Francesco Caponi

Last Name

Caponi

First Name

Francesco

ORCID

0000-0003-3229-7876

Organisational unit

03820 - Boes, Robert / Boes, Robert

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Publications 1 - 10 of 12

BASEveg: A python package to model riparian vegetation dynamics coupled with river morphodynamics
Caponi, Francesco; Vetsch, David F.; Vanzo, Davide (2023)
SoftwareX
River morphology is closely linked with riparian vegetation dynamics, because of the interwoven interactions between plants, flow, and sediment transport. However, open-source tools that model such interactions are currently missing. Here we present BASEveg, a python package to simulate riparian vegetation dynamics coupled with BASEMENT, a river hydro-morphodynamic simulator. BASEveg calculates plant growth based on water table fluctuations during low flow and incorporates the resulting plant properties affecting water flow and sediment transport on the computation of riverbed changes during floods. This new tool empowers scientists from different disciplines and fluvial managers to explore eco-morphodynamic processes at various spatial and temporal scales.
Numerical Modelling of River Hydro-Morphology Impact on Plant Seed Dispersal
Caponi, Francesco; Conde, Daniel A.S.; Vetsch, David F. (2023)
Proceedings of the 40th IAHR World Congress
Fluvial seed dispersal is a key factor controlling riparian vegetation dynamics along river margins. Seeds and vegetative propagules are transported by water flow along river channels, allowing plants to colonize new sites and favoring plant biodiversity. However, the specific relationship between river discharge, river morphology and seed dispersal remain largely unexplored. To fill this gap, we combine a new numerical model deploying a Eulerian-Lagrangian approach to track plant seed trajectories and deposition and a series of outdoor field experiments using seed mimics. Here we present the workflow and preliminary observations from the experiments conducted in an alpine floodplain in Switzerland. By linking deposition location and transport time of seed mimic with the spatial and temporal distribution of hydro-morphological units, we can provide a quantification of the role played by river hydro-morphology on seed dispersal. This quantification may support river managers in mitigating impacts of flow diversions and design better e-flows regulations favoring plant biodiversity and ecosystem resilience.
Eco-morphodynamic modelling for gravel bed rivers
Caponi, Francesco (2020)
Rivers provide vital services to society. Most of them are linked to floodplains, and riparian areas, which are key nexus between terrestrial and aquatic ecosystems. However, during the last centuries, the exploitation of river resources has led to a progressive degradation of riparian ecosystems, and loss of their associated services. The hydromorphological condition of rivers, largely impacted by channelization, is recognized as a key indicator for assessing riparian ecosystem integrity, and it is nowadays preventing rivers to achieve a good ecological status. In this context, the development of quantitative, predictive tools in support of river restoration plans urges. River morphology is widely recognized to result from the interactions between vegetation, flow and sediment transport. Riparian plants are known to modify flow patterns and sediment transport during floods, depending on specific above- and below-ground plant traits such as canopy and root biomass and density. In turn, hydromorphological processes influence the establishment, growth, and survival of plants. However, our understanding, and the ability to quantify, the co-evolution of vegetation and river morphology remain limited. In this research, we aim at quantifying the key underlying processes of this coevolution, which have so far been mostly described in a qualitative way, by developing modelling approaches able to identify and disentangle them. We focused on gravel bed rivers, common in Alpine regions and temperate environments. First, we investigated the hydromorphological and biological conditions needed for plants to establish on gravel bars after seed dispersal. By analysing a series of aerial images between 1996 and 2017 of a reach of the Alpine Rhine river, we found that vegetation has grown since 2005 along the more stable (steady) bars, while not on the more active, migrating bars. To interpret the observations, we developed a simple model that searches for the minimum time period needed for plants to resist hydrodynamic disturbances and successfully establish, and explored the influence of bar morphology and seed dispersal. Second, we studied the role of plant roots in mediating river morphodynamics, which has so far been poorly investigated in gravel bed rivers. We developed a model accounting for the main root-related feedbacks, and quantified their importance in a simplified river channel configuration. We found that the uprooting, that is, the mechanism by which plants are removed by flow erosion, is fundamental for describing river eco-morphodynamics, and that the effect of different root characteristics depend on the balance between root anchoring resistance and the erosion potential of the flow. Third, we investigated the role that both above- and below-ground plant traits have on vegetation survival to floods, and ultimately on biogeomorphic patterns. Motivated by observations in the Alpine Rhine river, we studied an alternate bar river morphology and tested different trade-offs between above- and below-ground plant traits. We found that differences among trade-offs emerge only when plant biomass develop enough to interact with river morphology, which may underpin a transition from a geomorphic to a biogeomorphic state. In addition, we were able to explore different mortality mechanisms of plants and their relation with plant traits. To conclude, in this research we were able to quantify eco-morphodynamic processes relevant for, but not limited to, gravel bed rivers and to shed light on their importance.
Numerical modeling of plant root controls on gravel bed river morphodynamics
