Aplicação do modelo QUAL2Kw para avaliação da capacidade de assimilação de cargas pontuais no Rio Itapanhaú. / Application of the model QUAL2Kw for assessment of point sources at Itapanhaú River.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2010

RESUMO

The presence of point sources in rivers and streams implicates in downstream impacts that can commit their respective future uses. For this reason, the mathematical modeling comes as a fundamental tool in the evaluation of those discharges in sense to evaluate legal service and to subsidize the licensing of activities to the competent organs. The main objective of the present work was to verify, through numeric simulations with the model QUAL2Kw, the capacity of assimilation of point sources in a reach of Itapanhaú River for dissolved oxygen, biochemical oxygen demand, ammonia, nitrates, total phosphorus, chlorophyll-a and pH according with tide conditions, always considering the established limits for the Resolution CONAMA 357/05 for class 2 rivers. It was necessary to accomplish the simulations considering the effect of the variation of the downstream water level in function of the proximity with the ocean, once those changes cause alterations in depth and velocity along the channel. Water level determination was accomplished by application of CLIV, which was developed by Fundação Centro Tecnológico de Hidráulica of the Universidade de São Paulo; the amplitude and phases of the harmonics in study were obtained through the method of the minimum squares and from the existent harmonic constants in Ilha Barnabé, Santos, SP. It was obtained reasonable calibration and validation results with the model QUAL2Kw, and the simulations were divided in dry and rainy period. In general, Rio Itapanhaú possesses a good capacity of assimilation of the loads at present, and there was not any non conformity in relation to the legal aspects. The most critical situation happened in both hydrological seasons in the high tide, where the concentrations of total phosphorus were very close to the limit of 100g/L. It was still accomplished uncertainty analysis for the dissolved oxygen and sensibility analysis for the reaeration coefficient, nitrification rate and hydrolysis rate of the organic phosphorus using Monte Carlo method. A last simulation was performed with increase of the load in 50%, and only total phosphorus and pH exceeded the water quality pattern limits.

ASSUNTO(S)

water quality qual2kw qualidade da água mathematical modeling recursos hídricos qual2kw modelos matemáticos water resources

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