In this paper we develop a two-dimensional modelling framework suitable to study the morphological evolution of vegetated braided rivers. The mathematical model features a unisize-sediment morphological model, which includes accounting for bank erosion, and a vegetation model. While these model components had already appeared separately in different contexts, here we improve and tailor them for modelling vegetated braided river dynamics. We implement a numerical solution to this problem in the framework of the pre-existing morphological model GIAMT2D. We devise a hydrograph-splitting technique to avoid excessive run times in the multi-decadal applications needed to appreciate vegetation-driven morphological change. This hydrograph-splitting technique uses the full model to solve for flood periods, while applying a fixed-bed approximation and only updating vegetation density during low-flow periods. Finally, we apply the developed formulation, tools and techniques to simulate an idealised reach of the Lower Waitaki River (Aotearoa – New Zealand), where we reproduce vegetation encroachment and morphological change observed between 1936 and 1964.

Development of a Numerical Model for Braided River Morphology and Vegetation Evolution with Application to the Lower Waitaki River (Aotearoa – New Zealand) / Stecca, G.; Fedrizzi, D.; Measures, R.; Hicks, D. M.; Hoyle, J.; Zolezzi, G.. - In: ADVANCES IN WATER RESOURCES. - ISSN 0309-1708. - 2022, 166:(2022), pp. 1-20. [10.1016/j.advwatres.2022.104236]

Development of a Numerical Model for Braided River Morphology and Vegetation Evolution with Application to the Lower Waitaki River (Aotearoa – New Zealand)

Fedrizzi D.;Zolezzi G.
2022-01-01

Abstract

In this paper we develop a two-dimensional modelling framework suitable to study the morphological evolution of vegetated braided rivers. The mathematical model features a unisize-sediment morphological model, which includes accounting for bank erosion, and a vegetation model. While these model components had already appeared separately in different contexts, here we improve and tailor them for modelling vegetated braided river dynamics. We implement a numerical solution to this problem in the framework of the pre-existing morphological model GIAMT2D. We devise a hydrograph-splitting technique to avoid excessive run times in the multi-decadal applications needed to appreciate vegetation-driven morphological change. This hydrograph-splitting technique uses the full model to solve for flood periods, while applying a fixed-bed approximation and only updating vegetation density during low-flow periods. Finally, we apply the developed formulation, tools and techniques to simulate an idealised reach of the Lower Waitaki River (Aotearoa – New Zealand), where we reproduce vegetation encroachment and morphological change observed between 1936 and 1964.
2022
Stecca, G.; Fedrizzi, D.; Measures, R.; Hicks, D. M.; Hoyle, J.; Zolezzi, G.
Development of a Numerical Model for Braided River Morphology and Vegetation Evolution with Application to the Lower Waitaki River (Aotearoa – New Zealand) / Stecca, G.; Fedrizzi, D.; Measures, R.; Hicks, D. M.; Hoyle, J.; Zolezzi, G.. - In: ADVANCES IN WATER RESOURCES. - ISSN 0309-1708. - 2022, 166:(2022), pp. 1-20. [10.1016/j.advwatres.2022.104236]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11572/441069
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