Development context
Cost-Benefit Analysis in the PAPI procedure
Since 2002, a procedure has been implemented in France to obtain funding from the State for flood management projects designed at local levels (Direction Générale de la Prévention des Risques 2017b). This procedure is embedded in programmes called “PAPIs” (for Programmes d’Actions de Prévention des Inondations), developed by local collectivities in charge of flood management at catchment level. The French State requires that PAPIs address several aspects of flood management, following the direction given by the European Union Flood Directive (UE 2007). Since 2011, it has also required that actions implying costly investments (mainly those that involve building large infrastructures, such as dykes or dams) be analysed through a Cost-Benefit Analysis (CBA). 1 PAPIs that comply with the specification given by the French State (Direction Générale de la Prévention des Risques 2017a) are judged by a commission called CMI (for Commission Mixte Inondation), which decides whether each PAPI shall be funded, modified or rejected.
The CBA was only introduced in the specification in 2011 (Direction Générale de la Prévention des Risques 2011). Before 2011, it was not mandatory to conduct a CBA of costly investments. In fact, Ledoux, Grelot, and Reliant (2003) brought to light the fact that the French practice of CBA applied to flood management projects was late compared to other countries, such as the United Kingdom (Penning-Rowsell et al. 2003) or the United States of America (USWRC 1983). Following a seminar held in 2007, which strengthened this observation, the French State created in 2008 a working group called the GT AMC (for Groupe de Travail sur l’Analyse Multi-Critère) composed of representatives from several entities: two departments of the French Ministry in charge of Environment (the DGPR (Direction Générale pour la Prévention des Risques) and the CGDD (Commissariat Général au Développement Durable)), and five external entities, which are the main reinsurance company in France (the CCR for Caisse Centrale de Réassurance), the CEPRI (Centre Européen de Prévention du Risque d’Inondation), the Cerema (Centre d’Etudes et d’expertise sur les Risques, l’Environnement, la Mobilité et l’Aménagement), Irstea (Institut de Recherche en Sciences et Techniques pour l’Environnement et l’Agriculture), and the MRN (Mission Risques Naturels). The aim of this working group was to develop an unique CBA methodology to be used by local collectivities to analyse their flood management projects.
The GT AMC first identified the aspects that needed improvement to provide a robust CBA methodology, and prioritized them in order to propose an acceptable first version of the CBA methodology. The GT AMC highlighted that one of the main aspects to be improved was the modelling of expected damage (Bournot 2008). As a first step, the GT AMC proposed to use an adaptation of “old” damage functions to conduct CBAs. These damage functions were developed during the 1980’s and 1990’s for some specific studies in France (Soubieux-Bournot et al. 2010). This led to the introduction of a mandatory CBA methodology in the PAPI specification in 2011, based on these “old” damage functions (Direction Générale de la Prévention des Risques 2011). Then, the GT AMC proposed to develop new damage functions, that should all fulfil the following specifications:
- transparency of the methodology used to develop them;
- consistency with the spatial databases that are available for the French territory;
- possibility to be easily updated with new data;
- possibility to be easily transferred to other contexts.
Development of flood damage functions to built assets
floodam.building is the result of several works within the GT AMC.
First, Irstea developed flood damage functions for the agricultural sector (Agenais et al. 2013). These flood damage functions relate to crops and must be applied at plot level. They were produced based on a formalization of expert knowledge that has been implemented as a computer tool called floodam.building, which is now called floodam.agri.
Secondly, the CEPRI started to work on flood damage functions for buildings dedicated to dwellings (CEPRI 2014). For this purpose, they used an approach comparable to the one used by the FHRC (Penning-Rowsell et al. 2005) and compatible with the one used by Irstea for flood damage functions for the agricultural sector. This approach is based on the decomposition of the building into components, for which elementary damage functions were established based on expert knowledge. To do an inventory of all the components that are present in buildings, the CEPRI used models of real buildings. Nevertheless, the process developed by the CEPRI to do the inventory of the components of a given building was not straightforward and quite time consuming. Thus, it soon appeared very difficult to improve flood damage functions to dwellings by using new representative buildings. In order to partly automate the damage functions development process, Irstea started in 2013 to develop a version of floodam.building for built assets.
Besides, the Cerema and Irstea started in 2012 to work on the development of flood damage functions for buildings dedicated to economic activities. For this purpose, the same approach based on expert knowledge and the breakdown of buildings into components was used.
It soon appeared that floodam.building could be used for any type of building, independently of its destination.
References
Footnotes
Since 2014, it has also been mandatory to provide other indicators to assess some projects, such as the expected number of inhabitants they protect by year (Magnier, Christin, and Peinturier 2014).↩︎