Caponi, Francesco; Siviglia, Annunziato (2018)
Geophysical Research Letters
When Does Vegetation Establish on Gravel Bars? Observations and Modeling in the Alpine Rhine River
Caponi, Francesco; Koch, Aurélie; Bertoldi, Walter; et al. (2019)
Frontiers in Environmental Science
Predicting when riparian vegetation establishes on river bars is crucial to estimate how morphology and ecology of gravel bed rivers respond to anthropogenic or climatic changes. However, the characteristic timescale required for vegetation establishment on gravel bars remains poorly investigated. The Windows of Opportunity (WoO) concept provides an ideal framework for estimating such timescale by analyzing time series of disturbance periods following seed dispersal. Here we present the results of a study conducted in a 41 km long reach of the Alpine Rhine river characterized by the presence of alternate gravel bars, which show differences in morphological activity and vegetated areas. We mapped the time evolution of vegetation cover between 1996 and 2017 by using aerial images and related vegetation occurrence to bar topography. Observations show that vegetation mainly colonized bar surfaces between 2005 and 2008, enduring on bars that showed less morphological activity. Only few patches, which were removed by downstream bar migration, were observed on bars that experienced significant morphological changes. This allowed us to identify conditions that were more favorable to vegetation recruitment and growth. To explain the vegetation pattern observed along the whole reach, we developed a simple modeling framework based on the WoO concept including the effects of flow variability on seed dispersal and seedling recruitment and survival. Model applications demonstrate that vegetation successfully establishes on bare areas if plants can withstand hydrodynamic disturbances for about 85 days after seed dispersal. We also identified timing and location of successful recruitment events and discussed how they are linked to bar morphology, seed dispersal, and riverbed morphodynamics. This study provides a first attempt to quantify the WoO in a gravel bed river with alternate bars, representing a step toward the development of quantitative tools for predicting river morphological trajectories.
River Ecomorphodynamic Models Exhibit Features of Nonlinear Dynamics and Chaos
Cunico, Ilaria; Bertoldi, Walter; Caponi, Francesco; et al. (2024)
Geophysical Research Letters
Modeling the nonlinear interactions between flow, sediment, and vegetation is essential for improving our understanding and prediction of river system dynamics. Using simple numerical models, we simulate the key flow-sediment-vegetation interaction where the disturbance is intrinsically generated by the presence of vegetation. In this case, biomass growth modifies the flow field, induces bed scour, and thus potentially causes vegetation uprooting when erosion exceeds root depth. Our results show that this nonlinear feedback produces deterministic chaos under a wide range of conditions, with complex aperiodic dynamics generated by a period-doubling route to chaos. Moreover, our results suggest relatively small values of Lyapunov time, spanning 2-4 growth-flood cycles, which significantly restrict the predictability of riverbed evolution. Although further spatial and temporal processes may add complexity to the system, these results call for the use of ensemble methods and associated uncertainty estimates in ecomorphodynamic models.
Butterfly effect in a deterministic ecomorphodynamic model
Cunico, I.; Bertoldi, W.; Siviglia, Annunziato; et al. (2024)
River Flow 2022
The eco-morphodynamic trajectory of rivers is dictated by the non-linear complex interactions among riparian vegetation, flow and sediment transport. Because of its non-linear dynamical nature, complexity can emerge from the model governing such interactions. The goal of this work is to investigate and quantify such complexity that could limit predictions of the river morphological trajectories. To this end, we conduct numerical simulations using a 1D deterministic model that couples hydro-morphodynamics with vegetation dynamics. We consider a straight channel with a vegetated patch perturbed periodically by a succession of triangular floods of constant amplitude. Vegetation growth occurs in between of two consecutive floods, and it may be uprooted during flood events. During the analysis we change the ratio between the flood frequency and the vegetation growth. Model results demonstrate that the response of the system can be chaotic, limiting the long-term predictability of the system to few flood events.
River Hydrodynamics and Seed Establishment Processes: A 2D Modelling Approach
Vanzo, Davide; Looser, Michael; Vetsch, David F.; et al. (2023)
Proceedings of the 40th IAHR World Congress
Riparian vegetation is a key indicator for the status of river environments. The understanding of seed recruitment dynamics is crucial to assess vegetation distribution and establishment. Such processes are linked to river hydro-morphodynamic processes, as seeds of many riparian species are transported along the river by water. In this study, we apply a 2D hydrodynamic model to simulate flow conditions across multiple hydrological years and test alternative hydrological scenarios. Then we applied a vegetation recruitment model based on the Windows-of-Opportunity logic to simulate seed recruitment in a braided, gravel-bed reach of an Alpine river. Results show that hydropeaking has an impact on riparian vegetation dynamics, but also that flow regulation effects are different depending on the hydrological year.
The role of vegetation uprooting on fluvial morphodynamics: a modeling approach
Caponi, Francesco; Siviglia, Annunziato (2018)
Proceedings of the 12th International Symposium on Ecohydraulics (Tokyo, 2018)
Eco-morphodynamic modelling for gravel bed rivers
Caponi, Francesco (2020)
VAW-Mitteilungen

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Francesco Caponi

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