16.1. Remote Sensing – Digital mapping, remote sensing and 3d models in Earth Science
The 2017 eruption of Erta ‘Ale volcano, Ethiopia: a case study in monitoring remote volcanoes with satellites.
Talfan Barnie1, Ashley Davies2, Gezahegn Yirgu3, Moore Chris4, Simon Carn5, David Pieri2, Clive Oppenheimer6, Juliet Biggs7, Tim Wright4 and Andy Hooper4
1Nordic Volcanological Center, Institute of Earth Sciences, Reykjavik, Iceland, 2Jet Propulsion Laboratory-California Institute of Technology, Pasadena, USA, 3School of Earth Sciences, Addis Ababa University, Addis Ababa, Ethiopia, 4School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UK, 5Department of Geological and Mining Engineering and Sciences, Michigan Tech, USA, 6Department of Geography, University of Cambridge, Downing Place, Cambridge, CB2 3EN, UK, 7School of Earth Sciences, University of Bristol, Wills Memorial Building, Queens Road, Bristol, UK
Most volcanoes on Earth are not monitored by local sensor networks, but we can potentially track all subaerial eruptions using spaceborne sensors. Here we investigate the prolonged fissure eruption of Erta ‘Ale volcano in northern Afar, Ethiopia, which began in January 2017. We are unaware of any local installations of monitoring equipment despite the longevity of the eruption and the geodynamic significance of the volcano, which lies on an axial volcanic range of the Red Sea rift system. The volcano is of particular importance, as over the past 15 years or so the behaviour of the lava lake(s) in the summit caldera have apparently tracked or even heralded volcanic and tectonic activity witnessed across the broader Afar-Red Sea region since the early 2000s. Using a suite of routinely-, manually- and automatically-commissioned satellite image acquisitions, we have been able to follow the eruption with high-temporal resolution. In particular, we have been able to reconstruct time series of gas and lava emissions, and ground deformation. We have also been able to document variation in activity at the lava lake itself, monitoring lava level and tracking individual overflows on time scales of tens of minutes. Integrating observations of both the lava lake and vent, which represent two windows into the magmatic system, provides an unusual opportunity to contains the behaviour of a magmatic system during an eruption.
A 10-year series of surface kinematics of periglacial sorted circles from SfM close-range photogrammetry
Ivar Berthling1, Luc Girod2, Andreas Kääb2 and Radmil Popovic1
1Department of Geography, Norwegian University of Science and Technology, 2Department of Geosciences, University of Oslo
Sorted circles are one type of periglacial patterned ground, created by large-scale cryoturbation due to freezing and thawing of the active layer. It is one of the most conspicuous types of patterns created by geomorphic processes on the earth surface, and widely used as an example of emergence in complex systems.
Since 2007 we have attempted to document the spatial pattern of displacements going on in sorted circles at 79°N on Kvadehuksletta, Ny-Ålesund, Svalbard using Structure-from-Motion (SfM) photogrammetry and feature-tracking. Published results (Kääb et al. 2014) show the applicability of this method in terms of gaining high-resolution information on vertical and horizontal displacements within the sorted circle system. This presentation will document a decade of displacements within these sorted circles, but also comment on challenges and possible solutions for long-term SfM monitoring of sorted circles.
During 2007 and 2010 campaigns, we acquired the images from a portable ladder. In 2015, 2016 and 2017, images were shot from a camera attached to a long pole via a wifi connection to the camera. The design was set up to yield a theoretical resolution of the digital elevation model of around 1 mm.
Kääb, A., Girod, L., and Berthling, I. (2014): Surface kinematics of periglacial sorted circles using structure-from-motion technology: The Cryosphere, v. 8, p. 1041-1056.
Crystal-scale magnetic anomalies revealed by scanning magnetic microscopy
Nathan Church1 and Suzanne McEnroe1
1NTNU, Trondheim, Norway
Scanning magnetic microscopy (SMM) maps the magnetic field generated by petrologic thin sections or polished rock surfaces at the sub-mm scale, creating the possibility to resolve the contribution of individual grains and mineral phases to bulk magnetic signal. The instrument developed at NTNU has the capability to measure both remanence properties and, uniquely, the magnetic response in a field of known magnitude and direction. A series of case studies are presented to examine the capabilities of the microscope and to describe applications to the study of crustal magnetism. The use of well-characterized samples allows signals in magnetic scans to be attributed to grains of known composition, including the discrimination of signal associated with discrete oxides and assemblages of exsolved oxides in silicates, which can be observed to have differing directions of magnetisation. The ability of this instrument to image in fields mimicking those experienced in the crust allows the observation of the induced magnetic response, both qualitatively in the form of changes in magnetization direction, and quantitatively by varying experimental conditions. This capability gives SMM the ability to map both remanent response and generate a map of susceptibility, and provides a powerful new tool for the examination of bulk magnetic response in the Earth’s crust.
