How to Build a Pond Overflow?

My recently installed wildlife pond with a flexible liner is filling rapidly
with rain and it can only be few weeks before it overtops. I want to
control where the water overflows rather than let it settle anywhere. So I
think I need a sluice. I say 'think' because none of the books I've seen
mention the need for a sluice in a pond which is not stream-fed. But what is
the best way to make a sluice in a flexible liner?

Some details of my pond: the edge of the pond slopes gently for about a
metre and is covered with pebbles. The liner rises 1" vertically all round
the perimeter and nestles among large pebbles - this allows me to fill the
pond right to the edge. In winter the water table reaches within about 4"
of the ground surface. Beyond one end of the pond the ground runs level for
about a metre then falls away.

I don't mind a temporary seasonal sluice.

many thanks, Davy

On Wed, 4 Oct 2006 08:39:57 +0100, Davy wrote:

My recently installed wildlife pond with a flexible liner is filling rapidly
with rain and it can only be few weeks before it overtops. I want to
control where the water overflows rather than let it settle anywhere. So I
think I need a sluice. I say 'think' because none of the books I've seen
mention the need for a sluice in a pond which is not stream-fed. But what is
the best way to make a sluice in a flexible liner?

Some details of my pond: the edge of the pond slopes gently for about a
metre and is covered with pebbles. The liner rises 1" vertically all round
the perimeter and nestles among large pebbles - this allows me to fill the
pond right to the edge. In winter the water table reaches within about 4"
of the ground surface. Beyond one end of the pond the ground runs level for
about a metre then falls away.

You could just lower the liner slightly at the edge where you want it
to run away and then it will just overflow as it needs to. The pond is
only 1 inch above ground and the water table comes so high I don't
really think a sluice is practical whereas if you lower a couple of
foot of the edge by 1/8 inch (for example) it will just overflow there.

I'm not sure it's necessary though. Before the pond was put in the
water that fell there presumably ran down where the ground sloped away
and you are going to have the same amount of water trying to do that as
putting the pond in hasn't changed the surface area that will catch the
water. I doubt if the liner is perfectly level all the way round and it
will overflow a one point in particular so it might be worth gently
overflowing the pond and seeing where the water goes.

Of course it depends on the site and how big it is, you don't want a
stream of water racing all around one side of the pond digging the
edges out as it runs away :-)

--
Regards - Rodney Pont
The from address exists but is mostly dumped,
please send any emails to the address below
e-mail ngpsm4 (at) infohitsystems (dot) ltd (dot) uk