Frédéric Grelot

French National Institute for Agriculture, Food, and Environment (INRAE) | INRAE · Department of Waters

Flood damage assessment is crucial for evaluating flood management policies. In particular, properly assessing damage to the agricultural assets is important because they may have greater exposure and are complex economic systems. The modelling approaches used to assess flood damage are of several types and can be fed by damage data collected post-...

Estimating flood damage, although crucial for assessing flood risk and for designing mitigation policies, continues to face numerous challenges, notably the assessment of indirect damage. It is widely accepted that damage other than direct damage can account for a significant proportion of total damage. Yet due to scarcer data sources and lack of k...

Today, flood risk management practices incorporate non-structural measures that take into account the potential of ecosystems to prevent, regulate and reduce water-related hazards. However, the implementation of non-structural measures, such as floodplains and water retention areas, increases the exposure of rural and farming areas for better prote...

Flood damage assessment is crucial to address the challenges of climate and socioeconomic changes. Researchers and practitioners have developed several damage models to tackle local and regional situations. Particularly for direct damages to the residential sector, these models rely on numerous hypothesis (e.g. zero damage threshold) and parameters...

Estimating flood damage, although crucial for assessing flood risk and for designing mitigation policies, continues to face numerous challenges, notably the assessment of indirect damage. It is widely accepted that damage other than direct damage can account for a significant proportion of total damage. Yet due to more scarce data sources and lack...

Effective flood risk management requires a realistic estimation of flood losses. However, available flood damage estimates are still characterized by significant levels of uncertainty, questioning the capacity of flood damage models to depict real damages. With a joint effort of eight international research groups, the objective of this study was t...

Abstract. Effective flood risk management requires a realistic estimation of flood losses. However, available flood damage estimates are still characterised by significant levels of uncertainty, questioning the capacity of flood damage models to depict real damages. With a joint effort of eight international research groups, the objective of this s...

To limit the losses due to floods, public authorities can try to foster the adoption of private measures aimed at reducing the vulnerability of dwellings. However, the efficacy and cost-efficiency of such measures to reduce material losses are not well-known. In particular, the influence of building and flood characteristics on these variables has...

In coastal areas around the world, actors are responding to multiple global changes by implementing adaptation plans, often confined within a single-focal perspective with few explanations of targeted changes and cross-scale interactions. To better anticipate the raising coordination issues and the potential feedbacks generated by adaptation in the...

Floods can be managed at the collective and individual level. Knowing the interaction between measures taken at both scales can help design more efficient flood risk management policies. Here, we combine the data collected during a survey of 331 inhabitants of flood-prone areas in the South of France and spatial databases to empirically examine the...

To limit the losses due to floods, public authorities can try to foster the adoption of private measures aimed at reducing the vulnerability of the dwellings. However, the efficacy and cost-efficiency to reduce material losses of such measures are not well-known. In particular, a better understanding of the influence of buildings characteristics an...

La reconstruction, entendue comme l'ensemble des mesures pour rétablir un fonctionnement acceptable du territoire, est une notion de plus en plus traitée dans la littérature scientifique des risques. Elle peut faire l'objet, sans que cela soit systématique, de stratégies d'adaptation collectives et individuelles, planifiées et spontanées, aux objec...

RESUME. L’Observatoire Hommes-Milieux (OHM) Vallée du Rhône appréhende les dynamiques de l’hydrosystème et des sociétés riveraines sur l’ensemble du Rhône français. Depuis sa création en 2010, la mutualisation et la valorisation des données produites ont été structurées dans une Infrastructure de Données Spatio-temporelles (IDS), ce qui a renforcé...

RESUME. L’Observatoire Hommes-Milieux (OHM) Vallée du Rhône appréhende les dynamiques de l’hydrosystème et des sociétés riveraines sur l’ensemble du Rhône français. Depuis sa création en 2010, la mutualisation et la valorisation des données produites ont été structurées dans une Infrastructure de Données Spatio-temporelles (IDS), ce qui a renforcé...

