Operating interconnected reservoirs in the Ca River basin: Harmonizing interests

(Baonghean) - For the first time, Nghe An province has been assigned the task of commanding and operating the flood discharge from the Ban Ve and Khe Bo hydroelectric reservoirs, a very significant responsibility. However, with the timely involvement of relevant levels and sectors, and the regulations assigning tasks to the implementing units, initial results show effectiveness in operating the interconnected reservoir flood discharge system.

Previously, the Ban Ve and Khe Bo hydropower plants applied a reservoir operation procedure approved by the Ministry of Industry and Trade, prioritizing: structural safety - power generation - flood control for downstream areas. Because prioritizing power generation over flood control for downstream areas, and because the procedure used single-reservoir operation, there were instances of flood releases causing flooding and damage to downstream areas. Therefore, on August 11, 2014, the Prime Minister issued Decision No. 1337/QD-TTg, promulgating the Inter-Reservoir Operation Procedure on the Ca River basin during the annual flood season. This revised the priority order to: ensuring structural safety – flood control for downstream areas – power generation; and assigned Nghe An province to directly command the operation of flood releases from the Ban Ve and Khe Bo hydropower reservoirs.

Ban Ve - Tuong Duong Hydroelectric Dam Project

Mr. Hoang Hieu – Deputy Director of the Department of Agriculture and Rural Development, Chief of the Office of the Provincial Steering Committee for Flood and Storm Prevention and Control and Search and Rescue, said: “This is the first time Nghe An has been assigned the task of commanding the operation of flood discharge from the Ban Ve and Khe Bo hydropower reservoirs, so it requires a great responsibility. However, practical experience is still limited, therefore, the Provincial People's Committee assigned the Steering Committee for Flood and Storm Prevention and Control and Search and Rescue to coordinate with relevant levels and sectors to develop an implementation plan and draft the assignment of tasks to relevant units. With the active participation of relevant levels and sectors, many practical suggestions have been contributed. Currently, we have finalized the regulations on task assignment to the units.”

The Provincial Steering Committee for Flood Control and Disaster Relief is responsible for commanding and operating the interconnected reservoirs. In addition to advising the Provincial Steering Committee for Flood Control and Disaster Relief and the Provincial People's Committee on the operation and regulation of the Ban Ve and Khe Bo reservoirs, it is also responsible for inspecting and monitoring the implementation of reservoir operation orders and notifying relevant levels and sectors of these orders. In case of any unusual incidents, it must report promptly so that relevant ministries and sectors can direct appropriate response measures. According to the province's assignment of tasks, the North Central Meteorological and Hydrological Station will strictly implement the monitoring and forecasting regime, provide information, advise on calculating the total flood reduction value, flood discharge volume, and determine the reservoir water level for flood control and flood discharge time. Furthermore, the Directors of Ban Ve Hydropower Company and Vietnam Electricity Development Joint Stock Company (Khe Bo Hydropower Company) are responsible for implementing reservoir operation orders in accordance with regulations. Relevant departments and agencies such as the Ministry of Agriculture and Rural Development, the Ministry of Industry and Trade, the Ministry of Natural Resources and Environment, the Ministry of Information and Communications, and the downstream districts, based on their specific functions and responsibilities, will coordinate to implement synchronously all tasks related to the operation process, flood mitigation, and remediation of consequences caused by flood releases.

Mr. Nguyen Quoc Toan – Deputy Director of Ban Ve Hydropower Company, said: “The total capacity of the Ban Ve Hydropower reservoir is over 1.834 million m3, the normal water level is 200 m, and according to regulations, the highest water level before the flood season is 192.5 m. Under normal weather conditions, the company proactively operates and regulates the reservoir to ensure that the water level does not exceed 192.5 m. In case of an emergency storm, a near-shore tropical depression, or weather conditions that may cause rain and floods and could directly affect localities in the Ca River basin within the next 24-48 hours, the Head of the Disaster Prevention and Search and Rescue Command of Nghe An province will decide to operate the reservoir. Following this procedure, on September 23, the upstream water level at the Ban Ve Hydropower reservoir only reached 199.48 m (more than 50 cm lower than the normal water level), with an inflow of approximately 550 m.” Regarding the flood control and search and rescue operation, the Provincial Steering Committee for Flood and Storm Prevention and Control directed the plant to release a total of approximately 460 m3/h, including 300 m3/h released through the power generation units and 160 m3/h released through the spillway. The Khe Bo Hydropower Plant also strictly adhered to the inter-reservoir operating procedures. Mr. Do Van Manh, Deputy Director of the Khe Bo Hydropower Plant, stated: “The total capacity of the Khe Bo Hydropower Reservoir is 97.8 million m3, with a normal water level of 65m. While the Ban Ve Reservoir participates in flood control downstream, the Khe Bo Reservoir operates to regulate the discharge flow equal to the inflow. Therefore, the Khe Bo Hydropower Plant recently released approximately 800 m3/h, equal to the inflow.” It is also known that the Khe Bo Hydropower Plant must regularly coordinate closely with the Nam Mo Hydropower Plant to ensure rational reservoir operation.

The coordination between the Provincial Steering Committee for Flood and Storm Prevention and Control and the two hydropower plants has shown clear effectiveness in the operation of interconnected reservoirs. According to Mr. Hoang Hieu, Chief of the Office of the Provincial Steering Committee for Flood and Storm Prevention and Control, “The province’s proactive decision to operate interconnected reservoirs in flood situations will find the most advantageous solution to minimize damage to downstream areas by controlling artificial flooding during water release, harmonizing the interests of the locality and power generation; and simultaneously, maintaining water levels during the dry season. However, to effectively manage the operation of interconnected reservoirs, in the future, coordination and drills between relevant levels, sectors, and people in downstream areas will be strengthened. At the same time, investment in modern equipment and machinery for hydrological work and increased personnel will be necessary…” To facilitate the command and control of the operation of interconnected hydropower reservoirs and ensure synchronized and timely coordination between relevant levels and sectors, as well as in downstream areas, the province has provided 100 million VND to pilot the application of information provision via the telecommunications sector's text messaging system…

However, the current concern regarding the operation of the interconnected reservoirs in the Ca River basin is that only the operating procedures for the rainy season and flood season exist, while those for the dry season are still lacking. Mr. Phan Van De, Deputy Director of the Department of Agriculture and Rural Development, stated: “The Ca River originates in Laos, so obtaining information about water flow and weather patterns during the dry season is very complex. Therefore, without an interconnected reservoir operation procedure, the downstream areas will face difficulties in accessing water for production and daily life during the dry season. Currently, the Department of Agriculture and Rural Development is guiding irrigation companies and downstream districts to provide feedback on the draft operating procedures for interconnected reservoirs in the Ca River basin during the dry season.”

Text and photos:Hoang Vinh