Point process-based modeling of multiple debris flow landslides using INLA: an application to the 2009 Messina disaster

We develop a stochastic modeling approach based on spatial point processes of log-Gaussian Cox type for a collection of around 5000 landslide events provoked by a precipitation trigger in Sicily, Italy. Through the embedding into a hierarchical Bayesian estimation framework, we can use the Integrated Nested Laplace Approximation methodology to make inference and obtain the posterior estimates. Several mapping units are useful to partition a given study area in landslide prediction studies. These units hierarchically subdivide the geographic space from the highest grid-based resolution to the stronger morphodynamic-oriented slope units. Here we integrate both mapping units into a single hierarchical model, by treating the landslide triggering locations as a random point pattern. This approach diverges fundamentally from the unanimously used presence-absence structure for areal units since we focus on modeling the expected landslide count jointly within the two mapping units. Predicting this landslide intensity provides more detailed and complete information as compared to the classically used susceptibility mapping approach based on relative probabilities. To illustrate the model's versatility, we compute absolute probability maps of landslide occurrences and check its predictive power over space. While the landslide community typically produces spatial predictive models for landslides only in the sense that covariates are spatially distributed, no actual spatial dependence has been explicitly integrated so far for landslide susceptibility. Our novel approach features a spatial latent effect defined at the slope unit level, allowing us to assess the spatial influence that remains unexplained by the covariates in the model

A Multiphase First Order Model for Non-Equilibrium Sand Erosion, Transport and Sedimentation

Three phenomena are involved in sand movement: erosion, wind transport, and sedimentation. This paper presents a comprehensive easy-to-use multiphase model that include all three aspects with a particular attention to situations in which erosion due to wind shear and sedimentation due to gravity are not in equilibrium. The interest is related to the fact that these are the situations leading to a change of profile of the sand bed

Scale-dependence of lithological control on topography: Bedrock channel geometry and catchment morphometry in western Scotland

We propose that a scale-dependent topographic signature of erodibility arises due to fluvial and glacial erosion acting on different parts of the landscape at different times. For 14 catchments in western Scotland, we define three levels of substrate erodibility in order of decreasing resistance: quartzite rocks, nonquartzite rocks, and zones of fault-related fracture. Then, using digital topographic and planimetric data coupled with field measurements, we identify regression based scaling relationships between substrate erodibility and morphometric parameters at two spatial scales. Catchment-scale morphometry shows a weak to variable relationship with substrate metrics overall. Erodibility can be inferred from catchment steepness indices (i.e., channel steepness index and relief ratio), but the existence of multiple exceptions could confound a more general application of this approach. Nonetheless, major valley troughs trace fault zones and nonquartzite rocks, leaving much of the higher and steeper ground formed in quartzite. At the reach scale, bedrock channel slope is far more sensitive to substrate erodibility than is channel width. Quartzite outcrops steepen bedrock channels by a factor of 1.5–6.0, and in terms of unit stream power, channels increase their erosional capacity by a factor of 2.7–3.5. Yet only 4%–13% of this increase is due to channel narrowing. Based on a large data set of bedrock channel width (n = 5825) from four rivers, we find that width scales with drainage area (in m<sup>2</sup>) as W = 0.01A<sup>0.28</sup>. Our results are consistent with the view that width-area scaling is similar in all single-thread rivers subject to transport-limited conditions but that for increasingly sediment supply limited settings, erosional thresholds at the channel boundary are the key determinants of bedrock channel width

