Monitoring riverbank erosion in mountain catchments using terrestrial laser scanning

Sediment yield is a key factor in river basins management due to the various and adverse consequences that erosion and sediment transport in rivers may have on the environment. Although various contributions can be found in the literature about sediment yield modeling and bank erosion monitoring, the link between weather conditions, river flow rate and bank erosion remains scarcely known. Thus, a basin scale assessment of sediment yield due to riverbank erosion is an objective hard to be reached. In order to enhance the current knowledge in this field, a monitoring method based on high resolution 3D model reconstruction of riverbanks, surveyed by multi-temporal terrestrial laser scanning, was applied to four banks in Val Tartano, Northern Italy. Six data acquisitions over one year were taken, with the aim to better understand the erosion processes and their triggering factors by means of more frequent observations compared to usual annual campaigns. The objective of the research is to address three key questions concerning bank erosion: "how" erosion happens, "when" during the year and "how much" sediment is eroded. The method proved to be effective and able to measure both eroded and deposited volume in the surveyed area. Finally an attempt to extrapolate basin scale volume for bank erosion is presented

Fluvial Processes in Motion: Measuring Bank Erosion and Suspended Sediment Flux using Advanced Geomatic Methods and Machine Learning

Excessive erosion and fine sediment delivery to river corridors and receiving waters degrade aquatic habitat, add to nutrient loading, and impact infrastructure. Understanding the sources and movement of sediment within watersheds is critical for assessing ecosystem health and developing management plans to protect natural and human systems. As our changing climate continues to cause shifts in hydrological regimes (e.g., increased precipitation and streamflow in the northeast U.S.), the development of tools to better understand sediment dynamics takes on even greater importance. In this research, advanced geomatics and machine learning are applied to improve the (1) monitoring of streambank erosion, (2) understanding of event sediment dynamics, and (3) prediction of sediment loading using meteorological data as inputs. Streambank movement is an integral part of geomorphic changes along river corridors and also a significant source of fine sediment to receiving waters. Advances in unmanned aircraft systems (UAS) and photogrammetry provide opportunities for rapid and economical quantification of streambank erosion and deposition at variable scales. We assess the performance of UAS-based photogrammetry to capture streambank topography and quantify bank movement. UAS data were compared to terrestrial laser scanner (TLS) and GPS surveying from Vermont streambank sites that featured a variety of bank conditions and vegetation. Cross-sectional analysis of UAS and TLS data revealed that the UAS reliably captured the bank surface and was able to quantify the net change in bank area where movement occurred. Although it was necessary to consider overhanging bank profiles and vegetation, UAS-based photogrammetry showed significant promise for capturing bank topography and movement at fine resolutions in a flexible and efficient manner. This study also used a new machine-learning tool to improve the analysis of sediment dynamics using three years of high-resolution suspended sediment data collected in the Mad River watershed. A restricted Boltzmann machine (RBM), a type of artificial neural network (ANN), was used to classify individual storm events based on the visual hysteresis patterns present in the suspended sediment-discharge data. The work expanded the classification scheme typically used for hysteresis analysis. The results provided insights into the connectivity and sources of sediment within the Mad River watershed and its tributaries. A recurrent counterpropagation network (rCPN) was also developed to predict suspended sediment discharge at ungauged locations using only local meteorological data as inputs. The rCPN captured the nonlinear relationships between meteorological data and suspended sediment discharge, and outperformed the traditional sediment rating curve approach. The combination of machine-learning tools for analyzing storm-event dynamics and estimating loading at ungauged locations in a river network provides a robust method for estimating sediment production from catchments that informs watershed management

Application of unmanned aircraft system (UAS) for monitoring bank erosion along river corridors

