Biota affect hydrology, sediment transport, weathering, soil formation over variable temporal and spatial scales and thereby influence, hillslope, fluvial, coastal, and aeolian landscape form and dynamics. In turn, geomorphological processes have large impacts on ecological processes and biogeochemical fluxes by shaping topography and affecting water availability, which determines biological diversity and succession.

Understanding these feedbacks between biological and geomorphological processes is becoming increasingly important as new ‘building with nature’ projects emerge and also increasingly find its way into management (i.e. restoration projects, nature based solutions). Despite some advances, the conceptualisation and quantification of the processes, rates and feedbacks between geomorphology and ecology are still limited, particularly in systems that are sensitive to human-induced or natural environmental change (e.g. high-mountain and polar environments, deserts, hillslopes, rivers and wetlands, salt marshes and deltas). Furthermore, biogeomorphic feedbacks influence important environmental fluxes, and this connection remains poorly understood.

This session firstly seeks contributions that are investigating biogeomorphology on all spatial and temporal scales, including experimental, field and computational/numerical modelling studies. Secondly, the focus lies on studies investigating spatial and temporal variations in biogeomorphic systems controlled by complex feedbacks or heterogeneity in ecosystems which influence physical (e.g. sediment cohesion), biogeochemical (e.g. nutrient and carbon cycling) and ecological processes (e.g. biodiversity). This heterogeneity results in alterations to environmental fluxes (e.g. sediments, water, biogeochemical), the overall functioning of the systems, as well as any potential benefits from ecosystem services. By bringing together scientists from the fields of Geomorphology, Hydrology, Biogeosciences, and Soil Science, in this trans-disciplinary session we aim to stimulate discussion regarding the effects of ecosystem heterogeneity and complexity originating from biogeomorphic systems on environmental processes and feedbacks across varying spatial and temporal scales.

Transport of sediments in geophysical flows occurs in mountainous, fluvial, estuarine, coastal, aeolian and other natural or man-made environments on Earth and has been shown to play important formative roles in planets and satellites such as Mars, Titan, and Venus. Understanding the motion of sediments is still one of the most fundamental problems in hydrological and geophysical sciences. Such processes can vary across a wide range of scales - from the particle to the landscape - which can directly impact both the form (geomorphology) and, on Earth, the function (ecology and biology) of natural systems and the built infrastructure surrounding them. In particular, feedback between flow and sediment transport as well as interparticle interactions including size sorting are a key processes in surface dynamics, finding a range of important applications, from hydraulic engineering and natural hazard mitigation to landscape evolution and river ecology.
Specific topics of interest include (but are not restricted to):
-particle-scale mechanics of entrainment and disentrainment
-Discrete element modelling of granular processes and upscaling into continuum frameworks
-upscaling and averaging techniques for stochastic processes related to granular processes
-interaction among grain sizes in poorly sorted mixtures, including particle segregation
-momentum/energy transfer between turbulent flows and particles
-derivation and solution of equations in particular for multiphase flows
-reach scale sediment transport and geomorphic processes
-shallow water hydro-sediment-morphodynamic processes
-fluvial processes in response to reservoir operation schemes

Hydro-geomorphic connectivity has emerged as a significant conceptual framework for understanding the transfer of surface water and materials (e.g., sediment, plant propagules, and nutrients) through landscapes. The concept has had particular success in the field of catchment hydrology and fluvial geomorphology, but has also been employed in, for example, studies of soil erosion and hydrochory, and in neurosciences and social sciences. Connectivity as applied in various disciplines can be a transformative concept in understanding complex systems, allowing analyses of how such systems behave in terms of scaling, catastrophic/phase transitions, critical nodes, emergence and self-organization. However, recent research also highlights the widespread nature of natural longitudinal disconnectivity in river systems, such as beaver dams, log jams, lakes and wetlands. These and other forms of natural disconnectivity can have large spatial and temporal implications on ecological, geomorphic, hydrological and biogeochemical processes through buffering water and material fluxes. We aim to create a diverse interdisciplinary session that reflects a broad range of research seeking to illustrate the role of connectivity on various spatial scales as well as implications of and temporal and spatial variability of disconnectivity. We hope to use the session to develop a discussion of the dual roles of connectivity and disconnectivity to generate a basis for an integrated framework to be applied across the sciences in hydro-geomorphic systems and for managing complex systems and guiding river restoration.

