Narrandera is located on the Murrumbidgee River approximately 140 km downstream of the regional centre of Wagga Wagga. Most of the developed area of the town is located on higher ground to the north of the Main Canal, an irrigation water supply canal operated by Murrumbidgee Irrigation. The canal forms a boundary between the town and the floodplain to the south, with its southern bank acting as a “pseudo” levee embankment.

This report details the results of the review of previous flood studies for Narrandera, as well as the investigation of measures which are aimed at protecting parts of the town from damaging flooding and also increasing the hydrologic standard of several access roads. The investigation was undertaken in two phases:

• Phase 1 - the Flood Study Review and update, in which the previous studies were reviewed and updated using recent stream flow data, Light Detection and Ranging (LiDAR) aerial survey of the floodplain and a two-dimensional hydraulic modelling approach based on the TUFLOW system. Phase 1 led to the determination of a revised set of design flood hydrographs for input to the hydraulic model and new flood levels in the study area. It also provided a more accurate assessment of the patterns of flow at Narrandera.
• Phase 2 – the Feasibility Study, in which the levee options identified in the Narrandera Floodplain Risk Management Study (SKM, 2009a) were assessed using the TUFLOW model in combination with the available LiDAR survey data. Phase 2 led to the preparation of preliminary design concepts, cost estimates and an economic analysis of each measure.