Territory Stories

Miscellaneous Correspondence and Data on Alice Springs Flooding 1986



Miscellaneous Correspondence and Data on Alice Springs Flooding 1986


Hamlyn-Harris, D.; Galton, R. P.; Charrington, Rowan; Freyling, Ron


E-Publications; E-Books; PublicationNT; Report no. 33/1986







Publisher name

Northern Territory Government

Place of publication

Alice Springs


Report no. 33/1986

File type



Attribution International 4.0 (CC BY 4.0)

Copyright owner

Northern Territory Government



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Citation address


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I I I I I I I I I I I I I I I I I I I I 2 Mr. Paige, (cont) a. The first thing that happens is that the people responsible for flood warning are on duty. If the flow is 200 M3/sec we would start to crank up at emergency services procedure for evacuation. J think it is up to each organisation to decide what they will be doing during this time and the most you will have is 3 hours. I think it is up to each organisation to say in that rising moment, things are going to have to be done very quickly, what lS my organisation going to be doing?, thats the solution. b. The most physical damage will occur at the peak in the sense that that is when the water is highest, it is flooding most buildings at that stage and the velocity's the highest, so it will be eroding roads, causeways and culverts. So once again, you will look at what your organisation is doing prior to and at the peak flow. Does it affect you that roads are going to be out? Over what sort of area are you not going to be able to get access to places because roads are cut? It is at this stage where you get the situation where you got the highest expectation of wasing out (a) water rising mains, (b) eroding telecom cables, (c) rising sewerage mains, and possibly the gas pipeline is something that should be considered. So between the start and the peak of damage, you have got 4 hours, then we start looking at the Falling of the Hydrograph, and you might have another 10 hours or so. c. Once again look at what your organisation is doing during that time, things to consider are the peak of the damage is past and that you maybe struggling for access and communications. If this was a 1-00 flow, Heavitree Gap would not be there because of the road through the Gap would be completely gone. The road through the Gap is over designed for about 1-20 flow, and so would be topped at a 1-20 and once it is over-topped, it has got a much higher probability of eroding. During this period, what is your organisation going to be doing? Is it able to do the things its needed to do giving that you have got problems with access, you have got problems with communications and the welfare organisation is trying to look after people, provide them with food and drinking water. That sort of time scale comes out to 12-15 hours of a single flow. Now the experience in 1983 was in fact that there were two flows, and there is nothing to say that it will not happen again, so you would get One peak, the water flow starts to drop then another peak which is almost as big. That is what happened in 1983 and each peak was 24 hours apart. d. The fourth thing to consider is what happens when you get a duplicate event on the next day. Any comments?