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RAINFALL
The Mekong Delta (MKD) is the largest delta in Vietnam, comprising 13 provinces and cities with an area of approximately 40,000 km² and a population of over 17 million people. This is the most important rice bowl, fruit basket, and aquaculture center of the country, contributing more than 50% of rice production and 70% of Vietnam's exported seafood production. However, in the context of global climate change, the Mekong Delta is facing increasingly extreme rainfall phenomena in both frequency and intensity. Unusual rainstorms with huge amounts of water in a short period have been causing serious impacts on the natural environment, the lives, and the livelihoods of people in the region.
Current Status of Extreme Rainfall
According to data from the Southern Regional Hydro-Meteorological Center, in recent years, the Mekong Delta has recorded many extreme rain events with rainfall far exceeding the multi-year average. Many measuring stations in the provinces of Can Tho, An Giang, Kien Giang, and Ca Mau have recorded daily rainfall ranging from 100 to 200mm, with some places even exceeding 250mm—equivalent to an entire month's average rainfall in just a few hours. In particular, extreme rain events no longer follow traditional seasonal patterns but appear abnormally even during the dry season, causing difficulties for forecasting and response work.
The main cause of extreme rainfall is identified as the impact of global climate change. Rising sea surface temperatures in the East Sea increase the evaporation process, creating conditions for the formation of large thunderstorm clouds and violent rain spells. Besides, the interaction between weather systems such as the Southwest monsoon, tropical depressions, storms, and the intertropical convergence zone is becoming increasingly complex and difficult to predict. The rapid urbanization process with surface "concretization" also reduces natural water permeability, making local flooding after heavy rain more severe in cities like Can Tho, My Tho, Long Xuyên, and Ca Mau.
Figure: A heavy rain event in the Mekong Delta region.
Impacts on Nature and People
Regarding the natural environment, extreme rainfall causes a series of serious consequences for the Mekong Delta ecosystem. First of all, heavy rain in a short period causes serious soil erosion, especially in riverside areas, canals, and coasts. Strong currents wash away the fertile topsoil, degrading the quality of cultivated land and increasing the riverbank erosion situation which is already very serious in the Mekong Delta. Every year, hundreds of hectares of riverside land are eroded, directly threatening the houses and production land of the people.
Extreme rainfall also causes disturbances to the water environment in the intricate system of rivers and canals of the delta. Heavy rainwater carries waste, agricultural chemicals, fertilizers, and pesticides from the fields into the rivers, causing water pollution and eutrophication. Many mass fish deaths have been recorded after heavy rains due to sudden drops in oxygen concentration and rising toxic substances. The coastal mangrove forest ecosystem—an important natural defense line—is also affected when heavy rain changes water salinity, impacting the growth of mangrove trees and aquatic species.
For the people, extreme rainfall causes great and multidimensional damage to the economy, society, and health. First, regarding agricultural production, heavy rains in a short period cause field flooding, killing thousands of hectares of rice, crops, and fruit trees during their growth period. According to statistics from the agricultural sector of the provinces, each extreme rain event can cause hundreds of billions of VND in damage to farmers in the region. The aquaculture industry also suffers heavy losses when ponds are flooded, and shrimp and fish escape or die due to environmental shock.
Regarding daily life, prolonged heavy rain causes serious flooding in residential areas, especially in low-lying areas and cities with poor drainage systems. Many traffic routes are deeply flooded, cutting off traffic and causing congestion and accidents. Houses are flooded, property is damaged, and people's daily lives are turned upside down. More seriously, extreme rain increases the risk of diseases such as dengue fever, diarrhea, skin diseases, and waterborne infectious diseases because the damp environment creates conditions for mosquitoes and bacteria to develop. Children and the elderly are the most vulnerable groups to these impacts.
Current Measures by Authorities and Residents
On the government side, authorities at all levels in the Mekong Delta have implemented many measures to respond and adapt to extreme rainfall. The hydro-meteorological monitoring and forecasting system has been invested in and upgraded with the installation of more automatic rain stations and the application of remote sensing technology and numerical forecasting models to improve accuracy and early warning time. Heavy rain warning bulletins are broadcast through many channels such as SMS messages, loudspeakers, television, and social networks so that people can respond in time.
Regarding infrastructure, many localities have invested in upgrading urban drainage systems, building regulation lakes, and drainage pumping stations in low-lying areas. The government has also issued land-use plans that take natural disaster risks into account, restricting construction in frequently flooded areas. Programs for planting protective forests and restoring mangrove forests are promoted to enhance natural water regulation capacity. In particular, Resolution 120/NQ-CP on the sustainable development of the Mekong Delta has directed the development of nature-based adaptation solutions and the transformation of crop and livestock structures to suit new climate conditions.
On the people's side, the Mekong Delta community has proactively implemented many measures to adapt to extreme rainfall based on experience and government support. Many households have reinforced their houses, raised floor levels, and built drainage systems around their homes to minimize damage during heavy rain. Farmers proactively monitor weather bulletins and adjust planting and harvesting schedules to avoid heavy rains, while applying adaptive farming techniques such as high-bed soil preparation, planting short-day varieties, and building drainage ditch systems in the fields. Aquaculture farmers reinforce pond banks and install protective nets and proactive supply-drainage systems. Communities also organize volunteer teams to support each other in overcoming the consequences after heavy rain, demonstrating the traditional spirit of solidarity and mutual assistance of the people in the West.
Conclusion
Extreme rainfall is one of the most visible manifestations of climate change in the Mekong Delta, causing serious and multidimensional impacts on the natural environment as well as the socio-economic lives of the people. Although authorities and the community have implemented many response and adaptation measures, the extreme rainfall situation is forecasted to become more complex in the future due to the impact of global climate change. To protect the sustainable development of this fertile delta, it is necessary to continue promoting investment in forecasting and early warning systems, upgrading drainage and flood regulation infrastructure, developing climate-smart agriculture, and raising awareness and response capacity of the community against extreme weather phenomena.