Supplementing regulations on inter-reservoir operation in the Red River basin during the transitional period and water storage

Hoa Binh Hydropower Plant

Decision No. 922/QD-TTg supplements regulations on inter-reservoir operations in the Red River basin during the transitional period, water storage: from September 16 to October 31.

Specifically, amend and supplement Article 9 on operations during late flood periods, transition periods, and water storage as follows:

1. From August 22 to September 15, based on the assessment of hydrometeorological trends by the Department of Hydrometeorology, the Minister of Agriculture and Environment decided to gradually accumulate water in Son La Lake to an elevation of 213 m, Hoa Binh Lake to an elevation of 115 m, Tuyen Quang Lake to an elevation of 118 m and Thac Ba Lake to an elevation of 58 m.

During the water storage process, if the Department of Hydrometeorology forecasts that there is a possibility of a flood, the Minister of Agriculture and Environment shall consider and decide on the operation and regulation to gradually lower the water level of the reservoirs, but not lower than the maximum water level value specified in Table 3. During the process of Hoa Binh, Tuyen Quang and Thac Ba reservoirs being operated and regulated to gradually lower the water level of the reservoirs to the elevation specified in Table 3, if a major flood occurs in the reservoirs or the water level at the Hanoi hydrological station is at risk of exceeding the elevation of 10.5 m, the Minister of Agriculture and Environment shall consider and decide on the operation and regulation of the reservoirs to cut and reduce floods for the downstream. If the flood flow into the lake continues to increase, the lake water level is at risk of exceeding the normal water level and the water level at the Hanoi hydrological station is at risk of exceeding the 11.5 m elevation, the Minister of Agriculture and Environment shall preside over and coordinate with the Ministry of Industry and Trade to consider and decide to use part of the flood control capacity of the project to reduce flooding downstream but must ensure the safety of the project.

2. From September 16 to October 31, Son La, Hoa Binh and Tuyen Quang reservoirs will be proactively filled to the normal water level. During the water filling process, in case the Department of Hydrometeorology warns or forecasts a storm, tropical depression or other weather conditions that are likely to cause floods that may directly affect the reservoir basin within the next 5 days, if the reservoir water level is higher than the 115 m elevation for Hoa Binh reservoir and 118 m for Tuyen Quang reservoir, the Minister of Agriculture and Environment will consider and decide on the regulation operation to gradually lower the water level of the reservoirs, but not lower than the water level of 115 m for Hoa Binh reservoir and 118 m for Tuyen Quang reservoir.

If the lake water level is lower than the elevation of 115 m for Hoa Binh Lake and 118 m for Tuyen Quang Lake, the lakes operate to maintain the current lake water level to receive floods.

3. During the water storage period, Son La reservoir is allowed to use its capacity from the normal water level to the maximum designed water level (217.83 m) to cut floods downstream.

4. When Hoa Binh, Tuyen Quang and Thac Ba lakes have accumulated to the normal water level but the flow to the lakes continues to increase, they are allowed to discharge water downstream equivalent to the flow to the lakes.

Operation in abnormal situations, natural disaster emergencies

Decision No. 922/QD-TTg also amends and supplements Article 12 on operations in unusual situations and emergency situations due to natural disasters:

1. During the flood season, when Son La, Hoa Binh, Thac Ba and Tuyen Quang reservoirs have exhausted their flood-cutting capacity, but the water level of the Red River at the Hanoi hydrological station continues to rise rapidly, or there is a risk of serious incidents occurring to the dike system, or it is assessed that there is a possibility of a flood greater than the 500-year flood occurring once, but smaller than the design flood of Son La reservoir (the 10,000-year flood occurring once), or emergency situations related to natural disasters occur, or unexpected situations occur as prescribed in this Procedure that threaten the safety of dikes, works and downstream areas, the Minister of Agriculture and Environment shall report to the Prime Minister, and at the same time report to the Head of the National Civil Defense Steering Committee for consideration and decision on the operation of reservoirs, or perform assigned and decentralized responsibilities according to the provisions of law.

2. In addition to the flood season operation time specified in Article 2 of this Procedure, the Minister of Agriculture and Environment shall decide on the operation of Son La, Hoa Binh, Thac Ba, and Tuyen Quang reservoirs according to the provisions of this Procedure when one of the following unusual flood cases occurs:

a) When downstream there is a risk of flooding of level 2 or higher according to regulations on natural disaster risk levels;

b) Incidents occur during the operation of construction safety assurance items;

c) There is a dike incident or there is a threat to the safety of the dike, hydraulic works, and downstream infrastructure;

d) Other situations that pose a threat to the safety of downstream areas as decided by the Head of the National Civil Defense Steering Committee;

d) The consideration and decision on operating plans for reservoirs in the cases specified in points a, b, c, and d of this clause to reduce floods downstream must ensure the safety of the works.

3. During the operation of the reservoir as prescribed in Clause 2 of this Article, when the downstream is at risk of flooding above level 3 according to the regulations on the level of natural disaster risk or the risk of incidents occurring during the operation of items that threaten the safety of the project or when there are complex natural disasters, with the risk of causing serious consequences and occurring on a large scale, the Minister of Agriculture and Environment shall preside over and coordinate with relevant ministries and branches to report to the Prime Minister, and at the same time report to the Head of the National Civil Defense Steering Committee for consideration and decision on response solutions or implementation of assigned, decentralized and coordinated responsibilities in responding to natural disaster emergencies according to the provisions of law on emergencies.

4. In addition to the flood season operating time specified in Article 2 of this Procedure, Son La reservoir is allowed to use its capacity up to the maximum designed water level (217.83 m) to cut floods for downstream areas.

Thanh Quang

Source: https://baochinhphu.vn/bo-sung-quy-dinh-van-hanh-lien-ho-chua-tren-luu-vuc-song-hong-thoi-ky-chuyen-tiep-tich-nuoc-102250514171529712.htm