A scene from Grantham, two months after the devastating 2011 floods.
A scene from Grantham, two months after the devastating 2011 floods.

Expert hydrologist gives evidence at Grantham flood inquiry

A LAWYER for Queensland Rail will on Tuesday likely cross-examine a water engineer who found a railway line worsened the devastating 2011 Grantham flood.

Dr John Macintosh began giving evidence on Monday about his hydrology report commissioned by the Grantham flood inquiry.

In the report, which was leaked last week before it could be officially tendered to the inquiry this week, he stated the 2m-high railway embankment running through the town blocked the path of floodwater, increasing peak flood flow intensities.

Following the report's findings, Queensland Rail's lawyer Judy Brien was granted leave to appear.

Dr Macintosh used numerous sources and computer modelling to compile his report, including residents' videos, photos and data from a registered surveyor and from Lockyer MP Ian Rickuss.

MORE: New study clears quarry of role in Grantham flood

Contrary to some locals' evidence, Dr Macintosh found the quarry did not severely worsen the flood that killed 12 people.

He said the most likely impact the quarry had was to delay flooding by one to three minutes as the pit filled with water.

The only other witnesses likely to give evidence before the inquiry's public hearing concludes on Friday are Stefan Szylkarski, who reviewed Dr Macintosh's hydrology report, and Dr David Newton.

Dr Newton was commissioned by Grantham quarry owner Denis Wagner to compile a hydrology report.