3D modelling and visualising of resource deposits in Norway with UAV technology and 3D MOVE
Iain Henderson1, Morgan Ganerød1, Espen Torgersen1 and Tom Heldal1
1Geological Survey of Norway
This study combines detailed terrain models and orthophotos of resource deposits in Norway with geological information underground. The terrain models are constructed using photogrammetry from a DJI Phantom4 drone and Litchi Mission Hub software. Individual flight plans are uploaded to the autonomously flying drone leading to better model construction and more efficient use of drone battery time. Point cloud data is uploaded to the Agisoft Photoscan Professional software, where the 3D mesh representing the ground surface is created and control points are added. The resultant georeferenced mesh is exported to 3D MOVE and integrated with underground geological data, producing a fully integrated terrain-geological 3D model. We have constructed several, widely different models: the Høgtuva Be-deposit i Nordland, the Kleivan slate mine in Oppdal, and the marble deposit at Fauske in collaboration with Norwegian Rose AS. A number of valuable products have beeen developed: Full digital 3D-models, volume calculations and mapped volumes, contour maps (depth to layer/volume) and volume thickness. These products contribute to a better understanding of the geology, a more effective running of the deposits and, not least, are attractive products for financial contributors and decision makers. This project is regarded as a development project where we have created the workflow required from initial drone flight planning, drone flying, point cloud management to model integration in 3D MOVE. This project is an initiative of the Mineral Resources Division at the Geological Survey of Norway in collaboration with several Norwegian Mining companies and is partly financed by Mineralklyngen Norge.
ASPECT spectral imaging CubeSat for planetary studies
Tomas Kohout1, Antti Näsilä2, Tuomas Tikka3, Mikael Granvik4, Antti Kestilä5, Antti Penttilä4, Janne Kuhno3, Karri Muinonen4, Kai Viherkanto2, Esa Kallio5 and Jaan Praks5
1Department of Physics, University of Helsinki / Institute of Geology, The Czech Academy of Sciences, 2VTT Technical Research Centre of Finland, 3Reaktor Space Lab Ltd, Finland, 4Department of Physics, University of Helsinki, 5Department of Electronics and Nanoengineering, Aalto University, Finland
ASPECT (Asteroid Spectral Imaging Mission) is a 3U (30 x 10 x 10 cm) CubeSat concept designed for deep space exploration of small Solar System bodies. The payload of ASPECT is a miniaturized visible – near infrared (500-2500 nm) spectral imager. The primary scientific task of ASPECT is orbital high resolution compositional mapping of the target surface with a meter resolution. The obtained compositional maps can be used to study space weathering and impact processes, as well as in evaluation of areas for subsequent sampling or in-space resource utilization (ISRU). ASPECT is proposed to be part of European HERA mission to asteroid Didymos or Japanese MMX mission to martian moon Phobos.
Environmental mapping and monitoring of Iceland by remote sensing (EMMIRS)
Gro B. M. Pedersen1, Olga K. Vilmundardóttir2, Fadi Kizel3, Nicola Falco4, Joaquin M. C. Belart1, Friðþór S. Sigurmundsson5, Gudrun Gisladóttir5 and Jón Atli Benediktsson3
1Institute of Earth Sciences, University of Iceland, Sturlugata 7, 101 Reykjavík, Iceland, 2Institute of Life and Environmental sciences, University of Iceland, 3Faculty of Electrical and Computer Engineering, University of Iceland, 4Lawrence Berkeley National Laboratory, CA, USA, 52Institute of Life and Environmental sciences, University of Iceland
Iceland is exposed to rapid landscape changes caused by natural processes and man-made activities, which impact and challenge the country. Fast and reliable mapping and monitoring techniques are needed on a big spatial scale. However, currently there is lack of operational advanced information processing techniques, which are needed for end-users to incorporate remote sensing (RS) data from multiple data sources. Hence, the full potential of the recent RS data explosion is not being fully exploited.
The project Environmental Mapping and Monitoring of Iceland by Remote Sensing (EMMIRS) bridges the gap between advanced information processing capabilities and end-user mapping of the Icelandic environment. This is done by a multidisciplinary assessment of the Hekla area, which encompass many of the rapid natural and man-made landscape changes that Iceland is exposed to.
An open-access benchmark repository providing high-resolution LIDAR topography and hyperspectral data for land-cover and landform classification is under construction. Furthermore, a multi-temporal archive stretching back to 1945 allows a decadal evaluation of landscape changes by the development of automated change detection techniques.
The development of pattern recognition and machine learning-based approaches to image classification and change detection is one of the main tasks of the EMMIRS project, aiming to extract and compute earth observation variables as automatically as possible. Ground reference data collected through a field campaign will be used to validate the implemented methods, which outputs are then inferred with geological and vegetation models. Here, preliminary results of an automatic land-cover classification based on hyperspectral image analysis are reported.
Safeguarding long records of geomorphological measurements using Structure-from-Motion from ground-based images
Ivar Berthling1, Bernard Hallet2 and Radmil Popovic1
1Department of Geography, Norwegian University of Science and Technology, 2Earth and Space Sciences Department, University of Washington
Modelling of the Earth System response to climate change benefits from records documenting sub-system response across climatic perturbations. For many of the processes that today are incorporated within an ESM, we do not have this advantage. One example is cryoturbation, the overturning of soil in permafrost areas, suggested highly relevant for the carbon budget. The process itself leaves no proxy records, except a mixture of soil organic carbon of variable age beneath the ground surface, so recorded values of soil surface displacements through time is needed for this purpose.
