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.
Check within Publication or with content Publisher.
0269-02-C1 12 October 2015 41 Table 5.5 Adopted Verification Event Initial and Continuing Loss Rates Verification Event Initial Loss (mm) Continuing Loss (mm/hr) December 1981 25.0 1.50 January 1984 67.5 6.00 January 1991 2.0 1.80 March 1995 12.0 1.50 February 1997 12.5 1.20 December 1999 13.0 6.00 January 2001 20.5 2.00 November 2008 0.0 0.50 January 2010 15.0 6.00 February/March 2010 15.0 1.50 April 2010 15.0 6.00 Table 5.6 and Table 5.7 provide a comparison of recorded and predicted peak discharges in the Todd River at Wigley Gorge (G0060046), Anzac Oval (G0060009) and Heavitree Gap (G0060126), Charles River at Big Dipper (G0060047) and Emily Creek Upstream Undoolya Road (G0060017) for the adopted verification events. A comparison of the time of the recorded and predicted flood peaks at each gauge is also provided. The following is of note with regards to Table 5.6 and Table 5.7: A good match was generally achieved between recorded and predicted peak discharges at Wigley Gorge. It should be noted that the gauge appears to be in error for the January 2001 and January 2010 flood events, particularly when compared to the recorded hydrographs downstream at Anzac Oval. An excellent match was achieved between recorded and predicted peak discharges at Anzac Oval for most verification events. The model under-predicts peak discharges at Heavitree Gap for 7 of the 11 events. However it should be noted that the Heavitree Gap rating curve is considered to be unreliable. Predicted peak discharges in the Charles River and Emily Creek are dependant on the input rainfall data. For most verification events there is only one pluviograph available within these catchments. For smaller verification events the rainfall recorded by the pluviograph is unlikely to have been representative of rainfall variation across the length of these catchments, due to the localised nature of the small storms which cause such events. The model under-predicts the peak discharge for the November 2008 flood event at all stream gauges except the Charles River at Big Dipper, despite the adoption of no initial rainfall loss and a 0.5mm/hr continuing rainfall loss. It is likely that the recorded rainfall data adopted for use in the model is not representative of rainfalls in the upper Todd River and Emily Creek catchments. The timings of predicted flood peaks are generally within one hour of the recorded flood peak at Anzac Oval. Predicted flood peak timings elsewhere in the catchment are generally within two hours of the recorded flood peak. The discrepancy between the timing of predicted and recorded flood peaks for the December 1999 event is due to the input recorded pluviograph data not reflecting the recorded hydrograph peaks. Overall the verification of the URBS model is considered acceptable.
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