Modelagem paramétrica para simulação dos campos de fetch e ondas: estudo de caso dos reservatórios de salto Caxias e Itaipu.

Abstract

The track which the wind blows transferring energy to the aqueous environment, known as fetch. is the fundamental factor for the study of wave generation. The concept of fetch was initially developed in marine environments, and the procedure for determination of this is called the oceanic method. However, this method didn't yield satisfactory results when applied to inland waters, such as lakes and reservoirs, creating the necessity of others methods for this cases, especially the Saville method. The present work aims to obtain the distribution of fetches for the reservoirs of Salto Caxias and Itaipu. Therefore, a review of the main methods of fetch calculations was performed, as well as the concepts related to the formation of waves by winds in reservoirs. This distribution for both reservoirs was determined through the application of the computational model ONDACAD, a software developed in AutoLISP language by the Department of Civil Engineering of the Universidade Estadual de Maringá. The fetch fields were elaborated for 16 wind directions in each reservoir, using the Saville method. For the main direction of each reservoir studied, the fetch field was also constructed from the oceanic method, allowing a comparison between the different methods. In order to demonstrate an important application of the fetch fields, a parametric model known as SMB was used to obtain the distribution of significant wave heights in the Salto Caxias reservoir, considering wind intensities of 5, 15 and 20 m/s. The results show that the maximum fetch is 3,3 km with North wind for Salto Caxias reservoir and 13,0 km with South-southwest wind for Itaipu reservoir.