During the 1980’ies, before the onset of accelerated climate warming in the Arctic, Bernard Hallet initiated measurements on the stone circles on Kvadehuksletta, Svalbard. The stone circles are a remarkable example of the effects of large-scale cryoturbation. Although these measurements are not continuous, the installations are partly still in place. They were re-measured in 2010, 2015, 2016 and again in September 2017. The purpose of this presentation is to document our work on safeguarding the remains of these installations, and to transform the methodology using Structure-from-Motion from ground-based images, to enable continuing these measurements into the future. Our goal is to document how ground surface movements and cryoturbation have responded to the amplified effects of global warming at high latitudes, and to understand this response.
UAV topographic survey of a migrating dune – pitfalls and first results (Sylt, southern North Sea)
Benjamin Eberhardt1 and Sebastian Lindhorst1
1University of Hamburg, Institute for Geology, Bundesstr. 55, 20146 Hamburg, Germany
High resolution topographic information is instrumental in analyzing sand transport processes on active coastal dunes. Unmanned aerial vehicles (UAV) greatly facilitate the on-site collection of aerial images and structure-from-motion (SfM) algorithms allow producing detailed topographic models from UAV-based photogrammetric surveys. First results from a SfM case study from an active (but partly vegetated) migrating dune (dune height up to 30 m) are presented including survey design, georeferencing issues and applied data processing steps. Aim of this study is to test the applicability of UAV-based topographic surveys to quantify sand transport volume along the slipface of the dune. The model comprises 2500 images with a resulting ground-sampling distance of 1.67 cm/pixel over an area of 550 x 530 m. Special attention is given to the identification of artifacts caused by the less structured, uniform sand areas.
UAV photogrammetry to monitor stability of rock climbing sites
Axel Hellman1, Mark D. Johnson1 and Anne Hormes2
1Department of Earth Sciences, University of Gothenburg, 2Institute of Geology, The Arctic University of Norway, Tromsø
Monitoring of steep rock faces and documenting their geostructural character to evaluate stability is a difficult task from the bottom of a steep rock face. Unmanned aerial vehicle (UAV) sensors and technology have seen a rapid development over the last five years. They can enable surveying and monitoring of rock-slope failures and detached blocks in areas previously inaccessible and hazardous (Boccali et al., 2017). For this project, we study two frequently visited rock-climbing crags in Sweden and Austria, both with documented rock-fall activity. In Sweden, a recent rock-fall destroyed a well-known climbing route in Fjällbo, Gothenburg. In Austria, Engelswand is a very popular climbing crag in Ötztal, where we counted 70 climbers on one Saturday, with reoccurring smaller rock-falls and occasionally larger blocks occurring in the spring during the melting period.
Our study explores the accuracy of UAV photogrammetry for the analysis of rock-fall hazards. In Austria, we tested a rough acquisition workflow deploying handhold GPS points as ground control points together with aerial imagery and telemetry data. We aim to compare the accuracy of this quick method with the more resource and cost-inefficient method of using a differential GPS and triangulation points to acquire a high precision of ground control points.
The UAV imagery is processed in different software packages for compilation and comparison of accuracy. 3D models, digital terrain models (DTMs) and point clouds are produced and will be used for kinematic analysis. Preliminary 3D model results suggest that the rough workflow provide accurate and detailed outputs.
Boccali, C., Biolchi, S., Zavagno, E., & Zini, L. (2017): Rock Fall Characterization in Climbing Spots: The Case Study of the “Napoleonica” Tourist Route (Trieste, NE Italy). In Workshop on World Landslide Forum (May, 2017), Vol. 2, pp. 107-115. Mikos, M., Tiwari, B., Yin, Y., & Sassa, K. Springer, Cham.
Classification of block fields in Norway using Machine Learning
Mads Nedergaard Paulsen1 and David Lundbek Egholm2
1Aarhus universitet, 2Aarhus Universitet
*Mads Nedergaard Paulsen, David Lundbek Egholm
Department of Geoscience, Aarhus University, Høegh-Guldbergs Gade 2,
* Corresponding author: mpaulsen [at] post [dot] au [dot] dk
The origin of Scandinavia’s extensive block fields has been a subject of debate for some time. One hypothesis suggests that the block fields mainly formed by pre-Quaternary warm-climate chemical weathering (Paasche et al 2006), while another hypothesis uses Late-Cenozoic cold-climate physical weathering mechanisms to explain the block fields through long-term periglacial landscape evolution (Goodfellow et al. 2014, Egholm et al. 2015). Several field studies have mapped the extent of selected block fields in Scandinavia, but the full distribution of block fields has not yet been studied.
In this master-degree study, we aim to use Machine Learning to map the distribution of block fields in Scandinavia. The vast amount of public available LIDAR data provides us with the opportunity to study distributions of landforms, e.g. along climatic gradients set by latitude or elevation. However, the shear data volume and the need for consistent objective mapping call for automatic classification methods based on topographic features such as elevation, surface slope, curvature, and roughness. We discuss the applicability of selected Machine Learning algorithms, such as k-means clustering, SVM, boosting gradient and Neural Networks, we evaluate pros and cons of the different algorithms.
