Heavy Rains Flood the Red River Delta

The 1971 Red River flood was the most severe in Vietnam’s history, causing 100,000 deaths and $100 million in damages to the national economy.

Summary of Event

In August, 1971, historically severe flooding of the Red River, North Vietnam’s largest river system, caused 100,000 deaths and $100 million in economic devastation. Flowing from China into Vietnam, the Red River merges with the Da, Thao, and Lo rivers near the capital city of Hanoi. From there the Red River flows toward the eastern seacoast, connecting with the Thai Binh River system in northeast Vietnam, and the combined river systems flow southeast to form the Red River Delta. In 1971, the Red River system affected an area of 85,550 square kilometers (63,127 square miles) of land and water that was important for the production of rice and other crops such as cotton, jute, coffee, tea, and sugarcane. The river system also provided water transport and support for a diverse aquaculture and fishing industry. Floods;North Vietnam
Red River flood
[kw]Heavy Rains Flood the Red River Delta (Aug. 20-21, 1971)
[kw]Rains Flood the Red River Delta, Heavy (Aug. 20-21, 1971)
[kw]Flood the Red River Delta, Heavy Rains (Aug. 20-21, 1971)
[kw]Red River Delta, Heavy Rains Flood the (Aug. 20-21, 1971)
[kw]River Delta, Heavy Rains Flood the Red (Aug. 20-21, 1971)
[kw]Delta, Heavy Rains Flood the Red River (Aug. 20-21, 1971)
Floods;North Vietnam
Red River flood
[g]Southeast Asia;Aug. 20-21, 1971: Heavy Rains Flood the Red River Delta[00410]
[g]Vietnam;Aug. 20-21, 1971: Heavy Rains Flood the Red River Delta[00410]
[c]Disasters;Aug. 20-21, 1971: Heavy Rains Flood the Red River Delta[00410]
[c]Environmental issues;Aug. 20-21, 1971: Heavy Rains Flood the Red River Delta[00410]
Pham Van Dong
Ho Chi Minh
Le Duan

Although the low-lying river delta and coastal lands made up only one-fourth of Vietnam’s territory, 70 percent of the population of Vietnam lived and worked in that region. Flash flooding and fast-flowing rainfall runoff from the mountainous areas that made up the remaining three-fourths of Vietnam added to the flooding of the Red River Delta on August 20-21, 1971, causing water levels to rise 5 to 10 meters (approximately 16 to 33 feet) above the level of the fields inside the dikes.

For twenty-five years prior to the 1971 flood, there was continuous economic development in the Red River basin, resulting in growth of population centers and settling of people on the river embankments. Immediately after the 1945 Red River flood, the worst in the nation’s history until it was eclipsed by the 1971 flood, the Vietnamese had strengthened the river dikes to protect against future floods. They added 255 million cubic meters of earth fill and 4.2 million cubic meters of rock revetment to the dikes and embankments. They also constructed flood-control devices such as dams, weirs, sluices, and hydraulic works to divert the river waters into irrigation ditches for crop production.

However, ongoing wars during the same period damaged many of the improvements to the sea and river dike systems. Ho Chi Minh, North Vietnam’s leader until his death in 1969, was a highly regarded military strategist, but he was less attentive to economic and social problems such as flood control. His successor, Le Duan, was more aggressive in developing strategies to mitigate water-related disasters, but constant warfare and the necessity to produce more food in the river delta placed increasing stress on the dikes, some of which were more than two thousand years old. Increased rural development led to destruction of the forests that helped to stabilize the soil and interfered with river dredging and floodwater diversion. By August of 1971, the Red River dike system was simply not adequate to withstand the heavy monsoonal rains and mountain runoff that flooded the entire Red River basin. The flood lasted fifty-five days, inundated 312,000 hectares (almost 771,000 acres) of land, destroyed agricultural and aquaculture production, and displaced 2.7 million people in the Red River Delta.

The loss of life and devastation of the agricultural economy during the 1971 flood shocked the Vietnam government into taking action to prevent a repeat of the disaster. Immediately after the flood receded, Prime Minister Pham Van Dong authorized the Central Committee on Flood and Storm Control to conduct an assessment of existing flood-control measures and to develop strategies to lessen the devastating impact of future floods and typhoons.

