Street view Godstow Lock

How is flow estimated?

EA GODSTOW Downstream graph
EA GODSTOW Upstream graph

Managing the river in drought (when the weirs are not running) -

Kings and Godstow locks are fairly similar in length and width but the depth at Godstow is double that of Kings. Godstow therefore takes twice as much water out of the reach as Kings puts in. If they were operated the same number of times the level of the water in the reach between them would fall. By permitting some flow through the weir at the upstream lock the reach is kept in balance.

[ Of course the above does not actually mean 'depth'. The depth of the locks is not material. It is the fall that matters - the drop, the difference in level between lock full and lock empty - which governs the volume of water used by the lock.


So every time both locks are cycled the reach will fall by 129 cubic metres unless made up by other means.
To put this in perspective the average flow here is about 14 cubic metres a second and it would be less than 1 cubic metre per second in drought.
The actual drop varies from a few centimetres in high flood to more than the nominal figure in drought.

from Environment Agency Guide 2012-2013

This section in 'The Stripling Thames' by Fred Thacker
[ Note that Fred's order is Godstow Lock, Godstow Nunnery, Godstow Bridge and then the Trout Inn ]
The Thames Path - from Pinkhill Lock into Oxford from FoxysIslandWalks

LEFT Bank, tel: 01865 54784, length: 110'0", width: 16'3"

1992: Skyscan's Aerial View of Godstow Lock and Port Meadow with Oxford in the distance, in The Secret Thames -

Godstow Lock
Skyscan's Aerial View Godstow Lock and Port Meadow.

Godstow Lock is for me the start of the upper river. Below Godstow is the Oxford section with its rowing and punts and eventually Salters Steamers.
I know Londoners think the upper river starts where London stops - but the upper river for me is that remote section above Oxford which few people know or have seen.
1909: Fred Thacker, The Stripling Thames -

Although there be other regions in England even richer in history and beauty, they lack the prestige and the crowning embellishment he [the Thames] bestows.
I have learned to love this countryside, to wish to revive for myself its ancient life, and to discover what share of the wide history of England it was immediately aware of. And I have therefore explored many libraries and gleaned some harvest from their discoloured folios and pamphlets; I have learned much through the courtesy of rectors and of lowlier men.

Some of us Rectors are actually quite lowly!

Godstow Lock
Godstow Lock.

1789: Jessop - "Woodward's Hole"
1790: Godstow Lock built; Harris, "keeper of the Oxford Gaol, being the Commissioners' adviser"

1896: Andrew Lang -

Godstow Lock, Andrew Lang, 1896
Godstow Lock, Andrew Lang, 1896.

1900s? Mrs Bryan Stapleton "Three Oxfordshire Parishes" -

The erection of the pound lock at Godstow - destroyed the fordway into Pixey [ the great mead above Port Meadow, ie the RIGHT bank between Godstow Lock and Kings Lock ]

Fred Thacker’s Map, 1920
Fred Thacker's Map, 1920.

Godstow lock plaque, 1928
Godstow Lock plaque, 1928

The point about a "continuous reach from Godstow to Oxford" was that prior to this the usual route from upstream to Oxford was by Dukes Cut to the Oxford canal and then Isis Lock back to the Thames.
Medley Weir was not finally removed until 1937

2004: From my log book -

In 2004 I came down through Godstow Lock in my punt. As I entered the lock there was light rain and some very dark clouds. As the level dropped so did the clouds and as I left the lock the rain came down in torrents.
I could hardly breathe let alone see where I was going. The water inside the punt was visibly deepening. I ran straight up the LEFT bank at right angles and sat down and began to bail. I reckon over an inch of rain fell in that hour I was there. I was frozen to the bone and when the hail started it felt like the end of the world.
However it slowly eased off and I punted up to the Trout and slopped into their lavatory and changed my clothes. A hot meal later and with everything gently steaming in the July sun all was well again.

The moral is - if you must get caught in a cloudburst, always do so near a hot meal!
But seriously - even at the height of an English Summer - weather can change a light hearted trip into a serious matter. Enough rain can fall in an hour to compromise the stability of some small boats. And hypothermia can affect anyone - anywhere.

2006: Waterways News -

Godstow Lock in Oxford was highly commended for its £400,000 refurbishment in the Environmental and Historic category. Located on the site of a 12th century nunnery managed by English Heritage, the lock is one of the narrowest on the Thames at just 4.95 metres wide. The unusual site meant all construction work had to be carried out sensitively within a very restricted working area.