Measuring salinity, keeping fresh water for spring rice irrigation in Nghe An

Nghi Quang sluice gate system is closed to prevent salinity. Photo: Van Truong

Guard the sewer, keep fresh water

At Nghi Quang sluice gate, Nghi Loc district at this time, irrigation workers are deploying equipment to measure salinity.

A worker said: Every day, we use salinity measuring devices in many different locations to get accurate results. After taking water samples from the surface, middle and bottom layers of the river, we use measuring devices to analyze and update data hourly to check and ensure the quality of the water source. From there, we promptly warn local authorities and the Nam irrigation system, recommending people to use water reasonably, minimizing the harmful effects of salinity intrusion.

When detecting salt intrusion, waiting for the low tide, the operating department must urgently open the 1.5 meter wide sluice gate to discharge the bottom (salt discharge) with a flow rate of about 10m³/S.

Mr. Hoang Van Huong - Head of Nghi Quang sluice station said: Nghi Quang sluice system located in Nghi Quang and Nghi Thiet communes, Nghi Loc district has an important position in preventing salinity, keeping fresh water, serving irrigation production for the Southern Nghe An region with 23,000 hectares of rice, industrial parks, and people of Nam Dan, Nghi Loc, Hung Nguyen districts and Vinh city.

Workers of Nghi Quang bara sewer system take water samples to measure salinity on Cam River. Photo: Van Truong

Recently, due to the Lam River water level being too low, there is little fresh water in the downstream area of ​​the Cam River, so since the end of spring, every year there has been salt intrusion, especially from the Nghi Quang sluice area to Phuong Tich bridge, Nghi Phuong commune, causing difficulties inagricultural production

The current difficulty is that the Nghi Quang sluice system is seriously degraded, the entire system of 13 automatic gates, flat valve gates, arc gates, and automatic door locks are all broken, the traffic bridge is degraded, and the bridge beams are damaged. Saltwater infiltrates through the gate leaks; during the drainage season, the locking system is damaged so it cannot actively drain the flood.

"Currently, to deal with the saline intrusion caused by the leaking sewer system, we have to use old blankets rolled up and hire divers to "fill" them in. However, this is only a temporary solution. In the long term, the Nghi Quang bara system needs to be upgraded, otherwise the saline intrusion will increase, affecting the quality of water sources and crops," Mr. Hoang Van Huong added.

According to the report of Nam Irrigation Company Limited, thanks to the good implementation of water source monitoring, about 3,000 hectares of rice along the Cam River in the communes of Nghi Tien, Nghi Hung, Nghi Phuong... Nghi Loc district and some communes of Hung Nguyen district, up to this point, the irrigation water source is still safe and not affected by saltwater intrusion.

Nghe An has no salinity monitoring station.

Mr. Nguyen Truong Thanh - Head of the Irrigation Sub-Department said: In recent years, Nghe An is one of the provinces affected by climate change. Especially drought and salinity intrusion in the hot season have caused many agricultural production areas of the province to lack irrigation water.

Workers had to borrow local boats to go to the middle of the Cam River to take water samples to measure salinity. Photo: Van Truong

To protect crop areas and minimize damage caused by drought and salinity intrusion, the Irrigation Department directed irrigation management units in the Southern system of Nghi Loc, Hung Nguyen, and Nam Dan districts to assign workers to be on duty at the main sluice gates in the area. Strengthen water source monitoring on rivers, at the locations of main sluice gates and in the fields, pumping stations at risk of salinity, and completely close the main sluice gates when salinity intrusion occurs. At the same time, notify the locality about the quality of water sources, absolutely do not pump when the salinity concentration is >= 1‰.

The functional unit updates the water level of each tide and measures the water quality, presses and releases salt appropriately. Strictly manage water sources, prevent leakage and loss; during the period of severe drought and salinity, prioritize water for daily life, drinking water for livestock, etc.

At the same time, localities in the province are taking measures to maintain and repair damaged and degraded works; speeding up the construction progress of drought and salinity prevention works to put them into operation, promptly preventing salinity and storing fresh water to serve production and people's lives during the hot season, such as the project to upgrade the Mo River dike, the section through coastal communes including Quynh Bang, Quynh Luong, Quynh Minh, Quynh Nghia (Quynh Luu)...

The meter reports salinity measurement data. Photo: Van Truong

A representative of the North Central Hydrometeorological Station said: Nghe An has a system of Lam and Cam rivers that are often affected by salinity in the hot season, however, the difficulty is that Nghe An does not have any salinity monitoring stations. Currently, the hydrometeorological agency only has one salinity monitoring point on Lam river (near Ben Thuy bridge - Vinh city).

This salinity monitoring station is mainly operated manually, mainly during the hot season to monitor some salinity intrusions. Due to the lack of salinity monitoring stations, mainly manual operations, salinity monitoring is still facing many difficulties, and detailed assessment of salinity intrusion in the whole region is not possible.

In the long term, it is necessary for the State and investment projects to modernize and automate the salinity measurement system to assess the current status of salinity, as well as accurately and quickly forecast salinity intrusion to ensure effective rice irrigation.

Van Truong