Flood Warning and Damages in Alice Springs: Part 1 Executive Summary. Part 2 Tangible Damages Part 3 Intangible Damages & Emergency Procedures
Handmer, John; Smith, D. I.; Greenaway, Mark
E-Publications; E-Books; PublicationNT; Report ; 53/1989
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Power and Water Authority
Report ; 53/1989
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Technical Report WRA89053 Viewed at 03:02:00 on 18/02/2010 Page 123 of 139. I 1 I I I I I I I I I I I I I I I I I I Flood I"litigation Perfonnance The Hood mitigation performance of the "partially full" dam is superior to that of the "full" dam, providing the dam has had time to empty prior to the onset of the next flood. In reaiity tloods sometimes follow soon after another flood. and the dam may not have time to fully empty. Under these circumstances the 11000 mitigation performance will approach that of a "full" dam. The tlood mItigation performance of the "partially full" dam over a range of floods is given in Table I. The peak flows for the "partially full" dam assume that water in the darn is at the low level outlet at the start of the storm. The peak Hows given in brackets arc those assuming two storms follow one after the other and the dam has not had time to empty. Real tloods would lie between these two extremes. TABLE 1 fLOOD MITIGATION PERFORl\fANCE OF "PARTIALLY FULL" DAM Annual Exceedance Probabilit, Flood Peak Flow at Dam Site Hood Peak Flow at Dam Site (Average Return Interval) No Dam WITH 'P ARTIALL Y FULL' DAM m31s m'/s 50 % (2 years) 2oo 16 (150)' 20% (5 years) 550 41 (290) 10% (10 years) 800 149 (356) 1 % (loo years) 13SO 400 (490) 0.2% (500 years) 2100 894 ( 1150) Probable Maximum Flood 123oo 9964 (11008), NOTES: 1. 2. Figures in brackets indicate peak flow at dam site if dam full to EL658 at start of storm. Difference between 9100 m'/s for full dam in EfS is due to effect of auxiliary spillway. 5