Katherine flooding, 2003/2004 wet season

L. Rajaratnam, S. J. Tickell and R. Farrow
Department of Infrastructure Planning and Environment, Natural Systems Division, April 2004

The Katherine region and in particular the Tindal Creek catchment experienced well above average rainfall events during December 2003, February and March of 2004. The direct cause of the flooding was the several high daily rainfall events starting with the highest even on the 23rd December. The situation was worsened by the fact that the underlying limestone aquifer filled to overflowing in many areas. This has never been recorded before. In an average rainfall year a substantial proportion of rainfall drains directly underground via sinkholes, caves and factures in the rock. Above average rainfalls since the 19996/1997 wet season have raised regional watertables to their present high levels. Runoff has increased substantially this season because the high watertable has blocked downward drainage to the aquifer. Clearing, urbanisation and drain construction in the catchment have also added to increased runoff. The conveyance of the drainage system in Tindal Creek could not cope with this increased runoff and flooding occurred on both sides of Bicentennial Drive.