The tropical climatic conditions have risen the need for developing new technologies that contribute for the improvement of the methods still employed in design and management of agricultural drainage systems. Considering the Brazilian humid and subhumid climatic regions, a methodology was developed based on the drainage criteria SEW30, the water balance and the drainage equation of Krayjenhoff van Leur-Maasland. The effects of spacing and depth of drains on productivity of crops for a critical period of drainage was characterized basing on the value of SEW30 calculated from the water table hydrogram during development period of the crop. In the second stage the calculated value of SEW30 was compared to experimental value determined for the crop and soil type. When the calculated values of SEW30 did not match with the experimental values, a new value of spacing was tested in the iterative form until agreeable difference is obtained. The space between drains obtained through application of proposed methodology was larger than the one obtained by traditional drainage criteria.
simulation model; water balance; drainage criteria SEW30
