Aiuaba Experimental Basin, Brazil

Location

The Aiuaba experimental basin is located in the municipality of Aiuaba, State of Ceará, Northeast of Brazil (watershed’s outlet 6°42’S; 40°17’W). It is located inside the Brazilian ‘drought polygon’, the tropical semiarid area of the country, with high inter-annual and intra-annual precipitation variability, average precipitation of 650 mm.yr-1, class A pan evaporation of 2,550 mm.yr-1, and monthly average temperatures ranging from 24°C to 28°C.

Catchment size

The Aiuaba catchment has an area of 12 km2.

Climate

Tropical semiarid area of the country, with high inter-annual and intra-annual precipitation variability, average precipitation of 650 mm.yr-1, class A pan evaporation of 2,550 mm.yr-1, and monthly average temperatures ranging from 24°C to 28°C. According to the Köppen classification system, its climate is ‘Bs’. In the basin 78% of the rainfall corresponds to real evapotranspiration, 13% to runoff and 9% to percolation.

Geology

The geology of the southern side of the watershed (upstream) is characterised by the crystalline complex, consisting of Granite, Migmatitic Gneiss and Banded Gneiss with fascis of Mica Schist (Mamede 2008). On the northern side (downstream) the Santarém meta-sedimentary formation is found. The basin soils - usually shallow with rock fragments - are mainly the Planosol and the red-yellow Podsol (Creutzfeldt 2006).