Excessive streambank erosion is a significant source of fine sediments and associated nutrients in many river systems as well as poses risk to infrastructure. Geomorphic change detection using high-resolution topographic data is a useful method for monitoring the extent of bank erosion along river corridors. Recent advances in an unmanned aircraft system (UAS) and structure from motion (SfM) photogrammetry techniques allow acquisition of high-resolution topographic data, which are the methods used in this study. To evaluate the effectiveness of UAS-based photogrammetry for monitoring bank erosion, a fixed-wing UAS was deployed to survey 20 km of river corridors in central Vermont, in the northeastern United States multiple times over a two-year period. Digital elevation models (DEMs) and DEMs of difference allowed quantification of volumetric changes along selected portions of the survey area where notable erosion occurred. Results showed that UAS was capable of collecting high-quality topographic data at fine resolutions even along vegetated river corridors provided that the surveys were conducted in early spring, after snowmelt but prior to summer vegetation growth. Longer term estimates of streambank movements using the UAS showed good comparison to previously collected airborne lidar surveys and allowed reliable quantification of significant geomorphic changes along rivers

Assessing the importance of river bank erosion for fine sediment delivery to Bassenthwaite Lake

Available evidence from lake sediment core records and short-term sediment flux sampling programs has suggested increased fine sediment deposition and suspended sediment transfers to Bassenthwaite Lake, Cumbria, U.K over recent decades. This increase in sedimentation has been associated with a decline in water quality in the lake which is thought to have had serious consequences for the population of the vendace (Coregonu albula), which also declined markedly during the 1990ร and into the 21 St Century. Recent studies of sediment delivery risk in the catchment have suggested that there are potentially large sediment sources in the lowland river network, especially the River Derwent between Derwent Water and Bassenthwaite Lake. The aim of this research is to describe the characteristics of fluvial suspended sediment transfers to Bassenthwaite Lake through direct monitoring of the River Dement and Newlands Beck (at the head of Bassenthwaite Lake) in order to assess the potential contribution of river bank erosion on the lowland River Derwent to fine sediment delivery. Three suspended sediment monitoring stations at Portinscale and Low Stock Bndge on the River Derwent and at Newlands Beck Bridge are used to assess changes in sediment transport along these important river reaches. The potential contribution of river bank erosion to fluvial sediment delivery was assessed by river bank mapping and surveying of erosion features on the 5.7km reach of the River Derwent between Derwent Water and Bassenthwaite Lake, along with a detailed study of morphological change on three river banks near Low Stock Bridge using a terrestrial laser scanner. The main findings of this project suggest that the River Derwent dominates suspended sediment transfers to Bassenthwaite Lake. The fine sediment load transported on the Derwent is over five times greater than that of Newlands Beck and the mean suspended sediment concentration on the lower Derwent is 56% higher than that on Newlands Beck. Specific catchment sediment yields for the River Derwent and Newlands Beck, based on effective drainage area, are 50.871 km(^2) a(^-1) and 35.721 km2 a(^-1) respectively. A high proportion of all suspended sediment transfers in the lowland Bassenthwaite Lake catchment were observed to occur in high-magnitude, low-frequency flow events, with approximately two- thirds of total suspended sediment transport occurring in just over 10% of the time. There is also direct evidence for increased fine sediment supply on the lowland River Derwent, as an estimated 1,158 ta(^-1) increase in the overall sediment load was observed on the 3.7 km reach of the Derwent between Portinscale and Low stock Bridge. Hysteresis analysis and analysis of suspended sediment transfers during high flow events on the Derwent support this hypothesis. Overall, 21.1% of all river banks on the River Derwent were assessed as eroded, with 9.4% of banks undergoing active river bank erosion. Therefore, it is suggested that river bank erosion is a significant fine sediment source in the lowland Bassenthwaite catchment, and that it is responsible for a large proportion of sediment inputs on the lowland River Derwent (c. 18.9%), and ultimately to Bassenthwaite Lake