Public information:
CHAT PROGRAMME

1) General introduction by the conveners (“setting the context”) – 5 min

2) ‘Mentimeter’ poll (conveners, authors, audience) – 5 min

3) Displays (max. 7 min per display):

• Invited “speakers” first (Gordon Grant, Ellen Wohl, Rebekah Levine)
• Then following the order as shown in the official EGU session programme (and in your panel to the right of the chat window)

Procedure: Each display will be announced by the session moderators asking the “speakers” to post key messages related to their display material. Then the audience is kindly asked to post questions/statements for discussion.

4) Concluding remarks (conveners) – 5 min

The erosion, transport, temporary storage, and deposition of sediment govern the fluxes and distribution of solid mass on the surface of the Earth. The rate and extent of these mass fluxes is controlled by the complex interplay of surface processes that act across a range of spatial and temporal scales. Understanding these processes and their dependence on external forcing (e.g. climate, tectonics) and internal feedbacks (autogenic dynamics) is instrumental for constraining the cycling of sediment from source-to-sink, and to invert sedimentary archives for past environments.
A growing body of studies continues to develop a process-based understanding of the coupling between climate, tectonics, erosion, and the transport of solids across large catchments. Important insights into sediment recycling and residence time have been provided by recent advances in geochemical and geophysical techniques, highlighting the dynamic nature of sediment transport. However, many challenges remain including; (1) fully quantifying the time- and spatial scales of sediment transport, (2) tracking signals across catchments and inverting sedimentary records, and (3) assessing the importance of large and infrequent events in controlling erosion and sediment transport.
In this session we welcome field-based, experimental, and modelling studies, that (1) constrain mechanisms, rates, and scales of erosion, transport, and deposition processes, (2) analyse the influence of internal and external forcing on these processes, (3) investigate the propagation of geochemical or physical signals across the earth surface (such as changes in sedimentary fluxes, grain size distributions, cosmogenic nuclide concentrations) and (4) invert sedimentary archives to learn about past environments. Contributions across all temporal and spatial scales are welcome. We particularly encourage early career scientists to apply for this session.

Solicited presenter: Elizabeth Dingle (Simon Fraser University)

The changes in mineral and organo-mineral assemblages during pedogenesis are affected by chemical weathering and transformation of primary minerals over a wide range of time scales. The subsequent formation and transformation of secondary minerals are tightly linked to hydrological conditions and biological processes. Changes in mineral types, organo-mineral organisation and reactivities constrain the biogeochemical cycles of major elements (e.g., silicon, carbon, nitrogen, phosphorus, and sulphur) and trace elements (e.g., iron, manganese, antimony, cadmium, molybdenum, and selenium) which are often intricately coupled and controls the release, transport, and immobilization of nutrients and toxic trace elements, especially in redox-dynamic soil environments. The distribution of elements in soil affects soil quality, biota, ecosystem health, and ultimately, Earth’s climate and life. In this session, we invite field, laboratory, and modelling studies from a molecular-level to ecosystem observations exploring:
(1) the mechanisms and rates of mineral weathering, formation, and transformation at different time scales, as well as the links to biogeochemical element cycling,
(2) the speciation, reactivity, and environmental fate of elements during soil wetting and drying, freezing and thawing, and changing water-flow regimes, and
(3) the impact of mineral weathering and redox oscillations on element turnover, climate, and biota.

Dissolution, precipitation and chemical reactions between infiltrating fluid and rock matrix alter the composition and structure of the rock, either creating or destroying flow paths. Strong, nonlinear couplings between the chemical reactions at mineral surfaces and fluid motion in the pores often leads to the formation of intricate patterns: networks of caves and sinkholes in karst area, wormholes induced by the acidization of petroleum wells, porous channels created during the ascent of magma through peridotite rocks. Dissolution and precipitation processes are also relevant in many industrial applications: dissolution of carbonate rocks by CO2-saturated water can reduce the efficiency of CO2 sequestration, mineral scaling reduces the effectiveness of heat extraction from thermal reservoirs, acid rain degrades carbonate-stone monuments and building materials.

With the advent of modern experimental techniques, these processes can now be studied at the microscale, with a direct visualization of the evolving pore geometry. On the other hand, the increase of computational power and algorithmic improvements now make it possible to simulate laboratory-scale flows while still resolving the flow and transport processes at the pore-scale.

