Southern Oxford

[Proper Job]

A mate just forwarded me some info from BW regarding current reservior reserves for the Oxford Summit

 

In 2011 serious restrictions to navigation were in place from early July to the end of the season. Matt Wells, Hydrologist for British Waterways reports “Last year was one of the driest years on record across the southern half of the country. As a result the underlying hydrological conditions have remained stressed and consequently reservoir refill during the winter so far, has been lower than we’d usually experience in the South East. The group of reservoirs we call the Oxford & Grand Union hydrological unit, feeding the Grand Union Mainline down to Milton Keynes as well as the Oxford Canal and the Leicester Line in the South East Waterway, currently remain lower than we’d expect for this time of year. We currently estimate that there is a greater than 25% risk that the Oxford & Grand Union reservoir group will not reach a refill target holding of 80% full by the start of the main boating season. We monitor water resources closely during the winter refill period. As a result of the risk to reservoir refill becoming apparent, on 13th January we announced £700,000 of additional investment with the aim of increasing water resources resilience in drought prone areas of the network. Examples of schemes identified in the Oxford & Grand Union hydrological unit include; works to reservoir and canal feeders, and back-pumping at Braunston.” Matt has kindly provided a graphic illustration of the present position on water resources.

 

The graph below show the current state of reservoir levels that feed the Southern Oxford summit

 

 

The green line represent reservoir levels last year

 

The blue is what they would hope for

 

The red is the levels to date.

 

Given that the route to the South via the GU is shut and any traffic will have to go via the Southern Oxford, I can't see levels recovering that much.

 

It's gonna be a dry Summer

[MoominPapa]

Some hope there, since the new year the reservoirs have been filling faster than they were last year, and faster than they do on average in January. If that trend continues it might be OK.

 

I wonder when refill stops and drawdown starts? It looks like 1200 Ml is "reservoir full" which is typically achieved by week 11, and then inflows exceed outflows 'till week 16 or so. If the current rate of filling continues to week 16, it will be above 1000Ml, but only if consumption doesn't increase before then.

 

 

MP.

[matty40s]

Some hope there, since the new year the reservoirs have been filling faster than they were last year, and faster than they do on average in January. If that trend continues it might be OK.

I wonder when refill stops and drawdown starts? It looks like 1200 Ml is "reservoir full" which is typically achieved by week 11, and then inflows exceed outflows 'till week 16 or so. If the current rate of filling continues to week 16, it will be above 1000Ml, but only if consumption doesn't increase before then.

MP.

 

A BW bailiff in the area said they were praying that there was no extended freeze this winter, as Boddington was so low, the fish stocks would be frozen solid.

 

Thats an awfully large shortfall to make up, and would need major rainfall over and extended period to achieve. ........with resulting flooding problems.

[scrumpylurcher]

We have still not had the rainfall in the areas mentioned by BW, concerns for the situation later this year are well founded.

[Proper Job]

Some hope there, since the new year the reservoirs have been filling faster than they were last year, and faster than they do on average in January. If that trend continues it might be OK.

 

I wonder when refill stops and draw-down starts? It looks like 1200 Ml is "reservoir full" which is typically achieved by week 11, and then inflows exceed outflows 'till week 16 or so. If the current rate of filling continues to week 16, it will be above 1000 Ml, but only if consumption doesn't increase before then.

 

 

MP.

I'm not sure I share your optimism.

 

My interpretation:

Looking at the average expectation (blue line), Filling starts at about week 40 and it take about 19/20 weeks to get to maximum (week 7 of the of the following year. Over that period about 500 Ml of water is added.

 

On an average year the start point is around 700 Ml. This year the start point around 400 Ml. Assuming that we get average rain fall, that will add another 500 Ml to level. This would take them up to around 900 Ml.

 

Filling started around week 49 (400 Ml) of last year. 6 weeks later it's at 550'ish. If you extrapolate that out, you still get to around the 900 Ml when the draw off starts (around week 19). If draw off starts earlier (as it did last year - week 14) it'll struggle to be half full.

 

All of the above assumes traffic levels to be 'typical', but if the GU remains closed to Southbound traffic for any length of time, the traffic level will probably well above normal.

 

I think it'll be time to head for the river around early June

[MoominPapa]

I'm not sure I share your optimism.