Floods cause significant economic damage. In Europe, hydrological phenomena (floods and landslides) caused more than 140 billion euros of damage between 1980 and 2011. In France, floods have been responsible for around 30 billion euros of damage over the last 25 years. One resident in four and one job in three in France are affected by flood risk....

Floods cause significant economic damage. In Floods cause significant economic damage. In Europe, hydrological phenomena (floods and landslides) caused more than 140 billion euros of damage between 1980 and 2011. In France, floods have been responsible for around 30 billion euros of damage over the last 25 years. Economic assessment aims to objecti...

Le dispositif national de Programmes d’Actions de Prévention des Inondations (PAPI) intègre dans son cahier des charges la nécessité de réaliser des analyses coûts-bénéfices (ACB) pour les projets d’investissement les plus importants, regroupant les mesures structurelles qui modifient l’aléa (axes 6 et 7 des PAPI). L’ACB permet d'évaluer la pertine...

We demonstrate the use of sensitivity analysis to rank sources of uncertainty in models for economic appraisal of flood risk management policies, taking into account spatial scale issues. A methodology of multi-scale variance-based global sensitivity analysis is developed, and illustrated on the NOE model on the Orb River, France. The variability o...

L’expression « vivre avec » apparait de maniere recurrente aujourd’hui dans le domaine des inondations. Quelle politique fonde-t-elle ? Comment se traduit-elle dans l’action publique ? A partir du cas de la basse vallee de l’Orb (Herault, France) et plus particulierement du quartier du Faubourg a Beziers, cet article discute de la forme que peut pr...

After major floods occurred in 2003 on the Rhone River (France), the State and local authorities created a new institution at river level, in order to tackle flood issues at a supposedly more functional scale. Called Plan Rhone, this new partnership combined several policy sectors and several administrative levels, with the aim of developing the ri...

Cost-benefit analyses (CBA) of flood management plans usually require estimating expected annual flood damages on a study area and rely on a complex modelling chain, including hydrological, hydraulic and economic modelling, as well as geographic information system-based spatial analysis. As most model-based assessments, these CBA are fraught with u...

In Europe, economic evaluation of flood management projects is increasingly used to help decision making. At the same time, the management of flood risk is shifting towards new concepts such as giving more room to water by restoring floodplains. Agricultural areas are particularly targeted by projects following those concepts since they are frequen...

In Europe, economic evaluation of flood management projects is becoming a commonly used decision tool. At the same time, flood management policies shift towards new concepts such as giving more room to water by restoring floodplain and living with floods. Agricultural areas are particularly targeted by these policies since they are more frequently...

Variance-based global sensitivity analysis (GSA) is used to study how the variance of the output of a model can be apportioned to different sources of uncertainty in its inputs. GSA is an essential component of model building as it helps to identify model inputs that account for most of the model output variance. However, this approach is seldom ap...

This article describes an assessment of the contribution of provisioning services provided by the Ga-Mampa wetland (1 km) to the livelihoods of local stakeholders, including monetary values for some services. The study used a combination of data collection approaches including a questionnaire survey, focus group discussions, key informant interview...

In order to increase the reliability of flood damage assessment, we need to question the uncertainty associated with the whole flood risk modeling chain. Using a case study on the basin of the Orb River, France, we demonstrate how variance-based sensitivity analysis can be used to quantify uncertainty in flood damage maps at different spatial scale...

What amount of flood damages miss assessment methods by negelecting induced damages on activity?

Cette publication analyse le risque inondation à l'échelle régionale et plus précisément à l'échelle du bassin de la Vilaine.

La Bretagne a subi ces vingt dernières années plusieurs événements hydroclimatiques exceptionnels qui ont touché de nombreux secteurs urbanisés notamment dans les communes périphériques de Rennes et les centres urbains de l'axe de la Vilaine. Cette succession d'événements a déclenché une réflexion sur le risque inondation à l'échelle régionale et t...

