Proposta metodológica para estimativa da produção de sedimentos em grandes bacias hidrográficas: estudo de caso Alto Jaguaribe, CE

• Autor(a) principal: Wiegand, Mário Cesar
• Data de Publicação: 2009
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Ceará (UFC)
• Texto Completo: http://www.repositorio.ufc.br/handle/riufc/18635
• topic: Irrigação e drenagem; Produção de sedimentos; Bacias hidrográficas; Pequena açudagem; Sediment yield; Large river basins

Estimation of sediment yield in large river basins has great importance for the analysis and monitoring of water availability and, consequently, for water resources management. However, there are several difficulties related to such estimation. Thus, the scope of this study was to propose a methodology to estimate sediment yield in large river basins with a large number of dams. The study basin is located within the Upper Jaguaribe basin and presents an area, obtained by SRTM data, of 20,670 km². The sediment yield estimation was based on a suspended sediment rating-curve, obtained by measurements of liquid and solid discharges at the basin outlet. The bedload was estimated using the model of Einstein and Brown. Also, the estimation of sediment retention in reservoirs located upstream the basin outlet was carried out. They were classified as small dams (< 50 hm³), which were grouped into five classes according to their storage capacity, and strategic dams (> 50 hm³). Note that sediment yield was obtained for a 25-years period (1984-2008). The results obtained for total sediment yield within the basin was about 450 t.km-².year-1. From this total, about 130 t.km-².year-1 reach the basin outlet, of which 79% correspond to suspended sediment and 21% is bedload. On the other hand, approximately 320 t.km-².year-1 are retained in the surface reservoirs: 91% are trapped in small reservoirs and 9% are trapped in the large dams of the basin. It can be concluded that the results obtained in this study for the total sediment yield in a large river basin is in agreement to that obtained by other authors in South America. It should also be pointed out that the small dams play an important role in the region, not only in relation to the accumulation of water, but also to the retention of sediment generated in the basin. Such retention prevents that the sediment reaches the strategic dams (Orós, for instance), reducing their sedimentation rates and thus, minimizing the impact of sedimentation on overall water availability in the basin.