To receive the verbal updates from Environment Agency (EA) officers, Brianne Vally, Stuart Mollard and Natasha Gibbs.

Stuart Mollard, Project Manager for the DHEFIM (EA), presented an update on the Datchet to Hythe End Flood Improvement Measures (DHEFIM). He informed that the DHEFIM was in its Appraisal Stage (January to June 2024), which was split into four key elements, encompassing the next couple of years. The Project Definition (Summer to Autumn 2023) had been completed and the Environment Agency (EA) was in the Optioneering Stage (Autumn 2023 to Spring 2024).

 

Stuart Mollard also provided the project’s progress in the last three months:

·       Project objectives had been updated and the study area had been confirmed,

·       Public engagement events took place in Wraysbury and Datchet in November 2023.

·       Some potential funding partners had been identified who may be potential beneficiaries to the scheme. This would also be linked to the developing engagement plan.

·       Some technical work had also taken place in the last three to six months, which then fed into the Appraisal Stage. These included:

o   Groundwater and surface water flood risk.

o   Desk studies on geo-technical and geo-environmental aspects.

o   Examined the scheme within the context of land use planning,

o   Examined aquifer recharge feasibility,

·       Developed some additional ground investigation proposals, namely investigate what information was available from previous investigations in the area and identifying some gaps.

·       Continued discussion to ensure that EA flood modelling was proportionate and adequate for what it was being used for.

 

The intended end result of the Appraisal Stage was to create a draft short list of options which would then be shared. At the moment, the EA had a long list of potential measures which they would filter out the non-feasible measures. The filtered list would then be subjected to a detailed assessment and modelling whereby each optional measure would be assessed against the project objectives and the criteria of fitting within a capital expenditure program. The end result would be a shortlist of potential optional measures.

 

Once the shortlist was near completion, the EA would engage with stakeholder groups and local communities by sharing the proposals and then acquire feedback from them before finalising a list of potential measures before forwarding this list.

 

In regard to the work surrounding the stakeholder engagement, Stuart Mollard informed that it was important to keep the public informed as well as consulted and involved throughout the process, which was the reasoning behind the public engagement events in Wraysbury and Datchet in November 2023. Alongside these public events, a new project website was created which provided material and updates of the key stages.

 

Stuart Mollard also informed that the EA would conduct a major consultation exercise in the summer of 2023 on the shortlist of potential measures in which it would then be finalised based on the feedback. Another consultation on the list of preferred optional measures would take place in summer 2025.

 

Stuart Mollard then announced that he sought to set up a group whereby the EA could liaise with the local community, under the working title of ‘Community Liaison Group’. After asking volunteers on whether they would like to become part of this group, 10 people had replied that they would be interested. As such, the EA would send invites out in the next few days. The first meeting was planned to be held in mid-February 2024 in Windsor. He explained that the purpose of this was to promote a two-way discussion group, allowing people to provide feedback and get involved. He offered to elaborate further of this group at the next Flood Liaison Group meeting as well as share details with anybody who was interested in being part of it.

 

Brianne Vally, Flood Risk Advisor for RBWM (EA), then gave a brief report on the DHEFIM and the recent flooding in January 2024. She explained that as part of the DHEFIM, the EA continued to work with its partners to understand the flood mechanisms in the affected area and information would continue to emerge over the coming weeks. The EA would then review the gathered available data linked to the January 2024 flooding event to ensure that it adequately understood, respond, and recover from a similar flooding event. Brianne Vally also highlighted that while the EA were determined to reduce the risk of flooding, it was not possible to protect against every eventuality.

 

Stuart Mollard added that the aim was to make use of the available data around what was flooded, where it was flood and why it was flooded, which would then help the EA further understand the ground conditions and the inter-relationships between the river water, water on the flood plains, groundwater and what happens when flood events took place.

 

Before starting her presentation, Brianne Vally conveyed her appreciation to community members and some Flood Group attendees for meeting with the EA’s Community Information Officers as well as forwarded sympathies to those affected by the recent flooding event.

 

Brianne Vally then gave an overview of the flooding event in January 2024. Starting with the current situation, she informed that the Thames Catchment had received 72% of the average monthly rainfall with the catchment still saturated. River levels had dropped but nevertheless remained high with tributary rivers likely to react with further rainfall. Therefore, Thames River levels were likely to remain high, particularly if more rainfalls occur. As of the meeting, there were no flood warnings in the Borough and the groundwater alert in the eastern part of the Maidenhead area was no longer in force due to declining water levels.

 

Brianne Vally then explained the timeline of the flooding event across the Thames Valley in January 2024:

·       The Borough received a number of storms from late-September 2023 to early-January 2024 which then caused the ground to become saturated.

