Study on solutions for operating inter-reservoirs in Vu Gia – Thu Bon river basin to reduce salt intrusion

Abstract

    In dry season, salt intrusion has frequently occurred at Vu Gia and Vinh Dien tributaries located atdownstream of Vu Gia - Thu Bon River Basin. This might be explained by the fact that the freshwater flow from upstream is not strong enough to prevent seawater to intrude. In addition, the flowregime in the rivers is also greatly affected by the operation of hydropower plants located at theupstream. Although there is an procedure for operating inter-reservoirs in Vu Gia - Thu Bon riverbasin (1537/QD-TTg), its implementation faces many difficulties due to conflicts betweendifferent water uses, leading to salt intrusion problem. This study has proposed a new operationplan to reduce salt intrusion in this river. Accordingly, with the same amount of water, Dak Mi 4areservoir should discharge from 22pm to 6am instead of continuously discharging 24 hoursaccording to the current procedure of 1537/QD-TTg. The results show that the new operation plandoes not affect Dak Mi4a's electricity production and reduce salt intrusion compared to the currentoperation procedure.