TY - JOUR A1 - Calsamiglia, Aleix A1 - Garcia-Comendador, Julian A1 - Fortesa, Josep A1 - Lopez-Tarazon, José Andrés A1 - Crema, S. A1 - Cavalli, M. A1 - Calvo-Cases, A. A1 - Estrany, Joan T1 - Effects of agricultural drainage systems on sediment connectivity in a small Mediterranean lowland catchment JF - Geomorphology : an international journal on pure and applied geomorphology N2 - Traditional drainage systems combining man-made channels and subsurface tile drains have been used since Roman times to control water excess in Mediterranean lowland regions, favouring adequate soil water regime for agriculture purposes. However, mechanization of agriculture, abandonment or land use changes lead to a progressive deterioration of these drains in the last decades. The effects of these structures on hydrological and sediment dynamics have been previously analyzed in a small Mediterranean lowland catchment (Can Revull, Mallorca, Spain, 1.4 km2) by establishing an integrated sediment budget with a multi-technique approach. Moreover, the recent advances in morphometric techniques enable the completion of this analysis by the accurate identification of active areas (i.e. sources, pathway links, and sinks) and improve the understanding of (de-)coupling mechanisms of water and sediment linkages. In this study, the Borselli's index of connectivity (IC; Cavalli et al. (2013)'s version) derived from a LiDAR-based high resolution DEM (>1 pt m−2; RMSE < 0.2 m) was used to evaluate the spatial patterns of sediment connectivity of the catchment under two different scenarios: (1) the current scenario, including an accurate representation of the 3800 m of artificial channels and levees (CS - Channelled Scenario), and (2) a hypothetical scenario in which these anthropogenic features were removed (US - Unchannelled Scenario). Design and configuration of the drainage system in Can Revull generated changes favouring lateral decoupling between different compartments, with hillslopes-floodplain and floodplain-channels relationships, showing a general decrease of IC values, and high longitudinal connectivity along the artificial channel network. Field observations corroborated these results: structures enabled rapid drainage of the water excess also promoting low surface runoff within the field crops, proving to be an effective management practice for erosion control in agricultural Mediterranean lowland catchments. By contrast, US demonstrated that the abandonment of the current agricultural practices and the subsequent destruction of the drainage system could lead the higher soil loss rates owning to more intense/effective processes of sediment connectivity. KW - Sediment connectivity KW - Traditional drainage systems KW - Catchment management KW - Soil erosion KW - LiDAR Y1 - 2018 U6 - https://doi.org/10.1016/j.geomorph.2018.06.011 SN - 0169-555X SN - 1872-695X VL - 318 SP - 162 EP - 171 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Jara-Munoz, Julius A1 - Melnick, Daniel A1 - Brill, Dominik A1 - Strecker, Manfred T1 - Segmentation of the 2010 Maule Chile earthquake rupture from a joint analysis of uplifted marine terraces and seismic-cycle deformation patterns JF - Quaternary science reviews : the international multidisciplinary research and review journal N2 - The segmentation of major fault systems in subduction zones controls earthquake magnitude and location, but the causes for the existence of segment boundaries and the relationships between long-term deformation and the extent of earthquake rupture, are poorly understood. We compare permanent and seismic-cycle deformation patterns along the rupture zone of the 2010 Maule earthquake (M8.8), which ruptured 500 km of the Chile subduction margin. We analyzed the morphology of MIS-5 marine terraces using LiDAR topography and established their chronology and coeval origin with twelve luminescence ages, stratigraphy and geomorphic correlation, obtaining a virtually continuous distribution of uplift rates along the entire rupture zone. The mean uplift rate for these terraces is 0.5 m/ka. This value is exceeded in three areas, which have experienced rapid emergence of up to 1.6 m/ka; they are located at the northern, central, and southern sectors of the rupture zone, referred to as Topocalma, Carranza and Arauco, respectively. The three sectors correlate with boundaries of eight great earthquakes