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).

Vegetation/Land use

The 12 km² watershed has been integrally preserved since 1978. It is naturally covered by the Caatinga, a tropical xerophytic deciduous broadleaf vegetation, consisting of a dense mixture of trees, bushes and cacti.

Measurements/Equipment

The Aiuaba experimental basin has been monitored since January 2003. Some of the instruments, however, have been installed only recently. Since the beginning of the year 2011, the following instruments and/or experimental sites are being used in the monitoring process: three rainfall stations (every 5 min); three soil moisture stations (hourly); one water level station (inside the reservoir, hourly); two discharge gauging stations (EF3 built in January 2011, 700m upstream the formerly installed EF1: combined use of these data will provide useful transmission losses information, hourly); one sediment sampler (one sample per event); and a monitored hillslope (100m2, with 90 metal pins to quantify sediment detachment, transport and deposition, controlled yearly, except in case of extreme wet seasons). The discharge gauge station EF2 instrument has presented technical problems and is temporarily inactive.

Links to project webpages

SESAM

References

• Creutzfeldt, B. (2006): Remote sensing based characterisation of land cover and terrain properties for hydrological modelling in the semi-arid Northeast of Brazil
• Cunha Costa, A. (2012): Analyzing and Modelling of Flow Transmission Processes in River-Systems with a Focus on Semi-Arid Conditions
• Mamede, G.L. (2008): Reservoir Sedimentation in Dryland Catchments: Modelling and Management