Modelagem de fósforo em açudes do semiárido cearense

Abstract

The eutrophication of water bodies is one of the most serious environmental, health and economic problems faced by society. This problem may be even more critical in semi-arid regions, where the reservoirs have their volume reduced during the dry season and yet they continue to receive nutrients – particularly phosphorus - from urban, industrial and agricultural activities, resulting in a significant reduction in the quality of their waters. In this sense, modeling the concentration of total phosphorus arrises as a importante tool for effective management of water resources of the State. Since much of the reservoirs of the Ceará are located in the northeast semi-arid, it is appropriate to calibrate the concentration of total phosphorus model for this region so that the results obtained by simulation may be more consistent with the reality observed in the State. The sedimentation coefficient of phosphorus (Ks) is the parameter to be calibrated for the analysis area. The particularities of the Ceará semi-arid imposes such calibration, although the literature shows equations for calculating the Ks for tropical and temperate regions. The results from calibration indicate that the proposed equation for the semi-arid region of Ceará better representes the data obtained by COGERH for the four reservoirs analyzed than the equations for the other regions considered. The validation of the equation with the data from reservoirs in the semi-arid region of Rio Grande do Norte seems to indicate that this equation well represents the behavior of the reservoirs in the Brazilian semi-arid.