Using a coastal storm hazard index to assess storm impacts in Lisbon

Coastal areas are among the most dynamic earth systems as they are exposed to powerful agents. Near-shore wave energy is one of the most important triggering factors for erosion and flooding and is often neglected for severe infrastructure damaging, property losses and loss of life. These consequences are amplified with high population density and heavy infrastructure implantation as it happens in Lisbon (Portugal). In this context, it is of great importance for coastal stakeholders, decision-makers and civil protection entities to estimate precisely the spatial distribution of storm hazard for prevention and mitigation purposes, as well as to design adjusted answers for calamity responses. We apply a coastal storm hazard index (CSHI) considering triggering and conditioning variables involved in the effects of an extreme storm, namely: 100-year return period of SWAN modelled Hs, and its spatial distribution across the study area, land use, number of buildings, height, slope, geology, geomorphology, erosion/ accretion rates, width of the systems, exposure of the coastline, bathymetry and legally protected areas. The variables were weighted according to a hierarchical analysis process and classified into five classes of exposure. A validation process was then implemented by comparing the occurrences identified in the last two decades newspapers and the storm hazard classification, showing a satisfactory validation results. The results show a classified storm hazard map that identifies the most and the less exposed areas. High values of CSHI occur in areas with excessive human pressure, low heights sandy systems with significant costal erosion rates. The main type of consequences identified are associated with inland flooding and erosion, resulting in the destruction of coastal protection infrastructures, and population displacement leading to great economic and social impacts and loss of life.info:eu-repo/semantics/publishedVersio

Sedimentological characterization of Antarctic moraines using UAVs and Structure-from-Motion photogrammetry

In glacial environments particle-size analysis of moraines provides insights into clast origin, transport history, depositional mechanism and processes of reworking. Traditional methods for grain-size classification are labour-intensive, physically intrusive and are limited to patch-scale (1m2) observation. We develop emerging, high-resolution ground- and unmanned aerial vehicle-based ‘Structure-from-Motion’ (UAV-SfM) photogrammetry to recover grain-size information across an moraine surface in the Heritage Range, Antarctica. SfM data products were benchmarked against equivalent datasets acquired using terrestrial laser scanning, and were found to be accurate to within 1.7 and 50mm for patch- and site-scale modelling, respectively. Grain-size distributions were obtained through digital grain classification, or ‘photo-sieving’, of patch-scale SfM orthoimagery. Photo-sieved distributions were accurate to <2mm compared to control distributions derived from dry sieving. A relationship between patch-scale median grain size and the standard deviation of local surface elevations was applied to a site-scale UAV-SfM model to facilitate upscaling and the production of a spatially continuous map of the median grain size across a 0.3 km2 area of moraine. This highly automated workflow for site scale sedimentological characterization eliminates much of the subjectivity associated with traditional methods and forms a sound basis for subsequent glaciological process interpretation and analysis