·       Flooding began in January 2024 with rain falling on already saturated ground. The EA received word on Thursday 4^th January 2024 that there was intense rainfall in many places whereby tributary rivers had higher river-levels and consequently caused the Thames river-levels to rise. As a result, a number of communities were affected. With continuous rainfall being received, the River Thames water levels continued to rise for several days.

·       Groundwater increased in some locations with the EA still doing operational response work to protect properties in West Berkshire and Great Shefford.

·       Between 1^st and 8^th January 2024, 73 flood warnings and many more flood alerts were issued.

·       An initial review of the January 2024 flooding had revealed that the flood levels from the recent flooding were similar to the flooding in January 2004 and slightly below the February 2014 flooding event.

·       As with other parts of Thames Valley, some communities within the Borough were significantly impacted, particularly Cookham and Wraysbury, but also some affected properties in Bisham, Old Windsor, Windsor, Maindenhead, Datchet, Bray, Hurley, White Waltham, and Waltham St Lawrence. The EA continued to work with the Borough to collect this data.

·       So far, data revealed that 150 properties across the Borough had been affected, including 59 internal property flooding.

·       The EA continued to work with its professional partners to understand the flood mechanisms in the affected area and information would continue to emerge over the coming weeks.

 

Brianne Vally then gave an overview of the EA’s response to the flooding:

·       Monitored groundwater conditions, where data was available, and fluvial catchments.

·       Issued flood warning where appropriate to warn and inform communities.

·       Both in advance and during the flooding event, EA operations staff cleared assets, rivers and streams, where appropriate and safe to do so to enable the free flow of water.

·       Deployed Community Information Officers in affected areas.

·       Supported Local Resilience Forum activities at Strategic and Tactical level across Thames Valley and at the Tactical level in Surrey.

 

The EA also continued to operate and clear its assets:

·       Thames weirs were fully drawn, allowing the river to act in a natural state.

·       Operated EA assets along the Lower Colne and Colne Brook according to its operating procedures

·       Began operating the Windsor, Maidenhead and Eton Flood Alleviation Scheme, which included the Jubilee Flood Relief Channel early-January 2024. As part of this, the EA had made regular gate movements in line with its operating procedures as the levels increased.

·       Closed the Cookham flood gates on 4^th January 2024 and operated pumps at Cookham and Myrke Ditch.

·       By 7^th January 2024, the EA had made the maximum gate movements possible, and the Jubilee Flood Relief channel was running at full capacity. At this point, the EA put out a flood warning for the Windsor and Maidenhead area and informed the local MP. 

 

Brianne Vally then explained the EA transition from response to recovery:

·       11^th January 2024 – stopped pumping at Myrke Ditch.

·       13^th January 2024 – stopped all pumping operations at Cookham. 

·       15^th January 2024 – made the last gate operation and returned the Jubilee Flood Relief Channel to normal operation (10 cubic metre per second). In addition, all pumps at Cookham/Mryke Ditch were returned to depots. Footpaths and Marsh Lane car park were re-opened.

 

Aware of some concerns relating to the impact of the Jubilee Flood Relief Channel affecting communities downstream, Brianne Vally reassured that the EA sought to ensure that flood responsive measures did not move flood risk from one community to another. She added that the Jubilee Flood Relief Channel was part of the Maidenhead, Windsor and Eton Flood Alleviation Scheme (MWEFAS) which reduced the risk of flooding to approximately 3,000 properties in Maidenhead, Windsor and Eton. In addition, the EA operated the weir gates at Taplow to control the amount of water being diverted into the Jubilee Flood Relief Channel. Essentially, the Jubilee Flood Relief Channel ensured that communities downstream were not adversely impacted by flooding.

 

Brianne Vally also informed that an independent Mechanism of Flooding Report mentioned that “the primary impact of MWEFAS [was] to advance the timing of the flood peak by 5-6 hours in the reach down to Old Windsor, reducing to 2-4hrs below Staines.”

 

In terms of the EA’s upcoming activities, Brianne Vally informed that the EA were:

·       Carrying out an internal debrief to reflect on what went well, what did not go well, and any recommendations for improvement.

·       Supporting the Thames Valley Local Resilience Forum multi-agency debrief and the Borough's section 19 report, where appropriate.

·       Establishing its recovery command and control structure, which would include restoring EA staff, systems and assets as quickly and efficiently as possible, where appropriate ready for future incidents.

 

Brianne Vally reassured that the EA would continue to work with the Borough to mitigate local flood risk across the EA’s area boundaries in parallel with flood-protection plans in Surrey and south-west London.   

 

Brianne Vally concluded her update by encouraging any residents to report on the impact of flooding to the Borough to gather data as part of investigations into the flooding incident. She also highlighted that this could also be reported to the EA through the hotline on 0800 80 70 60.