dating back to 1730. The Topocalma and Arauco sectors, located at the boundaries of the 2010 rupture, consist of broad zones of crustal warping with wavelengths of 60 and 90 km, respectively. These two regions coincide with the axes of oroclinal bending of the entire Andean margin and correlate with changes in curvature of the plate interface. Rapid uplift at Carranza, in turn, is of shorter wavelength and associated with footwall flexure of three crustal-scale normal faults. The uplift rate at Carranza is inversely correlated with plate coupling as well as with coseismic slip, suggesting permanent deformation may accumulate interseismically. We propose that the zones of upwarping at Arauco and Topocalma reflect changes in frictional properties of the megathrust resulting in barriers to the propagation of great earthquakes. Slip during the 1960 (M9.5) and 2010 events overlapped with the similar to 90-km-long zone of rapid uplift at Arauco; similarly, slip in 2010 and 1906 extended across the similar to 60-km-long section of the megathrust at Topocalma, but this area was completely breached by the 1730 (M similar to 9) event, which propagated southward until Carranza. Both Arauco and Topocalma show evidence of sustained rapid uplift since at least the middle Pleistocene. These two sectors might thus constitute discrete seismotectonic boundaries restraining most, but not all great earthquake ruptures. Based on our observations, such barriers might be breached during multi-segment super-cycle events. (C) 2015 Elsevier Ltd. All rights reserved. KW - LiDAR KW - Subduction earthquakes KW - Marine terraces KW - Seismotectonic segmentation KW - Permanent uplift KW - Maule earthquake KW - Coastal uplift KW - TerraceM Y1 - 2015 U6 - https://doi.org/10.1016/j.quascirev.2015.01.005 SN - 0277-3791 VL - 113 SP - 171 EP - 192 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Jara-Munoz, Julius A1 - Melnick, Daniel A1 - Pedoja, Kevin A1 - Strecker, Manfred T1 - TerraceM-2: A MatlabR (R) Interface for Mapping and Modeling Marine and Lacustrine Terraces JF - Frontiers in Earth Science N2 - The morphology of marine and lacustrine terraces has been largely used to measure past sea- and lake-level positions and estimate vertical deformation in a wealth of studies focused on climate and tectonic processes. To obtain accurate morphometric assessments of terrace morphology we present TerraceM-2, an improved version of our MatlabR (R) graphic-user interface that provides new methodologies for morphometric analyses as well as landscape evolution and fault-dislocation modeling. The new version includes novel routines to map the elevation and spatial distribution of terraces, to model their formation and evolution, and to estimate fault-slip rates from terrace deformation patterns. TerraceM-2 has significantly improves its processing speed and mapping capabilities, and includes separate functions for developing customized workflows beyond the graphic-user interface. We illustrate these new mapping and modeling capabilities with three examples: mapping lacustrine shorelines in the Dead Sea to estimate deformation across the Dead Sea Fault, landscape evolution modeling to estimate a history of uplift rates in southern Peru, and dislocation modeling of deformed marine terraces in California. These examples also illustrate the need to use topographic data of different resolutions. The new modeling and mapping routines of TerraceM-2 highlight the advantages of an integrated joint mapping and modeling approach to improve the efficiency and precision of coastal terrace metrics in both marine and lacustrine environments. KW - TerraceM KW - marine terraces KW - tectonic geomorphology KW - geomorphic markers KW - LiDAR KW - coastal geomorphology KW - neotectonics KW - morphometry Y1 - 2019 U6 - https://doi.org/10.3389/feart.2019.00255 SN - 2296-6463 VL - 7 PB - Frontiers Research Foundation CY - Lausanne ER - TY - JOUR A1 - Korzeniowska, Karolina A1 - Pfeifer, Norbert A1 - Landtwing, Stephan T1 - Mapping gullies, dunes, lava fields, and landslides via surface roughness JF - Geomorphology : an international journal on pure and applied geomorphology N2 - Gully erosion is a widespread and significant process involved in soil and land degradation. Mapping gullies helps to quantify past, and anticipate future, soil losses. Digital terrain models offer promising