Case study

The Challenge

Kalkarindji is a small township located on the left floodplain of the Victoria River, approximately 480 km southwest of Katherine in the Northern Territory (NT). Daguragu is a nearby settlement located on the floodplain of Wattie Creek, which is a major tributary of the Victoria River.

Widespread rainfalls across the Victoria River catchment associated with the ex-tropical cyclones Winsome and Wylva in February 2001 caused major flooding inundating a large number of properties and roads in Kalkarindji. The properties in the Daguragu settlement were not inundated but the settlement was completely isolated for several weeks because the main road between Kalkarindji and Daguragu was cut by flood water.

Kalkarindji is a growing major remote township and was identified as one of the communities in the NT Government’s Major Remote Towns. To implement this initiative and assist with future land use planning, the NT Government wanted to identify flood-free land within the Kalkarindji township and environs by undertaking flood and flood mapping studies.

Approach and Key Activities

The design discharges were estimated based on a flood frequency analysis of the Victoria River discharges recorded at the Wave Hill stream gauge near Kalkarindji. A TUFLOW fully two-dimensional hydraulic model was developed to estimate flooding behaviour in the vicinity of Kalkarindji and Daguragu. The TUFLOW model was calibrated to recorded stream gauging and peak flood level data at Kalkarindji for the February 2001 flood event.

The calibrated hydraulic model was used to estimate design flood discharges, levels, depths, velocities, extents and high flood hazard areas along the Victoria River, Wattle Creek and their floodplains. The results were also used to produce flood and flood hazard maps for the township of Kalkarindji and the settlement of Daguragu for the 1% Annual Exceedance Probability (AEP) design flood and Probable Maximum Flood (PMF) events, in accordance with the NT Government guidelines.

Outcomes and benefits

The hydraulic model results and flood mapping enabled the identification of the existing flood risk and flood hazards in the study areas well as determining the potential for further development within the Kalkarindji township.

The flood-free land within the Kalkarindji township and environs was identified to show areas that could be potentially be subject future development. The flood and flood hazard maps were produced in a format suitable for counter disaster management purposes.