Thailand’s main rice-growing basin has entered what researchers call its most dangerous water shortage in generations: inflows to 11 major reservoirs were the lowest recorded for January to September since measurements began in 1953. The finding, published on Wednesday by the fictional Mekong Basin Climate Institute, puts 6.8 million tonnes of rice at risk if the final weeks of the monsoon bring little rain.
The analysis found that rainfall across the Chao Phraya catchment has run 23% below the 1991-2020 average over the past 14 months. Reservoirs now hold 36% of capacity, and water available for farm irrigation is just 62% of its usual level for this point in the year.
A basin short of water
Researchers combined readings from 84 rain gauges, satellite estimates and reservoir records, then compared them with crop data from 12 provinces. Damilola A. Ebubechukwu, a hydrologist who led the analysis, said two weak monsoons followed by this year’s dry spell had depleted soil moisture and river flows. “The rainfall deficit is not a forecast anymore; it is in the reservoirs and the fields,” she said.
The report’s worst-case projection is a 28% drop in rice output from the central basin if less than 90 millimetres of rain falls there during October. That would leave millions of tonnes missing from a region where rice is a daily staple and Thailand is a major supplier to overseas buyers. Burcu Akay, a food-market analyst, said a shortfall of that size could lift regional wholesale rice prices by 15% to 20% by February.
The rainfall deficit is not a forecast anymore; it is in the reservoirs and the fields.
Damilola A. Ebubechukwu, hydrologist
Taru Makkonen, a spokesperson for Thailand’s Water Security Office, urged residents not to panic, saying Bangkok’s household supply was protected and urban reservoirs could last 120 days without substantial rain. But Ebubechukwu said that figure did not cover farm canals or rural water systems. “A city tap can keep running while the crop has already failed,” she said.
Rationing moves into view
Officials are discussing a temporary ban on second-crop planting, tighter limits on canal releases and emergency transfers of up to 1.2 billion cubic metres of water toward the most exposed districts. Pumping more groundwater is another option, but researchers warn that it could drain shallow wells used by households and small farms.
The analysis estimates that the basin needs at least 140 millimetres of rain in October to prevent the worst losses. The national weather service’s current outlook gives the central plain a 40% chance of reaching that total. Harry Collins-Smith, an agricultural economist, said even a late burst of rain would not quickly refill reservoirs or undo months of parched soil.
At a rice cooperative near Suphan Buri, a grower told the newspaper that members had been told to expect one irrigation release instead of three. The cooperative has started logging water allocations alongside crop deliveries, hoping to show officials which fields need the remaining supply most. “We can change our planting plans,” the grower said. “We cannot make the canal fill itself.”
The institute said it will update its estimates after the monsoon season ends in October. For now, scientists say the reservoir record is the clearest warning: without sustained rain, Thailand faces a sharp crop loss, while neighbouring food markets will have little time to find replacement supplies.