Egholm et al., 2015. The periglacial engine of mountain erosion – Part 2: Modelling large-scale landscape evolution. Earth Surface Dynamics, 3, 463-482.
Goodfellow et al., 2014. Arctic–alpine blockfields in the northern Swedish Scandes: late Quaternary – not Neogene, Earth Surf. Dynam., 2, 383–401.
Paasche et al., 2006. Weathering characteristics of arctic islands in northern Norway. Geomorphology 82, 430–452Top
16.2. Holocene coastal morpho-sedimentary systems: Archives, processes and forcing mechanisms
Did cuspate foreland formation trigger large-scale barrier coast retreat?
Mikkel Fruergaard1, Lasse Sander2, Jérôme Goslin1, Thorbjørn Joest Andersen1, Peter Johannessen3, Lars Henrik Nielsen4 and Morten Pejrup1
1Department of Geosciences and Natural Resource Management, University of Copenhagen, 2Alfred-Wegener-Institute, 3Geological Survey of Denmark and Greenland, 4Geological Survey of Denmark and Greenland (GEUS)
The stratigraphic evolution of barrier systems is controlled by the ratio between rate of sea-level rise and rate of sediment supply from external sources. Because of increasing coastal erosion and flood risk caused by the global rising sea level, many studies on barrier system evolution are focused on understanding the impacts of sea-level changes despite changes in sediment supply are equally important controlling coastal evolution. In this study we investigate how changes in sediment supply influenced the large-scale coastal evolution of the Danish Wadden Sea barrier coast. This coast is wave-dominated and angular wave approach generates a large southward-directed littoral drift. The Wadden Sea is bounded towards the north by the cuspate foreland of Blåvands Huk and the shallow marine shoal of Ulven. Based on detailed sedimentological and chronological investigations of ~60 km barrier coast we present several stratigraphic evidences that the coast experienced region-wide flooding and coastal erosion between 4500 and 1400 years ago. New chronological data suggest that coinciding with the flooding and erosion, sediment accumulation and accretion took place in the area directly north of the Danish Wadden Sea. We suggest that the retreat of the coast was related to the construction of cuspate foreland of Blåvands Huk that largely trapped the littoral drift from the north, preventing the sand reaching the Wadden Sea coast and thus shifted the depositional locus northward from the Wadden Sea. The study indicates how sediment supply and large-scale morphology of the coast can control coastal evolution.
High-resolution Holocene windiness and storminess over the North Sea: insights from Filsø lake, Western Denmark.
Jérôme Goslin1, Lars B. Clemmensen1, Mikkel Fruergaard1 and Lasse Sander2
1Institute for Geosciences and Natural Resources Management – University Of Copenhagen, 2Alfred Wegener Institute – Sylt
Possessing long and accurate archives of past storm events is one key towards a better understanding of the atmospheric patterns driving these latter and of how coastal systems reacted in the past to changing forcing mechanisms. During the last decade, several Holocene storminess chronologies have been based on aeolian influxes within coastal lakes and mires (e.g. Björck and Clemmensen, 2004; De Jong et al., 2006; Nielsen et al.; 2016; Orme et al.,2016).
This study presents a high-resolution (pluri-annual) history of Holocene past windiness and storminess over the North Sea reconstructed from a coastal lake of Western Denmark. Past aeolian activity and storminess are reconstructed using aeolian sand inputs preserved within the organic-rich lake sediments.
Our data demonstrate high-frequency variations of aeolian sand influx between ca. 5000 and 2200 yrs B.P. that we believe adequately reflect the changes in past wind-climate and storminess. Impressively cyclic pluridecadal-scale “breathing patterns” in storminess activity are observed between ca. 5000 and 4300 years B.P. A massive sand invasion is then observed around 4300 yrs B.P., in accordance with the first period of dune building obsreved along the west coasts of Denmark (Clemmensen et al., 2001; 2009) and simultaneousl to a period of climate deterioration widely recognized elsewhere in Europe and globally. The signal then progressively slowly fades-out, most probably reflecting coastal progradation and dune fixation.
These results will allow us to discuss potential internal and external climate forcing mechanisms, as well as to question the interdependencies between aeolian activity, sedimentary dynamics and relative sea-level.
Detailed dynamic development and sedimentary architecture of a Holocene to Recent micro-tidal barrier-island, Danish Wadden Sea.
Peter Niels Johannessen1, Mikkel Fruergaard2, Lars Henrik Nielsen1, Lars Nielsen2, Ingelise Møller1, Thorbjørn Joest Andersen2, Stefan Piasecki1 and Morten Pejrup2
1Geological Survey of Denmark and Greenland (GEUS), 2Department of Geosciences and Natural Resource Management
The Rømø barrier-island is 14 km long, 4 km wide and the Holocene deposits c. 15 m thick. It is a very sand-rich system as it receives coastal drift sand from north and south along the shoreface. It is separated from the mainland by a 8 km wide lagoon. Average tidal range is around 1.8 m. During strong westerly storms, the water level increases considerably, up to 5 m above mean sea-level.
