Good management of water resources requires a good allocation of their availability, especially in public irrigated schemes in Tunisia. This paper contributes to a better reallocation of available water resources at the farm and regional levels. A case study was discussed in the Kalâa Kebira region, in the center-east of Tunisia. Regional models based on aggregation and the possibility of water transfer between two irrigated schemes was tested. The results show that a good seasonal allocation is possible with a total regional exchange of 9.60% m3 of water available between these two schemes. This reallocation is beneficial at the regional level, recording an increase of 2.12% in agricultural income and less beneficial, except for farms that are less competitive, in terms of use of water resources. This reallocation also allows for cultural diversity and specification of agricultural farms. Competitiveness in the water use, diversification and specification of agricultural production systems help to preserve natural resources but they also help to satisfy demand of the regional market.Good management of water resources requires a good allocation of their availability, especially in public irrigated schemes in Tunisia. This paper contributes to a better reallocation of available water resources at the farm and regional levels. A case study was discussed in the Kalâa Kebira region, in the center-east of Tunisia. Regional models based on aggregation and the possibility of water transfer between two irrigated schemes was tested. The results show that a good seasonal allocation is possible with a total regional exchange of 9.60% m3 of water available between these two schemes. This reallocation is beneficial at the regional level, recording an increase of 2.12% in agricultural income and less beneficial, except for farms that are less competitive, in terms of use of water resources. This reallocation also allows for cultural diversity and specification of agricultural farms. Competitiveness in the water use, diversification and specification of agricultural production systems help to preserve natural resources but they also help to satisfy demand of the regional market.