data for automatically detecting and mapping gullies especially in vegetated areas, although methods vary widely measures of local terrain roughness are the most varied and debated among these methods. Rarely do studies test the performance of roughness metrics for mapping gullies, limiting their applicability to small training areas. To this end, we systematically explored how local terrain roughness derived from high-resolution Light Detection And Ranging (LiDAR) data can aid in the unsupervised detection of gullies over a large area. We also tested expanding this method for other landforms diagnostic of similarly abrupt land-surface changes, including lava fields, dunes, and landslides, as well as investigating the influence of different roughness thresholds, resolutions of kernels, and input data resolution, and comparing our method with previously published roughness algorithms. Our results show that total curvature is a suitable metric for recognising analysed gullies and lava fields from LiDAR data, with comparable success to that of more sophisticated roughness metrics. Tested dunes or landslides remain difficult to distinguish from the surrounding landscape, partly because they are not easily defined in terms of their topographic signature. KW - Gullies KW - Surface roughness KW - Curvature KW - Digital terrain model (DTM) KW - LiDAR KW - Geomorphometry Y1 - 2017 U6 - https://doi.org/10.1016/j.geomorph.2017.10.011 SN - 0169-555X SN - 1872-695X VL - 301 SP - 53 EP - 67 PB - Elsevier Science CY - Amsterdam ER - TY - JOUR A1 - Malinowski, Radostaw A1 - Höfle, Bernhard A1 - Koenig, Kristina A1 - Groom, Geoff A1 - Schwanghart, Wolfgang A1 - Heckrath, Goswin T1 - Local-scale flood mapping on vegetated floodplains from radiometrically calibrated airborne LiDAR data JF - ISPRS journal of photogrammetry and remote sensing : official publication of the International Society for Photogrammetry and Remote Sensing N2 - Knowledge about the magnitude of localised flooding of riverine areas is crucial for appropriate land management and administration at regional and local levels. However, detection and delineation of localised flooding with remote sensing techniques are often hampered on floodplains by the presence of herbaceous vegetation. To address this problem, this study presents the application of full waveform airborne laser scanning (ALS) data for detection of floodwater extent. In general, water surfaces are characterised by low values of backscattered energy due to water absorption of the infrared laser shots, but the exact strength of the recorded laser pulse depends on the area covered by the targets located within a laser pulse footprint area. To account for this we analysed the physical quantity of radio metrically calibrated ALS data, the backscattering coefficient, in relation to water and vegetation coverage within a single laser footprint. The results showed that the backscatter was negatively correlated to water coverage, and that of the three distinguished classes of water coverage (low, medium, and high) only the class with the largest extent of water cover (>70%) had relatively distinct characteristics that can be used for classification of water surfaces. Following the laser footprint analysis, three classifiers, namely AdaBoost with Decision Tree, Naive Bayes and Random Forest, were utilised to classify laser points into flooded and non-flooded classes and to derive the map of flooding extent. The performance of the classifiers is highly dependent on the set of laser points features used. Best performance was achieved by combining radiometric and geometric laser point features. The accuracy of flooding maps based solely on radiometric features resulted in overall accuracies of up to 70% and was limited due to the overlap of the backscattering coefficient values between water and other land cover classes. Our point-based classification methods assure a high mapping accuracy (similar to 89%) and demonstrate the potential of using full-waveform ALS data to detect water surfaces on floodplain areas with limited water surface exposition through the vegetation canopy. (C) 2016 International Society for Photogrammetry and Remote Sensing, Inc. (ISPRS). Published by Elsevier B.V. All rights reserved. KW - ALS KW - LiDAR KW - Point cloud KW - Inundation KW - Full-waveform KW - Water Y1 - 2016 U6 - https://doi.org/10.1016/j.isprsjprs.2016.06.009 SN - 0924-2716 SN - 1872-8235 VL - 119 SP - 267 EP - 279 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Obu, Jaroslav A1 - Lantuit, Hugues A1 - Fritz, Michael A1 - Pollard, Wayne H. A1 - Sachs, Torsten A1 - Guenther, Frank T1 - Relation between planimetric and volumetric measurements of permafrost coast erosion: a case study from Herschel Island, western Canadian Arctic JF - Polar research : a Norwegian journal of Polar research N2 - Ice-rich permafrost coasts often undergo rapid erosion, which results in land loss and release of considerable amounts of sediment, organic carbon and nutrients, impacting the near-shore ecosystems. Because of the lack of volumetric erosion data, Arctic coastal erosion studies typically report on planimetric erosion. Our aim is to explore the relationship between planimetric and volumetric coastal erosion measurements and to update the coastal erosion rates on Herschel Island in the Canadian Arctic. We used high-resolution digital elevation models to compute sediment release and compare volumetric data to planimetric estimations of coastline movements digitized from satellite imagery. Our results show that volumetric erosion is locally less variable and likely corresponds better with environmental forcing than planimetric erosion. Average sediment release volumes are in the same range as sediment release volumes calculated from coastline movements combined with cliff height. However, the differences between these estimates are significant for small coastal sections. We attribute the differences between planimetric and volumetric coastal erosion measurements to mass wasting, which is abundant along the coasts of Herschel Island. The average recorded coastline retreat on Herschel Island was 0.68m a(-1) for the period 2000-2011. Erosion rates increased by more than 50% in comparison with the period 1970-2000, which is in accordance with a recently observed increase along the Alaskan Beaufort Sea. The estimated annual sediment release was 28.2 m(3) m(-1) with resulting fluxes of 590 kg C m(-1) and 104 kg N m(-1). KW - Coastal erosion KW - LiDAR KW - carbon fluxes KW - mass wasting KW - landslides KW - digital elevation model Y1 - 2016 U6 - https://doi.org/10.3402/polar.v35.30313 SN - 0800-0395 SN - 1751-8369 VL - 35 SP - 57 EP - 99 PB - Co-Action Publ. CY - Jarfalla ER - TY - THES A1 - Richter, Rico T1 - Concepts and techniques for processing and rendering of massive 3D point clouds T1 - Konzepte und Techniken für die Verarbeitung und das Rendering von Massiven 3D-Punktwolken N2 - Remote sensing technology, such as airborne, mobile, or terrestrial laser scanning, and photogrammetric techniques, are fundamental approaches for efficient, automatic creation of digital representations of spatial environments. For example, they allow us to generate 3D point clouds of landscapes, cities, infrastructure networks, and sites. As essential and universal category of geodata, 3D point clouds are used and processed by a growing number of applications, services, and systems such as in the domains of urban planning, landscape architecture, environmental monitoring, disaster management, virtual geographic environments as well as for spatial analysis and simulation. While the acquisition processes for 3D point clouds become more and more reliable and widely-used, applications and systems are faced with more and more 3D point cloud data. In addition, 3D point clouds, by their very nature, are raw data, i.e., they do not contain any structural or semantics information. Many processing strategies common to GIS such as deriving polygon-based 3D models generally do not scale for billions of points. GIS typically reduce data density and precision of 3D point clouds to cope with the sheer amount of data, but that results in a significant loss of valuable information at the same time. This thesis proposes concepts and techniques designed to efficiently store and process massive 3D point clouds. To this end, object-class segmentation approaches are presented to attribute semantics to 3D point clouds, used, for example, to identify building, vegetation, and ground structures and, thus, to enable processing, analyzing, and visualizing 3D point clouds in a more effective and efficient way. Similarly, change detection and updating strategies for 3D point clouds are introduced that allow for reducing