REMOTE SENSING METHODS FOR THE INVESTIGATION OF THE EVOLUTION AND DYNAMICS OF ALPINE LANDSCAPES

Whilst the effects of present-day climate change are apparent in many environmental systems, much less is known about its impact upon the geomorphic systems characteristic of Alpine environments. This is an important knowledge gap because of the potential vulnerability of Alpine landscapes. The gap exists for two primary reasons: (1) observing climate forcing is challenging because it is manifest over timescales of decades to centuries, over which timescale geomorphic data are commonly scarce; and (2) the geomorphic response of landscapes to climate change can be complex, reflecting both spatially differential sensitivities to climate forcing and the effects of landscape heritage associated with historical glacial activity. Nonetheless, there is a consensus in the scientific community about the potentially high sensitivity of Alpine regions to climate change, because of the vulnerability of permafrost, glacial and nival processes to changes in atmospheric temperature and precipitation and the large amount of sediment stored on the associated hillsides. One approach to addressing this knowledge gap is to harness the power of remote sensing. A number of active and passive remote sensing methods could be employed for the reconstruction and monitoring of both whole landscapes and individual landforms. This Thesis aims to use such approaches to quantify the geomorphic dynamics of high mountain areas at the timescale of decades and so in the context of recent and rapid climate warming. It does so recognizing that both endogenous (landscape legacy) and exogenous (climatic forcing) processes may matter. To support this primary aim, a secondary aim arises: the evaluation of the potential of a number of remote sensing techniques for landscape and landform monitoring at multiple temporal and spatial scales. Thus this Thesis also tests in an Alpine setting the geomorphological potential of photogrammetric methods, using both aerial and hand-held sensors and both traditional and the innovative Structure-from-Motion processing approaches, and Terrestrial Laser Scanner techniques. The Thesis shows that remote sensing approaches prove to be an advantageous approach for a number of scales of application. In particular, over large spatial extents and in the case of decadal scale climate forcing of Alpine landscapes, photogrammetry was found to be capable of quantifying process rates within the limits of detection determined by the resolution of historical imagery. The information unlocked from aerial archives reveals distinct geomorphic responses to cold and warm periods and to changes in rates of precipitation and snow cover. Nonetheless, whilst enhanced sediment production is observed locally, evidence suggest a weak propagation of climate change signals through the landscape due to impeded connection to the river system and/or sediment transport capacity limitation. -- Bien que les effets des changements climatiques actuels soient visibles dans de nombreux systèmes environnementaux, un manque de connaissances des impacts sur les paysages alpins persiste. Cette lacune existe pour deux raisons principales : (1) l'observation du forçage climatique représente un défi, car ses conséquences se manifestent sur des périodes de plusieurs décennies, voire des siècles, pour lesquels les données géomorphologiques sont généralement rares ; et (2) la réaction du paysage aux changements climatiques peut être complexe, reflétant à la fois des sensibilités différentes au niveau spatial et les effets du patrimoine paysager, comme par exemple son histoire glaciaire. Néanmoins, il existe un consensus dans la communauté scientifique à propos de la haute sensibilité potentielle des régions alpines au changement climatique, en raison de la vulnérabilité du pergélisol et des processus glaciaires et neigeux aux changements de température atmosphérique et des précipitations et en raison de la grande quantité de sédiments stockés sur les versants alpins. Une stratégie pour aborder ces problématiques s'appuie sur le potentiel de la télédétection. Une série de méthodes de télédétection active et passive peuvent être utilisées pour reconstruire