Comparison of a systemic modelling of farm vulnerability and classical methods to appraise flood damage on agricultural activities

International audienceIn 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 a CBA, flood damage estimation on agricultural areas becomes an issue to tackle. In this paper, firstly, a review of existing methods to appraise flood damage on agricultural areas shows the gap between qualitative approaches that underline the complexity of flood damage on farm and the simplification made in flood damage appraisal methods. It confirms that the majority only take into account crop loss, simplification that may be irrelevant to appraise new policies. Moreover, modelling assumptions are often implicit and hardly questionable. Secondly, EVA model which has been designed to estimate and monetize damage categories, that were not taken into account before, is presented and assumptions modelling have been described as explicitly as possible. Third, a test bench of EVA model on a farm type is proposed to simulate damage distribution and when possible, to compare the results with existing methods. More than the figures, the interesting part of our work is to point and try to explain differences. Finally, the outlooks concerning the use of the model at a larger scale are discussed. The main contribution is to open the black boxes that are usually used to appraise flood damage in order to make modelling assumptions more explicit and questionable by experts and decision-makers

De la vulnérabilité de la parcelle à celle de l'exploitation agricole : un changement d'échelle nécessaire pour l'évaluation économique des projets de gestion des inondations

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 telle évaluation, lorsque les politiques visent à une modification de l'événement physique à l'origine de l'inondation ou à une modification de la vulnérabilité des enjeux exposés à cet événement. / Flood management policies promoted by French government impact agriculture land in two ways. Firstly, they may be designated as potential areas for flood expansion. Secondly, since the 2003 law, local authorities have the right to flood these areas more than those which have been deemed to be more vulnerable (urban areas). Meanwhile, policy-driven appraisals of flood management projects are becoming commonplace in France. This highlights the need to better understand agricultural vulnerability and to develop methods for quantifying it. To introduce our approach, we first present the research conducted by Plan Loire which marks a shift away from existing practices of agriculture vulnerability assessment by considering vulnerability at the farm scale rather than at the plot scale. Based on ex-post flood damage assessment and the results of stakeholders questionnaires in the agricultural sector, forty seven determinants of farm vulnerability to flooding were identified and classified. These determinants were used to draft a guide for farmers. This guide aims to highlight the impacts their farm activities could face in case of flooding and to identify measures to mitigate their vulnerability. At the present, this guide is used along the Rhone River and will be probably used along the Loire River in the future. The current application of these guides to mitigate vulnerability of farms revealed the need for further research which is partly presented here. By focusing on the farming system, we aimed at providing a framework to economically assess agricultural vulnerability to flooding. Firstly, we identified flood effects at the farming system scale including possible interactions with the territorial scale, in order to propose a conceptual model which provides a framework for economic assessment. Finally, we discuss the implications for projects economic appraisal. The provided framework for agricultural vulnerability assessment would enable a selection of most efficient measures to mitigate farm vulnerability using a ratio depending on the agricultural context. It would also help to prioritize projects to reduce vulnerability by economic appraisal at a wider spatial scale such as water basin

Review Article: economic evaluation of flood damage to agriculture - review and analysis of existing methods

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 frequently located in floodplain areas and since the potential damage to such areas is expected to be lower than to cities or industries for example. Additional or avoided damage to agriculture may have a major influence on decisions concerning these projects and the economic evaluation of flood damage to agriculture is thus an issue that needs to be tackled. The question of flood damage to agriculture can be addressed in different ways. This paper reviews and analyzes existing studies which have developed or used damage functions for agriculture in the framework of an economic appraisal of flood management projects. A conceptual framework of damage categories is proposed for the agricultural sector. The damage categories were used to structure the review. Then, a total of 42 studies are described, with a detailed review of 26 of them, based on the following criteria: types of damage considered, the influential flood parameters chosen, and monetized damage indicators used. The main recommendations resulting from this review are that even if existing methods have already focused on damage to crops, still some improvement is needed for crop damage functions. There is also a need to develop damage functions for other agricultural damage categories, including farm buildings and their contents. Finally, to cover all possible agricultural damage, and in particular loss of activity, a farm scale approach needs to be used

Review Article: "Flood damage assessment on agricultural areas: review and analysis of existing methods"

