Date of this Version
University of Nebraska–Lincoln Office of Research and Economic Development (2010). Proceedings of the 2010 Water for Food Conference. Lincoln.
Impacts of Weather Variability on Rice and Aquaculture Production in the Mekong Delta
Although farmers in Vietnam’s Mekong Delta adapt to current weather variabilities, they may be unequipped to deal with future changes in global climate, Nguyen Hieu Trung said. He presented results from a study investigating the impacts of weather variability on rice and aquaculture production.
To cope with seasonal flooding as well as limited water and salinity intrusion during the dry season, Vietnam developed a rice irrigation system using canals and sluice gates. Cropping calendars and diversification also were introduced.
Today, in dry fields, farmers cultivate rice and fish together. Farming is typically done on a small scale, with most producers managing less than a hectare or two.
To date, the system yields well, but climate variability is predicted to increase temperatures, reduce rainfall and raise sea levels, threatening productivity in the delta.
Trung and his colleagues investigated the impacts of short-term weather variability on rice and aquaculture production to suggest adaptive strategies for the future. Using weather statistical series data from 1990 to 2008, participatory community appraisals and individual household structured interviews, the researchers analyzed the effects of weather variability on agriculture and aquaculture production to determine how farmers adapt to weather and climate variability.
The results indicate that farmers use a cropping calendar based on weather variables. For example, farmers recognize that every two to four years, low January temperatures and abnormally high February rainfall cause a 0.6-ton loss per rice paddy, which is consistent with statistical data. When the temperature increases 1 degree in aquaculture settings, shrimp yields decrease 0.7 ton per hectare.
The study illustrates that scientists can learn much from farmers about how weather variation affects their experiences and strategies. “This is very important for our assessment of the vulnerability of climate change in the future,” Trung said.
For rice production, farmers cope by integrating nutrient management to help rice better tolerate weather anomalies and by using appropriate rice cultivars and cropping calendars. Farmers also irrigate using groundwater, which is illegal, and create field ditches to drain the surplus water and to prevent soil acidification, a problem in the Mekong Delta. To reduce temperature’s impact on aquaculture, farmers deepen ponds, adjust feed and exchange pond water for intensive Pangasius catfish culture. In shrimp ponds, farmers grow aquatic plants to stabilize the temperature and reduce water pollution. The household’s economic livelihood strongly influences coping measures; poor households are the most vulnerable, with low resilience to change.
Adaptation strategy is a time-dependent and location-specific learning process, Trung said. “We should have a systems approach, which includes an integral combination of agriculture production system and food security and livelihoods, and this approach should be from top down and bottom up.”