CE01 - Milieux et biodiversité : Terre fluide et solide

Detailing Urban Flood Impact – DEUFI

DEUFI project: Detailing Urban Flood Impact

Although urban floods were largely investigated, the flow exchanges between streets and buildings are poorly documented in the laboratory and in the field. DEUFI project fills this gap focusing on the hydraulic processes inside and outside one urban block and assessing how this knowledge can be useful to estimate the damages and the number of fatalities.

Main project issues

DEUFI project should end-up with improved urban flood simulation methods capable of (i) estimating the flow intrusion within built-up areas, (ii) evaluating the spatial distribution of human exposure and material damage and (iii) proposing best-practice recommendations, in relation with the citizen perception and behaviour during short duration high floods. <br />In order to determine the influence of the building openings on the flow pattern, the urban flood is considered at three scales: the facade (including one or several openings such as doors, gates...), the block (built-up area surrounded by streets and including one or several buildings) and the district (including several streets and a lot of blocks). Information about hazard at one of these scales enables to estimate the level of risk and to take decisions about flood risk management for individuals or groups of citizens. <br />At the façade scale, the calculation of the flow discharge through the openings is the first step to evaluate the influence of these exchanges. At the block scale, the difference between flood hazard (water depth and velocity, time of submersion) inside and outside the building is put forward particularly for damage assessment but the opening is also creating a disturbance in the flood hazard in the neighbouring streets, which may be important for safety evaluation. At the district scale, we investigate the flow propagation and its uncertainty taking into account the exchanges between streets and buildings (among other factors). Strategies for flood management should be elaborated from results at that scale.

DEUFI project is structured in three work packages combining hydraulics, damage estimation and citizen approaches: laboratory experiments (WP1), field cases (WP2) and hydrodynamic models (WP3). WP1 gathers three sets of laboratory experiments (plus 2 from our foreign partners) dealing with urban flow patterns at the facade, block and district scales respectively. WP2 focuses on two field cases in order to apply the developed methods on real configurations that differ by their geographical environment (origin of flooding, street slopes …). WP2 groups the development of tools at the field scale and the application of these tools on the two field cases in view of evaluating the relevancy for local stakeholders. WP3 develops hydrodynamic models that enable to pass from the laboratory to the field scale, validates them against WP1 results and compares their efficiency to produce results on the field cases useful for local stakeholders.
DEUFI project associates seven French partners dealing with hydraulics, economy, geography, sociology, hydrology, applied mathematics and computer sciences together with two foreign teams involved in related researches in their own countries.

Experiments at INSA laboratory show the strong effect of the obstacles present in the street on the exchange flow between the street and the building.
Experiments at INRAE laboratory show that the exchange flow depends also of the number and localizations of the openings in the building walls and of the flow pattern inside the building.
Steady flow experiments at ICUBE show that the flow distribution downstream a district is only slightly influenced by the upstream distribution.
In order to automatically identify openings in the facades of the buildings, deep learning techniques are promising and could be used also to identify obstacles in the streets.
Surveys near the population and the flood risk managers show that in Oullins the population has been reassured by the recent recalibration of the Yzeron River. Thus, the level of risk awareness is low for rare and major floods. The work will therefore focus on the building of fine-scale impact scenarii for 100Y return period to 500 Y return period floods, scenarii that will be useful for local risk managers. In the case of Nimes, concerns focus on human safety. The buildings in the Richelieu district are not suitable for the safety of people. Pre-diagnosis mortality data on human security have been consolidated and will be used to model human vulnerability in the Richelieu district.
A new algorithm was developed for exchanging flows inside Flood1D2D software.

A video of the flooding of a street and a building in the flume of the INSA laboratory is available at: youtu.be/-tvz3C3j7qM

The diffusion of DEUFI results will benefit of the close coordination with local population and authorities as well as the participation of a consultancy company accustomed to disseminating research results.

