The conquest of the territory of Piauí took place thanks to the expansion of cattle farms, starting from those existing in the São Francisco valley. So connected was the image of cattle to the fields of Piauí, for centuries, that in the popular car, when the ox died, the consoling chorus soon came: “Let’s go find another one, O little sister, over in Piauí.”
Located in the Northeast region, in the transition between the Amazon, the semi-arid hinterland and the plateaus of central Brazil – and with more than four fifths of its area included in the Polígono das Secas – the state of Piauí covers a land area of 252.379 km2 . It is limited to the north with the Atlantic Ocean, to the west with Maranhão, to the southwest with Tocantins, to the south with Bahia and to the east with Ceará and Pernambuco. Its capital is Teresina.
Geology and relief.
According to healthvv.com, Piauí has modest relief, with regular topography. About 92% of the territory is below 600m of altitude and 53% below 300m. Four units make up the morphological picture: the coastal lowland, the plateau of chapadas and cuestas, the plain of the Parnaíba River and the crystalline pediplane.
The coastal lowlands, in the north of the state, comprise a strip of sandy and low terrain, dominated by sandstone boards. Its western portion is formed by the Parnaíba river delta.
The plateau of plateaus and cuestas corresponds to the eastern part of the sedimentary basin of the Mid-North. In the central part of the state, the geological layers have a horizontal arrangement and form plateaus with altitudes ranging from 300 to 600m. In the eastern part, the layers are inclined and form baskets, with altitudes of 500 to 700m. The most important of them develops along the border with Ceará, where its front forms the Serra da Ibiapaba and marks the eastern limit of the sedimentary basin. The Parnaíba plain, narrow and elongated, joins the north with the coastal lowland and inland extends to the south and east.
Two types of climate occur in Piauí, the Köppen AW and BSh. The AW climate, tropical with rain and dry winters, dominates most of the state. It registers average annual temperatures of 25 to 27o C and annual rainfall of 700mm, in the south, and 1,200mm, in the north. The BSh climate, hot semi-arid with summer rains and dry winters, occurs in the southeastern portion of the state. Records thermal averages of around 24o C and rainfall of approximately 650mm, subject to irregularities.
The entire drainage network in Piauí belongs to the hydrographic basin of the Parnaíba River, the main in the state, whose course forms the limit with Maranhão. The tributaries and sub-tributaries of the right bank of Parnaíba are part of it, among which Longá, Poti, Canindé and Gurguéia stand out, as the longest course. Only these and Parnaíba are perennial rivers; the rest are temporary, that is, they stop running in the dry season. Parnaíba had its course interrupted, upstream of Floriano, by the dam of the Presidente Castelo Branco hydroelectric plant (formerly Boa Esperança), which gave rise to a large artificial lake.
Flora and fauna.
Piauí covers four types of plant formation: the caatinga, in the south and southeast portions of the state; the cerrado and the cerradão (denser than the cerrado), in the north and east; and the forest, quite devastated, in a narrow strip to the west, along Parnaíba, and to the east, over the Ibiapaba mountain range. In both forest and cerrado areas, extensive carnaubals and babassu trees are found. Other palm trees and tanning and oilseed species are present in these places, in less important formations. The fauna varies according to these differences in flora and corresponds to that found in the cerrado and caatinga of the bordering states.
In its colonization process, Piauí received a large contingent of Brazilians from other states, especially from Bahia and São Paulo. Even so, the state’s demographic density has always remained very low. It is also notable, in the demographic map of Piauí, the constant predominance of the rural population over that of the cities. The areas with the highest population density correspond to the lower Parnaíba valley and the region drained by the Canindé basin, which are the main agricultural areas in the state. In the south of Piauí, the population is thin.
Piauí’s territory is distributed among the areas of influence of the cities of Fortaleza CE (the north) and Recife PE (the south). To the north, the performance of Fortaleza takes place through Teresina and Parnaíba. To the south, Recife operates through Floriano. Other major cities in the state are Picos, Campo Maior, Piripiri, Oeiras, Floriano, Barras, São Raimundo Nonato, Pedro II and União.