CONCENTRAÇÃO DE SEDIMENTOS EM SUSPENSÃO: RESERVATÓRIO DE CACHOEIRA DOURADA – GO/MG, Brasil (concentration of suspended sediment in Cachoeira Dourada reservoir - GO/MG, Brazil)
Abstract
A determinação da concentração de sedimentos em suspensão (CSS) no lago da usina hidrelétrica de Cachoeira Dourada foi realizada em duas campanhas, uma em junho de 2003 e outra em fevereiro de 2005. A CSS referente aos períodos úmido e seco apresentou o predomínio de valores até 10 mg/l. Todavia na desembocadura dos córregos das Araras e Corgão as concentrações foram superiores a 10 mg/l bem como aquelas entre o córrego do Corgão e Flecha, cujos valores chegaram a 15 mg/l. Os índices de visibilidade (SEC) da água entre a barragem e o córrego do Corgão apresentaram valores com amplitudes entre 100 - 120 cm e 80 - 100 cm nos períodos úmido e seco respectivamente. Os menores valores de CSS e SEC para o trecho compreendido entre o córrego do Candango e o córrego dos Patos podem estar relacionados ao aumento da seção transversal, à diminuição da velocidade de escoamento e à existência de vários bancos de macrófitas aquáticas.
Palavras-chave: Reservatório, sedimentos em suspensão, índices de visibilidade
ABSTRACT
The determination of the sediments in suspension concentration (CSS) in the Cachoeira Dourada Hydreletric Plant’s reservoir, was realized in two periods, the first in June 2003 and the other in February 2005. The humid and dry periods’ referred CSS showed the predominance of values up to 10 mg/l. However, in the Araras and Córgão rivers mounths, the concentration values reached more than 10 mg/l, like those ones between Corgão and Flecha rivers, which values reached 15 mg/l. The water visibility index (SEC) between Corgão dam and its stream presented values with amplitudes between 100-120 cm and 80-100 cm in the humid and dry periods, respectively. The minor values (CSS and SEC) to the stretch located between Candango and Patos streams can be related to the transverse section’s increase, out flowing’s speed reduction and to the existence of accumulations of water macrophytes.
Key words: Reservoir, sediments in suspension, visibility index
RÉSUMÉ
La détermination de la concentration des sédiments en suspension (CSS) Réservoir le lac de l’ usine hydroélectrique du District de Cachoeira Dourada a été realisée Réservoir des deux étapes: une en juin 2003, et d’autre en février 2005. La CSS référente aux périodes humide et sèche ont présentée des valeurs jusqu’à 10 mg/l. Néanmoins dans l’embouchure des ruisseaux des Araras et Corgão les concentations sont supérieures aux 10 mg/l, bien comme lesquelles entre les ruisseaux Corgão et Flecha, dont les valeures sont arrivés aux 15 mg/l. Les índices de visibilité (SEC) de l’eau entre le barrage du réservoir et le ruisseau Corgão ont présenté des valeures avec l’ampleur entre 100 – 200 cm et 80 – 100 cm dans les périodes humide et séche respectivement. Les mineures valeures de CSS et SEC pour le trajet compris entre le ruisseau dos Patos peuvent être rapportés à une croissance de la section transversale et à la diminution de la vitesse d’écoulement et à l’existence de plusieurs bancs de macrophytes de l’eau.
Mots clés: Réservoir, sédiments en suspension, visibilité de l’indice
DOI: 10.4215/RM2009.0816.0018
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