Thoughts - When is a Shoreline a Shoreline?
Frequent visitors know that I have a dream - to map shorelines of the world at a level of precision which I call Enhanced Vector Shorelines (EVS). Using Landsat ETM+ 2000 imagery, which I might add is the same imagery used to create the Prototype Global Shoreline (PGS), I would delineate, using vectors, all shorelines. PGS came close, but still requires a considerable amount of "fine tuning" before it would mirror EVS precision. In addition, PGS, at the request of the National Geospatial-Intelligence Agency (NGA), followed a mapping protocol that excluded water-inundated shoreline (swamps, some wetlands, etc.). Not all was excluded, but some.
My initial question - When is a Shoreline a Shoreline? - begs to be answered. Intuitively, the WVS seems to track the shoreline. It would be the shoreline that EVS would follow, after improving upon it. PGS, however, follows the inland shoreline. I guess you would call it the permanent shoreline.
If I am a sailor steering my craft into this area, I would be sad when my boat ran aground well before the PGS depicted shoreline was reached. In NGA's zeal to create a consistent shoreline I believe they left out shoreline that all of us map makers, sailors, maritime engineers and coastal commissions would require.
As I make the above statement, I am keenly aware of the nature of these water-inundated shorelines. They are highly dynamic, fluid entities that often exist fleetingly. On the other hand, if they can be imaged by Landsat, or any of the other satellite imaging concerns, they should be mapped.
Most certainly, NGA, along with MDA, have a plan of attack for these shorelines that aren't shorelines. The PGS is a "prototype" waiting to be finished. It is most probably a funding issue that once satisfied will tackle the mapping of the world's dynamic shorelines.
My EVS-approach would be to map these outer margins as shorelines during phase one. If it floats and it is attached, map it. This would include the outer limits of wetlands, mudflats, river deltas, etc.) They would be tagged as dynamic in nature, subject to change. These shorelines, once tagged, could then be monitored on a scheduled basis for any substantitive changes. When changes are detected, digital mapping would be updated. Paper maps would be updated through existing channels (Notice to Mariners, etc.) on a less frequent schedule.
So all of you "sea-faring" folks, all of you with coastal shoreline interests - When is a Shoreline a Shoreline? PGS solution or EVS solution?
