Economic instruments for water management in the presence of positive externalities: the case of rice-based irrigation in Sri Lanka
Instruments de gestion de l`eau en présence d`externalités positives : le cas des systèmes rizicoles au Sri Lanka
Résumé
In a number of countries, the water sector is currently facing with two main problems: water conflicts and water managers` budget deficits. The implementation of economic instruments, like water pricing or water reallocation through market, is frequently advocated as an appropriate solution to solve these two problems. However, a number of scholars and practitioners have highlighted that the use of such instruments may have significant third part effects and they have proposed to 'internalise` these negative externalities. After reviewing literature on externalities (section 1), we argue that such negative externalities reveal the existence of significant positive externalities in the pre-reform situation. This argument is supported by a detailed case study conducted in a Sri Lankan irrigation system, where positive externalities induced by irrigation in the current situation are identified and quantified (section 2). The case study helps to understand why the implementation of a new pricing system for irrigation water, which would significantly modify the allocation of water within the hydrosystem, is not acceptable by the beneficiaries of the positive externalities. Then, we propose a water pricing system which takes into account the positive externalities of irrigation and which is therefore more likely to be accepted by all the parties involved water management (section 3).
Dans un certain nombre de pays, le secteur de l`eau est actuellement confronté à deux principaux problèmes : les conflits et les déficits. La mise en place d`instruments économiques, tels que la tarification ou la réallocation de l`eau au travers de la création de marchés, est fréquemment proposée comme la solution appropriée à la résolution de ces deux problèmes. Toutefois, ces solutions ne prennent pas en compte les problèmes d`externalités. Nous nous proposons ici, avec l`exemple de systèmes rizicoles du Sri Lanka d`aborder cette question et de voir quels sont les moyens d`intégrer ces externalités.