The trend in the Australia, the USA and elsewhere has been for the growing adoption of 2D models as the new benchmark for investigations of flooding on rural and urban floodplains and assessment of flood mitigation schemes.

The applications of three packages (TUFLOW, SOBEK and xpswmm2D) to assessments of flooding in rural and urban areas due to severe storm events are outlined in three case studies.

The first case study is of the Macquarie River floodplain at the inland city of Dubbo. The flood study was undertaken to define the nature and extent of flooding and flood hazard for a range of design rainfall events in the 194 km2 floodplain.

The second case study outlines the assessment of overland flows due to local rainfall only in a coastal urban catchment in Gosford. The assessment of pre and post-development overland flows is outlined. The sensitivity of the model to changes in rainfall parameters, hydraulic roughness, downstream boundary and pipe blockage is also discussed.

The third case study outlines the assessment of overland flows in a small urban catchment in Sydney. The assessment of pre and post-development overland flows and potential impact of failure of a road embankment on overland flows through a proposed apartment development is outlined.

It is concluded that the 1D/2D modelling capabilities of packages routinely applied in Australia offers new opportunities to undertake more detailed investigations of rural and urban flooding for improved planning of new developments and/or redevelopment projects on floodplains.