Inadequacies in management of lakes, irrigation dams and hydroelectric power plants
(Baonghean.vn) - Ensuring the safety of lakes, irrigation and hydroelectric dams has been an issue of concern to state management agencies and public opinion for many years.
The management, supervision and operation of reservoirs, dams and hydroelectric reservoirs will directly impact the production and living activities of the people. However, the reality of the past time shows that there are still many shortcomings and inadequacies related to this work.
MANY DAMS ARE UNSAFE
Nghe An currently has 1,061 reservoirs, including 55 large reservoirs, 220 medium reservoirs and 786 small reservoirs. According to decentralization, irrigation limited liability companies manage 101 reservoirs; localities manage 960 reservoirs. Currently, only 2/1,061 reservoirs have gates and operating procedures, the rest are regulated by free spillways.
The largest reservoir in Nghe An today is Vuc Mau Lake (Hoang Mai town). The lake has a capacity of 75 million m3, basin area 215km2, providing irrigation water for 3,431 hectares, aquaculture water for 400 hectares, and domestic water for 119,000 people in the area including 19 wards and communes of Hoang Mai town and Quynh Luu district. The lake has 5 regulating gates operated by electric winches. The project was renovated and upgraded in 2010 and the water intake culvert was repaired in 2020. This is the only irrigation reservoir in Nghe An province that has a SCADA monitoring system connected to the General Department of Irrigation.
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Spillway discharge of Vuc Mau reservoir. Photo: Pham Bang |
The flood in late September and early October was caused by the circulation of storm No. 4.Hundreds of households in Hoang Mai town were severely flooded., lasting for many days. The initial cause was believed to be due to the flood discharge of Vuc Mau reservoir. However, according to the report of Bac Nghe An Irrigation Company Limited - the unit managing and operating Vuc Mau reservoir, the flood discharge of the reservoir strictly followed the procedures. Accordingly, at that time, there was very heavy rain in Hoang Mai area, blaming Vuc Mau reservoir for causing severe flooding is incorrect.
Before storm No. 4 made landfall, the unit also proactively discharged floodwaters, when the water level in the reservoir had not yet reached 21m - the normal water level, or even 22.72m - the flood cut-off level. According to the leader of the Bac Nghe An Irrigation Company Limited and through the investigation of Nghe An Newspaper reporters, one of the causes of flooding was the silting up of the Hoang Mai River, blocking its flow. In particular, the construction of the North - South Expressway project by some units has caused rocks and soil to block the flow, causing prolonged flooding and slow water drainage.
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Flooding in Hoang Mai town in late September 2022. Photo: Nhat Thanh |
The current state of many lakes and dams, especially those managed by local authorities, is seriously deteriorating. According to annual statistics, dam and reservoir management units only have enough funds to repair and reinforce severely damaged items that pose a high risk of being unsafe before the flood season.
According to statistics from the Department of Agriculture and Rural Development, from 2000 to now, 374 lakes have been upgraded and repaired; 687 lakes have not been repaired or upgraded, of which 70 are severely damaged and at risk of being unsafe. In addition, most reservoirs do not have measuring and monitoring equipment; specialized irrigation staff at district and commune levels are limited, so reservoirs managed by localities are not proactive in natural disaster prevention and control. Some contents on dam and reservoir safety management according to the law have not been implemented due to financial difficulties such as: Setting up protective markers for dams and reservoirs; establishing operating procedures; dam safety inspection; installing monitoring and operating systems, information equipment, warning of dam and downstream areas' safety; building flood maps...
MORE TRANSPARENCY IS NEEDED IN THE OPERATION PROCESS OF HYDROPOWER RESERVOIR SYSTEMS
Currently, there are 32 hydropower projects in the area, of which 22 hydropower plants have been put into operation with a total capacity of 934.9 MW. Of the 22 hydropower plants in operation, only two are designed to prevent flooding downstream: Ban Ve (Tuong Duong) and Hua Na (Que Phong). According to the operating process, Ban Ve Hydropower Plant haswater regulation function(store a part of the flow in high water years to supply more water in low water years). The capacity of Ban Ve reservoir is 1.8 billion m3, at the normal water level elevation of 200m, of which 320 million m3is the capacity to prevent floods.
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Panorama of Ban Ve Hydropower Plant. Photo: Linh Chi |
Similarly, Hua Na Hydropower Plant is designed to regulate water annually. Hua Na reservoir operates according to the inter-reservoir operation process on the Ma River basin. The reservoir capacity is 569.35 million m3At normal water level, the reservoir has a flood capacity (from 235m to 240m) of 100 million m3. Hua Na Lake flows downstream to Cua Dat, Thanh Hoa province.
In addition to Ban Ve and Hua Na hydroelectric reservoirs, the remaining 20 reservoirs operate on a day-night regulation mode. That is, they regulate and redistribute the river flow to suit the water demand within a day. These reservoirs also do not have flood prevention capacity, and do not have the function of cutting and reducing floods for downstream areas. In addition, the situation of the reservoir bed being silted up is a real problem for small and medium-sized hydroelectric plants. Therefore, the water storage capacity is not guaranteed as originally designed. When there is heavy rain, the water level is not yet at the flood discharge level, but many plants have to discharge flood water. And then the people in the downstream areas are directly affected.
