Segmentation of topographic change by geomorphic units to assess physical habitat transitions in a restored river

River restoration schemes that utilise natural processes need to be monitored post-implementation to inform adaptive management, to assess their success at delivering sustained ecological improvements and to contribute to the design of other schemes. All three of these monitoring objectives require an understanding of the geomorphic mechanisms that cause channel adjustment and how they shape the mosaic of geomorphic units that make up physical habitat. In the last decade repeat, high-resolution topographic surveys of river restoration schemes have become commonplace through the application of a range of geomatics technologies including echo-sounders, laser scanners and Structure from Motion photogrammetry. Such datasets offer opportunities to map geomorphic change and geomorphic unit evolution to quantitatively analyse the relative roles of different processes in generating physical habitat. Here, we present results from an investigation into the morphodynamics of the Whit Beck river restoration scheme, implemented by the West Cumbria Rivers Trust, UK. We use repeat Digital Elevation Models (DEMs) to quantify patterns of erosion and deposition using the Geomorphic Change Detection (GCD) toolbox and to map geomorphic units, using the Geomorphic Unit Tool (GUT). The segmentation of maps of erosion and deposition with maps of geomorphic units quantifies physical habitat transitions. The resulting analysis indicates the different mechanisms of adjustment that generate physical habitat throughout the restoration scheme and how they are linked to different initial conditions

‘InfraRivChange’: A Web Application to Monitor River Migration at Sites of Critical Bridge Infrastructure in the Philippines

No abstract available

Slope break and avulsion locations scale consistently in global deltas

Understanding how deltas respond to changing sea level is crucial as deltas provide important ecosystems, are inhabited by ∼500 million people, and are nexuses of food, energy and economic activity. The response of delta distributary channels to sea-level rise depends on the geomorphic controls on delta morphology and their scaling relationships. Our data from 105 deltas globally show strong scaling between the upstream distances to slope breaks and to avulsion nodes, and confirm the previously-known scaling between backwater and avulsion lengths. The break in slope is proposed to be the principal control on delta development, along with other proposed secondary controls. We identify and discuss the implications of this slope break-avulsion length scaling, leading to a conceptual model of delta morphology and sedimentology. This model suggests how deltas may respond to future sea level rise and guides interpretation of deltaic deposits in the rock record

Applications of Google Earth Engine in fluvial geomorphology for detecting river channel change

Cloud‐based computing, access to big geospatial data, and virtualization, whereby users are freed from computational hardware and data management logistics, could revolutionize remote sensing applications in fluvial geomorphology. Analysis of multitemporal, multispectral satellite imagery has provided fundamental geomorphic insight into the planimetric form and dynamics of large river systems, but information derived from these applications has largely been used to test existing concepts in fluvial geomorphology, rather than for generating new concepts or theories. Traditional approaches (i.e., desktop computing) have restricted the spatial scales and temporal resolutions of planimetric river channel change analyses. Google Earth Engine (GEE), a cloud‐based computing platform for planetary‐scale geospatial analyses, offers the opportunity to relieve these spatiotemporal restrictions. We summarize the big geospatial data flows available to fluvial geomorphologists within the GEE data catalog, focus on approaches to look beyond mapping wet channel extents and instead map the wider riverscape (i.e., water, sediment, vegetation) and its dynamics, and explore the unprecedented spatiotemporal scales over which GEE analyses can be applied. We share a demonstration workflow to extract active river channel masks from a section of the Cagayan River (Luzon, Philippines) then quantify centerline migration rates from multitemporal data. By enabling fluvial geomorphologists to take their algorithms to petabytes worth of data, GEE is transformative in enabling deterministic science at scales defined by the user and determined by the phenomena of interest. Equally as important, GEE offers a mechanism for promoting a cultural shift toward open science, through the democratization of access and sharing of reproducible code

Analysis of the fluvial stratigraphic response to the Paleocene–Eocene Thermal Maximum in the Bighorn Basin, U.S.A.

Geological deposits can reveal how environments of the past have responded to climate change, enabling important insights into how environments may respond to our current anthropogenically induced warming. The Paleocene–Eocene Thermal Maximum (PETM) occurred ca. 56 Ma and was a short-lived (approximately 200,000 years) global warming event (5–8°C rise). The PETM has been investigated at several terrestrial and marine localities across the globe. However, many studies are based on single successions, with very few sites being placed within a well-defined spatial and temporal context and with comparisons limited to deposits that lie immediately above and below the event. Due to the inherent variability of sedimentary systems, it is imperative that the appropriate context is provided to fully understand the impacts of climate change on landscapes and subsequent deposits. This study examines 28 locations, totaling over 4 km of recorded stratigraphy, within a newly defined quantified sedimentary basin context (Bighorn Basin, USA) to evaluate variability of fluvial response to the PETM. We show that channel-body and story thicknesses across the PETM are not statistically significantly different from deposits outside the climate event, implying that there is not a consistent sedimentary response to the climate event across the basin. Based on our large dataset we calculate that precipitation would have had to double for statistically significant changes in deposit thickness to be generated. We discuss how climatic signals may be lost due to the self-organization, spatial–temporal varied response and preservation potential in large fluvial systems. This study gives a new quantified perspective to climate events in the geologic record

River Styles and stream power analysis reveal the diversity of fluvial morphology in a Philippine tropical catchment

Characterisation of hydromorphological attributes is crucial for effective river management. Such information is often overlooked in tropical regions such as the Philippines where river management strategies mainly focus on issues around water quality and quantity. We address this knowledge gap using the River Styles Framework as a template to identify the diversity of river morphodynamics. We identify eight distinct River Styles (river types) in the Bislak catchment (586 km2) in the Philippines, showing considerable geomorphic diversity within a relatively small catchment area. Three River Styles in a Confined valley setting occupy 57% of the catchment area, another three in a partly confined valley setting occupy 37%, and two in the remaining 6% are found in a laterally unconfined valley setting. Five characteristic downstream patterns of River Styles were identified across the catchment. We observe that variation in channel slope for a given catchment area (i.e., total stream power) is insufficient to differentiate between river types. Hence, topographic analyses should be complemented with broader framed, catchment-specific approaches to river characterisation. The outputs and understandings from the geomorphic analysis of rivers undertaken in this study can support river management applications by explicitly incorporating understandings of river diversity and dynamics. This has the potential to reshape how river management is undertaken, to shift from reactive, engineering-based approaches that dominate in the Philippines, to more sustainable, ecosystem-based approaches to management