I think I can paraphrase this as

 

MP: if it continues to rain like it has for the last three weeks for the rest of the winter and the summer is wet(ish) we might just be alright.

 

PJ: if next year is dry like this one we're doomed.

 

We're both right and neither of us knows what future rainfall will be.

 

 

MP.

[classicstove]

The BW statement mentions back pumping at Braunston

 

When last at Braunston bottom lock, I was aware that pumps had been installed (under the grating the Union Canal Cariers side of the bridge) but they did not have a pipe from them to the top of the flight as the farmer would not allow BW into there field

 

Does anyone know what has happened about this or are we due to have a 6 inch pipe all the way up the towpath for the summer ?

[Chalky]

We're moored on the top pound of the South Oxford and although the levels are ok at the moment it doesn't take much for them to drop. Cropredy festival is usually a major draw on water resources.

 

Is there any back pumping on the Claydon flight and at Cropredy?

[Proper Job]

As far as I'm aware, the only back pumping is at Napton/Marston Doles

 

I think I can paraphrase this as

 

MP: if it continues to rain like it has for the last three weeks for the rest of the winter and the summer is wet(ish) we might just be alright.

 

PJ: if next year is dry like this one we're doomed.

 

We're both right and neither of us knows what future rainfall will be.

 

 

MP.

 

we're doomed

 

[LEO]

Some hope there, since the new year the reservoirs have been filling faster than they were last year, and faster than they do on average in January. If that trend continues it might be OK.

 

I wonder when refill stops and drawdown starts? It looks like 1200 Ml is "reservoir full" which is typically achieved by week 11, and then inflows exceed outflows 'till week 16 or so. If the current rate of filling continues to week 16, it will be above 1000Ml, but only if consumption doesn't increase before then.

 

 

MP.

 

Hi,

 

Interestingly enough BW produced a similar graph for Tring Reservoir Group refill estimates. This had a similar profile for 2011 actual refilling but did not show any profile for 2012.

 

Leo.

[BEngo]

The BW statement mentions back pumping at Braunston

 

When last at Braunston bottom lock, I was aware that pumps had been installed (under the grating the Union Canal Cariers side of the bridge) but they did not have a pipe from them to the top of the flight as the farmer would not allow BW into there field

 

Does anyone know what has happened about this or are we due to have a 6 inch pipe all the way up the towpath for the summer ?

 

 

It was all sorted out. The Braunston back pumps work, but like everything else cost money to run and can't get water uphill as fast as it can be used.

 

N

[Chalky]

The Napton / Braunston pound had restricted opening hours on the locks last year due to low levels. (The Bascote pound was also hard work and we draw 22"). If the pumps are now fixed at Napton where's the extra water going to come from - you'll need to replace water used going down Claydon.

 

Is it possible to move water from the north of the network where there appears to be a surplus to the south where its in short supply? I remember reading about watergrid a few years ago but I think that was just drinking water in local areas.

[Proper Job]

I'm not sure how true it was, but I was told that the Napton pumps running for 24 hours equated to the 4 hour opening of the restrictions at Napton and Claydon

[john6767]

I'm not sure how true it was, but I was told that the Napton pumps running for 24 hours equated to the 4 hour opening of the restrictions at Napton and Claydon

 

That is what the lock keeper at Claydon told us when we when through in August. During the 4 hours of opening the water level dropped, and over the following 20 hours it made it back up again.

 

The Braunston pound is plenty full at the moment (or was when I was there last), it was pouring over the bywash at Calcutt.

 

If it was pumped back up Napton, is there the ability to have it extracted from the canal and into the reservoir? I understand that is what is happing With Earlswood Lakes; basically the excess water being extracted at Bradley is being stored at Earlswood.

 

 

 

Edited January 19, 2012 by john6767

[Proper Job]

When we went over the summit last August it took us over 5 hours to plough our way across (normally around 3 hours)

 

We moored (more like beached) top side of Maston Doles ready to go down the next day. As you say, the level definitely recovered a bit over night, although it was far from back to normal.

 

The chap we were talking to said the pumps made up the equivilent of 40 lockfulls a day, so I presume that would be about 20 down Napton and 20 down Claydon (5 locks per hour on each flight)