The participation of irrigation districts (IDs) in surface water transfers from agriculture-to-municipal uses is studied by examining IDs’ economic and political behavior, comparing their performance with non-districts (non-IDs), and analyzing the role of economic and demographic heterogeneities in water transfers. Economic modeling, econometric, and analytical techniques are used to investigate these issues. An economic model is developed to investigate how the collective-type institutional structure of IDs in the presence of local interdependencies (between internal water delivery and external water transfers) and increasing returns to scale in the internal water delivery causes reduction in marginal benefit of water transfers and the optimal transfers. The model is also used to investigate how the involvement of the U.S. Bureau of Reclamation in IDs causes more water uses in agriculture availing less for external transfers. The conjunction of multiple uses and exclusion rights without ownership rights in IDs’ water and vote-maximizing political structure of IDs are found to create disincentive for water conservation and transfers. Water transfer responses of IDs and non-IDs are empirically investigated by using a Quasi Maximum Likelihood Estimation (QMLE) technique. Based on the analysis of 38 years of time series water transfer data, IDs are found to be less responsive in water transfers relative to non-IDs in terms of water right-weighted transfers. It is found that water scarcity, private housing permits, and nonfarm establishments are positively associated with water transfers. The marginal effect of water scarcity on water transfer is stronger for non-IDs than for IDs. Impacts of economic and demographic heterogeneities on water transfer behavior of IDs are investigated using unbalanced panel data econometric techniques. Water right holdings and population in nearby cities of IDs are found to be significantly correlated with water transfer behaviors of IDs. Larger IDs with higher water right holdings and higher population centers in nearby cities are found to be more responsive to water transfers. The findings complement previous studies that commend public attention for policy redesign including institutional changes to motivate IDs to increase their water transfer activity.

En 2008, à l’issue du « Grenelle de l’Environnement » la France prend l’engagement de réduire de 50% les usages en pesticides des agriculteurs à niveaux de production inchangés. Comment y parvenir ? Un tel objectif est-il réalisable ? Cette thèse apporte des éléments de réponses grâce à l’étude de la demande en pesticides des agriculteurs et à son interaction avec l’offre de produits des firmes. L’exploitation de données individuelles permet d’analyser les déterminants des usages des agriculteurs liés aux caractéristiques des produits phytosanitaires. Le premier chapitre estime un système de demande en supposant que les produits sont homogènes au sein des grandes catégories de traitements. Il montre que la demande est peu sensible aux prix des produits à un niveau global. Il met en évidence que seule une taxe ad valorem très élevée permettrait d’atteindre l’objectif du "Grenelle de l’Environnement" , ce qui amputerait significativement les revenus des agriculteurs. Afin d’envisager une solution alternative, la suite de la thèse étudie une action simultanée sur l’offre et sur la demande. Il est préalablement nécessaire de construire un indice des prix qui intègre les spécificités techniques et réglementaires de ces produits. Cela fait l’ objet du second chapitre. Le prix ajusté est utilisé dans le troisième chapitre qui s’intéresse à l’équilibre du marché . La prise en compte de la structure de la concurrence rend possible l’identification des différentes sources de marges des firmes. L’analyse des changements de marges avant et après la modification de la procédure d’homologation des produits souligne une augmentation des marges des firmes après renforcement des exigences environnementales des caractéristiques des produits. / Following the “Grenelle de l’Environnement” the French government takes the commitment to reduce by 50% pesticide use while maintaining current production levels. How can we reach this objective? Is this target sustainable ? This thesis analyzes the demand of farmers and its interaction with firms supply. A desagregated dataset is constructed to analyze the determinants of farmers’ practices related to the characteristics of products and firms that market them. The first chapter estimates a demand system assuming homogeneous products within categories of pesticides. It confirms that the demand is not sensitive to the prices at an aggregated level. It shows that only a very high ad valorem tax would achieve the objective of the ”Grenelle de l’Environnement”. However, this measure would significantly reduce farmers' income. Alternatively, the thesis retains simultaneous action on both the supply and the demand. First, a price index is constructed in the second chapter. It introduces the technical and regulatory specificities of these products by exploiting the panel structure of the price series. Second, the adjusted price computed indexis used in the third chapter which retains structural econometrics framework to analyze the market equilibrium. Taking into account the structure of competition we compute the margins of firms which are generated by different competition conduct. These results are used to evaluate the effect of the modification of the homologation process on margins. We find that important source of margin was generated by this regulation which sustain innovation.