The barrier-island formation started for c. 8000 years ago and is still active, which allows detailed studies on recent sedimentary processes. Stacking geometries of different sand units have been unraveled based on: Seven c. 25 m long sediment cores, 35 km ground penetrating radar (GPR) reflection profiles, and dating of 70 core samples using optically stimulated luminescence (OSL) providing a unique stratigraphic framework.
Due to the detailed knowledge of the stratigraphic framework, depositional environments and precise ages, a detailed palaeo-geographic reconstruction of the Rømø barrier-island has been carried out. The barrier-island initiated as a short and narrow island. The first 5000 years the barrier island sand aggraded because sedimentation kept pace with the relative sea-level rise. The last 3000 years the barrier-island prograded seawards, as the rate of relative sea level rise decreased. This aggradational-progradational development has resulted in a thick and broad reservoir sand body.
This study shows that if there is a surplus of sand, a barrier island can aggrade and even prograde during a sea-level rise, creating thick barrier-island deposits.
Fruergaard, M., Johannessen, P.N., Nielsen, L.H., Nielsen, L., Møller, I., Andersen, T.J., Piasecki, S. & Pejrup, M.. Approved for publication in “Sedimentology”. (In press Article; doi: 10.1111/sed.12418): Sedimentary architecture and depositional controls of a Holocene wave-dominated barrier-island system.
Was the 4th largest Danish Lake (Mossø) once much larger?
Søren M. Kristiansen1, Niels Emil Søe1, Aart Kroon2, Anders Vest Christiansen1 and Bent Vad Odgaard1
1Department of Geoscience, Aarhus University, Denmark, 2University of Copenhagen, Department of Geosciences and Natural Resource Management, Denmark
Water levels of freshwater lakes can lower during the course of an interglacial and sedimentation can infill basins. Besides, wave actions develop spit systems in larger lakes by longshore sediment transport that may cuts of smaller basins. Here, we show combined effects of spit development, wave actions, antecedent topography and lake level changes on the Holocene development of the present-day Danish lake, Mossø. A variety of methods were used: coring, intensive profile digging and remote sensing, geophysical mapping by seismic reflection and electromagnetic induction, and dating by radiocarbon and optically stimulated luminescence. We find that Mossø has undergone water level changes of perhaps 6 m and shore erosion has varied accordingly. The sediment supply for spit formation depended of the vigor of erosion, on wind direction and strength and on building up of the platform in front of the spits. Strong spit activity was identified during three periods: c. 10 ka, 4.2 ka and 2.5-2.0 ka. The location of spit formation was determined by changes in lake level and also local bathymetry and sediment transport patterns. Two spits connected and were reinforced by a beach barrier by 2.5 ka, today constituting the eastern shoreline of present-day Lake Mossø. The data suggests presence of an early Holocene large palaeo-lake Mossø with a 25 km east-west extent from the present-day lakes Skanderborg Sø to Salten Langsø. Confirmation of this paleo-lake requires more investigations, as later erosions at the thresholds that connects Mossø to the adjacent lakes, and to river Gudenå, remains uncertain.
Christiansen AV, Pedersen JP, Auken E, Søe NE, Holst MK, Kristiansen SM (2016). Improved geoarchaelogical mapping with electromagnetic induction instruments from dedicated processing and inversion. Remote Sensing 8(12), 1022; DOI: 10.3390/rs8121022.
Soe NE, Odgaard B, Hertz E, Holst MK, Kristiansen SM, (2017). Geomorphological settings of a sacred landscape: Iron Age post battle deposits of human remains at Alken Enge, Denmark. Geoarchaeology 2017: 1-13. DOI: /10.1002/gea.21622.
Soe NE, Odgaard B, Nielsen AM, Olsen J, Kristiansen SM, (2017). Late Holocene landscape development around a Roman Iron Age mass grave, Alken Enge, Denmark. Vegetation History and Archaeobotany 26: 277-292. DOI: 10.1007/s00334-016-0591-x.
Soe NE, Odgaard B, Lykke-Andersen H, Kroon A, Kristiansen SM (submitted). Bathymetric control on Holocene spit migration in a lacustrine environment. The Holocene.
The occurrence and formation of wash-over deposits along the shores of the inner Danish Waters
Aart Kroon1, Lars Clemmensen1 and Verner B. Ernstsen1
1Department of Geosciences and Natural Resource Management University of Copenhagen, Denmark
Wash-over deposits occur along many beaches fringing the inner Danish Waters. They are often located on the Holocene barrier islands and spits and they are important accumulative features with a relatively high preservation potential. The barrier islands and spits are formed by alongshore driven wave-induced currents and they partly get their sediments from adjacent eroding glacial cliffs. Wash-over fans are often present at the landward side of the barrier or spit crest and they are formed during storms under a combination of high water levels and onshore directed high waves. The high water levels are however not always caused by wind set-up during storms in the inner Danish waters. The joint probability of water levels and waves shows that under 30% of the high water levels have large waves. This means that the frequency of occurrence of wash-over fan events is far less than extreme water level statistics would suggest. In the present paper, we will address the spatial occurrence of different types of recent wash-over fans in east Denmark using satellite images and lidar observations. We will also show the driving forces behind wash-over fan formation and show the frequency of occurrence of these driving forces.
