Priority water rights. Are they useful for improving water-use efficiency at the irrigation district level?

This paper examines the effectiveness of reforming water rights regimes in agricultural sector by replacing allocation procedures based on proportional rule with implementation a priority that establishes security-differentiated rights. The main objective is to assess whether this change improves economic efficiency at irrigation district level, particularly during cyclical scarcity events. To end, Positive Mathematical Programming model built simulate performance proposed reform an southern Spain. results show gains brought about are very small, which casts doubt its ability improve water-use local level (i.e., district) under current climate and availability conditions. In any case, further research needed suitability allocations rules basin scale greater farm heterogeneity, especially given likelihood more frequent, intense droughts due change.