Résumé
This paper aims at comparing several economic tools which may be implemented to mitigate current farmers' groundwater withdrawals in a conjunctive use context. We conduct a fined-tuned field work with farmers to understand the key points of substitution between underground and surface water at the farm level. A linear programming framework has been used to model fruits and vegetable production systems. It shows that groundwater demand is sensitive to its cost, advocating for effectiveness of price-based instruments to mitigate underground irrigation withdrawals. Although economists often advocate for such instruments superiority, surface water pricing and fees on groundwater consumption partially fail to satisfy our four criteria for instruments evaluation. A groundwater market could be more suited to groundwater management in a conjunctive use setting. Practical and legal hurdles impede however its implementation in our case study. We finally support the implementation of a quota system which could be framed by the so-called "Organism Unique" introduced by the 2006 Water and Aquatic Environment Law.