[extropy-chat] Re-save the world

[BillK]

On 2/17/07, kevinfreels wrote:
> OK. Bad example. I was more curious about rivers. I know that the levels of
> the rivers vary according to precipitation, but since they empty into the
> sea I was expecting them to show some kind of increase.
>


I think your expectation is wrong.   :)

The author of the flooding map has made several comments about
accuracy, which I quoted earlier.  His map should only be used to give
a general indication of how the rise in sea level might affect the
coastal areas.

He points out that no allowance is made for tidal rise and fall, or
how sea defences or levees might affect the flooding. The NASA
satellite radar elevation data also means that if there are trees or
buildings on the riverbank, this would increase the apparent height of
the riverbank. So from the flood map generation POV, rivers would
generally remain within their present riverbanks. He also mentions
that although his map generates a possible new coastline, this new
coastline would probably be subject to rapid erosion by the sea.

Rivers flow downhill, (have you noticed?)  :)  so usually they will
only be near sea level within a few miles of the coast. You get
coastal swampland and flood plains where the gradient is very low and
this type of coastal land will all get flooded by rising sea levels.
But faster flowing rivers generally flow between higher banks which
have been created by erosion over centuries to contain massive floods
during storms. So a rise in sea level would flood coastal land and
move the river / sea meeting point upstream from its present position,
but mostly still keep the shortened river within the present riverbank
structure.

If you are looking to purchase future sea view land 20 years before it
becomes a sea view, I wouldn't risk it.  You can't predict how quickly
the sea level will rise or where the sea level rise is going to stop.
You might buy land at a sufficiently high elevation, but it might be
cut off by flooded land all around. I would stay away from the coast
and not buy any river flood plain land either.

Scenic hills is what you want.  :)


BillK