Territory Stories

Flood Warning and Damages in Alice Springs: Part 1 Executive Summary. Part 2 Tangible Damages Part 3 Intangible Damages & Emergency Procedures

Details:

Title

Flood Warning and Damages in Alice Springs: Part 1 Executive Summary. Part 2 Tangible Damages Part 3 Intangible Damages & Emergency Procedures

Creator

Handmer, John; Smith, D. I.; Greenaway, Mark

Collection

E-Publications; E-Books; PublicationNT; Report ; 53/1989

Date

1989-04-01

Description

Made available via the Publications (Legal Deposit) Act 2004 (NT).

Notes

Date:1989-04

Language

English

Publisher name

Power and Water Authority

Place of publication

Alice Springs

Series

Report ; 53/1989

File type

application/pdf.

Copyright owner

Check within Publication or with content Publisher.

Parent handle

https://hdl.handle.net/10070/228902

Citation address

https://hdl.handle.net/10070/673596

Page content

Technical Report WRA89053 Viewed at 03:02:00 on 18/02/2010 Page 127 of 139. I ("GnC; '"--,, 1--______________ _ I I I I I I I I I I I I I I I I I I (a) Warnill~ofFl0oding in Town This warning time is relevant to people in Hood prone areas of the town because it allows them to move some of their property above Hood levei and thereby reduce losses. An infinite increase in warning time is available for floods with average return intervals between 6 years and 100 years because for these Hoods, flood peaks with the dam are less than the within-bank capacity of the river. For the 100 year flood, an additional 2.2 hours warning time would be available if the dam was full at the start of the storm, even more if the dam was only partially full (refer Fig. 3). (b) Warning TimeyVithinRiver Channel For large floods (greater than 10 year flood), additional warning time for nows up to 200 to 250m31s is negligible. This is because the initial now is coming from the 92km2 catchment downstream of the dam. Some additional warning time is apparent for smaller noods (refer Figs 4 & 5). The tlood mitigation dam would provide significant additional warning time for Hows greater than 300mJ/s. The conclusion to be drawn from the above is that additional warning time for the "partially full" dam would at least be equal to that for the "full" dam described in the EIS (refer 3.02). The benet Its of the above are: greater safety for residents of Alice Springs a reduction in potential damage caused by the floods removal of Hood prone land at least equal to that described in the EIS. Control of River Scour River scour downstream of the darn would be controlled as -outlined in the EIS, ie. by carting sand and gravel by truck from the sediment traps and placing it in the spillway low flow channel. The "partially full" dam has both an advantage and a disadvantage with respect to river scour when compared with the" full" dam. The "partially full" dam has the disadvantage that only a proportion of its discharge passes down the spillway channel and can transport sand into the river downstream. For the "full" dam, all discharge from the dam passes down the spillway channel and has the capacity to pick up sand placed therein whereas for the "partially full" dam, tlow only passes down the spillway channel when the 9


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