Influência do uso do solo nas vazões máximas da bacia do Rio Marrecas

Abstract

Understanding the changes in land use that affect hydrological processes in river basins is of paramount importance for planning and managing the use of water resources, as well as for mitigating the impacts caused by large floods. The development of the city of Francisco Beltrão, around the Marrecas river, with the initial intention of using water resources, became a social problem due to recurrent floods. Thus, this study aimed to analyze the impacts of the adaptation of the basin's soil on the generation of runoff. For the development of this work, two land use scenarios were generated, one representing current use, and another based on land use capacity classes. From these scenarios, peak flows were simulated, using the HEC HMS software, in seven precipitation probabilities, 2, 5, 10, 25, 50, 100, and 200 years, and analyses of the influence of these scenarios on the generation of maximum flow rates were carried out. The specific maximum flows of the sub-basins for the scenario of current use and tolerable specific maximum flows were also determined. The results obtained by hydrological simulations showed that the current use of the soil causes higher peak flows when compared to a scenario of land use in agreement with its usage capacities. In addition, it was found that approximately 50% of the basin's soils are unsuitable or at the limit of land use capacity. Using the specific maximum flow to the ideal scenario as a reference for maximum water production in the Marrecas River watershed, it can be inferred that the current land use has generated higher flow than it would be ideal for all the return periods investigated. These results show the importance of adopting soil and water conservation measures, with the objective of reducing runoff and dampening peak flows, as well as containing flood events. It was possible to identify the sub-basins with the greatest potential for generating runoff and consequent increase in maximum flow rates in the Marrecas River basin. The results achieved contribute to the planning of land and water use in the rural area of the basin and serve as a reference in the designing of environmental public policies in the city.