Territory Stories

Alice Springs Flood Investigation and Floodplian Mapping Study

Details:

Title

Alice Springs Flood Investigation and Floodplian Mapping Study

Creator

WRM Water & Environment Pty Ltd; Northern Territory. Department of Lands, Planning & the Environment

Editor

Roads, Greg

Collection

E-Publications; PublicationNT; E-Books; EXTA1463

Date

2015-10-12

Location

Alice Springs

Description

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.

Table of contents

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

Language

English

Subject

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

Publisher name

WRM Water & Environment Pty Ltd

Place of publication

Darwin (N.T.)

Series

EXTA1463

Format

vii, 95 pages : colour maps ; 30 cm.

File type

application/pdf.

Copyright owner

Check within Publication or with content Publisher.

Parent handle

https://hdl.handle.net/10070/259732

Citation address

https://hdl.handle.net/10070/494349

Page content

0269-02-C1 12 October 2015 74 9.4 DESIGN DISCHARGES Table 9.4 shows estimated design discharges at Wigley Gorge, Anzac Oval and Heavitree Gap from the URBS model for the various design events and from the results of the FFA (Refer Section 8). For the Heavitree Gap station, URBS design discharges are provided both upstream and downstream of the Gap. Based on URBS model results, the critical duration storm events producing the highest peak discharge were: Wigley Gorge - 6 hours for the 20 year ARI storm, 4.5 hours for the 50 and 100 Year ARI storms and 3 hours for the 200 and 500 Year ARI events and the PMP. Anzac Oval - 6 hours for events up to and including the 100 Year ARI storm, 4.5 hours for the 200 and 500 Year ARI events, and 3 hours for the PMP. Heavitree Gap - 9 hours for the 20 year ARI storm, 6 hours for the 50, 100, 200 and 500 Year ARI storms, and 3 hours for the PMP. The PMP critical duration is 4.5 hours downstream of Heavitree Gap, but remains unchanged for smaller ARIs. The following comments are made with respect to the design discharge estimates shown in Table 9.4: The URBS model results are consistent and comparable with flood frequency analysis results for 20 year, 50 year and 100 year ARI flood events at both Wigley Gorge and Anzac Oval; The PMF discharge downstream of Heavitree Gap (7666 m3/s) into the rural area south of Alice Springs area is more than 5 times the estimated 100 year ARI discharge (1368 m3/s). Upstream of Heavitree Gap PMF discharges are between 7 and 10 times the estimated 100 year ARI discharge. The reduction in peak discharges through the Heavitree Gap due to the upstream flood storage and choking effects are not significant for flood events up to 100 year ARI. The attenuation in peak discharge is significant for the PMF. Table 9.4 Estimated Design Flood Discharges at Wigley Gorge, Anzac Oval and Heavitree Gap Event ARI (Years) Peak Discharge (m3/s) Wigley Gorge Anzac Oval Heavitree Gap URBS FFA URBS FFA URBS FFA 20 710 689 748 724 791 (u/s) 772 (d/s) - 50 1044 1071 1090 1103 1160 (u/s) 1099 (d/s) - 100 1382 1428 1433 1447 1520 (u/s) 1414 (d/s) - 200 2501 - 2360 - 2458 (u/s) 2195 (d/s) - 500 3540 - 3308 - 3455 (u/s) 3005 (d/s) - PMF 12898 - 11369 - 11299 (u/s) 7666 (d/s) -


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