storage requirements and incrementally updating 3D point cloud databases. In addition, this thesis presents out-of-core, real-time rendering techniques used to interactively explore 3D point clouds and related analysis results. All techniques have been implemented based on specialized spatial data structures, out-of-core algorithms, and GPU-based processing schemas to cope with massive 3D point clouds having billions of points. All proposed techniques have been evaluated and demonstrated their applicability to the field of geospatial applications and systems, in particular for tasks such as classification, processing, and visualization. Case studies for 3D point clouds of entire cities with up to 80 billion points show that the presented approaches open up new ways to manage and apply large-scale, dense, and time-variant 3D point clouds as required by a rapidly growing number of applications and systems. N2 - Fernerkundungstechnologien wie luftgestütztes, mobiles oder terrestrisches Laserscanning und photogrammetrische Techniken sind grundlegende Ansätze für die effiziente, automatische Erstellung von digitalen Repräsentationen räumlicher Umgebungen. Sie ermöglichen uns zum Beispiel die Erzeugung von 3D-Punktwolken für Landschaften, Städte, Infrastrukturnetze und Standorte. 3D-Punktwolken werden als wesentliche und universelle Kategorie von Geodaten von einer wachsenden Anzahl an Anwendungen, Diensten und Systemen genutzt und verarbeitet, zum Beispiel in den Bereichen Stadtplanung, Landschaftsarchitektur, Umweltüberwachung, Katastrophenmanagement, virtuelle geographische Umgebungen sowie zur räumlichen Analyse und Simulation. Da die Erfassungsprozesse für 3D-Punktwolken immer zuverlässiger und verbreiteter werden, sehen sich Anwendungen und Systeme mit immer größeren 3D-Punktwolken-Daten konfrontiert. Darüber hinaus enthalten 3D-Punktwolken als Rohdaten von ihrer Art her keine strukturellen oder semantischen Informationen. Viele GIS-übliche Verarbeitungsstrategien, wie die Ableitung polygonaler 3D-Modelle, skalieren in der Regel nicht für Milliarden von Punkten. GIS reduzieren typischerweise die Datendichte und Genauigkeit von 3D-Punktwolken, um mit der immensen Datenmenge umgehen zu können, was aber zugleich zu einem signifikanten Verlust wertvoller Informationen führt. Diese Arbeit präsentiert Konzepte und Techniken, die entwickelt wurden, um massive 3D-Punktwolken effizient zu speichern und zu verarbeiten. Hierzu werden Ansätze für die Objektklassen-Segmentierung vorgestellt, um 3D-Punktwolken mit Semantik anzureichern; so lassen sich beispielsweise Gebäude-, Vegetations- und Bodenstrukturen identifizieren, wodurch die Verarbeitung, Analyse und Visualisierung von 3D-Punktwolken effektiver und effizienter durchführbar werden. Ebenso werden Änderungserkennungs- und Aktualisierungsstrategien für 3D-Punktwolken vorgestellt, mit denen Speicheranforderungen reduziert und Datenbanken für 3D-Punktwolken inkrementell aktualisiert werden können. Des Weiteren beschreibt diese Arbeit Out-of-Core Echtzeit-Rendering-Techniken zur interaktiven Exploration von 3D-Punktwolken und zugehöriger Analyseergebnisse. Alle Techniken wurden mit Hilfe spezialisierter räumlicher Datenstrukturen, Out-of-Core-Algorithmen und GPU-basierter Verarbeitungs-schemata implementiert, um massiven 3D-Punktwolken mit Milliarden von Punkten gerecht werden zu können. Alle vorgestellten Techniken wurden evaluiert und die Anwendbarkeit für Anwendungen und Systeme, die mit raumbezogenen Daten arbeiten, wurde insbesondere für Aufgaben wie Klassifizierung, Verarbeitung und Visualisierung demonstriert. Fallstudien für 3D-Punktwolken von ganzen Städten mit bis zu 80 Milliarden Punkten zeigen, dass die vorgestellten Ansätze neue Wege zur Verwaltung und Verwendung von großflächigen, dichten und zeitvarianten 3D-Punktwolken eröffnen, die von einer wachsenden Anzahl an Anwendungen und Systemen benötigt werden. KW - 3D point clouds KW - 3D-Punktwolken KW - real-time rendering KW - Echtzeit-Rendering KW - 3D visualization KW - 3D-Visualisierung KW - classification KW - Klassifizierung KW - change detection KW - Veränderungsanalyse KW - LiDAR KW - LiDAR KW - remote sensing KW - Fernerkundung KW - mobile mapping KW - Mobile-Mapping KW - Big Data KW - Big Data KW - GPU KW - GPU KW - laserscanning KW - Laserscanning Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-423304 ER -