Monday 26 November 2007

Mean Sea Level

Seems to me that the whole issue of this dispute - the legality of View Talay 7 project construction - hinges on the definition of Mean Sea Level.

The 'professional survey team' turned out on 15th November as scheduled, and surveyed the site of View Talay 7 to determine Mean Sea Level.

Not So Easy To Determine

Quoting http://en.wikipedia.org/wiki/Sea_level as follows:

Surveying the View Talay site

Mean sea level (MSL) is the average (mean) height of the sea, with reference to a suitable reference surface. Defining the reference level, however, involves complex measurement, and accurately determining MSL can prove difficult...

Taking a height reading at the View Talay site

MSL means the "still water level" — the level of the sea with motions such as wind waves averaged out — averaged over a period of time such that changes in sea level, e.g., due to the tides, also get averaged out. One measures the values of MSL in respect to the land. Hence a change in MSL can result from a real change in sea level, or from a change in the height of the land on which the tide gauge operates.

Measuring the sea level at the View Talay site

In the UK, mean sea level has been measured at Newlyn in Cornwall and Liverpool on Merseyside for decades, by tide gauges to provide Ordnance Datum for the zero metres height on UK maps...

Mean sea level does not remain constant over the surface of the entire earth. For instance, mean sea level at the Pacific end of the Panama Canal stands 20 cm higher than at the Atlantic end.

And from Wikipedia:

The term above mean sea level (AMSL) refers to the elevation (on the ground) or altitude (in the air) of any object, relative to the average sea level datum.

So, is that all perfectly clear now?

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