Warning of early risk of drought and saltwater intrusion in Nghe An
(Baonghean.vn) - Low water levels on rivers, forecasted severe heat, and deep and early seawater intrusion are factors that could cause saltwater intrusion to come early in some areas of Nghe An right from the end of the spring crop.
Early drought and saltwater intrusion
This year, right from the beginning of the spring crop, more than 1,000 hectares of rice in Thanh Chuong, Do Luong, Hung Nguyen districts... have been affected by drought. The reason is that many pumping stations along the Lam River in the Southern Irrigation System were unable to operate at times because the river water level was too low.
Since the beginning of the year, the water level at Nam Dan sluice has been at -0.6m/design 1.15m, even lower at many times, the water input source is extremely difficult. Mr. Bach Hung Trung - Head of Bara Nam Dan station said: If the river water is "exhausted" for too many days, there is a risk of saltwater intrusion, pumping stations along Lam River must regularly measure salinity before pumping. Recently, the unit has focused on dredging and clearing the junctions and channels along low canals and channels; organizing 24/24h duty to promptly open and close sluices when the tide rises and falls to keep water for the fields.
Since mid-April, saltwater has begun to intrude through Nghi Quang sluice gate (Nghi Loc), spreading to Nghi Thuan commune, located 9 km from the project; by the end of the month, saltwater intruded to Cam bridge at a fairly high level, the fresh water layer was only about 1.5 m. According to Mr. Nguyen Dinh Tuan - Deputy Station of Nghi Quang Bara Station, saltwater intrusion is a familiar phenomenon in many years. However, this year, due to the project's increasingly rapid and severe deterioration, the water difference between upstream and downstream is too large, pushing the saltwater source up quickly.
The water level on Lam River is too low, there is no fresh water at the end of Cam River, the sluice gate system is so degraded and damaged that salt water intrudes very quickly.
With the task of preventing salinity, keeping fresh water and serving irrigation for the Southern Nghe An region with 23,000 hectares of rice, in 2023, Nghi Quang bara has invested in renovating the gate and 6 flat valve gates. Currently, the Department of Agriculture and Rural Development has sent a document to the Department of Planning and Investment to continue upgrading the remaining 6 flat valve gates. While waiting, from the beginning of the spring crop, the management unit had to take a temporary measure of using blankets to block the gaps of the gates, but after a short time under the impact of water, these items were broken again. During peak periods, the unit had to assign people to be on duty,salinity measurement3-4 times/day.
Proactive early solutions
The fresh water source in the Southern Irrigation System mainly depends on Lam River water, so if the water level on the river drops, almost the entire system will not have additional fresh water, salt water will penetrate into the fields through Nghi Quang and Ben Thuy sluices.
Mr. Ta Duy Hien - Deputy Director of Nam Irrigation Limited Liability Company said: This year, according to forecasts, the temperature will be higher, the weather will be hot, the water level in the system will be lower and lower, the door system at Nghi Quang wharf is damaged so the water retention capacity will be limited, seawater will enter deeper and earlier, saltwater will penetrate more easily.
“A plan to combat drought and saltwater intrusion has been developed since the end of the winter-spring crop to be proactively implemented when needed. Currently, we are regularly monitoring the water quality on the river. If there are signs of saltwater intrusion, we will immediately implement a plan to seal the water at the bara.Nghi Quangand build a soft dam on the Cam River so that water from Nghi Quang sluice does not encroach too far into the end of the system in Nghi Loc district," Mr. Ta Duy Hien shared.
Currently, water levels at key projects such as the upstream of Nam Dan sluice, Ben Thuy sluice, Nghi Quang sluice, etc. are all lower than in previous years; water levels at pumping stations directly taken from the Ca River are also lower than in the same period in 2023.
Mr. Nguyen Truong Thanh - Head of the Irrigation Sub-Department said: Severe heat, low water levels in fields, rivers and streams are factors leading to the risk of seawater intrusion, affecting agricultural production. However, the issue of preventing and combating saltwater intrusion is still facing many difficulties, due to both objective factors of natural disasters, weather and the inadequacy and degradation of the construction system.prevent saltiness and keep sweetness.
“Management units must operate the final sluices of the system according to the correct procedures. Water supply units must regularly measure and check the salinity concentration, monitor and check the salinity concentration in rivers and pumping stations at risk of salinity daily to notify localities about the quality of water sources. Absolutely do not pump when the salinity concentration is >= 1%o,” Mr. Nguyen Truong Thanh recommended.
