, erosion, mud and debris flows. These processes can cause even bigger damage than just flash flood only. Because of a rapid and short-term event of flash flooding is quality forecast very important to reduce the damage. Quality forecast depends on several different factors which all should be considered. In the last years is popular use of remote sensing systems for more accurate flood forecasts. The thesis also presents different types of flood protection which are used to reduce the damage caused by flash flooding. With flood protection such as appropriate statutory regulations for building on zones at high risk of flooding, a higher number of rain-gauges, weather radars, satellite systems and quality structural measures we can achieve faster and more accurate flood forecasts and measures in time.

V nalogi je najprej pripravljen pregled in opisane različne klasifikacije masnih gibanj, med katere se uvrščajo tudi drobirski tokovi. Drobirski tokovi so predstavljeni podrobneje. Opisane so njihove lastnosti in prikazana klasifikacija glede na nastanek, velikost in hitrost. Opisane so tudi glavne razlike med drobirskimi tokovi in drugimi masnimi gibanji. Nadalje je predstavljen model Flo-2D in opisana njegova uporaba, način delovanja in postopek izdelave modela drobirskega toka. Opisane so dosedanje izkušnje z modeliranjem drobirskih tokov v Sloveniji in uporaba različnih matematičnih modelov, vključno s Flo-2D. Opisana je slovenska zakonodaja na področju varstva pred poplavami in erozijo, kjer je predpisana metodologija za izdelavo opozorilnih kart, kart nevarnosti in kart ogroženosti zaradi delovanja poplav in erozije. Predlagan je način izdelave opozorilnih kart in podrobnejših kart nevarnosti zaradi delovanja drobirskih tokov, pri čemer so drobirski tokovi razdeljeni na hudourniške in pobočne. Glavni del naloge je uporaba matematičnega modela Flo-2D pri modeliranju drobirskih tokov na hudourniških vršajih z uporabo javno dostopnih podatkov. Raziskava je opravljena na hudourniških vršajih pritokov Save Dolinke. V občutljivostni analizi modela je analiziran vpliv nastavitev kontrolnih parametrov modela, pozicije vhodnega hidrograma, Manningovega koeficienta hrapavosti ng, velikosti računskih celic, različnih reoloških karakteristik in vpliv različnih načinov modeliranja objektov na hudourniških vršajih. Obravnavana je možnost uporabe rezultatov modelov, izdelanih z uporabo javno dostopnih vhodnih podatkov za pripravo podrobnejših kart nevarnosti, kar bi pomenilo, da je take karte možno pripraviti z relativno majhnimi stroški, brez dragih dodatnih raziskav. Prikazana je tudi možnost izdelave kart nevarnosti z vmesnikom, ki je vgrajen v model Flo-2D. Kot največja pomanjkljivost med vhodnimi podatki so se izkazali podatki o terenu DMV5, kjer je zaradi avtomatske izdelave vsebovanih veliko napak o topografiji terena, ki lahko bistveno vplivajo na rezultate modela. Sicer pa je večina ostalih uporabljenih vhodnih podatkov dovolj dobro določljiva, da bi bil predlagani način dela uporaben za pripravo kart nevarnosti. IV The present thesis begins with an overview and different classifications of mass movements. Debris flows, one type of mass movements, are described in detail. First, their characteristics are presented and also classified according to the type of triggering, magnitude and velocity. The main differences between the debris flows and other mass movements are also described. In addition, the mathematical model Flo-2D is described. Its use, functioning and procedure of modeling debris flows are presented, as are the previous experiences with debris flow modeling in Slovenia and the use of different mathematical models, including Flo-2D. In the following chapter, the Slovene legislation in the area of flooding and erosion hazard is described. This legislation prescribes the methodology of preparing the preliminary hazard maps, hazard maps and risk maps due to the influence of flooding and erosion. The thesis proposes a protocol of preparing the preliminary hazard maps and hazard maps due to the debris flow effects. Debris flows are divided into torrential and slope debris flows. The main part of the thesis is dedicated to the practical use of the mathematical model Flo-2D in debris flow modeling of torrential fans using only the publicly available data. The alpine valley of Sava Dolinka River was selected as a test region. In the sensitivity analysis of the Flo-2D model, the influence of different parameters was tested: the control parameters settings of the model, the position of the incoming hydrograph, the Manning roughness coefficient, the computational grid size, different rheological characteristics and the influence of different ways of modeling objects on torrential fans. The possibility of using the results of the models made with publicly available data is evaluated in preparing hazard maps. This method would enable the preparation of hazard maps with relatively low costs and without the expensive extra surveys. The possibility of preparing hazard maps using an application proposed in the Flo-2D model is also presented. The topographic data DEM5 turned out to be the main deficiency of all the input data used in the research, as they can dramatically affect the model results and hazard area assessments. The rest of the applied model input data can be defined well enough to be efficient in preparing the hazard maps the way it is described in this thesis.

V diplomski nalogi bomo opisovali zemeljske plazove, katerih škoda v zadnjih desetletjih narašča tako doma kot po svetu. Proučili bomo ključne dejavnike povzročitve plazenja ter pristope in sanacije škode, ki je že povzročena ali bi morebiti še lahko nastala. Zaradi vse večje ogroženosti pred plazovi v Sloveniji bomo v nalogi opisali potrebne pristope k modeliranju plazovitosti in ogrožanju pred zemeljskimi plazovi. Prav tako bodo v diplomski nalogi predstavljeni zemeljski plazovi v drugih evropskih državah. V praktičnem primeru naloge pa se bomo osredotočili na izračun in rezultate izračuna računalniškega 2D modela, geološkega profila oziroma prereza P10a, sanacije plazu Znosnice na cesti R1-207, Odsek 1413 Col – Ajdovščina od km 2,400 do km 2,750, izračunanega s programom Plaxis 2D. Landslides will be described in this diploma paper as they have caused an increasing damage in the recent decades in our country as well as around the world. Key factors causing land movement will be examined together with the approaches for rehabilitation of damage which has already been caused or could possibly still arise. Due to the growing threat from landslides in Slovenia, the necessary approaches for modelling the landslides and threats from landslides will be presented in diploma paper. Landslides which occur in other European countries will also be presented in this paper. In the practical part of diploma paper we will be focused on the calculation and the results of 2D computer model, geological profile or cross-section P10a, remediation of landslide Znosnice on the road R1-207, Section 1413 Col – Ajdovščina from km 2,400 to km 2,750, calculated by Plaxis 2D programme.