HCM CITY — The Tiền and Hậu rivers in the Cửu Long (Mekong) Delta have become deeper in recent years instead of having silt build-up like in years past, experts have said.

The 250-kilometre-long Tiền and 200-km-long Hậu, tributaries of the Mekong, are two major rivers in the delta, which is the country’s largest rice, fruit and seafood producer.

Hoàng Văn Hùng, head of the Việt Nam Inland Waterways Administration South Branch, said their depth has been increasing faster since 2008, now at an average of three to seven metres.

The situation is occurring along their entire lengths, he was quoted as saying in Tuổi Trẻ (Youth) newspaper.

Nguyễn Hữu Thiện, an ecologist based in the delta, attributed the deepening to excessive sand mining and the impacts of hydropower dams upstream.

Hydropower dams along the Mekong in China have caused a 50 per cent reduction in fine grained sediments in the delta, he said.

Delta provinces are exploiting the Mekong uncontrollably, he added.

Lê Mạnh Hùng, deputy head of the Department of Irrigation, said in 2013 he presided over a research project on the impact of sand mining on the Tiền and Hậu rivers.

The delta provinces’ zoning plans for sand mining have not considered whether the mining could cause erosion of the river bed while mining process is not appropriate and does not safeguard river banks and beds from erosion, he said.

Besides, the provinces only estimate the reserves of sand and grant licences without evaluating the volume of sediments washed from upstream areas, he said.

“With the current mining volume, the delta will mine all sand reserves in the Tiền and Hậu rivers in less than 30 years.”

Huỳnh Yến Vân, deputy head of the Bến Tre Province Natural Resources and Environment Department’s Hydro-meteorology and Marine Resources Division, said a recent department study found that silt build-up in the Tiền, Hàm Luông and Cổ Chiên rivers is very slow and even absent in some places.

While silt deposits normally recover over a period of time, it is not happening now as a result, she said.

In Bến Tre, the provincial Fatherland Front earlier this month informed the People’s Council that the public opposed a plan to dredge a passage in the Tiền River in Chợ Lách and Châu Thành districts.  

The Tiền Giang Province People’s Committee has stopped issuing licences to mine sand in the Tiền to ensure the river bed and banks are not eroded.

However, three companies have been licensed by the Ministry of Transport to dredge a stretch of the river from its mouth to Đồng Tháp Province.

Earlier this month Tiền Giang petitioned the ministry to stop existing sand mining projects and not grant any new licences.

The Đồng Tháp People’s Committee has also petitioned the ministry not to dredge a passage in Châu Thành District’s An Hiệp Commune and Cao Lãnh District’s Bình Thạnh Commune.

Đinh Công Sản, deputy director of the Southern Institute of Water Resources Research’s Centre of River Training and Natural Disaster Mitigation, said some provinces in the delta have stopped issuing licences to mine sand.

The Government should study and identify areas where sand can be mined while also ensuring easier transportation there, he said.

Sản said a major programme that would cost 1 million euros and be funded by the EU would study erosion in the delta’s coastal areas.

All issues such as the impact of less silt carried down the Mekong to the delta, sand mining, climate change and rise in seawater levels would be evaluated, he said.

“Based on the evaluation results, sustainable solutions will be found.” —VNS