 

Councillor Coe asked a couple of queries. He first asked for confirmation that there was no gate movement on the Jubilee River at nighttime; to which Brianne Vally confirmed, elaborating that there was no gate movement between 10:00pm and 7:00am mostly due to operational health and safety reasons.

 

Councillor Coe then asked about how the standing operating procedures of the Jubilee River was established, namely what was the input of numbers and modelling when it was first set up. Brianne Vally explained that a public inquiry into the Maidenhead, Windsor and Eton Flood Alleviation Scheme (MWEFAS) started in 1992, which was then finalised in 2002. From there, some operating procedures which were put in place at the time had evolved since then; though, in spite of this, the operating principles were kept in line with the review of the flooding event in 2003. She added that the EA were working to update some of the information in the public domain in regard to the operation of MWEFAS and suggested that Councillor Coe could be a ‘sounding board’ on whether the updated information on the Gov.uk website answered some of his queries.

 

Regarding the speed of water being let through into the Jubilee River, Councillor Coe then asked whether the EA allowed water to flow through at an earlier stage during a flooding event or managed the water flow at a slower pace from the same start point. Joe Cuthbertson, Local Flood Risk Manager (EA), replied that the main changes which were made after reviews of the flooding events in 2003 and 2014 included changes to trigger levels at various points across the Jubilee River. In terms of changes to operating models, originally the EA operated at 20 cubic metres per second at a time; this had been reduced to smaller increments, whereby gate movements were enacted to allow an additional 10 cubic metres of water at a time. Essentially, the EA would start managing Jubilee River flow at its base flow and then increase in units of 10 cubic metres as the river flowed.

 

Councillor Coe then asked whether operating procedures would start earlier due to the smaller increments. While needing confirmation from technical leads to give an accurate answer, Joe Cuthbertson believed that operating procedures required a more frequent operation rather than an earlier one throughout a flooding event. During the height of the recent flooding event, the EA were operating three-to-four times a day.

 

Councillor Howard highlighted that there was much ignorance around what was happening with the Jubilee River, namely how it was being used and its impact; stating that many social media users were alleging that the EA were not managing the flooding. He suggested that EA personnel attended public meetings to inform people on how the Jubilee River worked, arguing that it would remove confusion as well as improve the EA’s reputation of engaging with communities and reassuring them that the EA was in control.

 

The Chair conveyed that effective flood information needed to be publicised so that residents were more aware and prepared for it, pointing out that some major infrastructural flood defences would not be implemented until 2033-35 and that more flooding events were likely to take place until then. Hence, he explained, he sought to improve the feeding of information through the Flood Group. He suggested that Brianne Vally forward the operating procedures of the Jubilee River to Councillor Coe, which could then be shared by other Flood Group members. He also suggested to bring back Councillor Howard’s item to the next Flood Group meeting.

 

ACTIONS:

·       Brianne Vally to forward the Jubilee Flood Relief Channel operating procedures to Councillor Coe, and potentially share this with the wider Flood Group.

·       Public awareness on how the Jubilee River was managed to be discussed at the next Flood Group meeting.

 

Councillor Coe highlighted to the EA that there was a general impression amongst some of the public that the Jubilee River delivered more water faster to Datchet which then led to other areas being flooded. He suggested that this may require an explanation and be rectified if there was an issue.

 

Parish Councillor Andrew Spillane (Wraysbury PC) raised that communication from the EA was different during the recent flooding event compared to 2014, namely what the peaks would be and the timings of these peaks. He requested to have better understanding of why the EA’s communication was different.

 

Parish Councillor David Burfitt(Hurley PC) highlighted that there was a sudden surge of water over a 6-hour period in Hurley, and then asked what caused this sudden surge. Brianne Vally responded that it was likely caused by the tributary rivers feeding into the River Thames and thus causing the river level to rise as a result. She offered to forward flood hydrographs on the water curve. She added that the increase in river levels at Marlow as well as off the Jubilee Flood Relief channels had similar, particularly at a considerable amount due to the recent intensive rainfall.

 

Joe Cuthbertson said that a few residents had remarked about river levels surging and added that it would be helpful for the EA to receive feedback on where flooding took place, how quickly it took place and to what depth. He reminded attendees that flooding events were always different whereby Thames flooding was influenced by which tributary catchments received heavy rainfall and when. For the flooding event of January 2024, the catchment became saturated after the wettest 6-month period in southeast England from July to December 2023, according to the Home Office, which was then followed by a widespread, heavy rainfall on 4^th January 2024. These factors would have caused a rapid rise in river levels; nevertheless, the EA would review all the data of the flooding and then compare and contrast this with previous flooding events.

 

Mike Williams, Wraysbury Flood Team, attempted to raise a couple of points but poor internet connection meant he could not be heard. The Chair suggested to add his points to the Zoom chat or email them.