The impact of human activity on the morphological evolution of braided rivers produces serious problems for the river management and consequently a wide range of questions to the research community. In this work we explore the response of a braided network to variations in the sediment supply which can be induced by river interventions like dam construction or sediment mining. We have focused in particular on the simple case of a confined braided network with constant discharge and well-sorted, cohesiveless bed material. It is well known that within the context of a one-dimensional formulation the governing hyperbolic system can be readily reduced to a simple diffusive scheme when the hypothesis of local equilibrium is satisfied. The main objective of the work is to asses the suitability of such simple model to investigate the time evolution of bed profile in a braided network. Theoretical findings are tested with the results of two long-term runs in a 23 m long and 1 m wide sand-bed flume, starting from an equilibrium configuration and varying the sediment supply. This analysis reveals that the bed morphology eventually reaches an equilibrium status and, consequently, the long-term variation of the bed elevation can be predicted with the simple diffusive scheme. Further investigations are needed to study the response of the braided network in the early stages of the experiments, when the morphology is clearly in a non-equilibrium state. In these conditions the complete hyperbolic model could serve as an useful tool to model the channel response to varying conditions.

A diffusive 1D model for the evolution of a braided network subject to varying sediment supply / Redolfi, Marco; Tubino, Marco. - STAMPA. - (2014), pp. 1153-1161. (Intervento presentato al convegno 7th International Conference on Fluvial Hydraulics, RIVER FLOW 2014 tenutosi a Lausanne nel 2014).

A diffusive 1D model for the evolution of a braided network subject to varying sediment supply

Redolfi, Marco;Tubino, Marco
2014-01-01

Abstract

The impact of human activity on the morphological evolution of braided rivers produces serious problems for the river management and consequently a wide range of questions to the research community. In this work we explore the response of a braided network to variations in the sediment supply which can be induced by river interventions like dam construction or sediment mining. We have focused in particular on the simple case of a confined braided network with constant discharge and well-sorted, cohesiveless bed material. It is well known that within the context of a one-dimensional formulation the governing hyperbolic system can be readily reduced to a simple diffusive scheme when the hypothesis of local equilibrium is satisfied. The main objective of the work is to asses the suitability of such simple model to investigate the time evolution of bed profile in a braided network. Theoretical findings are tested with the results of two long-term runs in a 23 m long and 1 m wide sand-bed flume, starting from an equilibrium configuration and varying the sediment supply. This analysis reveals that the bed morphology eventually reaches an equilibrium status and, consequently, the long-term variation of the bed elevation can be predicted with the simple diffusive scheme. Further investigations are needed to study the response of the braided network in the early stages of the experiments, when the morphology is clearly in a non-equilibrium state. In these conditions the complete hyperbolic model could serve as an useful tool to model the channel response to varying conditions.
2014
Proceedings of the International Conference on Fluvial Hydraulics, RIVER FLOW 2014
Lausanne, che
CRC Press/Balkema
9781138026742
Redolfi, Marco; Tubino, Marco
A diffusive 1D model for the evolution of a braided network subject to varying sediment supply / Redolfi, Marco; Tubino, Marco. - STAMPA. - (2014), pp. 1153-1161. (Intervento presentato al convegno 7th International Conference on Fluvial Hydraulics, RIVER FLOW 2014 tenutosi a Lausanne nel 2014).
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11572/147121
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 2
  • ???jsp.display-item.citation.isi??? ND
social impact