Why we need a two-stage channel

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Critics of the Oxford Flood Alleviation Scheme claim that the proposed new stream and secondary channel deliver little benefit. Oxford Flood Alliance disagrees. We were formed in 2007 by people from communities most vulnerable to flooding. We believe that the proposed two-stage channel is vital to protect those communities.

The planning application documents include an updated comparison between the scheme as designed and the scheme minus the two-stage channel (Appendix Q to the Environmental Statement). This document shows clearly that those communities OFA grew out of, especially those along the Botley Road, would flood more frequently and to a greater depth without the channel.

  • In an event with a 20% chance of happening in a given year, the kind of event we might expect to see every 5 years, Duke St starts to flood without the channel.
  • In a 5% chance event Duke and Earl St flood, so does Marlborough Court. With the channel, only Duke St is affected. Flooding on Osney Island is more extensive than with the channel, though some areas are affected even with the channel.
  • In a 2% chance event Bulstake Close would go under without the channel, sections of Botley Rd would flood, flooding on Osney would be more extensive than with the channel, and St Frideswide’s church and vicarage would flood. Earl and Duke St, and Marlborough Court flood at this level even with the channel. Flood depths will be greater without the channel.
  • In a 1% chance event Mill St and adjoining streets flood without a channel, as do Henry Rd, Helen Rd, Binsey Lane, and the whole of Old Botley. There is extensive flooding on Osney. Parts of Grandpont, Jericho, St Thomas and Hythe Bridge St also flood without a channel.

There is no perfect scheme and the most vulnerable communities are already having to accept that the project cannot protect them against a 1% chance event, or even in some cases a 5% chance event. Community and household-level flood defences will still be needed in these situations. The scheme with ‘no channel’ would be significantly less effective.

Overall, the flood alleviation scheme has to balance a range of competing interests. Protecting all homes and businesses at risk from a 1% chance event is not achievable. It would cost too much and have too great an impact on the local environment. OFA believes the proposed scheme is a reasonable compromise between improving flood protection for the city and meeting concerns about cost, disruption to people’s lives, biodiversity and recreation.

If you live or work in any of the flood-affected areas, or travel through these areas for work or school, you will be better off with the channel.

OFAS CPO inquiry confirmed

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DEFRA has now confirmed that an inspector will be appointed to hear objections from landowners to Compulsory Purchase Orders issued as part of the Oxford Flood Alleviation Scheme. The project team has been expecting an inquiry of this kind to be established, and the decision comes as no surprise.

The project needs to acquire land in order to build the scheme, and is following the legal processes required for this to happen. This is a normal part of any infrastructure project. Where individual landowners object to their land being acquired they have the right to have their arguments heard by an independent planning inspector. This is the process which the Secretary of State has now confirmed will take place. A date is yet to be set but we expected this to happen towards the end of the year.

The inquiry will be an independent forum where the merits or otherwise of criticisms of the scheme can be determined. The CPO inquiry is separate to the planning application process currently underway with Oxfordshire County Council, which is also providing independent scrutiny of the scheme. We are waiting currently for the date of the Planning Committee meeting where the application will be decided to be confirmed.

OFA in the news

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OFA steering group member Simon Collings was interviewed Monday 22 May for a BBC News report on a new flood resilience training centre which has opened at Wallingford. The BeFloodReady centre provides advice and training on how to make properties more resilient to flooding.

With flooding expected to increase as a result of climate change, household level preparedness will become increasingly important. Exceptionally heavy downpours of the kind we have already seen this year, can cause flash flooding in areas which have not flooded before. It is particularly in these areas where property level measures can help protect against flooding and facilitate quick recovery where flooding does occur.

Simon spoke about being flooded in 2007, and the benefits which flood resilience measures brought during the 2014 floods when a submersible pump kept water out of the house (picture below). OFA has long been an advocate of property level resilience measures, and welcomes this new initiative from DEFRA.

Floodgates, air brick covers and pumps are, however, only effective up to a point. Household resilience measures have a contribution to make to flood risk management but they are not an alternative to the Oxford Flood Alleviation Scheme. We need both.

OFAS and rights of way

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A number of West Oxford residents have recently been asking about how the existing right of way along Hinksey Causeway, also known as Monk’s Causeway, will be affected by the Oxford Flood Alleviation Scheme. This is the footpath which runs from The Fishes in North Hinksey to Osney Mead.

