Vincent Dauphin: Evaluation de la vulnérabilité des bâtiments d’habitation individuelle à Delémont ; vers une nouvelle approche de la gestion du risque d’inondation.

Vincent Dauphin
Co-supervisors: Prof. Michel Jayboyedoff, Marc Choffet

The vulnerability, when it’s not defined quantitatively, tally with a rate of damage. However, this definition is not commonly accepted, which is certainly harmful to the consideration of its fair value. In a context of risk management bound to flooding hazard, consideration of the vulnerability may bring different concrete solutions, as the increasing number of publication can prove it. However, it has difficulties to impose itself as an applicable concept to reduce the risk at an acceptable level.

The existing literature also leaves a part of vulnerability to the little investigated floods, it is the quantitative approach. The possibility to use a tool recently developed to quantify the amount of damages potentially reached by a building of individual house, according to the height of water reached in the building, to explore this leaved part. The obtained result is under the shape of a curve of amount of damages and height of water describing and quantifying in a precise manner the constructions materials, caoatings and equipments in the building. The tool attribute a damage capacity to each elements described and its replacement value. However this data capture is relatively tedious if a high number of building must be analysed. Thereby the principal idea of this achieved work is to propose a typology of the built reflecting as a satisfied manner the reaction in front of floods for all kinds of buildings.

Once the typology established for each building on the zone of study – the maximal extension zone of a flood of Sorne, on the municipality of Delémont (Jura, Switzerland) – which is confronted to different buildings analysed in details. Finally quick damages on average, depending on the type of buildings, have been obtained to be spread to the totality of a portfolio composed of a high number of individual residential buildings in the zone of study.

However the vulnerability is bounded to the chance of a risk study. An analysis work of chance of the zone of study trying to define the heights of water that can reach the buildings is presented for the study zone. The second step of the practical approach aims the validation of the typology and the quantification of the vulnerability of the objects that can be find in the portfolio. Once the chance and the vulnerability are quantified, it is possible to quantify the risk, integrating the total potential loss into the approach (issued of the insurance database.)

All the concepts bounded to the management of the evaluation of the risk of flood is presented in the dedicated theoretical part. In the practical part it quickly has needed to face a major problem, the incompatibility between insurances data of the buildings and the georeferenced data of the GIS. Indeed the insurances data are organised around the address to define the building with which they are attached, while the SIG data use either the geographical coordinates, or the specific identifiers. The tedious work of compatibility between the two types of data was made manually.

In the end, the approach that is proposed – although exploratory –l allows to quantify the flood risk by each building of the portfolio by the quantification of the three elements of the equation risk : the vulnerability, the hazard and the total potential loss.