Polar gravel beach-ridge systems – sedimentary architecture and use as climate archive (South Shetland Islands, Antarctica)
1University of Hamburg, Institute for Geology, Bundesstr. 55, 20146 Hamburg, Germany
The sedimentary architecture of polar gravel-beach ridges is presented and it is shown that ridge internal geometries reflect past wave-climate conditions.
Ground-penetrating radar (GPR) data obtained along the coasts of King George Island (South Shetland Islands, Western Antarctic Peninsula) show that beach ridges unconformably overlie seaward-dipping strata of the strand plain. Whereas strand-plain progradation is interpreted to result from swash sedimentation at the beach face under enduring calm conditions, ridge construction reflects enhanced wave action at the beach due to elevated storminess or reduced nearshore sea ice. The internal sedimentary architecture of individual beach ridges is interpreted to reflect maximum wave-runup height during the time of ridge construction. Ridges at sheltered parts of the coast exhibit either seaward-dipping beds, interpreted to result from swash deposition, or an aggradational stacking pattern being the result of wave overtopping. At exposed beaches, larger ridges develop composed of seaward- as well as landward-dipping beds. Development of individual beach ridges is seen to result from multiple storms rather than single events.
The number of individual ridges which are preserved from a given time interval varies along the coast depending on the morphodynamic setting: Sheltered coasts are characterized by numerous small ridges, whereas fewer but larger ridges develop on exposed beaches.
Data show that even ridges at higher elevation can be subject to later reactivation and reworking. This questions sea-level reconstructions based solely on morphology and dating of polar beach ridges and advise careful investigation of the stratigraphic architecture prior to sampling for dating purposes.
Lindhorst, S. & Schutter, I., 2014. Polar gravel beach-ridge systems: Sedimentary architecture, genesis, and implications for climate reconstructions (South Shetland Islands / Western Antarctic Peninsula). Geomorphology, 221: 187-203. DOI: 10.1016/j.geomorph.2014.06.013
Stratigraphy and sedimentary architecture of polder fills along the North Frisian Wadden Sea (southern North Sea) – potential archives of sea-level and climate variability (project SEASTORM)
Amalie Cordua1, Sebastian Lindhorst1 and Christian Betzler1
1University of Hamburg, Institute for Geology, Bundesstr. 55, 20146 Hamburg, Germany
During the past millennium the North Sea coast was altered by sea-level and climate fluctuations as well as by the onset of human land reclamation. Polders, areas embanked along the coast during the last millennium, bear unique sedimentary archives of coastal evolution during different time intervals. These archives are so far unread.
As a first result of the ongoing project SEASTORM, stratigraphy and sedimentary architecture of selected polders on the German Eiderstedt peninsula are presented. The peninsula has been shaped by land reclamation since the 10th century, and since the 12th century the history of polder embankment is documented. The sedimentary successions were investigated on the basis of a sedimentological dataset (grain size, XRF, core description, X-radiographic images, and radiocarbon ages); depositional geometries were imaged by means of ground-penetrating radar. A LIDAR-based high-resolution digital terrain model allows for geomorphological investigations.
The sedimentary succession preserved in the polders documents the complex geological evolution of the area comprising multiple phases of salt-marsh growth, re-flooding and erosion. Correlation of sedimentary successions in different polders aims on overcoming local-scale effects to reconstruct changes in sea level and climate oscillations.
Chronology and late Holocene evolution of Caleta de los Loros, NE Patagonia, Argentina
Lasse Sander1, Morten Pejrup2, Andrew Sean Murray3, Gerardo M. E. Perillo4, Luís Ariél Raniolo4 and Mikkel Fruergaard2
1Alfred-Wegener-Institute, List/Sylt, Germany, 2University of Copenhagen, Copenhagen, Denmark, 3Nordic Laboratory for Luminescence Dating, University of Aarhus, Denma, 4Instituto Argentino de Oceanografia, Bahía Blanca, Argentina
Caleta de los Loros is a coupled beach ridge and tidal lagoon system located on the northern shore of San Matías Gulf, Patagonia, Argentina. The study is based on remotely sensed data, sediment cores and a comprehensive dataset of ages determined using optically stimulated luminescence (OSL). We present observations on the geomorphology, sedimentology and chronology of the field site and propose inferences on the drivers behind its late Holocene evolution. Caleta de los Loros is located in a topographical depression within a cliffed shoreline composed of friable sand and gravel stones. The oldest marine deposits of Holocene age formed in the inner part of the depression around 2300 yr ago. Between 1000 and 500 yr ago, an up to 4 km wide strandplain formed in the exposed southern part of the system. The tidal lagoon subsequently experienced a period of increased sedimentation between 500 and 100 yr ago. The system is hence much younger than similar coastal environments in Patagonia and shows no apparent relation to changes in the rates of mid- to late Holocene sea level change (Schellmann & Radtke, 2010). However, stages in the morphosedimentary evolution of Caleta de los Loros are concurrent with proposed changes in humidity and wind regime for northern Patagonia as well as with changes in human occupation and subsistence strategy (Favier-Dubois and Kokot, 2011; Marcos et al., 2012). Caleta de los Loros presents a new example of the potential importance of sensible environmental changes for the rapid and non-linear development of coastal systems.
