Prime Minister Prayut Chan-o-cha called for immediate construction of basins to catch rain and runoff from tropical depression Vamco, which is likely the last major storm of the rainy season.
"Water must be retained wherever there is rain and flooding. If it is private land, villagers must contribute some land to be ad hoc water-retention basin. The government will compensate," Gen Prayut said at Government House on Tuesday.
The premier did not explain how so many small reservoirs could be built before Friday when the former tropical storm is expected to dissipate.
Nonetheless, he said village and sub-district officials should quickly locate ponds in low-lying areas and fast drainage channels should be constructed to funnel rain and floodwaters to the ad hoc reservoirs.
"Today there is last burst of water from the depression covering the East, the Northeast and Bangkok. The rain that covers 70% of those areas must be retained. Otherwise, we will have to wait until the next rainy season. If we are able to capture it, we will survive," the prime minister said.
He admitted to being concerned about the present level of water reserves, saying that water in dams accounted for less than 30% of their total capacities.
Under the circumstances, crops could be planted in upstream and midstream areas and farmers in downstream fields would have to change their occupations. Agricultural officials would give them advice, Gen Prayut said.
Ekkasit Sukdeethanaporn, director of the Chao Phraya Dam, which supplies water to the Central Plain, said Tuesday that Vamco brought rain to most parts of the country and would increase water reserves by at least 20%.
However, he emphasised the need to minimise water consumption because reserves at four major dams in the Central Plain amounted to only 2.2 billion cubic metres, almost half the 4 billion cubic metres they held at this same time last year.
Wanchai Sakudomchai, director-general of the Meteorological Department, announced Monday evening that Vamco already had weakened into a low pressure system that covered the northeastern provinces of Nakhon Ratchasima and Buri Ram and would later move to the Central Plain.
He predicted widespread rain and some heavy downpours in the lower Northeast, the Central Plain and the East from Tuesday to Friday.