DNO - On the afternoon of June 11, the Department of Natural Resources and Environment held a scientific workshop to review and evaluate difficulties and obstacles and collect opinions from experts, scientists, and management units on proposals to supplement and adjust the operating procedures of inter-reservoirs in the Vu Gia - Thu Bon river basin.
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| Scene of the scientific conference. Photo: HOANG HIEP |
This workshop took place right after the salinity of Tuy Loan River and Yen River downstream of An Trach Dam had just decreased due to the hydropower plant releasing water at a higher flow rate than before, combined with 2 days of rain and low tide, so there were many heated discussions.
Dr. Le Hung and Dr. To Thuy Nga, lecturers of the Faculty of Hydraulic Construction, University of Technology - University of Danang, proposed that the dam crest elevation on the Quang Hue River during the dry season be 2.6m and the solution to operate the Song Bung 5 and Song Bung 6 hydropower reservoirs corresponding to the above dam crest elevation to ensure continuous flow downstream.
At the same time, supplement the regulation on the lowest water level according to 5 stages during the flood season to minimize the risk of not being able to fill the lake or not being able to accumulate much water in years without floods.
The highest water level before flood and the lowest flood receiving water level of the reservoirs are also proposed to be divided into 4-5 stages instead of just 2 stages to increase flexibility in flood cutting and reduction operations for downstream areas, while still ensuring the highest water accumulation at the end of the flood season.
Along with that, supplement the regulation to assign the authority to manage the water discharge of hydroelectric reservoirs to the Chairman of the People's Committee of Da Nang City when the water level of Yen River at the upstream of An Trach dam drops below 1.8m for more than 12 hours in 1 day or when the salinity of Cam Le River at the raw water intake of Cau Do Water Plant is greater than 1,000mg/l for more than 12 consecutive hours, in order to limit the situation of Yen River water level dropping too low and salinity intrusion too deep into Tuy Loan River and Yen River at the downstream of An Trach dam as in the past.
Representatives of some units managing and operating hydroelectric reservoirs proposed some additional solutions to ensure flood reduction and water supply operations downstream.
The representative of the owner of Dak Mi 4 hydropower reservoir proposed to consider recalculating the water level at Ai Nghia Hydrological Station appropriately to save and use water from this hydropower reservoir effectively; allow Dak Mi 4 hydropower reservoir to generate electricity 2m below the dead water level to ensure electricity and water supply in case the flood season comes late; discharge water to the downstream of Vu Gia river 8m below the dead water level...
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| Dr. Le Hung, lecturer of the Faculty of Hydraulic Construction, University of Technology - University of Danang, proposed to add regulations on the lowest water level during the flood season in 5 stages instead of just 2 stages. Photo: HOANG HIEP |
However, some representatives of the reservoir owners suggested that there should be more results to verify the hydrological situation in some specific years and argued that the nature of hydroelectric reservoirs is different from that of irrigation reservoirs. At the same time, there is no consensus on the regulation of the highest water level before the flood and the lowest water level during the flood in 4-5 stages because it will cause damage to electricity output and revenue, making it difficult to ensure the assigned targets and plans for electricity production.
Former Deputy Director of the Department of Agriculture and Rural Development Huynh Van Thang said that in this revision of the inter-reservoir operation process, it is necessary to limit conflicts in water exploitation and use; harmonize the interests of relevant parties in power generation and water supply for downstream areas.
In particular, pay attention to the issue of preventing salinity intrusion in the downstream of Vu Gia - Thu Bon rivers, not allowing salinity to penetrate deep into the mouth of Vinh Dien river at Vom Cam Dong (Dien Ban town, Quang Nam province) and Tuy Loan river as in the past.
Mr. Huynh Van Thang suggested that it is necessary to adjust the operation of Song Bung 4A and Song Bung 5 hydropower reservoirs to play the role of regulating daily water resources for the downstream of Vu Gia River during the dry season.
Accordingly, based on the water flow from the hydroelectric reservoirs regulating the yearly discharge, the two hydroelectric reservoirs Song Bung 4A and Song Bung 5 store and regulate with a steady flow for 24 hours a day, instead of discharging with a large flow for a period of time during the day. The State needs to have a financial mechanism for Song Bung 5 hydroelectricity to regulate water sources, creating a continuous flow downstream.
Head of the Irrigation Sub-Department (Department of Agriculture and Rural Development) Le Van Tuyen suggested that the revision and adjustment of the inter-reservoir operation process in the Vu Gia - Thu Bon river basin should limit the impact on the exploitation and use of water by people downstream of the An Trach dam as well as create a smooth, effective and quick coordination mechanism in solving problems related to water exploitation and use downstream.
Deputy Director of the Department of Natural Resources and Environment Nguyen Hong An suggested that the exploitation and use of water in the Vu Gia - Thu Bon river basin needs to harmonize the interests of relevant parties with the goal of ensuring people's lives above all.
The Department of Natural Resources and Environment will synthesize the opinions at the workshop and will report and submit to the Coordination Board for integrated water resources management of the Vu Gia - Thu Bon river basin and the coastal area of Quang Nam - Da Nang to report and propose to the Ministry of Natural Resources and Environment to adjust the inter-reservoir operation process in the Vu Gia - Thu Bon river basin in the coming time.
HOANG HIEP
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