Floodplain Management Policy, Alice Springs Report by the Alice Springs Floodplain Working Group
Verhoeven, T. J.
E-Publications; E-Books; PublicationNT; Report ; 37/1983
Made available via the Publications (Legal Deposit) Act 2004 (NT).
Dept. of Transport and Works
Report ; 37/1983
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Technical Report WRA83037 Viewed at 04:02:48 on 18/02/2010 Page 9 of 14. J J J '1 J 'j ! , ! c I I -' J I -' I .1 , , I: -= " , , -d.::. -, . I ' , !. I , ~ .:.% ,~, r 3.5. 3.5.1. 3.5.2. "< - 3 ...... :) . .. 3.5.4. 3.5.5 . 3.5.6. 3.5.7. . \1 ! I MITIGATION HEASURES The Northern Territory Flood ?la~2 Management Committee's interim policy sta~es inter alia that structu~al works designed to change floodwater behaviour or alter the course of st-reams a:!:"e not encoy.raged.. S'C.ch '.-larks viould include levee banks constructed on the floodplain except in special circw~stances. This indicates that future road crossings of the Todd River should be eit~er bed-level crossings (such as the Ross Highway causeway - with acceptance by the populatio~ noted) or high-level bridge crossings (a large expense for the nuw~er of times required), One mitigation measure which would significantly reduce tr:.e extent 2.~d cos::' of flooding would be a dam constructed on the Todd River at the Telegraph Statio~ Gtilisi~q Spillway Alternative 'A' as de~icted at appendix 'C'. The effect on flooding as a ~esult 0: constructing a dam on the Toed River :.lsir:.g various spillway options has been studied and documented by the Department of Transport and Works and by the Sno' .... y ~lountains Engir,eerir:g Corporation. Spillway Alternative A provides the greatest benefit for flood mitigatior:. The impact of the dam with Spillway 'At canst-ruction would be to reduce the Q100 event to the extent of a Q20 event, Peak discharge is reduced from 1000 cubic metres/second to 620 cubic metres/secor,d. This impact is realised by comparlng appendices 'B' and '0'. The Working Group found that in the opinion of long time residents of the TOW~f the bed of the Todd River is not as lew as it used to be thereby indicating a build up 0= silt. Work undertaken by the Departmen;:: of Transport and Works at various qo~aes in the area also indicate aggrada tion c;: streams. It is estimated that aporoximatelv cne metre of alluvial material h~~ been built up in the Todd River in this century. If the dam were to oroceed, the silt would gradually be scoured out by t:'le river. Build up of reeds as exists at the CasiLo causeway should be removed . ----,-------------,-