Preprints
Filtering by Subject: Geomorphology
Mechanisms for avulsion on alluvial fans: insights from high-frequency topographic data
Published: 2020-12-17
Subjects: Earth Sciences, Geomorphology, Physical Sciences and Mathematics
Avulsion is a key process in building alluvial fans, but it is also a formidable natural hazard. Based on laboratory experiments monitored with novel high-frequency photogrammetry, we present a new model for avulsion on widely graded gravel fans. Previous experimental studies of alluvial fans have suggested that avulsion occurs in a periodic autogenic cycle, that is thought to be mediated by the [...]
Chevrons: origin and relevance for the reconstruction of past wind regimes
Published: 2020-12-15
Subjects: Climate, Earth Sciences, Geology, Geomorphology, Meteorology, Other Life Sciences, Sedimentology, Stratigraphy
Since its first use in the late 80’s, the term chevron has been employed in numerous studies to describe large U- and V-shaped ridges found in or near shorelines worldwide. Most studies have so far focused on Bahamian chevrons that are exclusively of Late Pleistocene age, and on the supposed Holocene chevrons found in S-Madagascar and Australia. In the Bahamas, these deposits have been [...]
Mapping Landslides With a Generalized Convolutional Neural Network
Published: 2020-12-13
Subjects: Geomorphology, Other Earth Sciences, Risk Analysis
Landslides are a common secondary hazard triggered by major earthquakes or extreme rainfall events in steep terrains. Rapid mapping of event landslides is crucial to identify the areas affected by damages as well as for effective disaster response. Traditionally, such maps are generated with visual interpretation of remote sensing imagery (manned/unmanned airborne systems or spaceborne sensors) [...]
An Active Learning Pipeline to Detect Hurricane Washover in Post-Storm Aerial Images
Published: 2020-12-02
Subjects: Environmental Monitoring, Geomorphology, Physical Sciences and Mathematics
We present an active learning pipeline to identify hurricane impacts on coastal landscapes. Previously unlabeled post-storm images are used in a three component workflow — first an online interface is used to crowd-source labels for imagery; second, a convolutional neural network is trained using the labeled images; third, model predictions are displayed on an interactive map. Both the labeler [...]
Operationalising coastal resilience to flood and erosion hazard: A demonstration for England
Published: 2020-12-02
Subjects: Geomorphology, Nature and Society Relations, Physical and Environmental Geography, Sustainability
Resilience is widely seen as an important attribute of coastal systems and, as a concept, is increasingly prominent in policy documents. However, there are conflicting ideas on what constitutes resilience and its operationalisation as an overarching principle of coastal management remains limited. In this paper, we show how resilience to coastal flood and erosion hazard could be measured and [...]
Reconstructing the morphologies and hydrodynamics of ancient rivers from source to sink: Cretaceous Western Interior Basin, Utah, USA
Published: 2020-11-25
Subjects: Earth Sciences, Geology, Geomorphology, Hydrology, Sedimentology, Stratigraphy
Quantitative reconstruction of palaeohydrology from fluvial stratigraphy provides sophisticated insights into the response, and relative impact, of tectonic and climatic drivers on ancient fluvial landscapes. Here, field measurements and a suite of quantitative approaches are used to develop a four-dimensional (space and time) reconstruction of palaeohydrology in Late Cretaceous palaeorivers of [...]
A Vision for the Future Low-Temperature Geochemical Data-scape
Published: 2020-11-21
Subjects: Biogeochemistry, Computer Sciences, Databases and Information Systems, Earth Sciences, Environmental Sciences, Geochemistry, Geology, Geomorphology, Hydrology, Other Computer Sciences, Other Earth Sciences, Soil Science
Data sharing benefits the researcher, the scientific community, and most importantly, the public by enabling more impactful analysis of data and greater transparency in scientific research. However, like many other scientists, the low-temperature geochemistry (LTG) community has generally not developed protocols and standards for publishing, citing, and versioning datasets. This paper is the [...]
