Alice Springs Flood Investigation and Floodplian Mapping Study
WRM Water & Environment Pty Ltd
Northern Territory. Department of Lands, Planning & the Environment
E-Publications; PublicationNT; E-Books; EXTA1463
WRM Water & Environment (WRM) was commissioned by the Department of Lands & Planning (DLP) to undertake a flood study of the Todd River in the Alice Springs area. The aim of the study is to develop a 2 dimensional flood model, which allows flood flow in a complex flood plain to be modelled, to determine the extent and severity of riverine flooding in the town of Alice Springs and the Alice Springs rural area south of Heavitree Gap. The purpose of the study is to produce floodplain maps of the Alice Springs and its rural area for land use planning and counter – disaster purposes. This study is an extension of the Alice Springs Farms Area Floodplain Mapping Study (WRM, 2006), undertaken by WRM on behalf of the Department of Planning & Infrastructure in 2006 in order to develop detailed Todd River floodplain maps for the rural area south of Alice Springs.
Made available via the Publications (Legal Deposit) Act 2004 (NT).
1. Introduction -- 2. Catchment Description -- 3. Available Data -- 4. Calibration and Verification Events -- 5. Hydrologic Model Calibration and Verification -- 6. Hydraulic Model Development -- 7. Hydraulic Model Calibration -- 8. Flood Frequency Analysis -- 9. Design Event Hydrology -- 10. Design flood levels and extents -- 11. Conclusion -- 12. References -- Appendix A
Alice Springs Flood Investigation; Floodplain Mapping; Flood control; Northern Territory; Alice Springs; Flood damage prevention; Floodplain management
WRM Water & Environment Pty Ltd
vii, 95 pages : colour maps ; 30 cm.
WRM Water & Environment Pty Ltd and Northern Territory Government
0269-02-C1 12 October 2015 4 2 CATCHMENT DESCRIPTION 2.1 UPSTREAM CATCHMENT The Todd River catchment covers an area of 525km2 to the Heavitree Gap as shown in Figure 1.1. The upper headwaters of the catchment to the north and north east of Bond Springs comprise open grasslands on undulating plains. The lower reaches of the catchment drain through the MacDonnell Range where channels are very confined and the terrain is generally steep and rocky. Flood discharges tend to flow at very high velocities with high rates of runoff through the MacDonnell Range. There are two major tributaries of the Todd River, Colyer Creek and the Charles River, both of which drain into the Todd from the west upstream of Alice Springs. Both these tributaries are located within the MacDonnell Range and exhibit similar drainage characteristics to the Todd River i.e high runoff rates and high velocities. 2.2 STUDY AREA 2.2.1 Alice Springs Figure 2.1 shows the key drainage features in the vicinity of the township of Alice Springs. Much of the town is located on the floodplains of the Todd and Charles rivers, and flood behaviour in both rivers is significantly affected by the low level crossings, causeways and bridges linking the CBD with the eastern suburbs. Substantial flooding of the Alice Springs CBD and southern suburbs (immediately upstream of Heavitree Gap) has occurred during historical floods. Through Alice Springs, the Todd River channel is wide and shallow with a sandy bed and isolated stands of Coolabah trees. Runoff from the Alice Springs local stormwater catchments, and upstream hill slope catchments is conveyed to the Todd River via a number of constructed stormwater channels, which are prone to backwater flooding during Todd River flood events, inundating low lying areas of adjacent suburbs. Floodwater overflowing from the Charles and Todd rivers generally drains in a southerly direction through the town parallel to the railway corridor before ponding upstream of Heavitree Gap. All Todd River floodplain flows then must drain back into the Todd River channel to drain through the Heavitree Gap between Mount Johns and Mount Gillen. 2.2.2 Rural Area Figure 2.2 shows the key drainage features of the rural area and the Todd River south of Heavitree Gap. The rural area is located downstream of Heavitree Gap and is often referred to as the Alice Springs Farms area. There is an older urban area to the east of the Todd River immediately to the south of Mount Johns and extensive rural residential dwellings to the south east along the Ross Highway. The Amoonguna Settlement is located about 7.5km to the south