Information about footpath diversions is available here on the Oxford Flood Alleviation Scheme website. Scroll down to the relevant section. The impacts of the diverted public footpaths were assessed in the Environmental Statement Chapter 6 Recreation and Public Access, which forms part of the planning application for the scheme.

Two sections of Hinksey Causeway will be affected.

The first is the section which runs from Osney Mead past the electricity sub-station to where the ‘electric way’ starts (photo below). This path has to be moved 10m east to allow for the construction of a flood wall and flood gate, part of the flood defence which will run down the eastern side of Oatland’s Park and extends down to this area. This section of the path will be stone surfaced.

In the case of the other affected section, the issue is that the existing right of way doesn’t correspond to the path people actually use. OFAS will use the route people actually walk, so the legal right of way is being re-registered so the legal rights apply to the route people actually use. This section will have timber decking, a boardwalk. It will cross the two stage channel – an area which will be boggy at wet times of year.

Re-alignment of a public right of way is a legal process, hence the formal notices which have appeared recently in the press and along the path. The Environment Agency has to follow this process to establish the new legal rights of way. This path will remain a right of way and, apart from the initial section at Osney Mead, will follow the current route.

The footpath will be temporarily closed while it’s being constructed, this includes making a new footbridge, but people will have Willow Walk as an alternative.

This is a summary of information supplied to us by the Environment Agency under Open Public Licence.

Natural flood management, storage and property-level defences

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Some critics of the Oxford Flood Alleviation Scheme have talked about the need for a ‘catchment-wide’ approach as an alternative. There are certainly benefits to thinking about the whole upper Thames catchment, but could such an approach deliver results within a meaningful timescale?

One issue OFA looked at early on, once the Flood Alleviation project was underway, was the potential for natural flood management techniques to contribute to reducing flood risk in Oxford. In August 2015 we organized a seminar and heard from a range of experts on this subject.

The overall conclusion was that natural flood-management techniques can bring benefits in smaller catchments, especially in lower-order flooding events. Isolated projects in the upper Thames would, however, have no measurable impact on Oxford with its large catchment (about 2,500 km2 upstream).

A complete re-landscaping of the Thames catchment might, if it could be achieved, reduce flood peaks by 10–15% – so helping with the flood risk but not solving it fully. Achieving the transformations in land-use necessary to deliver this benefit would require radical new legislation and/or a new culture of approaches to land management, taking ‘around 40 years’ to implement.

We found that storage could potentially play some role, but the volume of water involved in a major flood cannot be contained upstream of Oxford. The Environment Agency has always been clear about this. An effective upstream storage area would need to store approximately 50 million m3 of water. This is equivalent to an area the size of Oxford under 1 metre of water. There’s not enough capacity in the floodplain to store that amount of water.

The Environment Agency is exploring options for some future element of storage to mitigate against worsening climate change. Storage is not a viable alternative to the flood scheme but could be a useful backup in the future, as could major changes to land use upstream.

As well as these two options we also spent a lot of time looking at property-level resilience measures. Several steering group members made significant alterations to their homes to reduce the impact of floodwater in their property and speed up recovery after a flood. A number of us were allocated flood gates, air brick covers, and small submersible pumps by the City Council, funded by the EA. The pumps proved vital in Jan 2014 in keeping water out of vulnerable houses on Osney Island (see picture below).

There are things we can do at household level but these are only effective up to a certain scale of flooding. They are not a substitute for the flood scheme. Even with the scheme in place some properties still face risk and will need to deploy property-level defences. 

A decade on and a key decision point

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We are expecting the County Council to decide on the planning application for the Oxford Flood Alleviation Scheme in the next few months. This is a major milestone for the project. Here’s a brief reminder of how we got here.

Back in the autumn of 2013 members of the OFA steering group met with the Environment Agency to discuss a list of ten ideas we had proposed for further reducing flood risk in the city. These ideas were additional to the ‘short-term measures’ already implemented following the 2007 floods.

The EA had analysed our suggestions. Some were discounted as the likely benefits were less than the cost, but some of the ideas they agreed would work. Their advice, however, was not to treat these as isolated projects, but to revisit the business case for a larger flood scheme capable of providing a much higher level of protection. The measures we had proposed would be more effective if they were part of such a scheme.

