Sediment transport and morphodynamics of two dynamic and highly modified rivers: valley management issues and keys for river stakeholders

(1)

HAL Id: hal-01285863

https://hal.archives-ouvertes.fr/hal-01285863

Submitted on 9 Mar 2016

HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci- entific research documents, whether they are pub- lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers.

L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Sediment transport and morphodynamics of two dynamic and highly modified rivers: valley management

issues and keys for river stakeholders

Margot Chapuis, Simon Dufour, Bruce Macvicar, André Roy, Bernard Couvert

To cite this version:

Margot Chapuis, Simon Dufour, Bruce Macvicar, André Roy, Bernard Couvert. Sediment transport and morphodynamics of two dynamic and highly modified rivers: valley management issues and keys for river stakeholders. 8th International Conference on Geomorphology, Aug 2013, Paris, France.

2013. �hal-01285863�

(2)

Région PACA

margot.chapuis@gmail.com

River hydrology and morphodynamics are significantly modified by human activities. In many watersheds, this has led to a flashier hydrological regime and an increase of flooding risk.

In addition, a river system can be highly instable at different spatial and temporal scales. When this instability conflicts with human use, sediment fluxes and morphody- namics issues become a key factor for river management. However, sediment mobility is frequently not considered by river managers.

We have studied two river systems, the Durance River (France) and Wilket Creek (Canada). Even if the spatial scales of these systems are significantly different, it is inter- esting to notice that management issues converge. More importantly, it appears that long-term management issues can only be solved by an integrative approach that con- siders sediment transport for the whole system.

The objective of this poster is to present a methodology to characterize gravel-bed river mobility in highly modified systems in order to support decision making for river stakeholders.

1. Problem statement and objective

1. Problem statement and objective 2. Study sites2. Study sites

Wilket Creek

Toronto, Canada

Sinuous gravel bed, local bedrock control 15 km²

15 m 0.9%

39 mm

Impervious watershed, dams, competition for valley occupation

Flash floods Durance River

Southern Alps, France Wandering gravel bed 14,000 km²

300 m 0.3%

44 mm

Dams, competition for valley occupation

Flash floods or long events System

Location

Description

Drainage area Width

Slope

D₅₀ ^{(>8 mm)} Main human features

Hydrology

3. Proposed approach and result examples 3. Proposed approach and result examples

(5) and (6).

River processes proposals and keys for river management

decisions.

P

P P

P

Avignon

Sisteron

Manosque Durance River

L'Asse

Le Verdon Rhône River

La Bléone

± ⁰ ¹⁰ ^{20 km}

Theoretical zone of direct influence of tributaries Zone of sediments reworking

Dam City Weir River

P

Serre- Ponçon L’Escale

Cadarache

Current longitudinal transfer processes of sedi- ments in the Durance River, if the management pro-

cedures of dams remain the same as today.

(5)

In Wilket Creek the information collected will be used to ensure the overall stability of the stream

while maximizing ecosystem services, particu- larly in restored channel sections.

(6)

Elevation (m.a.s.l.)

Distance to left bank (m)

35 30

25 20

15 10

5 0

114 115 116

111 112 113

XS 19

2013/02/01 2013/07/18

35 30

25 20

15 10

5 0

114 119

115 116 117 118

2013/02/01 2013/07/18 XS 6

Topographic surveys of cross-sections in the restored reach. Two significant floods occurred

between the two profiles.

(4)

Durance River Wilket Creek

Distance to the confluence (km)

6 4 2 0

130

110

90

Slope: 0.5%

Upstream dam Downstream dam 150

Longitudinal profile of Wilket Creek (2013) and definition of homogeneous reaches.

5 3 1

XS 6 XS 19

Restored reach

(2)

Slope: 1.2%

(3) and (4).

Stock renewal and sediment reworking in the channel.

River processes characterization

Sediment stocks and fluxes:

availability, timing of transit and renewal River

characterization Bed material

characterization

Hydrology

?

(1) and (2).

Definition of homogeneous

reaches according to sediment transport discontinuities or

slope breaks.

River physical characterization

River

characterization

Hydrology

Management guidelines

Definition of guidelines of ‘acceptable’

vs. ‘non-acceptable’ adjustments

River

characterization

Hydrology

? ?

?

Definition of relevant ‘management scales’

Longitudinal evolution of erosion rates per homo- geneous reach during the 1993-1998 and the 1998-2008 periods (Durance River) and redefini-

tion of homogeneous reaches according to sedi- ment dynamics.

(3) Stock renewal Sediment reworking

River kilometer (km)

Eroded surface (x 1,000 m²)

350

100

0 200

1993-1998 1998-2008

300 250

150

50

151.9 171.9 179.3 182.6 200.1 211.4 223.6 225.9 228.2 235.0 249.9 276.2 286.8 289.2

Asse

BléoneL'Escale Dam Cadarache Dam Pertuis pools Mallemort Dam Bonpas Dam Avignon pools

weir 6 bis weir CNRweir 66Bonpas Dam

weir 106

weir A Mallemort Dam

Cadarache Dam

L'Escale Dam AsseBléone

River kilometer (km)

Longitudinal profile of the Durance River (2008) and definition of homogeneous reaches.

0 100 200 300 400

150 200 250 300

(1)

The improved knowledge of river morphodynamics then enables us to give relevant management keys for river stakeholders.

The proposed methodology aims at giving insights of sediment transport processes and channel dynamics at different time and spatial scales. Management indexes or charts are to be developed according to specific river management long-term objec- tives and decision making is to be locally adapted.

4. Perspectives

4. Perspectives 5. References5. References

- Chapuis M. (2012). Mobilité des sédiments fluviaux grossiers dans les systèmes fortement anthropisés: éléments pour la gestion de la basse vallée de la Durance. PhD dissertation, Université Aix-Marseille 1, France, 252 p.

- Chapuis M. & Collomb D. (2012). La cicatrisation des rivières méditerranéennes françaises après les grandes perturba- tions de la deuxième moitié du XXe siècle: réponses des systèmes fluviaux et stratégies de gestion. Exemples de la Du- rance, du Var, de la Cèze. Revue Méditerranée, vol. 118, pp. 65-74.

- MacVicar B. J., V. Bevan & M. Chapuis (in prep.). Morphological response to urbanization and restoration of Wilket Creek: Canada´s first suburban creek. Canadian Water Resources Journal.

SEDIMENT TRANSPORT AND MORPHODYNAMICS OF TWO DYNAMIC AND HIGHLY MODIFIED RIVERS:

VALLEY MANAGEMENT ISSUES AND KEYS FOR RIVER STAKEHOLDERS

Margot Chapuis ^1,2, Simon Dufour ³, Bruce MacVicar ¹, André Roy ², Bernard Couvert ⁴

1 Civil & Environmental Engineering Faculty, University of Waterloo, Canada

2 Environment Faculty, University of Waterloo, Canada

3 COSTEL, University of Rennes 2, France

4 Artelia Ville & Transport, Marseille, France

Ontario Quebec

Ottawa

Toronto

New York Washington D.C.

Canada

United States

Wilket Creek (Toronto, Ontario, Canada)

Wilket Creek

Durance River (Southern Alps, France)

Paris

Lyon Marseille

France

Durance River