Water seasonality in granting permits and impact of irrigation in the Dourados River basin, MS, Brazil

The objective of this study was to evaluate water seasonality in the process of granting permits and the impact of irrigation in the Dourados River basin. For that, the hydrological behavior of the basin was analyzed. The minimal streamflows (Q(7,10) and Q(95)), irrigation withdrawal flow (Q(r)) and the percent variation of the grant flows relative to monthly seasonal period in relation to the monthly withdrawal flow were obtained. The results allowed to verify that using criteria based on the monthly streamflow allows for better management of water use, because it allows for greater utilization of this resource in times with high water availability and imposes a realistic restriction during critical periods. The average annual water withdrawal for irrigation in the basin during the studied period was on the order of 2.99 m(3) s(-1), and the withdrawal flow in the month of highest demand (August) was 5.95 m(3) s(-1).