Mesoscale modelling of periglacial landforms in the circumpolar Arctic

Arktinen alue lämpenee kiihtyvällä tahdilla, ja sillä voi olla merkittäviä vaikutuksia ekosysteemeihin, infrastruktuuriin ja alueen yhteisöihin. Tutkimalla periglasiaalisia muodostumia ja prosesseja, sekä hyödyntämällä paranneltuja menetelmiä on mahdollista saada lisätietoa muuttuvista ympäristöolosuhteista ja niiden vaikutuksista. Tämän opinnäytetyön tarkoituksena on kartoittaa tutkimuksen kohteena olevia muodostumia/prosesseja ja pyrkiä ennustamaan niiden esiintymisen todennäköisyys sirkumpolaarisella vyöhykkeellä hyödyntäen eri mallinnusmenetelmiä. Periglasiaalisia ympäristöjä esiintyy korkeilla leveysasteilla ja muilla kylmillä alueilla. Tavallisesti näissä ympäristöissä esiintyy myös ikiroutaa, joka on jäätynyttä maata ja joka reagoi tehokkaasti ilmaston lämpenemiseen. Ikirouta-alueilla esiintyy monia muodostumatyyppejä, joita tutkimalla ja mallintamalla voidaan saada tietoa muuttuvista olosuhteista Arktiksella sekä muodostumien ja prosessien levinneisyyksistä. Tässä tutkimuksessa tarkastelun kohteena oli neljä eri muodostumatyyppiä: kuviomaat, pingot, termokarstiaktiivisuus sekä solifluktio. Tutkimus koostui kymmenestä tutkimusalueesta sirkumpolaarisella Arktiksella, joista kaikista kartoitettiin muodostumia. Tutkimuksessa hyödynnettiin GLM, GAM ja GBM analyyseja, joilla mallinnettiin muodostumien esiintymistä Arktisella alueella perustuen ympäristömuuttujiin. Mallien kalibroinnissa hyödynnettiin logit linkkifunktiota ja evaluoinnissa selitettyä poikkeavuutta. Data jaettiin evaluaatio- ja kalibraatio aineistoihin, jotta ennustekapasiteettia voitiin arvioida. Ennusteiden tarkkuuden määrityksessä hyödynnettiin ROC/AUC arvoja. Termokarstiaktiivisuutta esiintyi eniten tutkituilla alueilla, ja solifluktiota kaikkein vähiten. Pingoja esiintyi tasaisesti kaikilla alueilla. Kuviomaata ei löytynyt tietyiltä alueilta, mutta jollain alueilla sitä esiintyi runsaasti. Ilmastomuuttujat ja maanpinnan keskilämpötila osoittautuivat merkittävimmiksi muuttujiksi selitettäessä muodostumien esiintyvyyttä sirkumpolaarisella alueella. GBM oli mallinnusmenetelmistä tarkin ja sillä oli paras ennustuskyky. Tulokset osoittavat, että kartoitus ja mallinnus mesoskaalassa on mahdollista. Tulevaisuudessa tuloksia voitaisiin hyödyntää Arktisen alueen monitorointi- ja globaalimuutostutkimuksiin, sekä mahdollisesti arvioitaessa periglasiaalisten muodostumien suhdetta alueellisiin ympäristömuuttujiin.The Arctic is warming with an increased pace, and it can affect ecosystems, infrastructure and communities. By studying periglacial landforms and processes, and using improved methods, more knowledge on these changing environmental conditions and their impacts can be obtained. The aim of this thesis is to map studied landforms and predict their probability of occurrence in the circumpolar region utilizing different modelling methods. Periglacial environments occur in high latitudes and other cold regions. These environments host permafrost, which is frozen ground and responds effectively to climate warming, and underlays areas that host many landform types. Therefore, landform monitoring and modelling in permafrost regions under changing climate can provide information about the ongoing changes in the Arctic and landform distributions. Here four landform/process types were mapped and studied: patterned ground, pingos, thermokarst activity and solifluction. The study consisted of 10 study areas across the circumpolar Arctic that were mapped for their landforms. The study utilized GLM, GAM and GBM analyses in determining landform occurrences in the Arctic based on environmental variables. Model calibration utilized logit link function, and evaluation explained the deviance value. Data was sampled to evaluation and calibration sets to assess prediction abilities. The predictive accuracy of the models was assessed using ROC/AUC values. Thermokarst activity proved to be most abundant in studied areas, whereas solifluction activity was most scarce. Pingos were discovered evenly throughout studied areas, and patterned ground activity was absent in some areas but rich in others. Climate variables and mean annual ground temperature had the biggest influence in explaining landform occurrence throughout the circumpolar region. GBM proved to be the most accurate and had the best predictive performance. The results show that mapping and modelling in mesoscale is possible, and in the future, similar studies could be utilized in monitoring efforts regarding global change and in studying environmental and periglacial landform/process interactions

Modelling and Terrestrial Laser Scanning Methodology (2009–2018) on Debris Cones in Temperate High Mountains

Producción CientíficaDebris cones are a very common landform in temperate high mountains. They are the most representative examples of the periglacial and nival processes. This work studies the dynamic behavior of two debris cones (Cone A and Cone B) in the Picos de Europa, in the north of the Iberian Peninsula. Their evolution was measured uninterruptedly throughout each August for 10 years (2009–2018) using the Terrestrial Laser Scanning (TLS) technique. The observations and calculations of the two debris cones were treated independently, but both showed the same behavior. Therefore, if these results are extrapolated to other debris cones in similar environments (temperate high mountain), they should show behavior similar to that of the two debris cones analyzed. Material falls onto the cones from the walls, and transfer of sediments follows linear trajectories according to the maximum slope. In order to understand the linear evolution of the two debris cones, profiles were created along the maximum slope lines of the Digital Elevation Model (DEM) of 2009, and these profile lines were extrapolated to the remaining years of measurement. In order to determine volumetric surface behavior in the DEMs, each year for the period 2009–2018 was compared. In addition, the statistical predictive value for position (Z) in year 2018 was calculated for the same planimetric position (X,Y) throughout the profiles of maximum slopes. To do so, the real field data from 2009–2017 were interpolated and used to form a sample of curves. These curves are interpreted as the realization of a functional random variable that can be predicted using statistical techniques. The predictive curve obtained was compared with the 2018 field data. The results of both coordinates (Z), the real field data, and the statistical data are coherent within the margin of error of the data collection.Fondo Europeo de Desarrollo Regional - Agencia Estatal de Investigación (grant TIN2016-76843-C4-2-R)Ministerio de Economía, Industria y Competitividad - Fondo Europeo de Desarrollo Regional (grant CGL2015-68144-R

