Análise de alterações em fenômenos agroambientais utilizando o método de entropia de permutação

Abstract

In this work we analyze the complexity of stream flow in the São Francisco River and hot-pixels detected in Amazonia, in order to evaluate the effects of human activity. Permutation entropy is employed which takes into account temporal causality by comparing consecutive values within the series. We also use this entropy method to analyze rainfall regime in Pernambuco, Brazil. For the São Francisco River, we analyze the influence of the Sobradinho dam construction on the hydrological regime. The results show that entropy of stream flow increases after the dam’s construction in 1979, which indicates more disordered and less predictable dynamics. For hot-pixels detected in Amazonia, the increase in entropy is related to severe droughts in 2005, 2007, and 2010. For temporal series of precipitation in Pernambuco, entropy values decrease with distance from the coast, indicating more predictability of monthly rainfall in the zona de mata and agreste regions, and less predictable rainfall dynamics in the sertão and vale do São Francisco regions.