Mudanças microclimáticas induzidas por alterações na cobertura e uso da terra na região do submédio São Francisco.

Abstract

This work aims to analyze the impact of changes on soil use and coverage upon the microclimate of the Submiddle São Francisco region. The hypothesis is that the anthropogenic interferences due to the CAI Juazeiro/Petrolina implementation in the 1990 decade brought to the region, besides the economical benefits with the increase in the agricultural productivity, strong environmental changes due to the expansion of the irrigated agriculture in Caatinga areas. The tendencies of alterations in climate variables were evaluated with a basis on historical data series of precipitation, atmospheric humidity, Wind, maximun and minimun air temperatures formed by observations in the Bebedouro (PE) and Mandacaru (BA) stations, located in experimental fields of the Embrapa Semiárido, and in the meteorological station of Petrolina (PE) which belongs to INMET. Satellite images were the basis for calculating the IVDN in four periods of the time series, allowing to assess the expansion of areas used for irrigated agriculture. Exploratory data analysis was performed using boxplots, which helped to identify dry and rainy years, in addition to showing important variations in other meteorological variables. The use in conjunction of the parametric methods (ANOVA and linear regression) and non parametric (Mann-Kendal and Pettit) contributed for attaining the objectives.The results indicate that the changes were more evident in the Mandacaru region, with an increase in atmospheric humidity, ATD and maximum temperature and a reduction in the minimum air temperature, with statistically significant results observed in the Regression Analysis and ANOVA. Wind and minimum air temperature were the most affected variables in Petrolina. In Bebedouro, temperatures were significantly affected. The Mann-Kendall and Pettitt tests showed important points in the analyzed period, with significant changes in the mid-1990s, in some variables, during the period of large financial investments by the Federal Government and CAI implementation. The expansion of irrigated areas contributed for an increase in atmospheric moisture and a reduction in wind intensity.