Estudo frequencial das necessidades de irrigação em quatro localidades do Estado do Rio Grande do Sul.

Abstract

This work relates basic resources for the implantation of hydro-agricultural projects in four regions of the State of Rio Grande do Sul, based on a frequencial study of irrigation ne oessities. The period of agronomia draught mas caracterized using the monthly hydric balance. A nathematical program in Fortran IV language mas prepa red in order to calculate the daily hydric balance for the four regions, with distinct periods of'meteorogical observations. Based on the monthly dejiciencies obtained from the hg dric balance, hydrological series and respective frequencies we re found, followed by plotting the curves of irrigation necessi ties versus frequencies for the driest period of the year (ganª rally from November to March). From the curves of irrigation necessities plotted versus frequencies, the probabilities of occurence of'months ofrnnnúman water consumption from 1 to 5 years in ten years, were deduced.

This paper presents basic subsidies for the implementation of hydro-agricultural projects in four regions of the state of Rio Grande do Sul, through a frequency study of irrigation needs. The period of agronomic drought was characterized using the monthly water balance. A mathematical program in FORTRAN IV language was prepared to calculate the daily water balance for the four locations, with distinct periods of meteorological observations. Using the monthly deficiencies obtained from the water balance, the hydrological series and their respective frequencies were organized, and then the irrigation needs x frequencies curves were drawn for the driest period of the year (November to March in general). From the irrigation needs x frequencies curves, the probabilities of occurrence of the months of maximum water consumption were deduced from 1 to 5 years out of 10.