Case study

Adelaide River Town Flood Study

ProjectAdelaide River Town Flood Study
ClientNorthern Territory Department of Environment and Natural Resources
LocationAdelaide River, Northern Territory
Disciplines/ServiceHydrological modelling
Flood frequency analysis
2D hydraulic modelling
Design Event Modelling including extreme events
Flood hazard mapping
Flood emergency response
Community consultation
Key team members

Dr Sharmil Markar
Project Manager

Daniel Sheehy
Flood Modeller

WRM ContactDr Sharmil Markar

The Challenge

Adelaide River Town area has a history of flooding from the Adelaide River. However, measures undertaken to date to manage the flood risk are limited. The key challenge for this project was to improve the understanding of flood behaviour and impacts, and better inform management of flood risk in the Adelaide River Town area. The study results would provide a sound technical basis to assist the Northern Territory Government to develop safer and more resilient communities by improving planning for flood emergency events as well as improving planning for development in the town.

Approach and Key Activities

The flooding characteristics in and around the Adelaide River Town area were determined by flood modelling. An XP-RAFTS rainfall runoff routing model of the catchment and a TUFLOW hydraulic model of the floodplain were developed and the two models were jointly calibrated to four historical flood events. Then the two models were validated against a further two historical events

A Flood Frequency Analysis (FFA) was undertaken to estimate design discharges for the Adelaide River at the Railway Bridge stream gauge.

The calibrated XP-RAFTS model was used to estimate current climatic conditions and year 2100 future climatic conditions (climate change conditions) design discharges for input to the TUFLOW hydraulic model. XP-RAFTS design peak discharge estimates were reconciled with design discharge estimates from the FFA.

The calibrated TUFLOW hydraulic model was used to estimate peak Adelaide River flood extents, depths and flood levels for the 5%, 2%, 1%, 0.5% and 0.2% AEP design flood events, for both current climatic conditions and year 2100 climate change conditions, as well as for the PMF event. Floodplain hazard classifications were determined for the current conditions and year 2100 climate change conditions 1% AEP design flood events, as well as for the PMF event.

Outcomes and benefits

The NT Government received a comprehensive set of flood depth and hazard maps for a range of design events up to the PMF across the Adelaide River floodplain for use in land use and flood emergency planning.

The flood model results were used to identify the existing flood risk and flood hazards throughout the Adelaide River town area including the Stuart Highway and to determine the potential for development in the town area.

In addition, flood emergency response classifications and potential flood evacuation routes were determined for the Adelaide River Town for different magnitudes of flooding