For a long time, we have been quite familiar with the phrase: "Inter-reservoir operation process". This process is regulated by the Government. Inter-reservoir operation can be simply understood as the coordination and unification in the process of operation, flood reception, flood discharge, flood reduction between adjacent hydroelectric plants and dams in the same area. The implementation of the inter-reservoir operation process during the rainy season is of great concern to state management agencies, local authorities and people. A leader of a mountainous district - a locality with many hydroelectric projects - said: The inter-reservoir operation process has detailed and specific regulations for each river branch, but the most important and most concerning thing is whether the plants have actually operated the flood discharge according to that process or not. "He announced that the flood would be released at 3 p.m., but it was already released at 12 p.m., so the downstream area would not be able to react in time," said the leader. He also said that there needs to be an online monitoring and surveillance system so that the provincial authorities can check and supervise, especially during times of complex floods.
Currently, online monitoring of flood discharge operations is only carried out at a few hydropower plants, many small and medium-sized projects cannot be closely monitored.
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Khe Bo Hydropower Reservoir operates flood discharge (photo taken at 9:42 a.m. on September 30, 2022). Photo: Provided by Tam Quang Commune People's Committee |
The 22 hydropower projects currently operating in Nghe An are all built in the Western region, formed according to the slope of the mountainous terrain. Figuratively speaking, hydropower plants are built in steps from high to low. For example, on the Nam Mo River. Just one section of the river has 7 medium and small hydropower plants. If we count the Southwest Nghe An region on the Ca River, there are up to 13 hydropower plants.
The construction of irrigation reservoirs like this, if not following the inter-reservoir operating procedures, will easily create disasters for the downstream areas. And through the floods in Western Nghe An, people still question the transparency of flood discharge activities. “Water is money. Keeping water is keeping money, it must be managed by an online monitoring system, every day, every hour, even every minute in extreme weather conditions to minimize damage to people. Electricity is also precious, but the lives and property of thousands of households are even more precious,” said a leader of a mountainous district.
In addition, according to the Department of Industry and Trade, the disaster response plans of some hydropower plants have not been fully developed and approved in terms of specific contents and situations. Some dam and reservoir owners have not yet made plans and coordinated with local authorities and local disaster prevention and control command boards to conduct drills of situations according to approved plans such as: Dam and reservoir protection plans; natural disaster prevention; flood prevention in downstream areas; emergency response.
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A working group from the Ministry of Finance conducted a field survey at the landslide site on the Lam River bank through Hung Nguyen district. Photo courtesy: Tien Dong |
HYDROLOGICAL MONITORING HAS NOT BEEN GIVEN LESS THAN ONE KIND OF ATTENTION
Understanding and monitoring hydrometeorological forecasts is very important in the operation of dams in general and hydroelectric reservoirs in particular. Especially the issue of hydrological monitoring. According to the assessment of the Department of Industry and Trade, hydropower plants basically comply with the regulations on monitoring regime as prescribed in Decree No. 114/2018/ND-CP, Decree No. 38/2016/ND-CP dated May 15, 2016 of the Government detailing a number of articles of the Law on Hydrometeorology, Decree No. 48/2020/ND-CP dated April 15, 2020 of the Government amending and supplementing a number of articles of Decree No. 38/2016/ND-CP. However, there are still some plants that have not fully implemented the data storage as prescribed in Article 16 of Circular No. 17/2021/TT-BTNMT dated October 14, 2021.
For example, the implementation of hydrological monitoring of hydropower plants with large installed capacity is Ban Ve and Hua Na. Specifically, Ban Ve Hydropower Company has coordinated with equipment suppliers to install hydrometeorological monitoring stations in the reservoir, including installing 1 hydrological station to monitor flow, water level, and rainfall factors in the upper reaches of Ca River, in My Ly commune, Ky Son district. Installing 21 automatic rain gauge stations, of which 12 stations are in Laos and 9 stations are in Vietnam. However, the monitoring system still does not meet the actual needs.
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Ban Ve Hydropower Company installs rain gauge stations in Laos. Photo: TC |
Hua Na Hydropower Joint Stock Company signed a service contract with the North Central Hydrometeorological Station to forecast hydrometeorology in the basin and forecast water flow to the reservoir. Currently, this company has not collected meteorological and hydrological data from Laos, and there are no rain gauge stations in the basin of Laos, so it has encountered many difficulties in the process of operating the reservoir.
Mr. Tran Quoc Toan - Deputy Head of the Irrigation Sub-Department (Department of Agriculture and Rural Development) said that currently, except for the Ban Ve Hydropower Plant which has installed a hydrological monitoring station system (although it has not met the requirements), the remaining medium and small hydropower reservoirs have not really paid attention to this issue. Meanwhile, the installation of a hydrological monitoring system will help hydropower plants forecast and calculate the water flow to the reservoir to regulate flood reception and discharge accordingly, avoiding falling into a passive position causing unpredictable damage.
