Mekong Delta braces for dry season with water storage arrangements
11 Oct 20 VNExpress Source People living in the Mekong Delta are installing tanks to store water for the dreaded dry season, and authorities are building artificial lakes.Pham Van Tien opens the cement tank which has rainwater from the previous night. During the last dry season Tien's family and some 11,000 others in the delta's Ben Tre Province suffered from a crippling water shortage.
The six tanks they had to store rainwater were not enough for Tien's family of four and their two cows. They often had to buy freshwater for VND80,000 ($3.46) for 1,000 liters and use it sparingly so that it lasted three or four days.
Tien, 35, says: "Droughts could come early in future, according to forecasts. So I hired workers to build four more tanks."
Each cost him around VND1.5 million, or twice as much as plastic ones.
Like Tien, many others in Ben Tre have been preparing for the upcoming dry season by building water tanks and dredging water channels.
Nguyen Van Hung said he recently bought a plastic container for water for VND3 million.
"The previous drought lasted too long. My family of six and our five cows had to endure thirst though we had dozens of cement tanks to store rainwater," he says.
To supply water to around 200,000 people in 24 communes and towns, a lake was dug in Ba Tri District late last year at a cost of VND85 billion. Kenh Lap measures five kilometers by 100 meters.
But within a few months it was contaminated by salt existing underground.
However, following dredging efforts and rains earlier this month, water level in the lake has reached two meters as of late. The lake is also being drained and resupplied as well to better prepare for the upcoming dry season.
Authorities have also been reinforcing eroded locations around it. Vegetation in its surrounding areas is returning to its usual shade of green four months after the last dry season ended.
Kenh Lap is not the only artificial lake built in Ben Tre to help alleviate the chronic water shortage during the dry season.
Lac Dia Lake, which will measure 57 ha in size and four meters deep, will be dug starting next year. With a capacity of 1.3 million cubic meters it will be the largest artificial freshwater lake in the delta. Construction is expected to take five years and cost VND352 billion.
Once completed, it will be able to supply enough water for five months of the dry season to around 59,500 families in Ba Tri District, 155,000 heads of cattle and businesses, schools and others, Nguyen Huu Lap, deputy chairman of the Ben Tre People's Committee, said.
"The province would propose to create some other lakes in three coastal districts."
Neighboring Tien Giang Province is considering turning the 19-km Nguyen Tan Thanh Channel into an artificial lake to store water. In February it was made into a dam at a cost of VND11 billion, but that has since been dismantled.
Nguyen Thien Phap, head of the province's Department of Agriculture and Rural Development's department of irrigation and flood prevention, said the channel, if approved, would be turned into a lake within two years at a cost of around VND400 billion, and provide water for over 800,000 people in the dry season.
Tien Giang also recently approved the construction of eight sluice gates and six wells at a cost of over VND280 billion in Ngu Hiep Isle in Cai Lay District to protect durian trees from saltwater and drought. Construction will begin next year.
The wells will only be used during the dry season, and be closed during the rainy season to conserve groundwater.
Ngu Hiep Isle is the province's largest durian growing area, accounting for around 1,500 ha of orchards of the province's 14,000 ha.
But it was worst affected by saltwater during the last dry season, forcing people to spend hundreds of millions of dong for irrigation.
Despite their best efforts, however, over 400 ha of durian, dubbed the king of fruit, died and another 140 ha were damaged, causing huge losses.
In the Mekong Delta around 80,000 families experienced water shortage as a result of the salinity, and around 43,000 ha of rice wer affected.
In the dry season in the first half of 2020, over 20,000 ha of rice were damaged, and many sluice gates and traffic infrastructure were damaged due to erosion.
Nguyen Tien Hai, the Ca Mau Party Committee Secretary, said late last month his province relies on rainwater and groundwater since it does not get water from the Mekong River.
But continued use of groundwater threatens to cause erosion.
The province has managed to secure approval from the government to dig a freshwater lake near the U Minh Forest. It would span around 100 ha and cost around $10 million to build, with the money to be provided by the World Bank.
Once completed, it will store over five million cubic meters of water, enough for 250,000 families during the dry season.
The construction of reservoirs and lakes for water storage is not without issues however. Nguyen Huu Thien, an independent expert on the Mekong Delta's ecosystem, said authorities need to decide if they should build one large water storage facility or several smaller ones.
The former would make it more convenient to manage and treat the water, but distribution would be expensive, he said.
Water storage facilities should take into account the rate of water loss through evaporation and water seeping into the ground. A high rate means lakes need to be larger, but digging deeper might result in acid sulfate soil affecting the water, he warned.
Solutions include reinforcement to prevent seepage and salinization. Plants could be used to cover water surfaces to prevent evaporation, or solar panels, which would also reduce costs, he said.
The Mekong basin is experiencing rain now, but it is forecast to be below normal by the National Center for Hydro-Meteorological Forecasting.
Flooding is also expected to be lower than usual this year, starting around mid-October before quickly coming to an end.
Flooding levels are in fact expected to be around half the normal levels, and possibly the lowest in a decade.
Lower flood levels mean saltwater would enter estuaries sooner and deeper than usual, the center said. By Hoang Nam