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

Des outils en appui aux gestionnaires des inondations : méthodes d'évaluation économiques et implication des habitants. Application à la gestion des inondations sur la basse vallée de l'Orb

National audienceSession 7 Outils: re-questionner l'évaluation. Ce document rassemble trois articles: 1. Des outils en appui aux gestionnaires des inondations : méthodes d'évaluation économiques et moyens d'implication des habitants 2. Comment évaluer les effets de la modélisation participative dans l'émergence d'une gouvernance territoriale ? 3. Démarches participatives et asymétries de pouvoir : éliciter et interroger les positionnement

The economic and livelihood value of provisioning services of the Ga-Mampa wetland, South Africa

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 evaluated their contribution to the livelihoods of local stakeholders. Using a direct market valuation technique and based on a mix of data collection approaches that include questionnaire survey, focus group discussions, key informant interviews, field observation and measurements and collection of market prices, we estimated the economic value of the main provisioning services provided by the wetland (collection of edible plants, crop production, livestock grazing, fishing, hunting, fuel-wood, reeds and sedge collection). The results show that the contribution of the wetland to the livelihoods of local community, estimated at an annual net financial value of $211 per household, far exceeds its annual cash income of$35 per household and is about half of the average monthly cash income from all income sources. Crop production contributes the highest gross and net financial value, whereas sedge collection yields the highest cash income. Most of the materials harvested from the wetland are used for household subsistence and are rarely sold. In addition to their economic and livelihood value, the wetland services are also essential to sustain the social and cultural responsibilities in gift giving to neighbours and relatives. The study concludes that the local people are highly dependent on the wetland ecosystem services in many ways but that current use exceeds sustainability levels, which jeopardizes their future livelihoods. We therefore recommend that the local stakeholders be supported in identifying alternative sources of livelihoods while simultaneously developing sustainable management strategies for small wetlands such as Ga-Mampa. In addition, other ecosystem services (regulating, supporting and cultural, including recreational benefits) provided by the wetland to local and downstream stakeholders need to be further studied and economically assessed.ZONE HUMIDE;ECOSYSTEME;GESTION DE L'EAU;ANALYSE ECONOMIQUE;VALEUR NON MARCHANDE;AFRIQUE DU SUD;ECONOMIC VALUATION;LIVELIHOOD ANALYSIS;MARKET VALUATION;PROVISIONING SERVICES;WETLAND ECOSYSTEMS

La méthode Inondabilité : appropriation par les hydrologues de la vulnérabilité dans le diagnostic sur le risque d'inondation

Direction d'ouvrage : Sylvia Becerra et Anne PeltierLa méthode Inondabilité a été développée dans les années 1990 par le Cemagref pour disposer d'un outil d'évaluation du risque d'inondation à l'échelle du bassin versant et proposer un cadre de négociation sur la notion de risque acceptable. Elle repose sur l'idée d'exprimer aléa (intensité physique du phénomène naturel) et vulnérabilité (sensibilité d'un usage du sol aux inondations) avec une même unité hydrologique, la période de retour. Pour l'aléa, il s'agit de la période de retour de la première crue inondante. Pour la vulnérabilité, l'usager indique le niveau de protection souhaité en terme de période de retour, le corollaire étant qu'il accepte ou tolère d'être inondé par des crues plus importantes. Après un rappel sur les principes de la méthode Inondabilité, nous présentons une discussion sur la définition hydrologique de la vulnérabilité, et un travail complémentaire effectué sur l'évaluation économique du consentement à payer pour bénéficier de mesures de protection contre les inondations. / The Inondabilite method has been developed in the nineties by Cemagref as a tool for flood risk assessment at a basin scale. The main idea was to propose a framework of negotiation on acceptable flood risk. Both components, flood hazard and flood vulnerabilty were defined as a return period, the former being related to the first overflowing event, the latter being related to the expected level of protection. After a presentation on the Inondabilite framework, a discussion gives the advantages and limitations of such hydrological assessment of flood vulnerability. A complementary work is presented on the economical assessment of the willingness of population to pay for flood risk mitigation

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

Hydro-socio-economic implications for water management strategies: the case of Roussillon coastal aquifer

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 overexploitation and saltwater intrusion. Geological, hydrogeological and socio-economical studies as a multidisciplinary approach on a coastal Mediterranean aquifer- the Roussillon - have been carried out in order to design effective water management strategies on areas sensitive to seawater intrusion risk. Geology provides geometry and architecture of the different aquifers, hydrogeology assess the seawater intrusion risk while socio-economic study includes consulting the stakeholders with the aim of suggesting water management and policy option acceptable to the majority of population. This paper then highlights the economic interests at stake, diversity of viewpoints expressed by stakeholders and political dimension of the issue, which are likely to be encountered for all similar situations on both sides of the Mediterranean Sea.GESTION DE L'EAU;STRATEGIE;HYDROGEOLOGIE;SOCIOLOGIE;ECONOMIE;MER MEDITERRANEE;ROUSSILLON

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

Une analyse coût-bénéfice spatialisée de la protection contre des inondations. Application de la méthode des dommages évités à la basse vallée de l'Orb

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. Il propose différentes formes de résultats : valeur actuelle nette, carte des dommages potentiels et carte des bénéfices attendus des projets, et montre comment ces résultats peuvent contribuer à la définition de stratégies de gestion des inondations, par exemple en déterminant les crues de projet. La discussion porte sur la transférabilité de la méthode, sur ses limites et les perspectives de développement. / This article explores the relevance of implementing a Cost-Benefit Analysis (CBA) of flood prevention policies via the Damage Avoided approach. Based on a case study in the Orb catchment (Hérault), the article reminds the different steps of the approach, in particular the modelization of assets in floodplains and the calculus of mean annual damages. The article proposes different ways to present the results : the net present value, a map of potential damage and a map of expected benefits, and shows how these results can contribute to the definition of flood management strategies, for example by the choice of design-floods. The discussion deals with the transferability of the method, its limits and perspectives for further developments

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