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Flooding within the urban landscape: a hydrogeomorphologist’s perspective

Pascale Biron

• Damage caused by rivers following the passage of hurricane Irene in 2011 in the MRC Brome-Missisquoi

Flood management in Quebec: reactive ratherthan proactive approach

Photos: Simon Lajeunesse

Hydrogeomorphology: two key elements for the natural dynamics of rivers

http://www.mfwwc.org/floodplain.html

Spiral flow (helical)

Meanders migrate laterally

Rivers flood regularly

Bankfull level reachedeach 1.5 – 2 years

Photo: Copyright Louis Maher; Earth Science World Image Bank

http://guiers.siaga.pagesperso-orange.fr/Le-Guiers/Lit-Min-Maj.htm

+ riparian wetlands(integrity space)

hydrogeomorphologicalapproach: levels really reachedby floods (≠ statisticalapproach)

Ice-jam flood on the Matane River

Are part of the minimum space required for streams – essential within freedom space from a hydrological and ecological perspective

http://www.hendersondesign-build.com

Example of wetland restoration des milieux humides on the Calapooia River (Oregon)

Included within the flood space

Rivière Matane (aval)Rivière Yamaska Sud-Est (amont)

Rivière de la Roche

Rivière Yamaska Sud-EstBiron et al. (2014)

Riparianwetland

Urbanenvironment(Cowansville)

Upstream of Cowansville

Freedom space: Is it feasable?

Rivière Veyle (north of Lyon, France)Photo: Hervé Piégay

Freedom space in VermontVermont Agency of Natural Resources

Budget of 3 billion € in the Netherlands

Water qualityWildlife habitat

Cost due to flood damages

Recreational activities ($$)

Spirit of communities

Relationship between impervious cover and surface runoff (from FISRWG, 1998)

Ontario: the hurricane Hazel (1954) effect

Toronto received 210 mm of rain in 12 hours

81 lives lost, $25 million in 1954 dollars.

https://trca.ca/conservation/flood-risk-management/history/

Flood management in Ontario

http://conservationontario.ca/what-we-do/flood-management

Europe: the early 2000s flood effect

York (UK) November 2000

http://ec.europa.eu/environment/water/flood_risk/implem.htm

https://www.gov.uk/check-flood-risk https://flood-warning-information.service.gov.uk/long-term-flood-risk

Citizens must be informed…

France

https://www.ecologique-solidaire.gouv.fr/prevention-des-inondations

US

https://msc.fema.gov/portal

https://www.cehq.gouv.qc.ca/zones-inond/carte-esri/index.html

Quebec flood maps

Flood maps: pdf documents

End of the study zone…

Flood limits??

Rigaud, west of Montreal

End of the study zone…

Working upstream to mitigate floods downstream (Belford, UK)

• Frequent flooding• Steep slopes• Shallow soil• Soil compaction (intensive

agriculture)

Belford

Wilkinson et al. (2010)

Watershed: 5.7 km2

Wilkinson (2010)

Examples of runoff attenuation features (RAF) (Wilkinson et al., 2010)

Runoff Attenuation Feature (RAF) used in the Belford watershed (Wilkinson et al., 2010)

Photos of RAF at full capacity (a) and before 6 September 2008 flood (b), with photos showing flow diversion during (c) and after (d) this event (Wilkinson et al., 2010)

96 mm of rain in 36 hours

http://wwtonline.edie.net/news/researchers-back-natural-flood-engineering#.U4zFjCgvDKA

Modelling

Wilkinson et al. 2010)

Modelling

Wilkinson et al. 2010)

Modelling

Wilkinson et al. 2010)

Modelling

Wilkinson et al. 2010)

Modelling

Wilkinson et al. 2010)

Flood in Morpeth –6 September 2008 event(no flood in Belford)

Coaticook: 2 major floods in the summer 2015

10 June 2015

http://www.lapresse.ca/la-tribune/estrie-et-regions/201508/03/01-4890134-une-tempete-de-grele-cause-des-dommages-a-coaticook.php

3 August 2015

Bassin versant du ruisseau Pratt:Similitudes avec ruisseau Belford(22 km2)

Waterville

Compton

Coaticook

Dixville

Vermont (É-U)

CoaticookCentre-ville

Fond de carte: Orthophotos 2013, MRC de Coaticook

Ruisseau Pratt (Coaticook):

Ruisseau Pratt in Coaticook(looking downstream), rebuilt as is after the summer 2015 floods

18 août 2015

Ruisseau Pratt in Coaticook(looking upstream)

18 août 2015

Ruisseau Pratt upstreamof Coaticook

18 août 2015

Freedom space problem?

septembre1924

avril 1982

avril 1994

août 2004

avril 2011

janvier 2014 juin

2015

juin 1943

février 1998

1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 2016

février 2016

août 2011

Début données CEHQ Waterville

Crue hivernale

Crue printanière

Crue estivale

19431998avril 2011201410 juin 2015 = 76 mm de pluie

10 juin 2015

Recoupement entre 1881 et 1945Présence des méandres abandonnés

jusqu’en 1945

Rivière Coaticook

1945

Rivière Coaticook

1966

Rivière Coaticook

1979

Rivière Coaticook

1993

Rivière Coaticook

2007

Rivière Coaticook

2013

Rivière Coaticook

1945 - 2013

Rivière Coaticook

1945 - 2013

0

1

2

3

4

5

6

1940 1950 1960 1970 1980 1990 2000 2010

Supe

rficie

de

mili

eux

natu

rels

(en

hect

ares

)4.7 hectares

Flood management: from grey to green infrastructure

http://www.vacd.org/~winooski/VtRainGardenManual.pdf

2015

Sponge city in China

http://www.initiatives.com.hk/sponge-city.html

Objective: better absorb rain to improve the environment.By 2020, 20 percent of cities should have modern sewer systems and infrastructure that allows for efficient absorption of water, with the number rising to 80 percent by 2030

http://www.phillywatersheds.org/what_were_doing/documents_and_data/cso_long_term_control_plan

PDEP (2006) http://www.elibrary.dep.state.pa.us/dsweb/Get/Document-48477/07_Chapter_6.pdf

Parking lot of Mountain Equipment, Longueuil Vinci Consultants, http://www.vinciconsultants.com/realisations.php

Seoul

Seoul https://www.quora.com/Is-it-possible-to-purify-the-Cooum-River-in-Chennai-and-bring-it-back-as-it-was-in-the-1940s

http://www.100resilientcities.org/you-cant-stop-urban-flooding/

“Nature has ways of dealing with water. We sometimes get in the way of those processes… We just need to move the water through our community as quickly as possible with as little damage as possible.”

Conclusions• Integrating hydrogemorphological concepts is

essential in flood management.• Quebec is lagging behind in the use of green

strategies to increase infiltration in urban zones (e.g. porous pavements, green roofs, naturalwetlands).

• Absolutely key to inform citizens about the flood risk so that they can adapt a more flood-resilientapproach (e.g. European flood directive)

• Flood mitigation: for each 1$ invested, 5$ saved

Remerciements

• Thomas Buffin-Bélanger, Simon Massé (UQAR)• Guénolé Choné (Concordia) • Marie Larocque (UQAM) • Simon Lajeunesse (MRC Brome Missisquoi)

http://www.eaurmc.fr/espace-dinformation