et surveiller le paysage entier et les éléments individuels qui le composent. Cette thèse vise l'application de ces approches pour quantifier les dynamiques géomorphologiques des paysages de haute montagne à l'échelle des décennies, et donc dans le contexte du réchauffement climatique récent et actuel. Cela est mis en pratique par la reconnaissance de l'importance des processus endogènes (héritage du paysage) et exogènes (forçage climatique). Le soutien à cet objectif en soulève un deuxième : l'évaluation du potentiel d'un certain nombre de techniques de télédétection pour le monitorage du relief et de ses formes géomorphologiques à plusieurs échelles temporelles et spatiales. Ainsi, cette thèse teste le potentiel des méthodes de photogrammétrie, en utilisant à la fois des senseurs aéroportés et portatifs et des approches de traitements traditionnels et innovants, et du balayage laser terrestre pour la recherche géomorphologique alpine. Les résultats obtenus montrent que les approches de télédétection se révèlent avantageuses pour des nombreuses échelles d'application. En particulier, sur de grandes étendues spatiales et dans le contexte du forçage climatique du paysage alpin, la photogrammétrie aérienne d'archive se montre appropriée pour la quantification des taux des processus dans les limites de détection déterminées par la résolution des photographies historiques. Les résultats démontrent l'existence d'une réponse géomorphologique distincte pour des périodes froides ou chaudes, ainsi que selon les variations des taux de précipitations et de couverture de neige. Néanmoins, alors qu'une production accrue de sédiments est observée localement, des évidences suggèrent une faible propagation des signaux du changement climatique à travers le paysage. Les raisons semblent être une faible contribution des versants au réseau fluvial et/ou une capacité de transport des sédiments limitée. -- Obwohl die Auswirkungen des aktuellen Klimawandels in zahlreichen Umweltsystemen beobachtet wurden, sind die Kenntnisse dieser Auswirkungen auf alpine Landschaften immer noch ungenügend. Diese Lücke existiert aus folgenden Gründen: (1) Das Beobachten klimatischer Auswirkungen auf alpine geomorphologische Prozesse stellt eine grosse Herausforderung dar, da diese sich über eine Zeitspanne von mehreren Jahrzehnten bis Jahrhunderten bemerkbar machen können, für die meist nur wenige geomorphologische Daten zur Verfügung stehen. (2) Durch die unterschiedlichen Empfind- lichkeiten verschiedener geomorphologischer Landschaftselemente sowie durch den grossen Einfluss des landschaftlichen Erbes, wie zum Beispiel der historischen Gletschertätigkeit, reagieren alpine Landschaftsentwicklungsprozesse sehr komplex auf Veränderungen des Klimas. Nichtsdestotrotz, auf- grund der hohen Empfindlichkeit des Permafrosts und der Gletscher- und Schneeprozesse gegenüber Veränderungen der atmosphärischen Temperatur und der Niederschlagsmenge sowie der grossen Menge an Sedimenten die an den Alpenhängen abgelagert werden und wurden, herrscht in der wis- senschaftlichen Gemeinschaft ein breiter Konsens über die potentielle hohe Sensibilität der alpinen geomorphologischen Systeme in Bezug auf den zu erwartenden Klimawandel. Fernerkundung bietet ein hohes Potential, um die geomorphologische Sensibilität zu erkunden. Aktive und passive Fernerkundungsmethoden können genutzt werden, um gesamte Landschaften sowie ihre einzelnen geomorphologischen Elemente historisch zu rekonstruieren und kontinuierlich zu überwachen. Die vorliegende Dissertation zielt auf die Anwendung dieser Ansätze, um die geomorpho- logische Dynamik der hochalpinen Landschaft über Jahrzehnte, und somit im Kontext der jüngsten Klimaerwärmung, zu quantifizieren. Der hier dargestellte Ansatz fokussiert vor allem auf die Bedeutung der endogenen (landschaftliches Erbe) und exogenen (klimatische Einflüsse) Prozesse. Die Umsetzung dieses primären Ziels zieht ein sekundäres Ziel mit sich: Die Bewertung des Potenzials einer Reihe von Fernerkundungsmethoden für das Monitoring von Landschaften und ihrer geomorphologischen For- men auf mehreren rüumlichen und zeitlichen Skalen. Damit wird das Potenzial photogrammetrischer Methoden, insbesondere luftgestützter und tragbarer Sensoren