Distribuição da precipitação mensal, anual e máxima diária anual na bacia hidrográfica do rio Formoso, Tocantins

Abstract

Precipitation is variable of notorious space-time variability, presenting direct effects on surface water availability. Information concerning the seasonal distribution of precipitation as well as their spatial distribution is essential for a variety of human activities. In view of this, the present study aimed to map, by using geostatistical techniques, the average monthly and annual precipitation as well as the annual maximum daily precipitation in the Formoso river basin, Tocantins. A geostatistical study was previously conducted using GeoR program, modeling the experimental semivariogram with the Spherical, Exponential and Gaussian models, estimated by the method of weighted least squares. From this study, the model with the lowest average error, which was calculated based on the cross validation method, was applied to the mapping process by ordinary kriging. It was found good performance of the geostatistical techniques in mapping the precipitation for the basin of the Formoso river, highlighting the Gaussian semivariogram model, which excelled in most of the studied events. Precipitation maps showed considerable variability of the monthly precipitation, with the highest values estimated for the northeastern and northwestern regions of the basin, however, smaller variability was observed for the annual maximum daily precipitation.