coast of Fortaleza, it is confined to a short rainy season. This season extends from January to April in the west, but in the eastern Sertão it generally occurs from March to June. However, rainfall is extremely erratic and in some years the rains are minimal, leading to catastrophic drought. The duration of droughts has increased over the last 36 years, with the 2012–2016 drought being the longest drought in the region's history. Because of this vulnerability to the climate, Sertão is also known as a “polygon of drought.” Due to global warming, more frequent, more severe and longer droughts are estimated to hit the region over the next 90 years. Despite the increasing severity of the droughts, Brazil has become increasingly able to mitigate the negative social impacts associated with drought. While generally successful in helping those enduring drought, drought relief programs have historically resulted in a so-called indústria da seca (drought industry). The term, coined by Antônio Callado, describes the phenomenon wherein local politicians use droughts as a tool to increase their electoral chances, effectively "trading drought relief for votes." This misappropriation of funds often benefits the wealthy—especially private landowners—to the detriment of the rural poor. Meio-Norte ("Midnorth") Meio-Norte is a transition area between the high rainfalls region of Amazon Rainforest and the semi arid region of Sertão (hot and drought) covering the state of Maranhão and half of Piaui. Hydrology The Northeast region comprises the drainage basins of the São Francisco, Canindé, and Parnaíba Rivers. Geology and topography Geographically, Nordeste consists chiefly of an eroded continental craton with many low hills and small ranges. The highest peaks are around in Bahia, while further north there are no peaks above . On its northern and western side, the plateaus fall steadily to the coast and into the basin of the Tocantins River in Maranhão, but on the eastern side it falls off quite sharply to the coast except in the valley of the São Francisco river. The steep slopes and long cliffs of the eastern coastline are known as "The Great Escarpment". The escarpment serves an extremely important climatic function. Because for most of the year Nordeste is out of reach of the Intertropical Convergence Zone, the easterly trade winds blow across the region, giving abundant rainfall to the coast but producing clear, dry conditions inland where the escarpment blocks moisture flow. This gives rise to four distinct