Impacts of land abandonment and climate variability on runoff generation and sediment transport in the Pisuerga headwaters (Cantabrian Mountains, Spain)

Producción CientíficaThe Atlantic mountains of Spain are suffering a strong landscape change due to a widespread and intensive emigration to urban areas since the 1950s. This process, representative of global developments in an imminent future, is dominated by urban societies and leads to deep landscape changes in which crop fields and grasslands are abandoned and progressively covered by forest and shrubs. These dynamics have caused in turn a decrease in the runoff and a general slowdown of geomorphological processes. The impacts of land cover change have been simultaneous to an irregularity in precipitation and a significant increase of temperatures. With this background, this paper assesses in detail the impact of landscape change occurred over the last decades (twentieth and twenty-first centuries) on the water and sediment yield in the Pisuerga catchment headwaters (Cantabrian Mountains, N Spain). We analyzed the different components of Global Change in a catchment of 233 km2 extent, that has passed from 15 to 2 habitants/km2, from multiple data sources. Evolution of land cover was reconstructed from aerial photographs, remote sensing and other resources. The climatic parameters have been studied through meteorological stations, and the hydrological and sedimentological responses over time are based on available runoff data and sedimentological analysis. Our results show a significant decrease in water and sediment transport mainly driven by vegetation increase occurred in a non-linear way, more intense immediately after abandonment. This fact opens the opportunity to control more accurately water resources in Mediterranean catchments through land use management.Ministerio de Economía, Industria y Competitividad - Fondo Europeo de Desarrollo Regional (project CGL2015-68144-R)Ministerio de Educación y Formación Profesional (grant FPU13/05837

Spatial variability in floodplain sedimentation: the use of generalized linear mixed-effects models

14 Pag., 4 Tabl., 5 Fig. © Author(s) 2010. This work is distributed under the Creative Commons Attribution 3.0 License.Sediment, Total Organic Carbon (TOC) and total nitrogen (TN) accumulation during one overbank flood (1.15 y return interval) were examined at one reach of the Middle Ebro River (NE Spain) for elucidating spatial patterns. To achieve this goal, four areas with different geomorphological features and located within the study reach were examined by using artificial grass mats. Within each area, 1 m2 study plots consisting of three pseudo-replicates were placed in a semi-regular grid oriented perpendicular to the main channel. TOC, TN and Particle-Size composition of deposited sediments were examined and accumulation rates estimated. Generalized linear mixed-effects models were used to analyze sedimentation patterns in order to handle clustered sampling units, specific-site effects and spatial self-correlation between observations. Our results confirm the importance of channel-floodplain morphology and site micro-topography in explaining sediment, TOC and TN deposition patterns, although the importance of other factors as vegetation pattern should be included in further studies to explain small-scale variability. Generalized linear mixed-effect models provide a good framework to deal with the high spatial heterogeneity of this phenomenon at different spatial scales, and should be further investigated in order to explore its validity when examining the importance of factors such as flood magnitude or suspended sediment concentration.Field works were funded by the Department of Environmental Science, Technology and University – Government of Aragon (Research group E-61 on Ecological Restoration)– and MEC (CGL2005-07059). The Spanish Research Council (CSIC) granted Álvaro Cabezas through the I3P program(I3P-EPD2003-2), which was financed by European Social Funds (UE). Research of M. Angulo-Martínez is supported by a JAE-Predoc Research Grant from the Spanish National Research Council (Consejo Superior de Investigaciones Científicas – CSIC).Peer reviewe