River discharge variability – a significant control on river morphodynamics, sediment transport, fluvial facies and architecture?

Piret Plink-Björklund, Chiara Cavallina, Sonia Campos Soto

River discharge variability seems a significant control on fluvial facies and architecture. Variable discharge rivers have been shown to experience formative Froude supercritical flow and support high sediment concentrations, promote formation of fluvial fans, and form volumetrically significant sedimentary records. Yet, our hydrological theory and models consider subcritical flow as the formative flow in rivers, and seemingly contradict the data. We invite contributions from modern and ancient rivers, flume experiments and mathematical modeling that explore the nature of variable discharge rivers, their sedimentary record, and the formative role of supercritical flow to further explore the significance of discharge variability in landscape evolution and the formation of the sedimentary record.

River processes, planforms and stratigraphic products

Paul Durkin, Anjali Fernandes, Amanda Owen, Stephen Hubbard

Broad session focused on fluvial styles, with an emphasis on their reliable detection in the sedimentary record. Process-product relationships leveraging direct measurements or time-lapse remote-sensing data, used to reconstruct bars from outcrop and both shallow and deep subsurface datasets. Discussion of “classic” fluvial facies models, including their strengths and weaknesses welcomed.

Controls on the preservation of fluvial strata and implications for paleoenvironmental reconstructions

Liz Hajek, Vamsi Ganti

Over long timescales, the preservation of fluvial sediments is controlled by the balance of accommodation creation and sediment supply in alluvial basins. Recent work has shown that the kinematics and morphodynamics of fluvial systems over shorter timescales – including bedform, bar, and channel migration and avulsion – also play a significant role in the preservation of channel and floodplain deposits. Furthermore, discharge variability may serve to enhance fluvial preservation in some systems. Understanding controls on the preservation of fluvial strata provides important insight into i) the relative contributions of different types of fluvial processes reflected in the stratigraphic record, ii) potential bias and uncertainty in quantitative paleohydraulic reconstructions, iii) the nature of time preservation in alluvial strata, and iv) strategies for correlation and subsurface prediction in fluvial deposits. This session aims to highlight studies of controls on fluvial preservation and the impact of preservation on paleoenvironmental reconstructions of ancient fluvial landscapes. We invite contributions that use field, experimental, and/or numerical approaches to explore controls on preservation in fluvial strata and studies that consider how fluvial preservation may aid or inhibit paleoenvironmental interpretation from fluvial sediments.

River Bedforms: Flow, Sediment and Morphological Dynamics

Daniel Parsons, Jim Best, Suleyman Naqshband

Complex interactions between river flow and the transport of mobile sediment give rise to a suite of bedforms that are essential to interpretations and reconstructions of fluvial palaeoenvironments. This session aims to highlight and explore the latest developments in research concerning the many aspects of the complex interactions between flow, bedforms and alluvial sedimentary structures. The session seeks to integrate research from the description and interpretation of bedforms in the rock record, through to field quantification of modern rivers, and experimental and numerical models of alluvial bedforms and their morphodynamics. We encourage contributions across a suite of spatial and temporal scales, from channel scale to the grain-scale, and from turbulence scales through to extreme events and longer-term impacts on bedform dynamics. The session encourages contributions from field, laboratory, theoretical, and numerical approaches intended to advance our knowledge of how to decipher information contained in alluvial bedforms, with an aim to foster discussions and debate between researchers investigating bedform dynamics and their sedimentary signatures.

Long-term, tectono-depositional evolution of river systems and their drainage networks through geological time

Alessandro Ielpi, Adrian Hartley

The session will be focused around contributions that depict the coupled tectonic and depositional evolution of drainage networks and fluvial basins over geologically significant time spans and/or large (up to pan-continental) scales. We seek submissions that integrate basin analysis, detrital-provenance analysis, and tectono-stratigraphy in ancient basins, but also morpho-stratigraphy, neotectonics, and palaeo-climatology on modern basin systems experiencing active landscape seismogenesis and fluvial deposition. Particular attention will be given to contributions that inform the geoscience community about the responses of fluvial networks to large-scale geodynamic events such as plate convergence and post-collisional unroofing of orogenic edifices.

Fluvial deposits and resources

Amanda Owen, Adrian Hartley

Fluvial systems host a range of societally important resources. They can be key aquifers, host minerals such as copper, uranium and gold, are oil and gas reservoirs as well as have the potential to be carbon capture and storage sites. In addition they have the potential in both shallow and deep sedimentary geothermal settings. Understanding the heterogeneity from the pore to basin scale is essential in understanding the distribution, and how to best recover and protect, resources hosted within fluvial systems. This session aims to examine our current understanding and future directions of fluvial deposits as key resource sites.

Anthropocene Rivers

Catherine Russel, Martin Gibling

In the age of the Anthropocene, rivers around the world are an important source of water and routes for transport. However, many have been intensely engineered to account for our needs through morphological adjustments and connection to infrastructure so that they can behave more efficiently in removing unwanted materials from an environment. Many of the unwanted materials are markedly different from what would be natural (i.e. pollution) and may be anything from an increase in silt due to intensive farming, through to entirely anthropogenic inventions such as chemicals and microplastics. In this session, we welcome abstracts that consider Anthropogenic changes to rivers with the goal to draw together the current understanding so that we can better mitigate future challenges.

Alluvial systems at the interface with other environments

Luca Colombera, Marcello Gugliotta, John Holbrook, Ivar Midtkandal

Alluvial systems interfacing with other sedimentary environments are controlled by the interaction of riverine and non-riverine processes. For example, the physiography and process regime of receiving seas and lakes affect river morphodynamics and behaviour. The geomorphology and evolution of upland alluvial environments are intimately connected with forms and processes of linked colluvial and glacial systems. Rivers and aeolian systems often interplay mutually, to shape dryland environments. Recognizing the sedimentary signatures of these interactions in fluvial depositional systems is important, because these translate to potentially complex styles of sedimentary heterogeneity in subsurface successions, and because they act as sensitive recorders of environmental change in the stratigraphic record. This session will showcase research that elucidates the forms and record of interactions between alluvial systems and neighbouring environments. The session aims to be broad in scope, welcoming contributions presenting studies based on field, subsurface or remote-sensing datasets, and on ancient successions and modern environments alike.