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 52 7.1, particularly considering the good fit achieved at Anzac Oval and Amoonguna. As discussed in Section 3.4.5, the Heavitree Gap rating curve, and potentially the gauge itself, are considered unreliable, and as such more importance was placed on achieving a good calibration at Anzac Oval and Amoonguna, as well as matching surveyed debris marks. The predicted hydrograph at Amoonguna matches well with the recorded hydrograph, particularly for the first flood peak. The under estimation of the second flood peak, and over estimation of the third flood peak, is consistent with predicted water levels at Anzac Oval, and the URBS model predicted hydrographs. Overall the calibration of the hydraulic model against the recorded water level hydrographs for the March 1983 flood event is considered to be acceptable. 7.2.2 Surveyed Debris Marks A comparison between surveyed debris marks and predicted water levels at various locations along the Charles and Todd rivers is provided in Table 7.1. Flood levels are also plotted in Figure 7.4 to 7.6. Generally, a reasonable calibration was achieved against surveyed debris marks along the Todd River channel, however predicted flood levels in the Charles River are consistently higher than surveyed debris marks. This may be due to the URBS model over predicting local catchment runoff from the subcatchments between the Big Dipper gauging station and the Anzac Oval stream gauge, resulting in higher flood levels being predicted along the Charles River. Variation of Mannings n and scour depths in the Charles River did not improve the correlation between surveyed debris marks and predicted water levels. Table 7.1 Summary of Surveyed Debris Marks and Predicted Water Levels, March 1983 Flood Event Location Surveyed Debris Level (m AHD) Predicted Water Level (m AHD) Difference (m) Charles River Knuckley Avenue 585.38 585.92 0.54 Tietkins Avenue 584.20 584.49 0.29 Hele Crescent 581.74 581.98 0.24 Smith Street 580.33 581.07 0.74 US Ulpaya Road 579.36 579.83 0.47 Todd River US Schwarz Crescent 578.92 578.62 -0.30 DS Schwarz Crescent 578.78 578.39 -0.39 Chewing Street 578.24 578.21 -0.03 Anzac Oval Stream Gauge 577.93 578.21 0.28 Renner Street 577.84 577.92 0.08 US Wills Terrace 577.44 577.48 0.04 DS Wills Terrace 577.56 577.27 -0.29 Parsons Street 576.90 576.76 -0.14 Sturt Terrace 576.37 576.40 0.03 Gregory Terrace 576.17 576.13 -0.04 DS Stott Terrace 575.74 575.51 -0.23 Tuncks Road 574.58 574.54 -0.04 Benstead Street 573.57 573.71 0.14 Breaden Street 572.56 572.57 0.01 Strehlow Street 571.88 572.00 0.12 Kempe Street 571.25 571.13 -0.12 US Stephens Road (Taffy Pick) 570.78 570.61 -0.17 DS Stephens Road (Taffy Pick) 570.83 570.41 -0.42 Walker Street 569.76 569.78 0.02 Heavitree Gap 568.21 568.13 -0.08 Heavitree Gap Stream Gauge 566.47 567.30 0.83