Sedimentation Study of La Esmeralda Reservoir, Colombia

Client: AES Chivor & Cia S.C.A E.S.P.

Contract Period: 2012-2013

La Esmeralda Reservoir, also know as Chivor, impounds water from the rivers Garagoa and Somondoco, in Colombia. The project consisted in the development of sediment management strategies at the 758 Mm3 Chivor hydropower reservoir, with 1,000 MW installed capacity. The reservoir is experiencing accelerated sedimentation, which also presents navigational problems in the delta region affecting protected indigenous communities.

The study consisted in the development of sustainable sediment management plan for the reservoir which supplies the AES-Chivor power station (1,000 MW, 8 pelton units operating under 800 m of head, 120 m3/s). This reservoir has now lost 24% of its capacity and sediments are approaching the deep power intake. Work involved preliminary site visit, data review and report, vibracore sampling of reservoir sediment to depths exceeding 60 meter, operational/energy and sediment transport modeling, and reporting.

Deep water sediment sampling was performed using the Vibe-Core D equipment to extract 3 meter long sediment core to analyze and document the sediment gradation along the reservoir. The sediment sampling established that no sand particles were found near the intake.

Sediment transport modeling was undertaken to better understand the rate and pattern of sediment deposition along the reach of the river over the next 100 years using the Bureau of Reclamation sediment transport model SRH-1D. The model results provided information on the useful life of the reservoir, by maintaining the current operational scheme, and also analyzed modifications to the minimum operational level to determine the benefits in relation to a reduction of the advancement of the delta deposits toward the intake.