in Kombination mit traditionellen und innovativen "Structure-from-Motion" Ansätzen, sowohl auch terrestrischen Laserscanning Techniken für die alpine geomorphologische Forschung getestet. Die Ergebnisse zeigen, dass die hier dargestellten Fernerkundungsansätze für eine breite Reihe von Anwendungsskalen vorteilhaft sind. Die Archiv-Luftphotogrammmetrie ist besonders für die Quan- tifizierung der Auswirkungen des Klimawandels auf geomorphologische Prozesse in grossen Land- schaftsausschnitten geeignet. Die Auflösung der historischen Luftbilder bestimmt die Detektionsgrenze dieser Prozesse. Die aus den Luftarchiven ermittelten Informationen zeigen, dass kalte und warme Klimaphasen, sowie Variationen der Niederschlagsmenge und der Schneedeckenmächtigkeit unter- schiedliche Auswirkungen auf geomorphologische Prozesse haben. Obwohl ein lokaler Anstieg der Sedimentproduktion beobachtet werden konnte, konnten nur geringe Anzeichen einer Ausbreitung dieser Klimawandelsignale in der Landschaft beobachtet werden. Die Gründe hierfür scheinen der geringe Beitrag der untersuchten Berghänge zum Gesamtwasserabfluss und/oder die beschränkte Sedimenttransportfähigkeit zu sein. -- Nonostante gli effetti del cambiamento climatico attuale siano evidenti in molti sistemi ambientali, una conoscenza deficitaria perdura riguardo il suo impatto sui paesaggi alpini. Tale lacuna esiste per due principali ragioni: (1) gli effetti del cambiamento climatico sono difficili da osservare, in quanto manifesti su scale temporali di decenni, o persino secoli, per le quali prevale una scarsità di dati geomorfologici esaustivi; e (2) la reazione del paesaggio a tali cambiamenti può essere complessa e riflettere al contempo delle sensibilità spaziali differenti e gli effetti del patrimonio paesaggistico, come ad esempio la cronistoria glaciale. Tuttavia, vi è un consenso nella comunità scientifica riguardo l'ele- vata sensibilità delle regioni alpine ai cambiamenti climatici, a causa della vulnerabilità di permafrost e processi glaciali e nevosi ai cambiamenti di temperatura atmosferica e di precipitazioni, oltre che all'ampio stoccaggio di sedimenti concentrato sui pendii alpini. Una strategia per colmare questa lacuna di conoscenza può essere l'avvalersi del potenziale delle tecniche di telerilevamento. Vari metodi di telerilevamento attivo e passivo possono essere impiegati per ricostruire e monitorare il paesaggio ed i singoli elementi che lo compongono. Questa tesi si propone di utilizzare tali metodi per quantificare le dinamiche geomorfologiche nelle regioni di alta montagna a scala temporale decennale, e quindi nel contesto del riscaldamento climatico recente e attuale. In tale approccio viene riconosciuta l'importanza dei processi di tipo endogeno (di eredità paesaggistica) ed exogeno (climatici). A sostegno di questo obiettivo primario, una seconda finalità si pone: lo sviluppo e la valutazione di diverse tecniche di telerilevamento per il monitoraggio dei rilievi alpini e delle loro forme geomorfologiche, a più scale temporali e spaziali. Pertanto, questa tesi mette alla prova metodi di fotogrammetria, utilizzando al contempo sensori aeroportati e portatili ed approcci tradizionali ed innovativi (come l'emergente Structure-from-Motion), e tecniche di scansione laser per la ricerca geomorfologica in scenari alpini. I risultati ottenuti dimostrano come gli approcci di telerilevamento rappresentino una risorsa efficace e vantaggiosa per una vasta gamma di applicazioni. In particolare, ad ampia scala spaziale e nel contesto di cambiamento climatico nelle regioni alpine, la fotogrammetria aerea d'archivio si è dimostrata appropriata per la quantificazione dei processi geomorfologici entro limiti di rilevamento determinati dalla risoluzione delle immagini storiche stesse. I risultati rivelano una reazione geomorfica distinta a periodi di caldo e freddo, oltre che a variazioni di precipitazioni e copertura nevosa. Ciononostante, malgrado un accrescimento della produzione sedimentaria sia presente a scala locale, la propagazione dei segnali di cambiamento climatico attraverso il paesaggio appare debole. La ragione risiede nello scarso contributo dei versanti al sistema fluviale e/o a limitate capacità di trasporto di sedimenti

