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 71 9 DESIGN EVENT HYDROLOGY 9.1 METHODOLOGY The calibrated URBS model was used to estimate design flood discharges in the Todd River catchment based on design rainfall Intensity Frequency - Duration (IFD) data from IEAust (1998). Design flood discharge hydrographs were estimated for a range of storm durations up to 72 hours for the 20, 50, 100, 200 and 500 Year ARI events. Estimates of the Probable Maximum Precipitation (PMP) event in the Todd River catchment were made using the Generalised Short Duration Method (GSDM) as described in BOM (2003a) and the Generalised Tropical Storm Method (GTSMR) as described in BOM (2003b). The PMP rainfall estimates were applied to the URBS model to generate flood hydrographs for the PMP design flood (PMPDF) in the Todd River catchment. For the purposes of this study, it has been assumed that the PMPDF is equivalent to the PMF for the Todd River catchment. 9.2 DESIGN RAINFALLS AND TEMPORAL PATTERNS 9.2.1 Design Events Up To 500 Year ARI Table 9.1 shows the adopted design rainfall intensities for the Todd River catchment. Design rainfall patterns and intensities were determined using standard procedures given in Australian Rainfall and Runoff (ARR) (IEAust, 1998) for the 20, 50 and 100 Year ARI events. Design rainfalls for the 200 Year and 500 Year ARI storms were interpolated using the method recommended in Book 6, Section 3.6.2 of ARR (1998). Extreme event GSDM temporal patterns (BOM, 2003a) were adopted for the 200 and 500 Year ARI design storms. Table 9.1 Adopted Design Rainfall Intensities, Todd River Catchment Duration (hours) Design Rainfall Intensities (mm/hr) 20 Year ARI 50 Year ARI 100 Year ARI 200 Year ARI 500 Year ARI 1 43.2 54.9 64.4 77.8 97.0 1.5 33.7 42.9 50.3 58.9 74.3 2 27.9 35.5 41.6 49.4 62.9 3 21.1 26.9 31.6 40.0 51.5 4.5 15.9 20.2 23.7 29.5 38.2 6 13.0 16.4 19.3 24.2 31.6 9 9.7 12.4 14.6 17.8 22.8 12 8.0 10.2 12.0 14.6 18.4 18 6.1 7.8 9.2 11.2 14.0 24 5.2 6.6 7.8 9.5 12.0 30 4.6 5.8 6.9 8.3 10.4 36 4.1 5.2 6.2 7.4 9.4 48 3.4 4.4 5.2 6.4 8.1 72 2.5 3.3 3.9 4.8 6.1


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