Because the Red River dikes were the primary defense against water-related disasters, the committee first examined the dikes and embankments. The inspection revealed 250 serious failures in the dike system during the 1971 flood. Many of the river dikes had been built thousands of years before with inferior material, and the lack of resources and equipment for timely repairs had contributed to their defective state. Termite nests and rodent holes, which could not be detected by visual observation, had created large cavities inside the dikes. Many of the sluices that allowed water to pass through the dikes had been damaged, and repairs had been neglected. The committee concluded that the river and sea dikes would need constant monitoring and timely repairs in order to protect life and agricultural production during floods, and it recommended that a government support system be established for that purpose.

Over the next ten years, the Department of Dike Management and Flood and Storm Control worked to establish better flood-control measures along the entire 3,000 kilometers (1,864 miles) of the Red River dike system. Provincial inspectors were hired to monitor the dikes and see that repairs were made in a timely manner to protect important economic areas and urban centers against flooding. A reforestation program was started as well, to try to prevent the rapid soil runoff, landslides, erosion of embankments, and silt-choked waterways that occurred during the 1971 flood.

The committee also called for more flood-diversion channels, along with river dredging and clearance for the flood-discharge channels. It was necessary to design flood-diversion channels so as to avoid damaging the river dikes. In most cases, changing the river channels required the resettling of people, because new agricultural development and settlements in the floodplain would be affected by shifting the river channels. For example, the new Da River Spillway required the resettlement of 45 percent of the nearby population. Also, the river had to be cleared of fallen bridges, sunken ships, and other debris, and the high riverbanks had to be reduced, to allow for discharge of floodwaters.

The 1971-1981 flood-control program included construction of upstream reservoirs to serve as catch basins for floodwaters. The Thac Ba Reservoir had reduced the Red River water level by 0.10 to 0.15 meter during the 1971 flood. A new Hoa Binh Reservoir was constructed in order to lower the Red River level at Hanoi by 1.2 to 1.4 meters in the event of another flood of the same magnitude. The reservoirs were useful in economic development as well as flood control, for they stored and supplied water for agriculture and electricity production. More reservoirs were planned, but the necessity to relocate the people displaced by the construction delayed further implementation of this program.


The 1971 Red River flood marked a turning point in flood control and disaster planning by the Vietnam government. Experts predicted that the high death count and economic losses caused by the flood could be magnified tenfold by another flood of the same proportions, owing to the economic and population development in the flood-prone Red River Delta. As a result of the initial assessment and later studies, Prime Minister Pham Van Dong reorganized the Water Resources Department so that flood control would be a priority at national and local levels. A permanent Central Committee for Flood and Storm Control was created, with participation by representatives from the Ministries of Agriculture and Rural Development, Construction and Transportation, the Hydro-Meteorological Agency, and the armed forces. This committee’s responsibilities included developing and implementing short-term and long-term plans for flood control and disaster management. Flood-control and dike management plans would emphasize prevention, whereas disaster management plans would concentrate on early warning of impending disasters and coordination of response, relief, and rehabilitation efforts. Emergency planning

Long-term plans for flood control included dike management, reforestation, environmental improvements, resettlement of people living on the dikes, construction of reservoirs and flood-diversion channels, and development of a warning system that would provide at least three days’ notice of impending flood disasters. Plans included strict enforcement of laws and ordinances regarding dike management, forestry and environmental protection, and a coordinated education effort to raise public awareness of flood prevention and control.

The ten-year program initiated immediately after the 1971 Red River flood led to consistent and increasing government support for flood control, the enactment of policies and laws for prevention or abatement of water-related disasters, and the establishment of institutional agencies for water resources management and flood control. The Red River itself gained an elaborate network of dikes, dams, canals, and locks that provided irrigation for crops as well as flood control. Floods;North Vietnam
Red River flood

Further Reading

  • Hill, R. D., ed. South-East Asia: A Systematic Geography. London: Oxford University Press, 1979. Describes river systems and population settlements of Vietnam.
  • Nguyen, Dinh-Hoa. From the City Inside the Red River: A Cultural Memoir of Mid-century Vietnam. Jefferson, N.C.: McFarland, 1999. Describes the impacts of problems such as food shortages and lack of social services on living conditions in North Vietnam,
  • Popkin, Samuel. The Rational Peasant: The Political Economy of Rural Society in Vietnam. Berkeley: University of California Press, 1979. Explains the importance and scope of the socioeconomic role played by the rural populations of Vietnam.

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