Geomorphic impact and assessment of flexible barriers using multi-temporal LiDAR data: The Portainé mountain catchment (Pyrenees)

Multi-temporal digital elevation models (DEMs) obtained from airborne LiDAR surveys are widely used to detect geomorphic changes in time and quantify sediment budgets. However, they have been rarely applied to study the geomorphic impact of engineering structures in mountain settings. In this study, we assessed the influence and behavior of flexible sediment retention barriers in the Portainé catchment (Spanish Pyrenees), using three LiDAR data sets (2009, 2011 and 2016) that covered a 7-year period. Densely forested mountainous areas present some limitations for reliable DEM analysis due to spatial variabilities in data precision, accuracy and point density. A new methodological approach for robust uncertainty analysis along channels, based on changes in cross-sectional elevations, was used to discriminate noise from real geomorphic changes. The obtained results indicated that erosion occurs along most reaches covering a large area, whereas deposition is localized in specific areas such as those upstream of sediment retention barriers and in the debris cone. Despite the presence of 15 flexible sediment retention barriers, the channels presented net degradation during both 2009-2011 and 2011-2016, with 2838 and 147m3 of material exported from the basin, respectively. For the same periods, the barriers retained 33% and 25% of the total deposition (up to 1300m3 per barrier), respectively, but also induced lateral and downstream incision, the latter reaching 703m3 for a single barrier. We detected a horizontal displacement of the net of up to 1.2m in filled barriers, resulting from net flexion. The interference of the natural river evolution by defense measures has resulted in a complex erosion-deposition pattern. The presented methods show high potential for the hydrogeomorphic study of mountain catchments, especially for a high-resolution assessment of flexible barriers or other engineering structures in remote areas

An intensity recovery algorithm (IRA) for minimizing the edge effect of LIDAR data

The terrestrial laser scanner is an equipment developed for surveying applications and is also used for many other purposes due to its ability to acquire 3D data quickly. However, before intensity data can be analyzed, it must be processed in order to minimize the edge or border effect, one of the most serious problems of LIDAR’s intensity data. Our research has focused on characterizing the edge effect behavior as well as to develop an algorithm to minimize edge effect distortion automatically (IRA). The IRA showed to be effective recovering 35.71% of points distorted by the edge effect, providing significant improvements and promising results for the development of applications based on TLS data intensity to many studies

Impact of bioturbation on sediment redistribution in coastal Chile - As estimated by combining remote sensing, machine learning and semi-empirical modelling

