Manmade lakes for water storage could curb floods, droughts, saltwater

April, 15/2016 - 09:00

Oceanographer Trương Đình Hiển talked to Tuổi Trẻ (Youth) newspaper about measures suggested to cope with drought and saltwater intrusion in the Cửu Long (Mekong) Delta region.

Oceanographer Trương Đình Hiển talked to Tuổi Trẻ (Youth) newspaper about measures suggested to cope with drought and saltwater intrusion in the Cửu Long (Mekong) Delta region.

There are currently two opinions on the situation in the Mekong Delta region. Many scientists have said dealing with saltwater intrusion and the lack of fresh water is a challenge for the region but also an opportunity to improve the area’s economic structure. However, others have said we still need to protect rice crops, which means protecting the fresh water sources. What do you think?

In my opinion, we still need fresh water to grow rice and other traditional crops to keep us alive. However, we cannot prevent saltwater intrusion completely.

So what measures can be adopted to deal with the issue?

Twenty years ago, I told former prime minister Võ Văn Kiệt it was a waste for the region to be flooded during the monsoon season when we still lacked water for cultivation and for pushing back saltwater during the dry season. Based on that, I proposed a solution for the Mekong region involving building a system of lakes to store the water. These lakes would also prevent floods during the monsoon. We could use that water to prevent droughts and saltwater intrusion during the dry season.

Gradually, we can develop new flood-resistant urban areas while developing a fresh water aquaculture economy and tourism trade. In particular, these lakes will also contribute to regulating the climate and environment and mitigating the impact of global economic changes on the region.

Will this plan exceed our capacity?

Just looking back at the history of the northern region, from the Lý Dynasty onwards, tens of decades ago, our ancestors built dykes to form Hà Nội and the whole cultivation area of the Hồng (Red) River Delta that we currently see. What did our ancestors have? They only had some millions of people without any modern equipment or scientific applications. They could not even borrow foreign capital as we can now. However, they were still able to do it and complete their mission. So why are we afraid?

Also, it should be noted that the dyke system of the northern region was built on a larger scale and took more time to build than the system of lakes I have proposed.

Regarding measures to execute the project, we should carefully study the location of the whole Mekong Delta region to find an area with high levels of alum in the soil, low agricultural productivity and not too many inhabitants so the lake system can be zoned off.

The lakes should be located near the valley of major rivers, such as Tiền River, Hậu River and Vàm Cỏ River.

In this first step, it is necessary to organise a wide range of conferences to collect opinions from scientists, the authorities and the locals.

After that, we will start digging lakes. I initially propose that each lake should be 5km x 10km or 5km x 20km wide and 10m deep, but this recommendation still needs more study. Soil dug up from the lakes could be used to build a flood-resistant residential area along the riversides.  

In your opinion, how many lakes will we need?

Based on my own calculations, we need more than 10 lakes, which are equivalent to the total area of some small districts, because not all areas in the Mekong Delta region suffer from droughts and saltwater intrusion.

However, we still need more studies on the trend of climate change in the future and the exact number of lakes needed if the proposal is approved. Such study is within the capacity of today’s scientists.

Moreover, we cannot dig all the lakes simultaneously. It will take 5-10 years or more. The number of lakes needed to be built will depend on the true demand.

What are the difficulties in carrying out this idea if it is approved?

Many countries in the world have done it, including Thailand. I think we can start the project in another year or two after conducting studies and collecting opinions from experts and scientists. With the current scientific and technological advancements and modern equipment, it will only take a year at the most to dig one lake.

However, it should be noted that everything we do needs the agreement of the people. We will receive support from everyone if the plan is carried out transparently and without corruption. I have even considered issuing bonds to mobilise capital from the people in order to run the project. — VNS