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, Concept d'utilité

. Harou, Quand l'eau est une ressource rare, elle devrait être gérée et allouée de façon efficace, c'est à dire de façon à maximiser les bénéfices qu'elle procure à la société, 2009.

, La consommation de l'eau fournit un certain nombre de biens ou services (possibilité de boire, de se laver, de se baigner ou d'avoir d'autres activités récréatives etc.), dont le consommateur tire une utilité. L'eau permet également de produire des biens qui seront ensuite consommés directement ou indirectement (possibilité d'irriguer ses cultures, production d'électricité etc.). L'utilité est une mesure du bien-être et de la satisfaction obtenue par la consommation, L'approche économique fournit des méthodes permettant d'évaluer les compromis entre des objectifs différents et concurrentiels, en exprimant leurs résultats via un dénominateur commun : l'utilité

, Pour pouvoir construire une fonction d'utilité sociale, des hypothèses additionnelles sont utilisées permettant d'agréger les fonctions d'utilité individuelles en les pondérant. Il s'agit d'une approche normative qui repose sur deux choix : d'une part au niveau de chaque agent on suppose un comportement utilitariste, L'analyse suppose que les agents économiques maximisent leur bien-être tel qu'ils le conçoivent, 1993.

, L'approche économique va tenter de passer de la notion d'utilité des biens et services, qui représente bien le bien-être des agents, à une valeur plus facilement mesurable et utilisable. En effet, l'utilité est intéressante en théorie car elle rend bien compte de l'hétérogénéité de agents, de l'hétérogénéité des biens et services qu'ils peuvent consommer

E. Cependant and . Qu, elle agrège des biens et services incommensurables la rend difficile d'utilisation. L'analyse économique décrite dans les sections suivantes va permettre de passer de l'utilité au surplus qui rend commensurable les consommations des différents biens, puis du surplus à des valeurs monétaires observables, qui pourront servir de point de départ pour les politiques d

U. , valeur de l'eau", rassemblant des chercheurs, gestionnaires de l'eau, représentants des gouvernements et ONG, a noté que le concept de "valeur" de l'eau n'était pas forcément clair pour les non-économistes, 2010.

, En effet, la valeur économique est différente du prix, et des biens n'ayant pas de prix de marché peuvent tout de même avoir une valeur économique

, note que l'acception moderne du concept a été formulée par Dupuit (1844), qui définit le « sacrifice maximum, en termes monétaires, auquel le consommateur est prêt » comme la mesure de la valeur d'usage du bien, et par Marshall (1879, 1880), qui définit la mesure économique de la satisfaction comme "ce que l'individu serait prêt à payer pour connaître cette satisfaction plutôt que de la manquer, Ces définitions illustrent bien que la mesure de la valeur du bien correspond à ce qu'il vaut aux yeux des individus, 2006.

. Ainsi, définit l'évaluation économique comme la tentative d'attribuer une mesure monétaire aux préférences des individus pour certains évènements ou alternatives. L'un des concepts fondamentaux est bien le concept de consentement à payer (terme utilisé aujourd'hui, noté CAP), c'est à dire la somme maximale qu'un individu est prêt à dépenser pour obtenir une unité d, 2005.

. Finalement, on pourra dire qu'une politique de gestion de la ressource en eau a des bénéfices quand il y a des effets positifs pour lesquels les partis