The burial activity of terrestrial bioturbators influences the microtopography, surface roughness, and physical properties of the soil. By reworking sediments, bioturbators increase soil permeability and porosity, which has implications for infiltration and erosion rates. The construction of underground tunnels distributes and concentrates nutrients and has a particularly positive effect on carbon storage in the soil. Previous studies have left several research gaps. The studies focused only on the habitat preferences of individual species and did not consider the varying amount of excavated sediment and the building density of individual species. It remains unclear which environmental parameters within the catchment area are primarily associated with the high density and distribution of all existing bioturbator structures. Furthermore, the previous authors did not address the daily sediment excavation dynamics by the animal, whether and how it is related to sediment redistribution driven by catchment-wide precipitation, and how much sediment the bioturbators transport to the surface throughout the year. My dissertation was part of the EarthShape consortium with the overarching research question of how microorganisms, animals, and plants influence the shape and development of the Earth's surface. The study was conducted at four study sites along the Chilean coastal cordillera: arid Pan de Azúcar, semi-arid Santa Gracia, Mediterranean La Campana, and humid Nahuelbuta. The workflow consisted of three work packages with the ultimate goal of determining the catchment-wide effects of bioturbation. Within the first work package, I tested whether the density of burrows and the distribution of structures can be predicted by vegetation patterns calculated from UAV and WorldView-2 data. Then I used the best model for catchment-wide prediction. Within the second work package, I tested whether bioturbator-driven sediment redistribution depends on precipitation-driven sediment redistribution. For this purpose, I deployed several time-of-flight-based cameras to monitor sediment redistribution on the trench surface and around the trench. In the third work package, I integrated bioturbation into a soil erosion model. Then I determined the influence of bioturbators on sediment distribution and the environmental parameters that determine the extent of this influence. My results showed that the distribution of structures created by bioturbating animals depends on vegetation patterns. The density of burrows created by bioturbating animals was best predicted by in-situ measured vegetation cover as well as the diameter and height of shrubs. In the arid and semi-arid zones, cactus height and cover were important predictors, while in the humid zone, tree trunk diameter and cover were selected by the model. However, plant species diversity was important in all climatic zones. When predicting burrow density using UAV images, indices of vegetation heterogeneity were also important. The density of structures increased with shrub, herb, and cactus cover in all climatic zones and decreased with tree canopy cover in the humid climate zone. The density of invertebrate structures was higher in rockier areas with less vegetation at all sites. Finally, a vegetation index describing high leaf area index was an important predictor. The distribution of structures throughout the catchment area was best predicted by the WorldView-2 NIR band and NDVI, as well as individual vegetation land cover classes. Topographic features derived from LiDAR data were not selected as important predictors, except for aspect. Secondly, the results showed that sediment redistribution triggered by bioturbators depends on rainfall-triggered redistribution. Immediately after rainfall events in the Mediterranean climate zone, increased sediment export by the animals was observed: the animals were observed reconstructing their structures after the rains and simultaneously excavating more additional sediment to the surface. In contrast, in the arid climate zone, sediment export was mostly not preceded by rainfall events. The results confirmed that the environment determines the extent of the impact of bioturbation on rainfall-induced sediment redistribution throughout the catchment area. The results showed that the key environmental parameters were elevation, surface roughness, slope, and vegetation cover derived from NDVI. Bioturbation increased sediment erosion in areas where erosion processes dominate (steep slopes, strong gradients, low surface roughness, low vegetation cover), and similarly increased sediment accumulation in areas with natural sediment deposition (high surface roughness, high vegetation cover, low slope). The model output demonstrated that bioturbation intensifies sediment erosion. Bioturbation amplified sediment erosion in all climatic zones except the humid zone. Monitoring the structures showed an increase in erosion of over 300% compared to the areas where the structures were embedded. According to the results of the soil erosion model, bioturbation had the strongest impact on erosion in the Mediterranean zone, followed by the arid and semi-arid zones. The effects of bioturbation were not significant in the humid zone. To assess long-term impacts, bioturbation needs to be integrated into landscape development models. However, these models have assumed a uniform distribution and spatial and temporal effects of bioturbation. My results demonstrated that the effects of bioturbation on sediment redistribution are not temporally and spatially consistent, and the distribution of bioturbation is not uniformly associated with vegetation. To realistically predict the long-term effects of bioturbation, the estimated spatial and temporal variations from this study need to be considered

Analysis of the temporal and spatial scales of soil erosion and transport in a Mountain Basin

open5siAnalysis of erosive processes and sediment transport in mountain environments has numerous implications for proper river basin management, land use planning as well as flood risk evaluation. Temporal and spatial scales of these phenomena may vary greatly during intense precipitation events with respect to normal conditions, thus introducing significant differences between long- and short-term related sediment yield and transport. In this work, the Erosion Potential Method is applied to Alpine catchments located in Northern Italy. Method downscaling in space and time is proposed to estimate an event-related sediment yield rather than an annual one. Interpretation of the results suggests that the long-term sediment accumulation could control the volumes transported during a single storm. Thus, some considerations on the estimation of long-term related sediment yield are further introduced. Finally, a 'chain' routing pattern of sediment yield through consecutively positioned basins is suggested as an alternative to a simple sum of the eroded volumes of all contributing basins when a subdivision of the catchment is adopted. Emphasis is put on the validity of the result with respect to the classical application of the method as well as on its usefulness for an integrated assessment of hydro-geological flood risk.Longoni, Laura; Ivanov, Vladislav Ivov; Brambilla, Davide; Radice, Alessio; Papini, MonicaLongoni, Laura; Ivanov, VLADISLAV IVOV; Brambilla, Davide; Radice, Alessio; Papini, Monic