Favier-Dubois CM and Kokot R (2011) Changing scenarios in Bajo de la Quinta (San Matías Gulf, Northern Patagonia, Argentina): Impact of geomorphologic processes in subsistence and human use of coastal habitats. Quaternary International 245(1): 103–110.
Marcos MA, Mancini MV and Favier-Dubois CM (2012) Middle- to late-Holocene environmental changes in Bajo de la Quinta, NE Patagonia, inferred by palynological records and their relation to human occupation The Holocene 22: 1271-1281.
Schellmann G and Radtke U (2010) Timing and magnitude of Holocene sea-level changes along the middle and south Patagonian Atlantic coast derived from beach ridge systems, littoral terraces and valley-mouth terraces. Earth-Science Reviews 103(1): 1–30.
16.3. Lidar in Geomorphology
Mapping morphology and vegetation in shallow water using topobathymetric lidar
Mikkel S. Andersen1, Zyad Al-Hamdani2, Laurids R. Larsen3, Frank Steinbacher4, Ramona Baran4, Bjørn M. Torsvik5 and Verner B. Ernstsen5
1NIRAS A/S, Denmark & Dept. of Geosciences and Natural Resource Management, Uni. of Copenhagen, DK, 2Geological Survey of Denmark and Greenland (GEUS), Denmark, 3NIRAS A/S, 4Airborne Hydro Mapping GmbH, Austria, 5Department of Geosciences and Natural Resource Management, University of Copenhagen, Denmark
The coastal zone is under pressure from human exploitation and climate change, which leads to a need for sustainable coastal zone management – a challenge which requires high resolution mapping and monitoring. Historically, there has been a gap of information in shallow water, however, the emerging technology of airborne topobathymetric lidar has proven capable of simultaneously capturing topographic and bathymetric elevation information, resulting in a seamless coverage of the land-water transition zone. The new technology also provides a potential for detailed identification and classification of shallow water morphological units and vegetation – which was previously impossible to map, or at best it was mapped in very low detail. The aim of the study was to 1) develop a procedure for processing topobathymetric lidar data and generating Digital Elevation Models (DEMs) in coastal zones, 2) automatically classify morphological units, and 3) investigate the potential of mapping shallow water vegetation. We show results from two locations with different environmental settings: the Knudedyb tidal inlet system in the Danish Wadden Sea and Rødsand lagune in the inner Danish waters.
Morphologic mapping and monitoring of sediment transport using high resolution topobathymetric Lidar in manifold geomorphic settings: Examples from Isar river in Munich and Wadden Sea in Denmark
Ramona Baran1, Frank Steinbacher1, Wolfgang Dobler1, Mikkel S. Andersen2, Laurids R. Larsen2 and Verner B. Ernstsen3
1AirborneHydroMapping GmbH, Innsbruck, Austria, 2NIRAS, Allerød, Denmark, 3Department of Geosciences and Natural Resource Management, University of Copenhagen, Denmark
Fluvial and coastal/tidal environments are valuable ecosystems under pressure due to globalization and/or climate change. Their detailed mapping is required to manage river courses and coastal zones in a sustainable way. Traditionally, the transition zones between land and water were difficult or impossible to map and investigate in high spatial resolution due to challenging environmental conditions. The new generation of airborne topobathymetric LiDAR potentially enables full-coverage and high-resolution mapping of land-water transition zones. Repeated surveys provide the opportunity for geomorphologic mapping, monitoring and quantifying fluvial and coastal sediment-transport. We first present results from two repeated topobathymetric surveys along the Isar river in Munich, Germany, to quantify and map river-bed changes related to a large flood (June 2013). We evaluated river-bed elevation differences between the survey before (October 2011) and after (July 2013) the flood yielding elevation differences of several decimeters to meters due to erosion and sedimentation of bed-material. The detailed analysis provides new possibilities to better manage inner-city river structures and support future planning on restoration along the Isar river. In a second study, we performed a topobathymetric LiDAR survey in the Knudedyb tidal inlet-system in the Danish Wadden Sea (April-May 2014). This dataset was used for detailed geomorphic analysis on the intertidal drainage-network and bedforms, and was further compared to a topographic LiDAR survey (2011) to evaluate and quantify morphodynamics, e.g. sediment-transport directions. Our results demonstrate that high resolution topobathymetric LiDAR is an efficient, widely applicable tool to monitor and measure fluvial and coastal sediment-transport and geomorphic processes.
Active rock glaciers at sea level in Finnmark, Northern Norway?
Karianne Lilleøren1, Vetle Aune1, Bernd Etzelmüller1 and Trond Eiken1
1Department of Geosciences, University of Oslo
Rock glaciers are geomorphological expressions of permafrost presence. Their state of activity indicates occurrence of current or former permafrost. A series of rock glaciers emerging at sea level have been identified in Nordkinnhalvøya, Northern Norway, and have earlier been classified as relict landforms (Lilleøren & Etzelmüller, 2011). However, a recently published permafrost model of the Nordic countries (Gisnås et al., 2016) simulates permafrost at similar elevations elsewhere in Finnmark, but mainly in mires as palsas.