Mignot, E., Camusson, L., & Riviere, N. 2020. Measuring the flow intrusion towards building areas during urban floods: Impact of the obstacles located in the streets and on the facade. Journal of Hydrology, 583, 124607. DOI: 10.1016/j.jhydrol.2020.124607
Finaud-Guyot, P., Garambois, P.A., Dellinger, G., Lawniczak, F., François, P. 2020. Experimental characterization of various scale hydraulic signatures in a flooded branched street network. Urban Water Journal, 16 (9), pp.609-624. DOI: 10.1080/1573062X.2020.1713173
Mignot E., Camusson L. & Riviere N. 2020. Experimental analysis of urban flood intrusion into buildings. River Flow 2020 conference proceedings.
Mejia-Morales M.A., Proust S., Paquier, A. & Mignot E. 2020. Influence of a porous urban block on the urban flood flow pattern. River Flow 2020 conference proceedings.

Although urban floods were largely investigated, the flow exchanges between streets and buildings are not documented in the laboratory and seldom in the field. DEUFI project will fill this gap focusing on the hydraulic processes inside and outside one building and assessing how this knowledge can be useful to estimate and reduce damages and fatalities.
The influence of the building openings along the streets is local but can diffuse to the general pattern of the flow propagation. Three scales are investigated for hydrodynamics purposes: the facade (including one or several openings such as doors, gates...), the block (built-up area surrounded by streets and including one or several buildings) and the district (including several streets and a lot of blocks). Information provided at one of these scales permits to estimate the level of risk and to take decisions about flood risk management at the individual or collective scales.
At the façade scale, the calculation of the flow discharge through the openings is emphasized being the first step to evaluate the influence of these exchanges. At the block scale, the difference between flood hazard inside and outside the building is put forward particularly for damage assessment but the opening is also creating a disturbance in the flood hazard in the neighbouring streets, which may be important for safety evaluation. At the district scale, one investigates the flow propagation and its uncertainty because of the exchange between streets and buildings but also because of other factors; strategy for flood management should be elaborated from results at that scale.
DEUFI project is structured in three work packages combining hydraulics, damage estimation and citizen approaches: laboratory experiments (WP1), field cases (WP2) and hydrodynamic models (WP3). WP1 gathers three sets of laboratory experiments using existing facilities and dealing with urban flow patterns at the facade, block and district scales respectively. WP2 focuses on two field cases in order to apply the developed methods on real configurations that differ by the geographical environment (origin of flooding, slopes …). WP2 groups the development of tools (software, data base …) at the field scale and the application of these tools on the two field cases in view of evaluating the relevancy for local stakeholders. WP3 develops hydrodynamic models that permit to pass from the laboratory scale to the field scale, validates them against WP1 results and compares their efficiency to produce results on the field cases useful for local stakeholders.
DEUFI project will end-up with improved urban flood simulation methods capable of (i) estimating the flow intrusion within built-up areas, (ii) evaluating the spatial distribution of human exposure and material damage and (iii) proposing best-practice recommendations, in relation with the citizen perception and behaviour during short duration high floods.
In order to reach these objectives, DEUFI project associates seven French partners dealing with hydraulics, economy, geography, sociology, hydrology, applied mathematics and computer sciences together with two foreign teams involved in related researches in their own countries. The diffusion of DEUFI results will benefit of the close coordination with local population and authorities as well as the participation of a consultancy company accustomed to building and disseminating research results.

Project coordinator

Monsieur André Paquier (RiverLy)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

G-EAU Gestion de l'eau, acteurs et usages
ARTELIA ARTELIA EAU & ENVIRONNEMENT
KICT Korea Institute of Civil Engineering and Building Technology / Hydro Science and Engineering Research Institute
Cerema-EMF Cerema Direction Technique Eau Mer Fleuve
GRED GOUVERNANCE, RISQUE, ENVIRONNEMENT, DÉVELOPPEMENT. DYNAMIQUES SOCIÉTALES ET GESTION DES TERRITOIRES
ULiege Université de Liège / Hydraulics in Environmental and Civil Engineering (HECE)
LMFA LABORATOIRE DE MÉCANIQUE DES FLUIDES ET D'ACOUSTIQUE
RIVERLY RiverLy
ICube Laboratoire des sciences de l'Ingénieur, de l'Informatique et de l'Imagerie

Help of the ANR 628,993 euros
Beginning and duration of the scientific project: December 2018 - 48 Months

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