Variance-based Sobol' global sensitivity analysis (GSA) was initially designed for the study of models with scalar inputs and outputs, while many models in the environmental field are spatially explicit. As a result, GSA is not a common practise in environmental modelling. In this paper we describe a detailed case study where GSA is performed on a...

In Europe, economic appraisals of flood management projects, generally Cost-Benefit Analysis, become a commonly used decision tool. At the same time, new flood management policies that may have strong impacts on farms, are promoted, i.e. floodplain restoration and vulnerability mitigation. Since damage must be estimated to estimate the benefits in...

The variance-based Sobol' approach is one of the few global sensitivity analysis methods that is suitable for complex models with spatially distributed inputs. Yet it needs a large number of model runs to compute sensitivity indices: in the case of models where some inputs are 2D Gaussian random fields, it is of great importance to generate a relat...

Les politiques publiques de gestion des inondations s'orientent vers la restauration des champs d'expansion de crue et de réduction de la vulnérabilité, qui auront un impact important sur les exploitations agricoles. L'évaluation des effets de ces politiques sur les exploitations agricoles n'est pas envisageable avec les méthodologies actuelles et...

In France, two new kinds of flood management policies are promoted: floodplain restoration and vulnerability mitigation. Few experience feedback exist on these policies but they may have strong impacts on farms. Flood management on Rhône River is highly illustrative of these policies and local authorities would like to appraise the efficiency of th...

This article analyzes the consequences for risk distribution of the French Flood Prevention Action Programme (PAPI). By redirecting floods from the most vulnerable to the least vulnerable areas, PAPIs expose farmers to greater flood risks. This has led local water management institutions to introduce compensation payments. The article outlines the...

Recent catastrophic flood events such as Elbe in 2002 or Rhône in 2003 have shown limits of flood management policies relying on dykes protection: worsening of flood impacts downstream, increased damage by dykes rupture. Those events, among others, contributes to radical changes on the philosophy of flood prevention, with the promotion of new orien...

En France, peu de travaux ont été consacrés à la caractérisation de la vulnérabilité des zones agricoles exposées aux inondations, encore moins à son utilisation dans le cadre d'une évaluation économique de politique de gestion des inondations. Nous proposons dans cet article un modèle conceptuel de la vulnérabilité agricole pouvant servir à une te...

La m�thode Inondabilit� a �t� d�velopp�e dans les ann�es 1990 par le Cemagref pour disposer d'un outil d'�valuation du risque d'inondation � l'�chelle du bassin versant et proposer un cadre de n�gociation sur la notion de risque acceptable. Elle repose sur l'id�e d'exprimer al�a (intensit� physique du ph�nom�ne naturel) et vuln�rabilit� (sensibilit...

L'analyse coût-bénéfice basée sur la simulation des dommages évités permet d'obtenir des indicateurs synthétiques sur l'exposition d'un territoire aux inondations (les dommages moyens annualisés), ainsi que l'intérêt ou non de mener une politique de prévention des inondations (les dommages évités moyens annualisés, la valeur actuelle nette). Ces in...

The size of the Ga-Mampa wetland (1 km2), in the Olifants River catchment in South Africa, was halved between 1996 and 2004. This jeopardizes the ecological integrity and influences the benefits people obtain from the wetland. This study therefore analysed the economic values of the provisioning services derived from the Ga-Mampa wetland and evalua...

Integrated Flood Management at catchment scale is the current paradigm. Dynamic Flood Retention is a relevant principle for its requirements, by mitigating floods wherever suitable opportunities exist on the catchment. It reduces the need for protection measures which impair river ecosystems, like levees and river training. This paper advocates the...

Cet article étudie la pertinence d'une analyse coût-bénéfice (ACB) basée sur la méthode des dommages évités pour évaluer des politiques de prévention des inondations. S'appuyant sur un cas d'étude dans la vallée de l'Orb (Hérault), il détaille les étapes de l'approche, notamment la modélisation des enjeux et le calcul des dommages moyens annuels. I...

