Jubilee River & Wraysbury floods

[ianc1200]

Did anybody else hear the interesting debate on BBC Radio Berks just after 8am this morning? A couple of residents & a very harassed EA official, with a lady from Ham Island saying how the EA should have closed the gates earlier & the real problem was the flood water going down the Jubilee River didn't get a chance to spread across the flood plain before it reached Wraysbury. In her words Ham Island had been sacrificed to save Maidenhead. However, if I heard correctly the point about the floods gates on the Jubilee River having not been closed early enough appears to be an admission it is causing flooding further down. The EA official also talked about a future flood relief channel for the Wraysbury area.

 

[GAJ52]

I have lived in Wraysbury for 30 years and the only significant flooding I remember is 2003 and now, seems strange how these floods have occurred AFTER the Jubilee River opened and nothing before, except the well known 1947 floods of course. With all the money spent on the Jubilee River you are never going to get any official admitting its use is causing more flooding downstream, they will always provide an 'expert' to counter this assumption.

 

[534l4rk]

I have lived in Wraysbury for 30 years and the only significant flooding I remember is 2003 and now, seems strange how these floods have occurred AFTER the Jubilee River opened and nothing before, except the well known 1947 floods of course. With all the money spent on the Jubilee River you are never going to get any official admitting its use is causing more flooding downstream, they will always provide an 'expert' to counter this assumption.

Does anyone know if the rainfall this time was more or less than in 2003 ?

 

[GAJ52]

I can't answer that one, the only thing different to 2003 was this time the flooding was quite slow over several hours, in 2003 my garden was flooded significantly within 45 mins to one hour as if there was a sudden surge of water ? Many local people blamed this onto the Jubilee River as it was the first time it was used after construction, but again the EA denied the JR was to blame !!

 

[oldgit]

Tonbridge vs Yalding vs Maidstone

If Tonbridge gets flooded its because "they " want to save Maidstone/Yalding.
If Yalding gets it its because all the councillors live in Tonbridge.
If Maidstone floods its all because......etc etc .
Yawn.

If you do not want to get flooded live on a hill...........

 

[TT_WO]

I can't answer that one, the only thing different to 2003 was this time the flooding was quite slow over several hours, in 2003 my garden was flooded significantly within 45 mins to one hour as if there was a sudden surge of water ? Many local people blamed this onto the Jubilee River as it was the first time it was used after construction, but again the EA denied the JR was to blame !!

After 2010, the operating procedures were changed to open the jubilee in smaller increments in the later stages of a flood event. The flow rate was increased from 145 to 170 cumecs, still a considerable reduction on the design capacity. I understand the flow reached 160 cumecs during the 2003 event, before damage occurred to the structure.

Could explain the slower rise in water level ?

 

[534l4rk]

After 2010, the operating procedures were changed to open the jubilee in smaller increments in the later stages of a flood event. The flow rate was increased from 145 to 170 cumecs, still a considerable reduction on the design capacity. I understand the flow reached 160 cumecs during the 2003 event, before damage occurred to the structure.

Could explain the slower rise in water level ?

I also understood that the operation of the Jubilee was in incremental steps as TT_WO posted and that to ensure that the capacity was not exceeded the rate of discharge was slowed to ensure that it did not exceed the agreed maximum rate (believed to be 180 cumecs) This showed on the E.A. data station logger at 1200 and 1800 on the 10th January showing 2 rises in levels after the previous falls. Slowing the discharge from the Jubilee to reduce further flooding down river obviously increased levels upstream to Maidenhead and Cookham.

My own observations suggest that the E.A. lock keepers have handled the situation well under the circumstances but the critical question in my view is whether we had more rain than in 2003 ?

 

[TT_WO]

I also understood that the operation of the Jubilee was in incremental steps as TT_WO posted and that to ensure that the capacity was not exceeded the rate of discharge was slowed to ensure that it did not exceed the agreed maximum rate (believed to be 180 cumecs) This showed on the E.A. data station logger at 1200 and 1800 on the 10th January showing 2 rises in levels after the previous falls. Slowing the discharge from the Jubilee to reduce further flooding down river obviously increased levels upstream to Maidenhead and Cookham.

My own observations suggest that the E.A. lock keepers have handled the situation well under the circumstances but the critical question in my view is whether we had more rain than in 2003 ?

