Trait-based numerical modelling of feedbacks between river morphodynamics and riparian vegetation – NUMRIP

A functional trait-based approach will allow to explore the response of plant units to various environmental factors (response traits) and the way plant units affect river morphodynamics (effect traits). The NUMRIP model will be structured into three main work packages: Spatial Analysis (WP1): Defining a semi-automatic procedure for creating 2D and 3D spatial information (digital elevation models [DEMs] and plant characteristics). Spatial data will be acquired on long-term monitoring sites along the Allier and Garonne rivers using remote sensing technologies. Trait-Based Characterisation and Statistical Modelling of Vegetation (WP2): Using spatial data on vegetation characteristics acquired with drones, together with in situ samplings in various vegetation stands representing different succession stages along the Allier and Garonne rivers; conducting statistical analyses of community functional diversity (FD) components related to the variety of trait values (e.g., richness, evenness, divergence), the most abundant trait values/modalities, or ‘community weighted mean values of traits’ (CWM), and the trait values of particular importance will define biogeomorphological functional response and effect groups. Development of the NUMRIP Model (WP3): Coding a hydrogeomorphological module, coding and calibrating a trait-based vegetation module, and developing an optimized code to ensure computing performance compatible with numerical model functioning. Vegetation dynamics will be modelled in terms of response to, and effect on river morphodynamics using the results of the remote sensing and field approaches. The river corridor will be described for the Allier and Garonne rivers with multiple square cells of 10x10 m or smaller, spatially arranged along the upstream-downstream gradient. For each cell, the response of riparian vegetation (regarding recruitment, survival, growth, succession processes) to hydrogeomorphological conditions, and its effect on hydrogeomorphological conditions (regarding morphological and biomechanical traits) will be modelled. Calibration will be based on the spatial and ecological data generated in WP1 and WP2.

The results will include theoretical developments related to feedbacks between hydrogeomorphological processes, fluvial landforms, and riparian vegetation dynamics; and the outcomes of the spatial analyses of the landscape mosaic with remote sensing technologies (see Scientific production section).

The NUMRIP model will be used to investigate potential trajectories of fluvial corridors subjected to changing vegetation cover/functional guilds, climate and flow regimes (flood frequency, amplitude, and timing), variations in groundwater availability, and anthropogenic river training works (e.g., damming, bank protections, channelization, flow regulation). The model will thus be designed to progressively become a decision-support system for river managers. It will allow analysis of the complex relationship between vegetation biodiversity and biogeomorphological resistance and resilience capacities of rivers and their riparian zones in the context of climate change, changing hydrogeomorphological disturbance regimes, and variations in water resources (e.g., groundwater availability). A scientific advance provided by the numerical model will also be the possibility to analyse past and potential long-term dynamic river equilibrium states. This will permit the exploration of hydrosedimentary and environmental conditions for the formation of different river styles (e.g., braided, island-braided, wandering, meandering, anastomosing) in the light of eco-evolutionary feedbacks between vegetation (trait selection) and morphodynamics over geological timescales.

Scientific articles are published in specialized journals in Ecology, Geoscience, Remote Sensing, and Environmental Management. The results are also presented at national and international conferences. A first prototype of the NUMRIP model will be produced at the end of 2025.

Exemples :
In preparation:
Courcoul C. et al. (en prép.). Using the plant functional trait approach to determine riparian vegetation succession trajectories in a biogeomorphological phase space.
Dav M. Ebengo et al. (en prép.). Integrative mapping of riparian vegetation functional units using multispectral imaging, unmanned laser scanning, topographic indices and field surveys.

Published:
Corenblit D., Steiger J. (2024). Fluvial biogeomorphological feedbacks from plant traits to the landscape: lessons from selected French rivers in line with A.M. Gurnell’s influential contribution. River Research and Applications.
O’Briain R. et al. (2024). Towards Biogeomorphic River Restoration: Vegetation as a Critical Driver of Physical Habitat. River Research and Applications.
Corenblit D. et al. (2024). Vegetation effects on river morphodynamics. Part I: research clarifications and challenges. Earth Science Reviews.
Corenblit D. et al. (2024). Vegetation effects on river morphodynamics. art II: Why is a functional trait framework important? Earth Science Reviews.
Corenblit D. et al (2024) Resilience and the physical science of rivers. Cambridge University Press.

Conferences :
Dov Corenblit et al. (2024). NUMRIP : modèle numérique de dynamique du paysage fluvial basé sur les rétroactions entre végétation et morphodynamique fluviale pour la gestion des rivières dans un contexte de changement global. Comprendre les socio-écosystèmes pour agir. 3ème édition de la Semaine Écologie, Environnement Biodiversité du CNRS. 27 mai 2024, Goyrans.
Corenblit D. (2024). Colloque «adaptation au changement climatique en lien avec les pratiques GEMA. 25 et 26 avril 2024, Négrepelisse.
Corenblit D. (2024). Journée SFN CeMEB, 28-29 novembre 2022, Montpellier.
Courcoul C. et al. (2024). ECOVEG17, 20 au 22 mars 2024, Amiens.
Corenblit D. (2022). Journée SFN CeMEB, 28-29 novembre 2022, Montpellier.
Corenblit D. et al. (2022). Atelier Eco-Evo, Prospective INEE 2022, La Rochelle.
Corenblit D. (2022). Journée DIPEE INEE, Clermont-Ferrand.
Garófano-Gómez V. et al. (2022). European Geosciences Union General (EGU) Assembly April-2022, Vienna, Austria.
Garófano-Gómez V. et al. (2022). 39th IHAR World Congress, 19-24 juin, Granada, Spain.
Mazal L. et al. (2022). Conférence « La biodiversité alluviale du bassin versant de la Loire 2022: fonctionnement, dynamique et suivis », Tours.

Modelling fluvial morphodynamics in the face of environmental changes requires the consideration of feedbacks between hydrogeomorphological processes and riparian vegetation dynamics. Hydrogeomorphological processes control vegetation dispersal, recruitment, establishment and succession. In turn, vegetation strongly impacts water flow and sediment transport. Only a restricted set of riparian plant traits are needed to describe the response of vegetation to, and its effect on, river morphodynamics. However, biogeomorphological feedbacks are still poorly considered in fluvial morphodynamics numerical modelling. The objective of the project NUMRIP is to develop a numerical model of river biogeomorphological dynamics integrating feedbacks between hydrogeomorphological processes and a set of key riparian vegetation functional traits. We will develop an innovative scientific tool for fluvial hydrosystems management and restoration.