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
Made available via the Publications (Legal Deposit) Act 2004 (NT).; 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.
1. INTRODUCTION -- 2. CATCHMENT DESCRIPTION -- 3. AVAILABLE DATA -- 4. CALIBRATION AND AND VERIFICATION EVENTS -- 5. HYDROLOGIC MODEL CALIBRATION AND VERIFICATION -- 6. HYDRAULIC MODEL DEVELOPMENTLOPMENT -- 7. HYDRAULIC MODEL CALIBRATION -- 8. FLOOD FREQUENCY ANALYSIS -- 9. DESIGN EVENT HYDROLOY -- 10. DESIGN FLOOD LEVELS AND EXTENTS -- 11. CONCLUSION -- 12. REFERENCES
Flood control -- Northern Territory -- Alice Springs; Flood damage prevention -- Northern Territory -- Alice Springs; Floodplain management -- Northern Territory -- Alice Springs; Alice Springs Flood Investigation; Floodplain Mapping
WRM Water & Environment Pty Ltd
vii, 95 pages : colour maps ; 30 cm.
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0269-02-C1 12 October 2015 76 10 DESIGN FLOOD LEVELS AND EXTENTS 10.1 GENERAL The calibrated TUFLOW model was used to derive design flood levels and flood extents for the following design floods: 20 Year ARI 50 Year ARI; 100 Year ARI; 200 Year ARI; 500 Year ARI; and Probable Maximum Flood. Design discharge hydrographs at the TUFLOW model boundaries were obtained from the calibrated URBS model as described in Section 9.4. 10.2 TODD AND CHARLES RIVER CHANNEL FLOOD LONG SECTIONS Figure 10.1 to Figure 10.4 show flood profiles along the main channels of the Todd and Charles rivers for all design floods considered. The following comments are of note: The Charles River low level crossings are overtopped for all modelled events. No hydraulic jumps are evident downstream of these crossings. The Wills Terrace and Schwarz Crescent causeways are overtopped for all events, and significant hydraulic jumps occur downstream of these crossings for all ARIs. The Wills Terrace pedestrian bridge is completely overtopped for events of 100 Years ARI or greater. The Stott Terrace Bridge is completely overtopped for events greater than the 500 Year ARI flood event, although the bridge appears to cause little afflux for events of less than 200 Years ARI. The Stephens Road (Taffy Pick) and Tuncks Road causeways are overtopped for all modelled events. No significant hydraulic jump is predicted downstream of either causeway. Heavitree Gap causes some afflux for all events, with backwater flooding upstream of the gap increasing substantially for events greater than 100 Year ARI. There is a hydraulic jump downstream of the Palm Circuit low level crossing for all design events modelled. The Ross Highway Bridge appears to affect upstream flood levels for all floods greater than the 50 year ARI design flood. The Ross Highway Bridge is completely overtopped during the PMF. Water levels at the Amoonguna stream gauge are similar for all design events, as the majority of floodwaters have overflowed from the main Todd River channel at this point.