Geração e propagação da vazão a partir de simulações com o modelo atmosférico BRAMS em bacias hidrográficas no Nordeste do Brasil.

Abstract

Hydrological models are traditionally used for representing and simulating, at basin scale, the processes of runoff generation and propagation over the river network. The majority of those models only considers the land surface processes of the hydrological cycle, using rainfall and temperature as input data. This characteristic of the hydrological models can be a limiting factor, particularly when studying the impacts of climate variability and change on water resources. In this work, the soil-vegetation-atmosphere transfer scheme (SVAT) of the atmospheric model BRAMS was used to produce flow in hydrographic basins. To this purpuse, was inserted into SVAT of the atmospheric model the calculation of runoff and was used a scheme of flow propagation to calculate discharge in hydrographic basins. Thus, attempts were made to maintain a consistency of processes, with the calculation of the terrestrial and atmospheric phases of water cycle by a single model. Four experiments were run for four events and analysed in various basins to evaluate the generated flow and sensitivities tests were made. Results show that, in most part of the basins, there was an overestimation of simulated flow. The parameterization reduced the simulated volume at rates between 10 and 40%, compared to the standard experiment, but still maintaining the flow overestimated. This overestimation was caused in part by rainfall and the soil umidity flux. The flow was very sensitive to the deepening of the soil layers, and succeeded in bringing together the hydrographs observed and simulated in several basins. Some basins, however, already in the standard experiment showed promising results and other showed greater influence of precipitation than other factors.