Re: (UK) Walton SBH cancelled

My colleagues tell me that while flow rates might not show clear
trends it is fairly certain that river velocities in the lower Thames
will be faster for a given flow than they were in the 1920s, as the
river has been 'cleaned up' - i.e. there are fewer weirs, jetties,
fish traps and assorted junk, and a shorter and steeper path - so
velocities increase and the river can carry more water without causing
over bank flooding.

Direct abstraction can also be very significant and will have reduced
peak flows substantially.

I had another look at some of the Kingston data, and looked at flows
in Oct/Nov/Dec - interestingly the 'quiescent ' period in the 1970s
and 1980s is not so visible in the autumn - although there is still
nothing I would class as a trend.

Andy


On Dec 15, 1:52 am, Carl Douglas <c...@xxxxxxxxxxxxxxxxx> wrote:
Neil.W.James wrote:
On 14/12/2009 10:45, carolinetu wrote:
Weybridge Silver Sculls was founded in 1956 and is the oldest small
boats head on the non-tidal Thames.  The fact that the first
cancellation was 1982 must be significant (or perhaps people were less
bothered about safety in the early days).

Caroline

Or perhaps the clientele has changed and thus the applicable safety
standards.

Observing the results from two old almanacs, the following categories
were presented in those years:

1965:
Novice, Junior, Junior Senior and Senior (All singles)
(That is, no specific age-related event.)

1985:
Novice, Novice Tr (whatever that was), Senior A/B/C, Elite, Veteran
B/C/D/E singles
Junior, Novice, Senior B, Elite, Womens Junior 16, Womens doubles
Junior U16 quads

And now
2009:
57 different classes from J13 onwards.

Neil

You'd be right, I think, to believe that fewer youngsters raced in
winter heads 40 years ago - junior & novice not then signifying any age
qualification.

I suspect that Tr may stand for "Tracer" - a passing attempt to create a
class of more stable shell.

And I do think it has been made harder to hold events in stronger stream
conditions.

Something for the statisticians to chew on here:http://www.metoffice.gov.uk/climate/uk/stationdata/oxforddata.txt

I'd suppose these Oxford rainfalls may be taken to reflect rates of
drainage into the upper Thames?

It would be interesting to know how river rise rates respond to heavy
rainfalls now and in the past, including the influence of abstraction
rates.  Rise rates might be higher now due to greater urbanisation &
road-building in the catchments & the effects further downstream of
upstream flood alleviation schemes.  I guess the abstraction may,
intentionally or otherwise, reduce peak flows except where reservoirs
are already full.

Cheers -
Carl

--
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