Royol Chitradon, chairman of the subcommittee that monitors and analyses water management for the Water and Flood Management Commission (WFMC), said his committee, the Bangkok Metropolitan Administration (BMA) and the Department of Disaster Prevention and Mitigation had jointly decided to cancel the drill.
Some low-lying areas of Bangkok and neighbouring provinces, such as Nonthaburi and Pathum Thani, had been hit by flash floods caused by the heavy rains, Mr Royol said.
Although the government had called off the drill, water-pushing machines were still in place to help speed up water drainage in canals.
The Royal Irrigation Department (RID) monitored the water flow for data that would help develop future flood prevention plans, he said. According to the RID, the water flowed at a speed of 17.136 cubic metres per second in Khlong Lat Phrao yesterday.
Mr Royol said water-pushing machines could speed up water drainage in the canal, where 29 machines have been installed.
"There was no flooding in Khlong Lat Phrao despite the high amount of rainfall on Thursday night. This shows that our machines were working well," he said.
The highest volume of rainfall in Bangkok on Thursday night was 145 millimetres per hour in Sapan Sung district. In Khlong Song, where the flood drill was called off yesterday, rainfall was measured at around 90 millimetres per hour, a figure higher than the WFMC had anticipated.
Bangkok governor Sukhumbhand Paribatra said the test was cancelled due to high water levels in various canals.
MR Sukhumbhand thanked the WFMC for cancelling the test.
He said although there was heavy rain throughout the night, City Hall's drainage system was coping with the situation. The tests on water pushing operations in Khlong Lat Phrao were carried out yesterday despite the closure of the canal's sluice gate, he added.
Prime Minister Yingluck Shinawatra said the cancellation would ease concerns over possible flooding.
Regarding Wednesday's test on the western canals of Bangkok, Ms Yingluck said the outcome was not perfect but showed some improvement.
Torrential rain in the North triggered flooding in many provinces yesterday.
As much as 800 million cubic metres of floodwater inundated vast areas of Sukhothai, Lampang and Phrae.
Run-off from the Yom River flooded more than 2,000 rai of farmland in Phitsanulok's Phrom Phiram district.
Somkuan Rungrueng, head of Moo 10 village of Phrom Phiram's tambon Tha Chang, said the floodwater is about 50cm deep. In Phitsanulok's Muang district, a downpour flooded a 300-metre stretch of road at tambon Hua Ror's centre. The water was about 20cm deep.
Mae Sot district chief Preecha Jaipetch instructed kamnans of tambon Dan Mae La Mao and Pa Wo to help residents evacuate their belongings and animals to higher ground in response to flash flood warnings.
Floods were also reported in Tak's Umphang municipality.