Is the Taplow guage the data logger station to which you refer?

I to believe that the operation of the Jubilee river has been managed well this time, compared with the first use in 2003.

It is seems that you believe (along with many others) that " Slowing the discharge from the Jubilee to/will reduce further flooding down river" this would seem to contradict the EA assertions that the operation of the Jubilee has no detrimental impact down river as the water is the same volume only delivered downstream by another route, ie, had it not been delivered by the Jubilee the same volume of water would have been delivered by the Thames.

Many riverside dwellers have reported the speed that flood waters increased in height during the 2003 event which does seem to indic

 

[TT_WO]

Sorry hit the wrong button, just to finish the sentence;

Many riverside dwellers have reported the speed that flood waters increased in height during the 2003 event, which does seem to indicate that the route that the water takes does seem to affect the level downstream given that it is the same volume of water!

 

[534l4rk]

Is the Taplow guage the data logger station to which you refer?

I to believe that the operation of the Jubilee river has been managed well this time, compared with the first use in 2003.

It is seems that you believe (along with many others) that " Slowing the discharge from the Jubilee to/will reduce further flooding down river" this would seem to contradict the EA assertions that the operation of the Jubilee has no detrimental impact down river as the water is the same volume only delivered downstream by another route, ie, had it not been delivered by the Jubilee the same volume of water would have been delivered by the Thames.

Many riverside dwellers have reported the speed that flood waters increased in height during the 2003 event which does seem to indic

Taplow – yes. My observations have been made using data from the monitor stations from Oxford and beyond down to Teddington. The subject related to river flooding seems to be controversial. Current thinking seems to support slowing down the rivers rather than speeding up. Whatever, the release of a greater volume at Datchet to my layman way of thinking will increase the likelihood of flooding further down. Certainly, the levels at Maidenhead appear to have been reduced by use of the Jubilee. I still believe the amount of rain compared with 2003 needs to be known.

 

[Chris_d]

Taplow – yes. My observations have been made using data from the monitor stations from Oxford and beyond down to Teddington. The subject related to river flooding seems to be controversial. Current thinking seems to support slowing down the rivers rather than speeding up. Whatever, the release of a greater volume at Datchet to my layman way of thinking will increase the likelihood of flooding further down. Certainly, the levels at Maidenhead appear to have been reduced by use of the Jubilee. I still believe the amount of rain compared with 2003 needs to be known.

Are you sure about that, I thought current thinking was to reduce the flow into the river not the river itself. Holding the water on flood plains by reducing the amount of fast flowing hard surfaces that allow water to drain into it too quickly is the problem, stuff on the news today about planting woodland that holds water in a flood plain and reduces flow etc. The river itself needs to flow as fast as possible to carry flood water away.

I remember in the 80's going to Hydraulics Research in Wallingford where my mother worked, they had a huge aircraft hanger with a scale model of the enitre Maidenhead flood plain modelled and the Jubilee river and Wraysbury areas down stream, for about 5 years this model was constantly filled with water and flooded the Jubilee river added and the effect of all scenarios mapped out, it was really quite impressive. So we have to trust the EA I don't think anybody on this forum is well enough informed to draw any real conclusions from casual observations.

 

[534l4rk]

Are you sure about that, I thought current thinking was to reduce the flow into the river not the river itself. Holding the water on flood plains by reducing the amount of fast flowing hard surfaces that allow water to drain into it too quickly is the problem, stuff on the news today about planting woodland that holds water in a flood plain and reduces flow etc. The river itself needs to flow as fast as possible to carry flood water away.

My impression was that letting it flow quickly from the Jubilee resulted in bottlenecks and flooding where the flow was restricted further down. In the past it would appear to me that more use was made of flood plains further upriver. Recent building development and use of gravel pits which have been excavated and then lined to take refuse disposal surely reduce flood absorbtion that used to prevail. Yes I did not put it very well - the point about slowing down the flow related to reducing the amount of water going into ther river. Once in the river it needs to be taken out to sea as quickly as possible. The use of the Thames Barrier was presumably made to allow maximum flow over the weirs at Teddington. I have stated that I am only making comment as a layman. For your information the levels reached below the Jubilee in many places did not reach those reached in 2003. I believe you have commented on the model before. I remember asking at meetings whether it would not be better that any flood alleviation schemes should start at the lower reaches of the non tidal Thames. I am still trying to find out if the rainfall this time was more than in 2003.

