The Brazilian Northeast is an area where political and social development has been hindered by the harsh environment of the arid sertão. Characterized by the presence of nine major rivers, among which are the São Francisco and the Parnaíba, the sertão has an average annual temperature of between 20 °C and 28 °C and a maximum of 40 °C.[11] The pluviosity of the area is source of concern for farmers and local governments alike.