Evaluation of the surface water quality in the Itapicuru river basin -: State of Bahia, Brazil

The Itapicuru River basin is located in the northeast of the State of Bahia, Brazil. It is a large basin with variable conditions in terms of soil, climate, topography, natural vegetation, and economy. About 80% of the total area is subjected to severe drought periods. Poor cropping systems and lack of adequate systems for disposing wastewater from the urban areas determine the water quality along the basin. This proposal airns to carry out a study on the actual situation of the surface water resources, including diagnostic and prognostic actions. The study presents a spatial analysis of the surface water quality using hydro chemical data of the water and sediments from 30 stations along the river and the tributaries, including points in the reservoirs of the dam and estuary region. The main processes related with the water quality are: erosion, concentrations of salt and nutrients, punctual contamination of metals and bacteria. The spatial distribution of the parameters in the different points is illustrated in maps. Zones showing higher values of coliforms, nitrogen, phosphor, chloride, conductivity and nitrates are in the high and medium part of the river, where there is low rainfall, higher demographic density and expressive social-economic dynamics. Closer to the chromium mines the concentration of iron and chromium in the sediments is above the limits. The results are associated with the environmental quality in order to have a characterization of the hydro chemical and social-economic elements, in different scales. Also critical areas are defined in detailed studies to help implement corrective actions to minimize or eliminate the contamination problems. It is expected that the results and achievements of this project will be useful in order to support the development of state and federal programs on the sustainability of water resources in the region.