 

[Outinthedinghy]

Snip.......... the water is the same volume only delivered downstream by another route, ie, had it not been delivered by the Jubilee the same volume of water would have been delivered by the Thames

I am not a flood management consultant or anything special but surely if you BUILD a new river you introduce new surface drainage water which is then placed immediately back into the natural river above Black Potts much more rapidly than if it had been allowed to drain naturally into the existing river via existing drainage channels.

It is obviously going to have a heavy impact immediately below where this water arrives, surely they can't deny it...

 

[TT_WO]

Taplow – yes. My observations have been made using data from the monitor stations from Oxford and beyond down to Teddington. The subject related to river flooding seems to be controversial. Current thinking seems to support slowing down the rivers rather than speeding up. Whatever, the release of a greater volume at Datchet to my layman way of thinking will increase the likelihood of flooding further down. Certainly, the levels at Maidenhead appear to have been reduced by use of the Jubilee. I still believe the amount of rain compared with 2003 needs to be known.

Taplow guage did cause me some confusion initially as the level in the Jubilee increases as the Taplow guage level registers a reduction in height. I assume this is because the guage is positioned immediately upstream of the Taplow weir and registers a drop as the weir is pulled. I would appreciate confirmation or otherwise.

The EA argument has always been the same amount of water arrives at Datchet and downstream that would have been delivered by the Thames alone and this is true if you ignore the water that would have been spread across the floodplains of Maidenhead. What is perhaps more relevant is the speed at which that water is delivered to Datchet when spread between the two channels and the resultant increase in volume of water that arrives at Datchet and downstream.

A comparison of the amount of rain preceding this event and the 2003 flood will be interesting. I remember when a similar comparison was available for 2003 and the 2000 floods there was more rain in 2000 but higher flood levels in 2003.

 

[TT_WO]

I do not see any evidence of the Jubilee being slowed in this event, rather contrary, the EA issued a notice stating that the jubilee had been operating at near its design capacity?? since 7th January, the highest flow since it was built.

I do not doubt that the EA did everything possible to simulate a flood with both computer and actual models but at the same time we should not ignore the claims of residents of Ham island who reported these were the highest flood level they had witnessed in 60 years.

 

[Chris_d]

Which flood was the highest in 60years?

I took this in 2006:

Thats nearly as high as 60years ago but I am sure the 2003 flood was higher as was last weeks, but err.... I can't be sure

 

[TT_WO]

Which flood was the highest in 60years?

Thats nearly as high as 60years ago but I am sure the 2003 flood was higher as was last weeks, but err.... I can't be sure

The report was from residents on Ham island (Radio Berkshire 14th) some of whom had lived there for 60 years and reported 2014 flood was the highest level they had ever witnessed.

I think 1947 flood was higher than 2003 which in turn was generally a little higher than this years flood, but not at Ham Island it would seem.

 

[boatone]

I don't think you can place too much reliance on fading memories of decades ago. The same people claimed in one news item that the river was flowing at 25mph IIRC. You only have to read a selection of newspaper and website articles to recognise the wide disparity of "(mis)information". Clearly things differ from year to year and location to location - a few years ago the river was flowing over the top of Bell Weir lock through the reception area of the Runnymede Hotel and out into the Windsor road but I don't think thats happened this year.

 

[apollo]

a few years ago the river was flowing over the top of Bell Weir lock through the reception area of the Runnymede Hotel and out into the Windsor road but I don't think thats happened this year.

Well it did cover the Windsor road as its been shut a week from the roundabout. I don't know about the hotel reception - but it would not surprise me it was that high.

Rumour has it that its the first time there has been fresh fish in the restaurant.....

 

[boatone]

Well it did cover the Windsor road as its been shut a week from the roundabout. I don't know about the hotel reception - but it would not surprise me it was that high.

http://www.runnymedehotel.com/flooding/

The hotel’s interior has been completely unaffected and a core team of staff is taking calls and enquiries and will reopen as soon as access via the A308 Windsor Road is restored and the car parks have drained to allow for guest parking.