Mekong floods bring benefits and costs. The Mekong annual flood rejuvenates wetlands and breeding grounds for aquatic plants, fish and animals, all of which are vital sources of income and food, particularly for poor communities. The annual flood also enriches soils with river-borne sediments and nutrients beneficial to agriculture, and replenishes reservoirs against water shortages in the dry season. The average annual value of flood benefits in the Lower Mekong River Basin (LMB) is approximately US$8-10 billion.
Floods become disasters when they are deeper than average, unexpectedly fast at their onset, or unusually prolonged. Flooding of the Mekong River and its tributaries are recurrent events. Each year it causes in varying degree of damage to agriculture, rural infrastructure, residential areas and essential services. It also endangers the lives of humans and has negative impacts on the environment. The annual cost of floods ranges from US$60-70 million.
The cost of droughts in the LMB dwarfs the cost of floods. Furthermore, unlike floods, droughts provide no apparent benefit. Droughts, which occur as a result of periods of very low river flow accompanied by low rainfall, can cause severe food shortages, damage the environment for animal lives, lead to poor biodiversity for aquatic lives, bank erosion, salinity intrusion and health problems for household communities due to contaminated water quality. Yields of rice and other lifeline crops plummet as a result of water shortages. Annual fish catches decline. Water levels become critically low, making transport of goods and services at some parts of the river difficult and at other points impossible.
Climate change, rapid urbanisation and environmental degradation further expose riverine communities, especially the poor and vulnerable, to greater risks.
Many regional, national, and local initiatives in the LMB have been carried out to reduce the risk of and vulnerability to floods and droughts. These efforts include huge investments in structural measures, such as flood and drought control reservoirs and detention basins, which are helpful but often have proved inadequate.
Preparedness and response measures for floods and droughts are highly dependent on the availability of accurate and timely meteorological and hydrological forecasting products and their effective and timely dissemination to both authorities and the public. The MRC, therefore, has been giving priority to forecasting and warning systems, providing the Member Countries with a range of information, forecasts and decision-support tools to better prepare for, monitor and respond to flood and drought risks.
Since the enormous flood of 1996, the MRC has been monitoring hydrologic conditions in the LMB to provide forecasting and warning services for flood conditions in the basin. The services are one of the MRC’s five Core River Basin Management Functions (CRBMF).
In 2006, the MRC established the Regional Flood Management and Mitigation Centre (RFMMC). The Centre serves as the MRC’s lead entity in delivering flood forecasting services, and in early 2019 was renamed ‘the Regional Flood and Drought Management Centre (RFDMC)’ to reflect an expansion in the range of services it provides.
The renaming signified the MRC’s efforts to address both flood and drought issues in an integrated manner and to provide faster and accurate forecasting and early warning information throughout the year.
The RFDMC services fall under four main activities: 1) river flow monitoring; 2) river flood forecasting; 3) flash flood guidance; and 4) drought forecasting and early warning.