We agreed with this analysis and accepted that a further programme of short-term measures would bring limited benefit. The time had come to look to a more enduring solution.

The floods of January and February 2014 were a timely reminder of the risk the city faced and created the political momentum we needed to get the project moving, including strong support from national government. The plan which grew out of these discussions is the Oxford Flood Alleviation Scheme.

Large infrastructure projects start high level and become more and more detailed as they pass the hurdles set for each stage. OFAS has been developed in this way, with the output from each iteration subject to consultation, independent scrutiny, and approval by DEFRA and the Treasury. Over the past ten years the scheme has evolved, taking on board many suggestions from individuals and groups. This process has helped ensure the scheme is as good as it can be.

The project design for which the EA is seeking planning permission is the product of ten years of research, design, consultation, review and revision. We’re now at a point where we need a decision. The County Council planning officers have subjected the scheme to rigorous scrutiny. Elected councillors on the planning committee will make their decision, guided by the officers. This is the democratic process for agreeing how we go forward.

We very much hope the Council will decide for the project. Climate change is already increasing risk of flooding, and Oxford urgently needs a flood alleviation scheme.

Seacourt P&R flooded in just 8 hours

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On Monday 3 April the Seacourt Park and Ride extension went from being largely dry in the morning to being underwater 8 hrs later. Here’s a picture of the car park taken by a local resident early on Monday morning:

This video clip, taken at around 10.30 the same morning, shows the rapidly rising water. You can see the water spreading across the car park in real time.

By 6.30 pm the car park looked like this:

And here’s a video clip which shows the flooded facility on Tuesday morning.

Oxford City Council shut the car park first thing on Monday morning, but the pedestrian and cycle pathway was not closed until 24 hours later, with many people trying to use it on the Monday. Some  turned back on encountering the flooding but others took their chances, ploughing through the floodwater in an attempt to access the bus stop.

The flood happened on a weekday. Given the speed of the rising water levels, there remains a question as to how promptly action would be taken at weekends, overnight, and on bank holidays, particularly to ensure the safety of pedestrians and cyclists. Water started to appear in the car park on the Saturday morning (1 April), when several cars were still parked there.

OFA identified safety issues as an area of concern during the planning process for the car park extension. River levels have not been especially high in this event. The level of the Seacourt stream at Minns estate, across the road from the Park and Ride, was 0.3 m below its peak in January this year.

Speed of recent river level rises concerning

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The striking thing about the flooding of the past few days is the speed at which river levels rose following several hours of torrential rain on the evening of Friday 31 March. This resulted in some flood events not previously seen in the county.

Tescos Extra in Abingdon was closed for two days due to a flooded car park, and Oxfordshire Wildlife Rescue suspend its operations after its centre near Didcot flooded on the Friday night. We have had reports of flooding at Sunningwell, north-west of Abingdon, and of flash flooding in Hurst Rise Rd and Hutchcombe Rd in west Oxford. The Eynsham Rd near the junction with the A420 was closed for a while due to flooding.

Botley Park. and the allotments to the east of the park, went from being completely dry on the Saturday afternoon to being flooded 24hrs later. Plot holders were taken by surprise at the speed at which their allotments flooded. At Seacourt P&R, the extension was fully flooded within 24 hrs.

Fortunately the amount of rainfall on Friday was not enough to cause more widespread disruption, but the speed at which rivers rose after just a few hours of heavy rain illustrate how vulnerable we would be in the event of a much bigger storm, and not just those areas known to be at risk from floods.

River levels have now stabilized in Oxford and Abingdon. Further up the Thames levels are either stable or falling.

River levels rising again

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River levels in Oxford have been rising again over the last few days following the heavy rainfall on 31 March. The Environment Agency rain gauge at Osney recorded 25.1mm of rail that day, and 5.2mm the day before. The gauge at Eynsham clocked 32.5mm of rain on 31 March and 4.4mm the day before. At the top of the Thames catchment Shorncote measured 21.7mm of rain on 31 March. Here’s a video of the deluge shot in South Hinksey on 31 March.

The rate of flow at Farmoor was 69.900 m3/s at 15.45 today, higher than the peak flow rate in the January floods. The rate is still going up. Currently levels in the city are rising slowly but are still well below those reached on 18 January.

Seacourt P&R extension started to flood on 1 April, with several cars parked there at the time. These have since been moved. The car park is now closed.

Botley Park flooded 3 April 2023