Response to the River Weirs - Good Practice Guide from Carl Douglas as posted
on the rowing ng:
"A hugely relevant section of this report is on p28 of the section
referred to directly above:
"2.3.9 Weirs suitable for canoeists
"(i) General
"In the context of this guide, a canoeist is taken to mean a
person in a kayak that is designed for use in white water. It is,
of course, recognised that canoes take many forms, and it is
necessary to consider the safety of any and all river users.
-snipped -
"Many existing weirs do not provide safe or suitable conditions
for canoeists. When modifications are carried out to such weirs,
or when new weirs are constructed, it is essential that the
potential interest of canoeists is considered in the planning and
design process (see Case Study H). It will not always be
appropriate to make weirs suitable for canoeists, but ignoring
the safety of river users in the design of such works will render
those responsible liable to prosecution in the event of an
accident, especially if the river is known to be used for
canoeing."
Allan & I have, quite separately, been working get the various
authorities, including the ARA, the BCU & the EA (& predecessors), to
accept the legal need to guard these installations. Hitherto the ARA &
the EA simply haven't wanted to know. Imagine my surprise upon seeing
in the EA's own document this direct statement of public liability.
Not only canoeists are vulnerable to the dangers inherent in the
hydraulic design of various man-made river installations. Rowers have
died in Thames sluices, yet the ARA has not given a toss. And the ARA
recently buried the results of its so-called enquiry into a major
accident at Hambledon sluices, below Henley (?to protect certain
reputations?).
The paragraph continues:
"(ii) The hydraulic jump
"A hydraulic jump is a mass of turbulent water that occurs when
very fast flowing water meets much slower and deeper water
(see Case Study H). Hydraulic jumps are therefore frequently a
feature immediately downstream of weirs. Canoeists refer to
them as standing waves (which describes their appearance) or
stoppers (which describes the impact that they can have on a
canoe!). A fundamental feature of the hydraulic jump is the
rotating flow pattern, illustrated in Figure 2.7, which can prevent
anything caught in the jump from escaping. It is this feature
that poses the greatest risk to a canoeist (and to anyone
finding themselves in the turbulent conditions downstream of a
weir). The return current brings the canoe or swimmer back to
the base of the weir, trapping them in turbulent water with the
inevitable risk of drowning."
That's _exactly_ what I've been saying on a number of occasions here on
RSR. I note that the BCU did become involved in this study, but the ARA
was nowhere to be seen. Another instance of human safety being at the
bottom of ARA priorities, I'm afraid.
As if to underline the particular dangers of Thames anti-scour sluices,
on p20 the report says:
"Raised sills – often constructed at the end of a stilling basin
to reduce the risk of bed scour, these can create intense
underwater currents that can trap a swimmer or canoeist"
Again, just what I've been saying about these installations
Does this report mean that the EA, having publicly recognised &
boom guards well upstream of it weirs, & particularly above its deadly
Thames sluices? These guard should be designed to keep rowers,
canoeists & inadvertent swimmers out of the killing zone (that area
upstream of the open sluices from which no swimmer can possibly escape).
Carl"
So, Mr Hawkesworth: now that the EA have admitted that some of their
structures are a danger to river-users (such as racing paddlers - the guide
does not recognise racing or touring paddlers as canoeists!!!) - with "the
inevitable risk of drowning", and acknowledge their liability - what does the
BCU propose to do to ensure the weirs are made safe?
Allan Bennett
Not a fan of water torture
--
>> Stay informed about: Safety of Thames Weirs (and others) 
FAQ
Profile
Private Messages
Log in
