Celso de Carvalho Braga
Abstract:
The construction of reservoirs for hydroelectric plants generates several environmental impacts, such as changes in the displacement and concentration of suspended solids, thus causing changes in aquatic fauna and flora. The study of suspended solids in a given river basin is important so that correct decisions can be made as to the planning of basin activities, since the amount of solids is directly associated with land use. Problems generated by suspended solids range from erosion, transport, deposition and compaction, and suspended solids impair water quality for human consumption. The present work aimed to analyze the spatial and temporal distribution of suspended solids concentration (CSS) in the main tributaries and lake of the Barra dos Coqueiros UHE, and its influence on the reservoir life from March to August 2011. The methods used to achieve the proposed objectives were: to calculate the suspended solids concentration according to the proposal of WETZEL AND LIKENS (1991), to verify the turbidity and water transparency levels according to the proposal of ESTEVES (1998) and TUNDISI. (2008), calculate the flow of tributaries by the float method, according to the proposal of RAMOS and OLIVEIRA (2003), PALHARES (2007), and calculate the total solid discharge of the main tributaries by the simplified method of COLBY (1964). takes into account: net discharge, average velocity, average depth, cross-sectional width and measured concentration of suspended solids. According to the data obtained, the following conclusion was reached: that the concentration of suspended solids has a good relationship with turbidity and water transparency data. In the rainy season reservoir data collection, the concentration of suspended solids ranged from 7.5 to 30.5 mgL-1, being higher than in the dry period collection, which ranged from 0.25 to 7.5 mgL-1. 1. The same is true for water transparency using the Secchi disc which ranged from 0.16 to 0.30 meters in the rainy season and from 1.40 to 3.50 meters in the dry period. Regarding turbidity, the indices found show that the light reflectance in the rainy season varied from 51 to 72 NTU, while in the dry period it ranged from 0 to 3.7 NTU. Regarding the evaluation of the spatial and temporal distribution of suspended solids concentration of the main tributaries of the Barra dos Coqueiros UHE reservoir, the Matrix Stream stands out among the analyzed tributaries, as it presents higher concentrations of suspended solids, ranging from 2.5 mgL- 1 in the dry season to 14.5 mgL-1 in the rainy season.