Particle energy partitioning and transverse diffusion during rarefied travel on an experimental hillslope
Published: 2020-11-19
Subjects: Earth Sciences, Geomorphology
Recent theoretical and experimental work (Furbish et al., 2020a, 2020b) indicates that rarefied particle motions on rough hillslope surfaces are controlled by the balance between gravitational heating of particles due to conversion of potential to kinetic energy and frictional cooling of the particles due to collisions with the surface. Here we elaborate how particle energy is partitioned [...]
Comparing patterns of hurricane washover into built and unbuilt environments
Published: 2020-10-23
Subjects: Geomorphology, Nature and Society Relations, Physical and Environmental Geography, Sustainability
Extreme geohazard events can change landscape morphology by redistributing huge volumes of sediment. Event-driven sediment deposition is typically studied in unbuilt settings – despite the ubiquity of occurrence and high economic cost of these geohazard impacts in built environments. Moreover, sedimentary consequences of extreme events in built settings tend to go unrecorded because they are [...]
A single multi-scale and multi-sourced semi-automated lineament detection technique for detailed structural mapping with applications to geothermal energy exploration
Published: 2020-10-22
Subjects: Geology, Geomorphology, Tectonics and Structure
A multitude of semi-automated algorithms, many incorporating multi-sourced datasets into a single analysis, now exist. However, these operate at a fixed pixel resolution resulting in multi-sourced methods being limited by the largest input pixel size. Multi-scale lineament detection circumvents this issue and allows increased levels of detail to be captured. In this study we present a [...]
Multi-scale hydro-morphodynamic modelling using mesh movement methods.
Published: 2020-10-22
Subjects: Applied Mathematics, Geomorphology, Mathematics, Numerical Analysis and Computation, Partial Differential Equations
Hydro-morphodynamic models are an important tool that can be used in the protection of coastal zones. They can be required to resolve spatial scales ranging from sub-metre to hundreds of kilometres and are computationally expensive. In this work, we apply mesh movement methods to a depth-averaged hydro-morphodynamic model for the first time, in order to tackle both these issues. Mesh movement [...]
Controls on denudation along the East Australian continental margin
Published: 2020-10-22
Subjects: Earth Sciences, Geomorphology, Physical Sciences and Mathematics
We report a comprehensive inventory of Be-10-based basin-wide denudation rates (n=160) and Al-26/Be-10 ratios (n=67) from 48 drainage basins along a 3,000 km stretch of the East Australian passive continental margin. We provide data from both basins draining east of the continental divide (n=37) and discharging into the Tasman and Coral Seas, and from basins draining to the west as part of the [...]
River Planform Extraction From High-Resolution SAR Images Via Generalised Gamma Distribution Superpixel Classification
Published: 2020-10-21
Subjects: Computer Engineering, Electrical and Computer Engineering, Engineering, Geology, Geomorphology, Hydrology
The extraction of river planforms from remotely sensed satellite images is a task of crucial importance to many applications such as land planning, water resource monitoring or flood prediction. In this paper we present a novel framework for the extraction of rivers from Synthetic Aperture Radar (SAR) images, based on superpixel segmentation and subsequent classification. Superpixel segmentation [...]
Fernandes and Roberts (2020) - preprint
Published: 2020-08-16
Subjects: Earth Sciences, Environmental Sciences, Geology, Geomorphology, Paleobiology, Physical Sciences and Mathematics, Planetary Sciences, Tectonics and Structure
There are many geoscience problems for which constraining histories of uplift or subsidence of Earth’s surface is of direct or indirect importance, for example reconstructing tectonics, mantle convection, geomorphology, sedimentary and chemical flux, biodiversity, glacio-eustasy and climate change. The least equivocal constraints on timing and amplitude of vertical motions on geological [...]
Bedload transport in rivers: size matters but so does shape!
Published: 2020-08-16
Subjects: Earth Sciences, Geomorphology, Hydrology, Physical Sciences and Mathematics, Sedimentology
Bedload transport modelling in rivers, which defines the threshold for pebble movement, takes into account the size and density of pebbles, but does not formally consider particle shape. The lack of analyses evaluating the influences of shape and density on particle mobility presents a major deficiency. To address this issue and to compare the relative roles of the density and shape of particles, [...]