[OSM-talk] Landsat vs PGS [was: Coastline and Rivers]

[Richard Fairhurst]

Thomas Walraet wrote:

> Raphael Studer a écrit :
>> Where does a river and and a coastline begin?
>
> IMHO, it's coastline if tides affect the water level. As proposed on
> this page : http://wiki.openstreetmap.org/index.php/Tidal_Rivers

I'm not sure it's that easy, but I don't know what the answer is. A  
couple of UK examples which are certainly not coastline:

- The River Severn can be tidal _way_ inland (as far as Tewkesbury) at  
certain, occasional spring tides, but is non-tidal above Gloucester  
the rest of the time. (Essentially it depends on whether the tide  
overtops the weir at Maisemore.)

- The Norfolk Broads are all tidal.

- The River Great Ouse is tidal for an "isolated" inland section of  
about a mile, where a tidal drain (the New Bedford River) joins it.

If one were to formalise it, I'd suggest that coastline becomes a  
river if it extends for over n miles at a width of less than j metres.  
IIRC the UK Government uses a definition similar to this. In reality,  
I suspect "use your judgement" is the best answer.

cheers
Richard