2.2 – Hydrogeology

The Federal District is situated in the Hydrogeological Province of the Central Shield, where there are two large types of aquifers: the Porous Aquifer Dominion and the Fractured Aquifer Dominion.

Porous Dominion: water occupies the pores between the minerals that constitute the body of rock. This dominion is composed of soils and rocks that are in the process of alteration. Due to its thickness and hydraulic conductivity, these aquifers can be classified as P1, P2, P3 and P4. The P1, P2, P3 systems are characterized by larger thicknesses (>5 m) and a respectively high, medium and low hydraulic conductivity. The P4 system is characterized by small thickness (<1m, reaching up to 2.5m) with low hydraulic conductivity.

Fractured Dominion: water accumulates in the fractures, cracks or faults. These aquifers compose the system of deep, subterranean waters, with depth a little greater than 250 meters. The conductivity of these aquifers is related to the amount of fractures, their openings and intercommunication. They are classified into four sets of aquifer systems: Paranoá, Canastra, Araxá and Bambuí. The Paranoá system is divided into the following subsystems: S/A, A, R3/Q3, R4 and PPC, while the Canastra system is divided into the F and Q/F/M subsystems. These aquifers are used by deep, pipe wells and present flows from zero to more than 100,000 L/h, with most wells providing between 5,000 and 12,000 L/h.