Cet article analyse les conséquences socio-économiques des politiques de ralentissement dynamique, mises en place en France dans le cadre des PAPI, programmes d'action pour la prévention des inondations. Ces politiques visent à réduire le risque à l'échelle du bassin, par exemple en transférant les inondations des zones très vulnérables vers des zo...

The size of the Ga-Mampa wetland (1 km2), in the Olifants river catchment in South Africa, was halved between 1996 and 2004. This jeopardizes the ecological integrity and influences the benefits people obtain from the wetland. This study therefore analysed the economic values of the provisioning services derived from the Ga-Mampa wetland and evalua...

In many Mediterranean coastal areas, agriculture, drinking water supply, tourism and industry strongly depend on the available groundwater resources. As a result of the significant economic development during the last three decades along the coast, abstractions from coastal aquifers have increased tremendously, frequently leading to overexploitatio...

Dans l'exercice de mod�lisation pr�sent� nous avons fait trois hypoth�ses fondamentales : (1) la gestion pr�ventive des inondations est avant tout une question de gestion du territoire ; (2) les inondations concernent assur�ment des agents individuels (qui sont assimil�s � des investisseurs) mais (3) sont principalement g�r�es � un niveau collectif...

En France, au contraire de pays comme les États-Unis, la pratique de l'évaluation économique a priori des actions collectives de lutte contre les inondations est largement déficiente. Ce constat est inquiétant dans une perspective d'allocation optimale de ressources nécessairement limitées. Quand elle existe, cette évaluation n'intègre pas les préf...

En France, au contraire de pays comme les États-Unis, la pratique de l'évaluation économique a priori des actions collectives de lutte contre les inondations est largement déficiente. Ce constat est inquiétant dans une perspective d'allocation optimale de ressources nécessairement limitées. Quand elle existe, cette évaluation n'intègre pas les préf...

Various techniques for economic valuation of the "reduction of flood risk" non-market good are reviewed. The potentiality of the contingent valuation method is specially discussed, on the basis of two surveys conducted in France. The results highlight an acceptability of flood risk beyond a certain protection level.

Various techniques for economic valuation of the "reduction of flood risk " non-market good are reviewed. The potentiality of the contingent valuation method is specially discussed, on the basis of two surveys conducted in France. The results highlight an acceptability of flood risk beyond a certain protection level.

Malgré sa présence dans le Code de l'Environnement, le principe de participation du public n'est pas appliqué à la gestion préventive des inondations. Cet article propose, dans le cadre des décisions centralisées encore majoritaire en France, un outil qui doit permettre de pallier cette lacune. Cet outil repose sur une adaptation de la méthode d'év...

Les crues et les inondations ont un caractère aléatoire qui rend complexe la prise de décision et la communication au citoyen. La description probabiliste du fonctionnement d'un cours d'eau rend le discours difficile, y compris parfois par les spécialistes et engendre souvent des contresens. Or, les enjeux économiques et sociaux des inondations néc...

In general, in many countries, public decisions about flood management are essentially based on administrative and technical criteria. Scientific hydrological knowledge allows for a good description of flooding phenomena (intensity, frequency, extension of the flood...). The stakes' determination gives an estimation of priorities (physical interact...

Ce texte se propose de répondre à la question du titre : " Gestion préventive des inondations : quels outils économiques pour l'aide à la décision? ". Cette question n'est traitée que pour le cas français. Pour ce faire, nous commençons dans une première partie par analyser le " contexte décisionnel " de la gestion préventive des inondations. Nous...

Cost-Benefit Analysis (CBA) is widely promoted as a tool for discussing efficiency of flood management policies. It gives rise to a global indicator, the Net Present Value (NPV), which allows the discussion of allocating regional, national, or supra-national fundings to local projects. Concerning flood management policies, CBA relies on damages avo...

The variance-based Sobol' approach is one of the few global sensitivity analysis methods that is suitable for complex models with spatially distributed inputs. Yet it needs a large number of model runs to compute sensitivity indices: in the case of models where some inputs are 2D Gaussian random fields, it is of great importance to generate a relat...