We invite contributions that seek a deeper understanding of reactive flow processes through interdisciplinary work combining experiments or field observations with theoretical or computational modeling. We seek submissions covering a wide range of spatial and temporal scales: from table-top experiments and pore-scale numerical models to the hydrological and geomorphological modelling at the field scale. We also invite contributions from related fields, including the processes involving coupling of the flow with phase transitions (evaporation, sublimation, melting and solidification).

Public information:
There will be a zoom session connected with the session on Tue, May 5th, at 18.00 CET

https://us04web.zoom.us/j/79628870111

The transfer of sediments and associated contaminants play an important role in catchment ecosystems as they directly influence water quality, habitat conditions and biogeochemical cycles. Contaminants may include heavy metals, pesticides, nutrients, radionuclides, and various organic, as well as organometallic compounds. The environmental risk posed by sediment-bound contaminants is largely determined by the sources and rate at which sediments are delivered to surface water bodies, the residence time in catchments, lakes and river systems as well as biogeochemical transformation processes. However, the dynamics of sediment and contaminant redistribution is highly variable in space and time due to the complex non-linear processes involved. This session thus focuses on sources, transport pathways, storage and re-mobilization, and travel times of sediments and contaminants across temporal and spatial scales as well as their impact on catchment and freshwater ecosystems.

This session particularly addresses the following issues:
• Delivery rates of sediments and contaminants from various sources (i.e. agriculture, urban areas, mining, industry or natural areas);
• Transport, retention and remobilization of sediments and contaminants in catchments and river reaches;
• Modelling of sediment and contaminant transport on various temporal and spatial scales;
• Biogeochemical controls on contaminant transport and transformation;
• Studies on sedimentary processes and morphodynamics, particularly sediment budgets;
• Linkages between catchment systems and lakes, including reservoirs;
• Analysis of sediment archives to appraise landscape scale variations in sediment and contaminant yield over medium to long time-scales;
• Impacts of sediments and contaminants on floodplain, riparian, hyporheic and other in-stream ecosystems;
• Response of sediment and contaminant dynamics in catchments, lakes and rivers to changing boundary conditions and human actions.

Debris flows are among the most dangerous natural hazards that threaten people and infrastructures in both mountainous and volcanic areas. The study of the initiation and of the dynamics of debris flows, along with the characterization of the associated erosion/deposition processes, is of paramount importance for hazard assessment, land-use planning and design of mitigation measures, including early warning systems.
A growing number of scientists with diverse backgrounds are studying debris flows and lahars. The difficulties in measuring parameters related to their initiation and propagation have progressively prompted research into a wide variety of laboratory experiments and monitoring studies. However, there is a need of improving the quality of instrumental observations that would provide knowledge for more accurate hazards maps and modeling. Nowadays, the combination of distributed sensor networks and remote sensing techniques represents a unique opportunity to gather direct observations of debris flows to better constrain their physical properties.
Scientists working in the field of debris flows are invited to present their recent advancements. In addition, contributions from practitioners and decision makers are also welcome. Topics of the session include: field studies and documentation, mechanics of debris-flow initiation and propagation, laboratory experiments, modeling, monitoring, hazard and risk assessment and mapping, early warning, and alarm systems.

Soil organic matter (SOM) is an ecosystem property that emerges from a suite of complex biological, geochemical, and physical interactions across scales. As the largest pool of actively-cycling terrestrial carbon, understanding how SOM persistence and vulnerability will respond to global change is critical. However, Earth System Models (ESMs) are often unable to capture emergent SOM patterns and feedbacks at across smaller spatial and temporal scales. Identifying, prioritizing, and scaling key driving mechanisms from detailed process models to advance ESMs is crucial, and better empirical constraints on SOM pools and fluxes are urgently needed to advance understanding and provide model benchmarks. Interdisciplinary research and observation networks collecting long-term, geographically-distributed data can help elucidate key mechanisms, and international efforts that synthesize and harmonize these data are needed to inform data-model comparisons.

We invite theoretical and empirical contributions that investigate controls on SOM across scales, from detailed process understanding to emergent landscape-scale dynamics in natural and managed ecosystems. We seek modelling studies that work across scales, data analyses that leverage multi-site networks and/or long-term experiments, or collaborations between empiricists and modelers within and across networks. Studies that use novel tools across scales, from microbial -omics to remote sensing, are also welcome.

This session has been promoted by:
• Sustainable Agro-ecosystems (AGRISOST, https://www.agrisost.org/en/)
• International Soil Modeling Consortium (ISMC, https://soil-modeling.org/)