Digging the canal over the 52km-distance proposed would cost about 3 billion baht, Deputy Prime Minister Plodprasop Suraswadi, who is also WFMC chairman, said.
Mr Plodprasop, who travelled to inspect the flooding in Prachin Buri last weekend, said the flooding there would ease in seven days if there is no more rain. Prachin Buri is bearing the brunt of the flooding this year.
Meanwhile, Industry Minister Prasert Boonchaisuk on Tuesday ordered state agencies to step up flood surveillance at Prachin Buri's 304 Industrial Park and put rapid-installation mobile dams on standby to guard the park from possible flooding.
Mr Prasert visited the park in Sri Maha Phot district and received a briefing on flood prevention measures from the park's management.
He ordered the Industrial Works Department and the Prachin Buri Industry Office to work with the Industrial Estate Authority of Thailand to step up surveillance at the park.
Two mobile dams, each 1.20 metres high, stand ready at the park. The mobile dams have a combined height of 2.4m and length of 20km, the minister said. The industrial park has no flood embankments, but its location is relatively high, he said.
Mr Prasert dismissed reports as untrue that the industrial park had been inundated.
The cabinet on Tuesday ordered state agencies to study whether a so-called Water Ministry should be established.
Mr Plodprasop said a water ministry is necessary to tackle flood problems and supervise projects under the 350-billion-baht flood and water management scheme.
He said the WFMC has monitored Typhoon Wutip and found the typhoon was weakening into a low pressure area. This would minimise the impact on the upper Northeast.
Water flowing into several major reservoirs would be less than expected.
He allayed concerns over the rising water level in the Pasak River, saying the situation was under control.
Dams were releasing water at 400 cubic metres per second, he said, adding the river could accommodate water from this discharge rate. He admitted water released earlier from dams might cause some sections of the Chao Phraya River basin to overflow.
However, he insisted that Bangkok would not be affected by any flooding as the WFMC and City Hall have worked out a flood prevention plan.
In Ayutthaya, floods have ravaged eight districts, affecting almost 30,000 households.
The eight districts are Bang Ban, Sena, Phak Hai, Bang Sai, Bang Pa-in, Phra Nakhon Si Ayutthaya, Tha Rua and Nakhon Luang.
A total of 97,324 people from 29,140 households have been affected.
Floodwaters rose to between 1-2m. In low-lying areas, floodwaters were higher than 2m.
Somsong Sappakosolkul, mayor of Phra Nakhon Si Ayutthaya municipality, Tuesday mobilised heavy machinery and lorries to speed up the reinforcement of flood embankments along U-Thong Road and flood-prone areas opposite Wat Na Phrameru, as flooding is expected there over the next few days.