A computer model was developed based on computerized spreed sheet to estimate the effective rainfall for irrigated rice by innundation. The model has considered the specific conditions of irrigated rice in the Rio Grande do Sul State in albaqualf soil. Two different irrigation water managements were considered: (i) using the actual situation used by farmers and; (ii) the management recommended by local research centers. In the first one, a water depth of 25mm was used since the beginning of irrigation and a progressive increase in the water table wafs used until a value of 100mm was reached. However, in the second one, the initial water depth of 25mm was increased only until reached 35mm, then was kept at this value, and when a higher water depth is recommended, it was elevated to 75mm. It was observed higher values of effective rainfall in the water depth management recommended by the research centers compared to water managementes mainly used by farmer. The implementation of this water depth managements can reduce water application up to 20%.
effective rainfall; irrigation; submersion
