Rain
Analyzing the annual rainfall totals for the state of Espírito Santo, it can be observed that the mountainous region presents the highest rainfall averages in the state, with an accumulated annual average precipitation ranging from 1,400 to 1,500 mm. There is a tendency for a decrease in annual precipitation in the northern region of the state, with annual totals between 1,050 and 1,100 mm observed in the extreme north, for example. In the municipalities bordering Minas Gerais, in the northwest region of the state, the rainfall index is the lowest, with precipitation in the range of 1,000-1,100 mm. As for the rest of the northern region, especially in the coastal plain, these values remain in the range of 1,100-1,300 mm.
Although annual rainfall totals are good indicators of the rainfall regime, it becomes important for agricultural purposes to examine the characteristics of this regime throughout the year. This is done through the analysis of monthly totals. The months from November to March have the highest rainfall volumes, with most of the state receiving more than 120 mm monthly. These rains are associated with natural convective processes, due to atmospheric instability typical of the hottest time of the year and also due to the formation of the meteorological system known as the South Atlantic Convergence Zone (SACZ), whose main characteristic is the occurrence of rains for several days. The months of April and October present transitional values between the wet and dry periods, which will be detailed below.
In the temporal analysis of rainfall in the state of Espírito Santo, monthly rainfall distributions for five municipalities in the state (Ecoporanga, Venda Nova do Imigrante, Alegre, Vitória, and São Mateus) are used as examples, considering the period from 1977 to 2006. The municipalities located in the western region of the state (Ecoporanga, Venda Nova, and Alegre) present a rainfall regime typical of the Southeast region of Brazil, with a rainy season from October to March and a dry season from April to September. In the municipalities of the eastern portion, the coastal strip (Vitória and São Mateus), this separation between rainy and dry periods is not as evident, mainly due to the higher humidity of this region in the winter period. The average distribution of rainfall is a good indicator to assess the potential of different regions regarding agricultural exploitation. The municipalities of São Mateus and Alegre, for example, have very close annual average rainfall totals (1,296 and 1,292 mm, respectively), but with distinct distribution, which may indicate, for example, the potential for differentiated irrigation use in the two regions.
Monthly rainfall (mm)