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 located in floodplain areas and are considered less vulnerable than other assets such as cities or industries. Since additional or avoided damage on agriculture may have a high influence on the efficiency of these policies, flood damage assessment on agricultural areas becomes an issue to tackle. This paper reviews existing studies addressing the question of flood damage on agriculture. Based on 41 studies, which can be qualitative or quantitative approaches, we propose a conceptual framework to analyze evaluation methods. Then, 26 studies which propose a method to evaluate agricultural damage are analyzed according to the following criterias: types of damage considered, influencing flood parameters chosen and monetized damage indicators used. The main findings of this review are that existing methods focus mainly on crop damage and do not allow correct evaluation of new flood management policies. Finally, future research challenges and recommendations for practitioners are highlighted

Modelling farm vulnerability to flooding: towards the appraisal of vulnerability mitigation policies

International audienceIn 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 these policies with an economic tool (Cost-Benefit Analysis) to help decision making. But the current methods of flood damage modelling do not make the appraisal of these policies possible; mainly because they do not take into account the organizational and temporal dimensions of damage formation and propagation at farm scale. After a presentation of the Rhône River context and policies, we review existing methods of flood damage modelling for agriculture and show the interest to focus on the farm scale instead of land plot scale. Based upon the theoretical frameworks for systemic approach, we detail the construction of our conceptual model of farm vulnerability before presenting a case study that shows how the model can be implemented to compute flood damage at farm scale. Finally, the outlooks concerning the use of the model to appraise vulnerability mitigation policies and its application at regional scale are developed

Caractérisation des stratégies de gestion pour la modélisation de la vulnérabilité des exploitations agricoles aux inondations : Lier les dimensions spatiale, organisationnelle et temporelle d'un système complexe

National audienceLes 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 le retour d'expérience quasiment inexistant. Il était donc nécessaire de développer un modèle de simulation des dommages directs et induits en prenant en compte la dimension systémique de l'exploitation agricole. Pour cela, nous proposons un modèle conceptuel de la vulnérabilité à l'échelle de l'exploitation agricole et montrons comment il nous a permis de mettre en évidence l'importance des stratégies de gestion post-inondation pour la modélisation des dommages. Nous présentons ensuite les résultats des enquêtes réalisées sur les exploitations arboricoles de la zone aval du Rhône pour la caractérisation de ces stratégies. Enfin, nous montrons comment nous avons intégré dans le modèle de simulation des dommages, les données recueillies par enquêtes. Les premiers résultats de simulation des dommages confirment l'importance de prendre en compte les effets induits de l'inondation sur le système " exploitation agricole ". En perspective, l'utilisation du modèle de simulation des dommages dans le cadre d'une évaluation économique des politiques de réduction de la vulnérabilité des exploitations agricoles sur la zone aval du Rhône est discutée

Characterization and economic evaluation of farm vulnerability to flooding

L'échec des politiques structurelles de gestion des inondations à réduire les dommages a orienté les décideurs publics vers la restauration de zones de rétention et la réduction de la vulnérabilité. L'évaluation économique de ces politiques requiert une évaluation fine des dommages agricoles car ils contribuent fortement à déterminer leur efficacité. Or, les méthodes existantes n'intègrent que les pertes de récolte. Considérant que la vulnérabilité des exploitations agricoles dépend de la sensibilité et de la capacité à se remettre en route, entraînant respectivement des dommages directs et induits sur l'activité, nous proposons un modèle conceptuel de vulnérabilité permettant l'évaluation de l'ensemble de ces dommages. Trois profils d'exploitants sont définis selon la possibilité de mobiliser des ressources externes (main d'œuvre et matériel) pour la remise en route. Le profil Interne ne dispose d'aucune ressource externe contrairement aux profils Prestation et Solidarité. Après implémentation, le modèle a permis d'évaluer les dommages de trois exploitations types sur le Rhône aval avec une valorisation financière puis économique. Les dommages supportés par les exploitants de profil Interne sont plus élevés que ceux des deux autres profils. Les dommages évités par la mise en place de mesures de réduction de la vulnérabilité sur ces trois exploitations sont ensuite évalués. Nous montrons que les mesures sont plus efficaces et peuvent être mises en œuvre avec un ratio bénéfice-coût supérieur à un, pour les exploitations fréquemment inondées. Elles sont également plus efficaces pour les profils Interne, la mise en œuvre de la solidarité se dégageant comme une mesure intéressante pour toutes les exploitations.The failure of structural flood control to mitigate economic losses has lead to a shift towards new policies: floodplain restoration and vulnerability reduction. The economic appraisal of these policies requires an in-depth evaluation of agricultural damage as they are key indicators to determine the efficiency of these policies. However, existing methods only consider harvest loss. We consider that farm vulnerability depends on sensitivity and ability to recover leading respectively to direct damage and induced damage on activity. Based on this, we propose a vulnerability model which allows evaluating the whole of these damages. Three farmer's profiles are defined depending on their ability to access to external resources (workforce and equipment) to recover after flooding. The “Internal” profile has no external resource as opposed to the “Service” and “Solidarity” profiles which can respectively rely on service providing and solidarity. The model is applied to evaluate damages on three farm types of the Rhône River downstream area with a financial and economic valuation. This reveals that damages endured by the profile “Internal” are much higher than those of the two other profiles. Then, avoided damages resulting from the implementation of mitigation measures to reduce vulnerability are evaluated. We prove that these measures are more efficient and can be implemented with Benefit-Cost ratio higher than one, only for the frequently flooded farms. Mitigation measures are also more efficient for the profile “Internal”. To organize solidarity between farms emerges as one of the most interesting measure for all farm types

