Authorities are stepping up efforts to create rain, the last resort in their fight against dry weather, as the recent Kujira tropical storm has created accommodating conditions for cloud seeding.
Chavalit Chookajorn, permanent secretary for the Agriculture Ministry, said on Saturday that the critically low reserves at major dams had worried His Majesty the King, who is a rainmaking expert.
The Bureau of the Royal Household recommended mobilising resources to speed up rainmaking now because Kujira had left some humidity in the air which facilitates the process.
The tropical storm became a low-pressure area over northern Vietnam on Thursday.
"Rainmaking will help, regardless of whether it rains in reservoirs or not," he said. "A few rounds of rain will keep crops alive for a month."
Mr Chavalit inspected the Pasak Jolasid dam in the central plains province of Lop Buri on Saturday. He said water reserves there totalled 65 million cubic metres, which would last 40 days.
The reserve level was the lowest since the dam's completion about 17 years ago, he noted.
"The concern is that the Pasak Jolasid dam will have water for consumption only for the next 40 days. Its water is used for farming and tap-water production for people in Lop Buri, Saraburi, Pathum Thani, Ayutthaya and Bangkok," he said.
The major dams — Pasak Jolasid, Bhumibol, Sirikit and Kwae Noi Bamrung Daen — have a combined 976 million cubic metres at present, roughly 5% of their total capacities and the lowest in 51 years, he said.
Fourteen airplanes would be deployed to make rain and add water to the dams and save farmland in 32 provinces of the North, the Central Plains and the West as weather conditions would be suitable for rainmaking until late October, Mr Chavalit said.
Past rainmaking programmes were 99% effective and they were the last resort for the time being, he said.
Lertviroj Kowattana, director-general of the Royal Irrigation Department, said the major dams in the Chao Phraya River basin would cut their water discharge from 31 million cu m per day to 28 million cu m from Sunday.
The discharge rate would be reviewed in the next 15 days if inflows remained critically low.
The dams are accepting only 4.5 million cu m per day, the lowest intake rate on record. The slower discharge rate is intended to extend water supplies over the next 45 days or until August, when some rainstorms are expected, Mr Lertviroj said.
Anond Snidvongs, executive director of the Geo-Informatics and Space Technology Development Agency, said Thailand would see the sharpest decline of rainwater in July and the situation would gradually improve from August to October, when the rainy season ends.
However, the amount of rain would be lower than normal throughout this rainy season due to the El Nino weather phenomenon. The water shortage could be worse than the El Nino impacts in 1997 because water demand is much higher now, he said.
Reserves in dams should stand at 3,500 million cu m by Nov 1, so that there would be enough water for consumption and environmental protection until the end of the next dry season next April, Mr Anond said.
Cattle graze in the drying reservoir of the Pasak Jolasid dam in Lop Buri. Behind them is the railway track structure that normally stands just above the water line. (Photo by Thiti Wannamontha)
