Modelagem hidrodinâmica e definição da capacidade de suporte do rio São Francisco Verdadeiro tributário do reservatório de Itaipu

Abstract

Aquaculture is a growing economic sector, with emphasis on the production of fish in cages in the large Brazilian reservoirs. The increase in aquaculture production has caused great concern due to the pollution potential of aquaculture. The long-term sustainability of many ventures depends on their ability to reduce waste production, which requires the delimitation of propitious areas as well as their carrying capacity. In this context, the hydrodynamic models assist in the understanding of complex aquatic systems to represent the patterns of transport of particles and contaminants in water among other In this context, the hydrodynamic models assist in the understanding of complex aquatic systems to represent the patterns of particles and contaminants transport in the water among others The objective was to study the hydrodynamics and limnological characteristics of the São Francisco Verdadeiro river tributary of the Itaipu reservoir in order to understand the behavioral pattern to better measure the support capacity model currently used for aquaculture activity. The Doppler equipment associated to the Delft 3D hydrodynamic software was used to define the residence times in five evaluated areas, and later calculation of maximum production capacity per propitious area, considering zootechnical data for two species of fish. The conventional water quality parameters were monitored and correlated by Principal Component Analysis (PCA). Our findings suggest that aquaculture activity that is currently performed on cages has not been impacting the environment. On the other hand, there is strong evidence of punctual and diffuse polluting sources which contribute significantly to the increase of nutrients,, mainly nitrogen and phosphate forms, resulting in the deterioration of water quality. Regarding the carrying capacity, the results found differed from those obtained by the conventional method. The methodological contribution with alterations of evaluation of the support capacity favors the interpretation and analysis of the areas to be used in the development of the activity, serving as a management and planning tool, allowing evaluating production scenarios, enabling the forsee of risks, reducing the activity impact on ecosystems.