VietNamNet Bridge - In recent years, the gradually-reducing rainfall has caused a water shortage in the Mekong Delta. The dry season is longer, enhancing alkalinity in soil and causing difficulty in aquaculture or farming. Disasters from climate change have been revealed. The granary of Vietnam - the Mekong Delta – is suffering severely, affected from climate change.

10° C "burns" 10% of rice output

Floods caused by flood-tide in Can Tho City.

In September 2013, some areas in Can Tho, the biggest city in the Mekong Delta, was severely flooded, affecting the lives and activities of people. This was very unusual compared to the past.

Mr. Ky Quang Vinh, director of the Climate Change Office of the Can Tho City People's Committee, said: "According to the observations, in the past 30 years in Can Tho, the numbers and intensity of rain was not much, but flooding was remarkable. The highest temperature did not rise much, but the lowest temperature in the day increased 1.40°C. This affects people's health and production.”

“According to research by the International Rice Research Institute, if the temperature increases 10°C, the rice productivity will be reduced by 10%. For the past 30 years, the water flow in the Mekong River has not increased, at about 22,000 m³ per second, but the flow from the sea increase greatly, from 13,000 m³ per second to 15,500 m³ per second."

Mr. Vinh alerted that in the future, the Mekong River flow will be likely equal with the sea level, so the sea water may be damaging to the Chau Doc area in An Giang province or beyond.

Meanwhile, Mr. Nguyen Huu Thien, an independent research, said: "Farmers in some coastal provinces said that in recent years, shorter rains caused the lack of water, especially the groundwater declined seriously. The longer dry season enhances alkalinity in soil, causing difficulty for aquaculture or farming. Prolonged heat killed oysters and pigs. In the coastal areas, the attack of sea water hinders production."

In the dry season, people in the coastal districts of Ben Tre province have to buy fresh water for the price of VND120,000 ($6)/m³ for domestic use and irrigation.

The most obvious manifestation of climate change in recent years, according to Dr. Le Anh Tuan, Deputy Director of the Climate Change Research Institute, Can Tho University, was in 2010, the Mekong Delta suffered from unusual drought and hot weather, with the outdoor temperatures from 39-40°C. Many coastal areas were hit by drought for more than 6 months. Salt water intruded deeply into the mainland, only 20-30 km from Can Tho City.

In 2011, unexpectedly high floods caused severe erosion in many places. In 2012-2013, hails appeared in the two provinces of Soc Trang and Bac Lieu. Many big rains in the late rainy season damaged crops.

Water level rises, land subsides

The natural water level is increasing, robbing a lot of land and house in the southern most province of Ca Mau.

According to a study by Dr. Duong Van Ni, University of Can Tho, the Mekong Delta was formed on soft ground.

"In 2013, not only Can Tho City, but many cities in the Mekong Delta as Long Xuyen (An Giang), Vinh Long ... were severely flooded more than before despite the sea level being  just above the average of many years ago. The difference in height (compared to sea level) is not large but the depth of flooding is higher. Some observations of scientists at home and abroad recently recorded that the ground of this city is showing signs of sinking down," Dr. Le Anh Tuan analyzed.

According to Dr. Tuan, concurrent with the rise of sea levels, the urban areas in the Mekong Delta are showing signs of depression. The causes, according to many scientists, the pressure of construction works on the plain geology, which is already weak. In parallel, groundwater exploitation is increasing, making the subsidence.

Dr. Duong Van Ni refered to the old problem which has great influence to the Mekong River Delta: the flood-preventing embankment and dike systems are built along all rivers and canals in the region.

This makes the river overflow area in the flood season narrowed, causing higher flood levels.

"The overall planning project for the Mekong River, implemented by the Netherlands, mentions the construction of large dikes around Dong Thap Muoi, Long Xuyen Quadrangle and Ca Mau peninsula, to form a water control system to increase agricultural production. This will make problems," Dr. Ni said.

In order to adapt to what is happening, Dr. Le Anh Tuan recommends the government continue monitoring of surface water hydrology and groundwater, improve the height of the seriously flooded areas, residential areas and significant traffic routes.

"Restoring the lowland areas, regulating water, controlling and restricting the exploitation of groundwater, and preventing illegal encroachment of canals and rivers are what the government should do right now," Tuan said.

The frequency of heavy rainfall is clearly increasingly

Dr. Ghi Nie, Chairman of the Union of Scientific and Technical Associations of Dak Lak province, said in the past 50 years, the average temperature in Vietnam has increased by 0.5°C, and the sea level has risen 20 cm. In addition, natural disasters, floods and droughts are more severe. The extreme weather events will continue to grow in number and frequency in regions across the country and they are unpredictable.

According to the latest statistics of the Department for Protection of Environmental Resources of Da Nang, in the period of 1976-2009, the temperature was usually at 25-26° C. In particular, the temperature increased about 0.5°C annually and it seems to continue to rise. The average rainfall in 2005-2010 in Da Nang was much larger than that of the previous years.

In the period of 1976-1994, there were only 3 years with the average annual rainfall of over 2,500 mm, but 15 years later (1995-2009), there were 6 years with the annual average rainfall of over 2,500 mm.

NLD