Monitoring of water use for irrigated rice cultivation on the southern Coast of Santa Catarina, Brazil

Rice growing is the main agricultural activity on the southern coast of Santa Catarina. The cultivation system used is flood irrigation with planting in the pre-germinated system. The activity is characterized by the high demand for water use, and thus there are water use conflicts and also impacts on water quality. Irrigation is carried out based on natural water availability and there are no structures for measuring the volumes used. This study aimed to monitor and evaluate the use of irrigation water in a collective system of irrigation association of rice producers. The inflow and outflow were monitored with Parshall and CTR gutters equipped with level sensors with hourly readings, for one period and three consecutive harvests. Water consumption for irrigated rice cultivation averaged 9894 m³ha-1. The need for irrigation showed mean values of 0.78 L.s-1.ha-1 with peak values of 1.10 L.s-1.ha-1. Rainfall makes an important contribution. It was found that it is possible to increase the efficiency of the irrigation system and reduce the value of water used for irrigation.