Dykes, canals to stem saltwater

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VietNam News English - 79 month(s) ago 7 readings

Nguyen Ngoc Anh, director of the Southern Irrigation Planning Institute, spoke with Vietnam News Agency about measures to help the Cuu Long (Mekong) Delta deal with drought and salt-water intrusion.

Can the Cuu Long (Mekong) Delta irrigation network up to handling increasingly fierce droughts and salt-water intrusion?

Climate change and rising sea levels have badly affected the Cuu Long (Mekong) Delta, especially in terms of river flow, low-water marks, which have dropped to below the average levels, and irrigation networks.

While irrigation demand remains manageable, the network's ability to deal with salt-water intrusion has revealed shortcomings, which have resulted in a deepening problem.

In remote areas, where fresh water is limited, intra-field canal systems are not capable of storing enough fresh water for crops.

To curb the impact of salt-water intrusion, farmers have been advised to plant different crops, to dredge canals and ditches regularly to improve water supply and to embank field edges more securely.

What about long-term measures?

Responding to current and future problems, the Southern Irrigation Planning Institute and the Ministry of Agriculture and Rural Development have been working with local authorities in developing palpable solutions aimed at stemming the advance of salt water.

Proposed suggestions currently centre on continued consolidation of sea and estuary dykes, the building of more intra-field canal systems and the upgrade of sewerage at big estuaries.

In areas such as Dong Thap Muoi on the Ca Mau Peninsula, irrigation works have yet to receive proper investment. At the moment we are busy examining sewage and irrigation systems in the Tien and Hau Rivers as well as various sea dykes to ensure the effective control of saltwater levels and the prevention of flooding in flood-prone areas.

One of our major objectives is to set up a stable fresh water supply to feed crops in the Tien River, Hau River and Dong Thap Muoi areas as well as in the Long Xuyen quadrangular and the Ca Mau Peninsula.

What does the Cuu Long (Mekong) Delta irrigation plan, drawn up by the Southern Irrigation Planning Institute, entail?

The plan includes six main features. Firstly, to continue upgrading irrigation works. Secondly, to continue the consolidation of river and sea dykes, under Programme 667, from central Quang Ngai Province to southern Kien Giang Province.

Thirdly, to review the diverging gate system to control flooding. Fourthly, to upgrade canal networks that lead water from rivers to cultivation lands as well as drain off the water. Fifthly, we plan to upgrade the sewerage systems of five Mekong River branches including Cai Lon, Cai Be, Vam Co, Ham Luong, Co Chien and Hong. The sixth point includes developing anti-flood systems in the region's big urban areas including Can Tho and Vinh Long cities. All work is expected to be completed between 2030 to 2050.

Sharing only one water supply network, rice and shrimp farming have long been in conflict, the one needing fresh water and the other salt. How can this problem be settled?

Brackish water shrimp farming started in the region from 1990-95 and re-emerged in 2001 due to the availability of brackish water, large-scale farming areas and high productivity.

Besides dependence on salt water, shrimp farming also needs fresh water in de-salting and in avoiding environmental damage.

The unplanned for expansion of shrimp farming resulted in water shortages in terms of both rice and shrimp production. Since last year, the Agriculture and Rural Development Ministry approved a project worth more than VND660 billion (US$32 million) to set up sewerage systems in Soc Trang and Bac Lieu provinces to assist in deflecting fresh and salt water and help settle the dispute. — VNS

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