Montas Kosolsomboon, 55, of Wat Saladeang Community in Bang Khae district, said she and her family have closely monitored the water level at Khlong Thawi Watthana in front of her house. The level is now only 10cm below the concrete walkway.
''I have already prepared cement blocks in case the water reaches the first floor of my house. Although the situation will be different from the heavy flooding last year, I can't help feeling scared,'' she said.
Wat Saladaeng is among seven communities declared by the Bangkok Metropolitan Administration as at risk of flooding during today's drill.
Umaporn Wannapa, 54, a vendor from the same community, said she was unhappy with the drill as the authorities have given little information to people who might be affected by it.
''All the information I get is from TV. No officials have come to provide the information to us. The authorities should tell the public exactly how high the water will get. They only discuss water volume in cubic metres but this does not give me any idea how high the water level will be,'' she said.
Instead of wasting its time on the drill, the government should focus more on dredging the canal, she said.
''I see no benefit from the test. Everyone knows clean canals can help speed up water flow. The government should speed up its work in clearing objects that obstruct water flow,'' she said.
Supaporn Yamtawee, 21, of Parunawas Temple community located along Khlong Mahasawat, said she did not oppose the test but it should be conducted when there was no rain.
The western part of the capital was hit by heavy rainfall yesterday, raising concerns that it might add to the chance of flooding during the water drainage test and many of the residents said they wanted the exercise to be postponed.
Officials from the Department of Royal Irrigation yesterday measured the amount of water at Khlong Thawi Watthana's water sluice gate. The water flow rate in front of the sluice gate was measured at 11.08 cubic metres per second while that behind it was 10.97 cu m/sec.
Additional water which would be drained through the gate during the test will not cause any flooding, they said.
Meanwhile, Prapat Teerapongtron, director of Thawi Watthana district, expressed confidence that residents would not be affected by the test since water levels would not be higher than 0.95 of a metre above mean sea level.
Currently, the water level at Thawi Watthana sluice gate is 0.77 of a metre above mean sea level.
According to the test plan, water from the Tha Chin River will be drained through Thawi Watthana sluice gate and be directed through Khlong Mahasawat, Khlong Phai, Khlong Bang Weg and Khlong Praya Ratchamontri.
Four water-measuring devices and 14 water-pushing machines have been installed along the way to record water volume and to speed up water flow.
The test will enable the officials to know how much water can be diverted into the capital to speed up its flow into the sea. The test will also allow the officials to improve the effectiveness of Bangkok's water drainage system.
Royol Chitradon, chairman of the Water and Flood Management Commission's sub-committee on water situation analysis, said the drainage test in western Bangkok was timed to start at 2pm today because the sea tides will be at the lowest level at 3pm.
The average water level in the canals used in the tests would be around 70cm high. However, in some parts of the route, the water level could become as high as 1.4m, but the testing team would try to keep the level at about 50cm by using water flow-accelerating devices, Mr Royol said.
The mouth of Khlong Thawi Watthana, which runs parallel to Phetkasem Soi 69, is one area on the route which may be at risk of surging water levels.
Therefore, a large number of water flow-accelerating devices were installed at the spot along with a boat from the Royal Thai Navy that will also be used to speed up the flow in the canal.