Emprego do método de Thornthwaite & Mather (1955) para cálculo do Balanço Hídrico Climatológico do Núcleo de Degradação de São Raimundo Nonato – Piauí

Abstract

The studies related to climatological aspects, that allow the knowledge about availability of water in the soil, constitute themselves in present time, valuable tools for agricultural and environmental planning. This work had the objective of preparing the climatological hydric balance for the Degradation Nucleus/Desertification of São Raimundo Nonato-PI. The hydric balance was determined from the Thornthwaite & Mather method (1955) with data disposed by Sudene (1990). The results indicate that 85% of the area of study presents high and average vulnerability to desertification. It was found meaningful time and spatial variations in the pluviometric volumes, with values ranging between 586 mm and 996 mm. The values of potential evaporate transpiration were superior to 1000 mm, result of an unlimited offer of solar energy, a remarkable characteristic of world´s tropical semi-arid regions. The number of dry months vary between 8 and 11, characterizing an ecological situation of hydric deficit in these months. All values of Humidity Effective Index were obtained for studied stations, and were negative, with values varying from -33 and -60, characterizing a semi-arid climate typology. The determination of components of the hydric balance allowed a greater knowledge of the climatic reality of the studied area, at the same time that it offers conditions of compatibilization between the water restrained in the soil and the different forms of the soils usage