We have now surveyed one of these rock glaciers, situated in Ivarsfjord, by repeated drone imagery (2016-2017) and Terrestrial Laser Scanning (2017). Digital elevation models (DEMs) were compiled from aerial photos from 1975, 1982 and 1992, and a network of miniature data loggers was employed over the rock glacier surface to evaluate near surface temperatures. Two short ERT (Electrical Resistivity Tomography) profiles were established from the top to the front slope of the rock glacier.
Our first results indicate both thermokarst development and front position advances since 1975. This implies that the rock glacier is active, but currently degrading. The ground surface temperature network indicates above 0˚C temperatures as an annual mean. We therefore believe that permafrost can be present even at coastal sites in Finnmark in special settings, indicating sporadic (palsas) to more wide-spread (rock glaciers) permafrost, but in a state of degradation at present.
With large-scale permafrost thaw occurring in the Arctic at present, this area could serve as a time-space substitute of High-Arctic landscapes like Svalbard or Siberia in a changing climate.
Gisnås, K., Westermann, S., Schuler, T.V., Melvold, K. & Etzelmüller, B. 2016: Small-scale variation of snow in a regional permafrost model. The Cryosphere 10, 1201-1215.
Lilleøren, K. & Etzelmüller, B. 2011: A regional inventory of rock glaciers and ice-cored moraines in Norway. Geografiska Annaler: Series A, Physical Geography 93, 175-191.
Better Visualisation of Air-borne Laser Scanning for geomorphological and archaeological interpretation
Thomas Ljungberg1, David Stott2 and Søren Munch Kristiansen1
1Institut for Geoscience, Aarhus Universitet., 2Institut for Geoscience, Aarhus Universitet; Arkæologisk IT, Moesgaard Museum.
Digital elevation models derived from high-precision Air-borne Laser Scanning (ALS or LiDAR) point clouds are becoming increasingly available throughout the world. These elevation models presents a very valuable tool for locating and interpreting geomorphological as well as archaeological features in the landscape. The elevation models are, however, not always directly useable, because the variations in elevation in the models often are orders of magnitude larger than the features of interest, which makes these hard to see. It is therefore usually necessary, and always advisable, to enhance (transform, improve, manipulate) the visual appearance of the elevation model, so that the features of interest are more clearly shown. In this paper, we discuss the usefulness of several advanced visualisation techniques for locating and interpreting a.o. fossil beach ridges, paleo-lake shorelines, sub-glacial meltwater courses, Iron Age Celtic field boundaries, and various other geological and archaeological phenomena under Danish conditions.
EcoMap Project: Baltic Sea environmental assessments by innovative opto-acoustic remote sensing, mapping, and monitoring.
Signe Schilling1, Zyad Al-Hamdani2, Verner Ernstsen1, Jørn Bo Jensen2, Aart Kroon1 and Jens Schneider von Deimling3
1IGN/KU, 2GEUS, 3University of Kiel
Remote sensing and classification of the seafloor are required to obtain a comprehensive view on the marine environment. It allows for analysing spatio-temporal dynamics, monitoring of natural seabed variations, and evaluating possible anthropogenic impacts, all being crucial in implementing marine spatial planning for sustainable use of the sea that leads to the economic growth of the region.
The EcoMap project will develop a remote sensing catalogue documenting the feasibility of latest opto-acoustic methods for improved Baltic Sea habitat monitoring. This catalogue will be developed in close co-operation with authorities to meet their requirements and will allow stakeholders with different interests to quickly judge which remote sensing method is ideally suited for respective monitoring tasks of specific habitats. EcoMap commenced in September 2017 and will continue for three years. The project is part of the BONUS Programme, co-funded by national research funding agencies of the three project partner countries Germany, Poland and Denmark. .
16.4. Open session in Geomorphology
Landslides in northwest Iran: a case study on the landslide hazard zonation in Baleghluchai watershed in Ardabil using AHP Fuzzy method
Keristineh Jananeh1 and Shahram Roostai1
1Geography Department, University of Tabriz, Tabriz, Iran
Landslides and slope instabilities are among the important natural hazards, which cause human and financial casualties and loss of economic resources every year. The northwest of Iran is prone to the occurrence of landslides due to its mainly mountainous topography, complex geology, abundance of tectonic activities and earthquakes and variable climate. These hazards mostly occur in natural slopes or those manipulated by human. This contribution includes a case study on the landslide potential zonation within the Baleghluchai watershed in NW Iran. First, the main factors including the slope and its direction, geology, soil, climate, distance from the road and river and land usage were determined. The method of current investigation was Fuzzy AHP in the GIS environment, based on which, after preparing data layers using the above-mentioned parameters and giving weights to them in the GIS environment, the landslide potential map, as well as classification was carried out by Fuzzy AHP method.
According to the final zonation map, the watershed was divided into 5 classes. Results showed that the largest part of the watershed (32.21%) has low landslide potential, while about 13.5% of it has very high potential. Areas with very high and high landslide potential (327.39 km2 area) are mainly located in the northwest of the watershed, with some small areas distributed in the south and east, while areas with very low and low potential (504.06 km2) are mainly found in the central to northwestern and southern parts of the watershed.Top