Re: [Paddlewise] Constricted Bay Entrances

>This month's "The Industrial Physicist" magazine, 
>http://www.tipmagazine.com/ has an interesting article about using 
>computer modelling to define tide variability, 
>http://www.tipmagazine.com/tip/INPHFA/vol-7/iss-5/p14.pdf
>
>The author is Derek Goring, the principal scientist of the Coastal 
>Hydrodynamics Group of the National Institute of Water and Atmospheric 
>Research Ltd. in Christchurch, New Zealand (d.goring_at_niwa.cri.nz).

I've heard Derek speak a couple of times and give a Power Point 
presentation of some tidal flows -

http://www.niwa.cri.nz/pgsf/CASHCANZ/peninsula.html

http://www.niwa.cri.nz/pgsf/CASHCANZ/cook.html

If you hunt around a bit more on the site you will probably find the flow 
round New Zealand (anticlockwise). Lyttelton, which is the port for 
Christchurch has one spring tide a month and I believe there is one other 
place in the world with this. The area effected is from a bit north of 
Timaru to somewhere near Kaikoura so there's a fair bit of open coast i.e. 
not caused by constricted waters. The tide heights from tide to tide are 
not  a "smooth" sine wave but quite ragged.

Off the coast in front of Christchurch there is also a surge every 40? 
minutes, quite small about an inch or so if I remember correctly.

> >Is it generally true that where a tide stream runs through a bottleneck,
> >such as a narrow entrance to a widening bay, slack water in the bottleneck
> >will not coincide with either high water or low water?

Then there can be the effect of the surge (top of the tide) going in and 
coming out giving a couple of small peaks.

Alex
.
.

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