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  NATURAL DISASTERS  -  Lessons from the Red River

How can the floods that strike Asia so regularly be forecast and the floodwaters managed more effectively? In making a detailed study of the Red River and its behaviour, the Vietnamese, Thai, Chinese and European researchers on the Flocods (FLOod Controle Decision Support) project sought to provide a response. The result is a decision-making tool designed to enable better management of the Red River floodwaters – plus those of other equally threatening rivers.

The Red River flows through China for more than half its 1 200 km course. In Vietnam, it forms a delta spreading over 120 km. Its basin covers about 80 000 km2 in the north of country which is home to almost one-third of the Vietnamese population. With a flow rate of about 430 m3/sec in the dry season, it can be eight to 14 times that rate in the rainy season. Between 1986 and 1995 its floodwaters caused over a thousand deaths.
The Red River flows through China for more than half its 1 200 km course. In Vietnam, it forms a delta spreading over 120 km. Its basin covers about 80 000 km2 in the north of country which is home to almost one-third of the Vietnamese population. With a flow rate of about 430 m3/sec in the dry season, it can be eight to 14 times that rate in the rainy season. Between 1986 and 1995 its floodwaters caused over a thousand deaths.
With its source in the mountains of China’s Yunnan Province, the Red River heads south-east in the direction of Vietnam where, before entering the Gulf of Tonkin, it forms a vast delta. Its mountain origin coupled with the monsoon climate explain its fickle nature and sometimes very violent floods. Its maximum flow rate (37 000 m3/sec.) was recorded in 1945 and the constructions that control its waters are designed for values of between 49 000 and 57 000 m3/sec.

The bulk of North Vietnam’s population and economic activity are concentrated in the delta region (the site of towns such as Hanoi and Haiphong), which produces one-third of the country’s rice crop. So efforts have long been made to control the Red River waters. When necessary, dykes can either be broken deliberately to allow the water to flow into sparsely populated areas or raised to protect sensitive areas. Reservoirs are constantly being built and the river bed is dredged regularly.

Due to upstream deforestation and demographic pressure, populations tend to settle in the former flood plains where the Red River continues to wreak havoc, both human and material.

The right choice
After several years of research on the Mekong Delta, Dan Nguyen, professor at the University of Caen (FR) and former student at the Ho Chi Minh University of Technology, wanted to develop a tool that would enable the Vietnamese authorities to choose the most appropriate response to Red River water levels. So a project was set up in 2001 that included Vietnamese experts from the Department of Flood Control and Dyke Management (DDMFC) and the Institute of Mechanics of Hanoi (IMECH) together with researchers from Thailand, China, France, Portugal and the Netherlands. Known as Flocods, it received European Commission funding of €900 000 towards a total estimated cost of €1 350 000. During the next three years this gave rise to extensive exchanges, in particular on the occasion of four conferences and study visits by European researchers to China and Vietnam and by Asian researchers to EU countries. “We are a long way from Europe and normally do not have the resources to visit our colleagues there. So this was a unique experience for young scientists,” stresses Nguyen Van Diep, a researcher at the IMECH.

Joint effort
The IMECH and the DDMFC compiled an inventory of information available on the Red River Delta, including economic data on population, agriculture, industries, commerce, tourism, transport, flood damage, etc. and technical data on control methods, rainfall, temperature, water level, topography and flow rate at various points. This was then used to test the socio-economic model designed by the team from the University of Twente (NL) who were charged with simulating the socio-economic impact of the floods and their management.  

Vietnamese researchers and scientists from France (Laboratoire de morphodynamique continentale et côtière de Caen, Institut national polytechnique de Toulouse), Portugal (National Laboratory of Civil Engineering, in Lisbon) and Thailand (Asian Institute of Technology) also helped improve the hydrological and hydraulic models for flood forecasting and management. All these models, as integrated in the Decision Support System, were also able to draw on data from satellite pictures thanks to the contribution of the Institut de Recherches pour le Développement (IRD - France) and the Institute of Automation (China).

In service
Some of the models developed by Flocods have been installed in Vietnam at two institutes very much concerned by this whole issue, namely the Central Committee for Flood Prevention and Storms and the National Centre for Meteorological and Hydrological Forecasting. In this way it is hoped not only to enable better management of the Red River floods but also to determine the size of the reservoirs that must be built or even estimate the impact of reforestation on flood size. “The DSS could also be used for other similar sites in the tropical or sub-tropical regions of Asia,” explains Dan Nguyen. “It is also being adapted to the Perfume River Basin in central Vietnam so as to put into place there a very short-term forecasting tool – in the range of three to six hours – and to identify the principal measures to combat the floods.” 


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