Caractérisation et évaluation économique de la vulnérabilité des exploitations agricoles aux inondations

The failure of structural flood control to mitigate economic losses has lead to a shift towards new policies: floodplain restoration and vulnerability reduction. The economic appraisal of these policies requires an in-depth evaluation of agricultural damage as they are key indicators to determine the efficiency of these policies. However, existing methods only consider harvest loss. We consider that farm vulnerability depends on sensitivity and ability to recover leading respectively to direct damage and induced damage on activity. Based on this, we propose a vulnerability model which allows evaluating the whole of these damages. Three farmer's profiles are defined depending on their ability to access to external resources (workforce and equipment) to recover after flooding. The "Internal" profile has no external resource as opposed to the "Service" and "Solidarity" profiles which can respectively rely on service providing and solidarity. The model is applied to evaluate damages on three farm types of the Rhône River downstream area with a financial and economic valuation. This reveals that damages endured by the profile "Internal" are much higher than those of the two other profiles. Then, avoided damages resulting from the implementation of mitigation measures to reduce vulnerability are evaluated. We prove that these measures are more efficient and can be implemented with Benefit-Cost ratio higher than one, only for the frequently flooded farms. Mitigation measures are also more efficient for the profile "Internal". To organize solidarity between farms emerges as one of the most interesting measure for all farm types.L'échec des politiques structurelles de gestion des inondations à réduire les dommages a orienté les décideurs publics vers la restauration de zones de rétention et la réduction de la vulnérabilité. L'évaluation économique de ces politiques requiert une évaluation fine des dommages agricoles car ils contribuent fortement à déterminer leur efficacité. Or, les méthodes existantes n'intègrent que les pertes de récolte. Considérant que la vulnérabilité des exploitations agricoles dépend de la sensibilité et de la capacité à se remettre en route, entraînant respectivement des dommages directs et induits sur l'activité, nous proposons un modèle conceptuel de vulnérabilité permettant l'évaluation de l'ensemble de ces dommages. Trois profils d'exploitants sont définis selon la possibilité de mobiliser des ressources externes (main d'œuvre et matériel) pour la remise en route. Le profil Interne ne dispose d'aucune ressource externe contrairement aux profils Prestation et Solidarité. Après implémentation, le modèle a permis d'évaluer les dommages de trois exploitations types sur le Rhône aval avec une valorisation financière puis économique. Les dommages supportés par les exploitants de profil Interne sont plus élevés que ceux des deux autres profils. Les dommages évités par la mise en place de mesures de réduction de la vulnérabilité sur ces trois exploitations sont ensuite évalués. Nous montrons que les mesures sont plus efficaces et peuvent être mises en œuvre avec un ratio bénéfice-coût supérieur à un, pour les exploitations fréquemment inondées. Elles sont également plus efficaces pour les profils Interne, la mise en œuvre de la solidarité se dégageant comme une mesure intéressante pour toutes les exploitations

Avis d'expertise sur l'analyse coût-bénéfice du PAPI de la Baie de l'Aiguillon : étude hydraulique complémentaire à l'échelle de la Baie de l'Aiguillon et de l'estuaire de la Sèvre

Cet avis porte sur la méthodologie de la mise en oeuvre de l'analyse coût-bénéfice du PAPI Baie de l'Aiguillon