Re: renewable energy

[Hugh Haskell <hhaskell@MINDSPRING.COM>]

At 17:20 -0400 8/11/02, chuck britton wrote:
> At 8:45 AM -0700 8/11/02, Leigh Palmer wrote:
> > Chuck Britton reports:
> >
> > > And the 'powers that be' are becoming more aware of the importance
> > > and possibility of limiting siltation by periodic release of silt
> > > laden water (water from the bottom of the lake rather than the 'top'
> > > water that normally flows through the penstocks.
> >
> > Can that be done easily? Does one have to bore a tunnel in or near
> > the dam far below the lake level? Can this be done at, for example,
> > Hoover Dam?
>
> Don't know about Hoover Dam but the Glen Canyon dam closed it's
> sluice gate in 1963. I'm supposing that this sluice gate was used to
> release the silt/water through the lower turbine tunnels.

One problem with building dams that end up trapping the silt being
carried by the river is that the silt often serves to enhance the
usefulness of downstream farmlands. Removing that source means that
the farms that used to depend on the silting to renew their fields
now must depend on other methods that are often expensive, and in
themselves environmentally dangerous. A case in point is the Aswan
dam in Egypt. I am told that it is silting up rapidly, and may not
make the 200-year lifetime that was envisioned, but meanwhile the
agricultural lands along the lower Nile that used to provide a
bountiful harvest are now marginal, and an area that was once a net
food producer is now a net food importer.

The dams also sometimes exacerbate the flooding problems they are
designed to control. In most cases, seasonal flooding would be no
problem on most rivers, except that we insist on building big cities
on the shores, and then somehow blame the river for flooding those
cities every so often. It seems to me that if we had not ever started
this habit of building on various flood plains, we would be much
better off. Our agriculture would be sounder, and the enormous
expenses we generate each year for flood recovery would be
significantly reduced.

Hugh
--

Hugh Haskell
<mailto:haskell@ncssm.edu>
<mailto:hhaskell@mindspring.com>

(919) 467-7610

Let's face it. People use a Mac because they want to, Windows because they
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