Weirs and Locks on The River Thames in England.

Huge violent weirs controlled by equally huge sluices to small quiet weirs some still controlled by Paddle and Rymer - The River Thames has them all.

There are several particularly impressive weirs on The River Thames - perhaps the best example is the weir at Hambleden - The Thames is fairly wide there and the weir is staggered across the water rather than straight across. You can walk right across Hambleden's weir and whilst doing so you get a feel of really being amongst the action of the river especially if there is plenty of water flowing. The most violent watere activity at a weir we have seen is the that found next to Abingdon Lock - the River Thames there is fairly narrow and Abingdon's weir goes almost straight across - after heavy rain the force of the water going through the sluices makes the whole structure shudder. Originally weirs were constructed by mill owners to create enough force to power their paddles - these weirs were constructed by placing stones and boulders on the river bed and holding them in place with interwoven wooden stakes and mesh. Fishermen also took advantage of this blockade because they could easily net the eels during the migration which occurs during May and June. Before locks were introduced on the river these weirs created quite a headache for boats - if going downstream the boats waited for a head of water to be created and then part of the weir would be removed and the boats would be "flashed" through the gap - boats heading upstream had to be pulled through manually. This breaking of the weir obviously took the flow away from the mills each time boats needed to pass through so boatmen and mill owners were not exactly the best of friends.
In many cases the weirs are situated close to the various Thames Locks and these days provide two particular functions:
The lock gates will always be closed at one end of the lock or the other and obviously the river's water has to go somewhere and the weir provides an escape route,
Secondly unlike on the canals which contain fairly static water and can get away with quite narrow sluices, although The Thames is not tidal (The Thames is subject to tides from Teddington out to the North Sea only) the volume of water in them and the rate of flow changes all the time - for instance after heavy rain fall - so the weirs have to be quite wide to cope and sometimes are staggered across the river rather than built straight across to allow for more volume control. The water authorities can control the river's height over most of the length of The Thames and where necessary restrict water flow by raising or lowering the paddles on the weirs - perhaps allowing the river to go over it's banks into water meadows in some locations upstream and protect more sensitive areas from flooding elsewhere. Equally if there is a shortage of water perhaps during a drought the weirs are used to maintain a certain depth of water in shallower parts of the river.
There are also various locations along the Thames where the weirs are a considerable distance away from the locks - for instance the Thames at Culham enjoys one of it's frequent loops and Clifton Cut was constructed in 1809 along with Culham lock near to Culham Bridge. The weirs themselves are actually across a water meadow from the lock at the edge of Sutton Courtney where there was once a paper mill - prior to the construction of Culham Cut the Mill owners used to charge heavy tolls for river traffic.
The following are photos of some of the Locks and Weirs which can be found on The River Thames - starting up at the River's first and highest lock at Lechlade and heading South - plus there are several photos of one of the few remaining active Paddle and Rymer Weirs which is located at Northmoor Lock in Oxfordshire.

Access to the Weirs on the Rivr Thames:

in some cases it is possible to walk right onto the weirs and in fact cross the Thames on them such as Marsh Weir outside of Henley, at Benson and at Hambleden. This is because the weirs are parts of public rights of way (footpaths) or form part of the route of a National Trail such as the Thames Path. Where we know (as of July 2012) you can at least get onto a weir the name of it is marked in green - (however even access to these weirs may be stopped temorarily for various "waterways" reasons).