Background reports

                                                                                                                                                               Page last updated: 30.09.2019
Links will be provided here to reports from the Environment Agency, B&NES, Bristol Water etc.

The Secretary holds hard copies of the following UWE maps:

a) For Chew Magna:

Surface Water Flow Accumulations and Directions

Surface Water Flooding 30 year and 1,000 year events

b) For the area bounded by Winford, Dundry, Pensford, Bishop Sutton, Chewton Mendip, East Harptree and Compton Martin:

- Land Elevations and Slopes, Surface Water Flooding, Groundwater Flooding, Soil Units, Standard Percentage Runoff,

Relative Runoff Generation, Soil Storage Potential, Geological Permeability Index, Combined Subsurface Storage Index.

- Briefing paper Chew Magna Flooding - September update pdf (click to open). The briefing also includes links to the following four reports, but links are individually provided below.
- Briefing paper Chew Stoke - What we have been doing pdf (click to open) also includes the links


November 2017 A research degree project by Richard Pardoe assessed the potential for land-based schemes to reduce flooding in the Winford Brook catchment. Potential schemes include the creation of 'run off retention' ponds. His report is entitled 'Identifying and prioritising landscape-based surface water management interventions in the Winford Brook catchment.' ( Report pdf, large file, click to open) is attached.


April 2017 Ricardo Energy and Environment report for Bristol Water, entitled 'Bristol Water Chew Valley Reservoir Resources NEP Investigation Phases 2 & 3'. A review to assess the impacts of the reservoir on downstream ecology - attached here (pdf, click to open). An Appendix is attached here (pdf, click to open).


November 2015 Eunomia Research and Consulting Ltd published a detailed technical report on the Winford Brook catchment, in particular aspects such as silting and soil erosion, and flood risk reduction (para 2.6 in main report). The report and accompanying slide presentation are attached here: 'Payments for Ecosystem Services - Round 3: Winford Brook PES Pilot Research Project' Report (large pdf file, click to open)  and here Slide Presentation (pdf, click to open).


B&NES published in September 2013 the four reports from JBA Consulting into the 2012 floods and the performance of the property level protections installed in 2010-11. B&NES together with the EA and Bristol Water also issued a briefing paper covering Chew Magna, with one covering Chew Stoke to follow shortly.) Click on the links to the briefing and all reports below:


- JBA Consulting - Chew Magna Flood Investigation. Final Report 2011-12 pdf (click to open)
- JBA Consulting - Chew Magna Flood Investigation. Technical Report  pdf  (click to open)
- JBA Consulting - Chew Magna Property Level Protection Scheme Evaluation Final Report  pdf (click to open)
- JBA Consulting - Chew Stoke Flood Investigation. Final Report 2011-2012 pdf (click to open)


An older report (by Babtie Brown & Root for the EA) from September 2004 reviewed a number of options to reduce flooding from the River Chew and Winford Brook. Options, which were costed, included upstream storage capacity, flood walls, and flood tunnels. The report 'Chew Magna Flood Defence Scheme: Pre-feasibility Study Review Final Report' is attached here (click to open). Potential annual 'Maintenance Costs' were provided and are attached here (click to open).


18 August 2015 Chew Magna Flood Modelling. At a public meeting on 28 July 2015 the Environment Agency gave a presentation of their computer modelling exercise into the September and November 2012 floods. Copies of the two sets of presentation slides are attached (Chew Presentation July 2015 and Chew Magna Model Presentation Final click to open. The EA has also provided a set of maps showing the flood extent and the modelling impacts - these maps are in the attached Word document (Maps click to open).  Their modelling assessed the potential for reducing flooding levels under a range of possible scenarios including reducing water levels in the reservoirs, altering the confluence of the River Chew and Winford Brook and removing the bridge on the B3130. The modelling results indicate that such actions would have not reduced the 2012 flooding sufficiently to have prevented property flooding.


April 2015 JBA Consulting 'Upper River Chew Hydrology and Model Update' Final Report April 2015' - a detailed technical review for the Environment Agency of the hydrology and modelling conducted after the 2012 flooding - report (pdf, click to open). (The JBA interim report dated Feb 2014 is attached here (pdf, click to open).) JBA also published an accompanying document 'Flood Estimation Calculation Record', attached here (pdf, click to open).


2 June 2014 The Department for Environment Food and Rural Affairs (DEFRA) has published (pdf attached click to open) 'Best Practice in Property Level Protection Systems - Advice for Local Authorities.' This gives advice on the best practice to follow when procuring and installing property level protection systems. The best practice is based on evaluation work carried out by JBA Consulting.  JBA Consulting also prepared the major reports into the 2012 Chew Magna and Chew Stoke floods, and are also managing the current Chew Magna project to enhance property level protection.


15 May 2014 Proposed drainage improvements on Tunbridge Road The Drainage and Flooding Team at B&NES have provided a draft drawing (attached, pdf click to open) showing the drainage improvement works proposed for Tunbridge Road. The aim of the scheme is to remove obstructions from the drains to restore full capacity. At the same time the gullys will be improved to maximise the inflow of water and minimise the potential for grills blocking and pots silting up. An additional gully is proposed to replace a failed soakaway which was removed a while back. Improvements are also to be made to the chambers on the system to allow better access for inspection and maintenance.

4 May 2014 Drainage matters in Chew Magna and Chew Stoke In April the Co-Chairs contacted B&NES drainage section to ask for a response to a number of questions about cleansing of drains and gullies in the area. The questions and the B&NES reply are attached (Word doc - click to open).  

3 April 2014 Flood Warnings - notes on a meeting held with the Environment Agency on 28th March attached (Word doc - click to open).  The meeting was called to consider how Flood Warning forecasting can be improved.

11 March 2014 Co-Chairs Rachel Wilson and Mike Curtis submitted questions for response by B&NES Planning, Transport & Environment Scrutiny Panel meeting on 4 March 2014. These questions covered issues such as outstanding matters concerning UK Flood Barriers, how the £200,000 allocation for Chew Magna PLP will be disbursed, and the proposed Strategic Flood Risk Management Group.  The full list of questions asked, and the Scrutiny Panel response, is attached here (Word doc click to open).

1 February 2014 CVFF Co-Chair Mike Curtis exchanged emails in early January with Bristol Water requesting action to reduce the water level of the Chew Valley Reservoir, because of the risk associated with high rainfall coupled with a full lake. The text of these emails is attached modelling Lake level reduction request 06 01 20 , Word doc click to open).  Subsequently Mike exchanged emails with Ed Lockington and Joby Graham (Environment Agency), and this correspondence together with Mike's comments and update is attached (Lake level reduction iss Jan 2014. Word doc click to open).

24 January 2014  Chew Valley Reservoir levels and drain off matters. Attached are two pieces of correspondence between the Flood Forum and Martin Berry of Bristol Water relating to the issues around active management of water levels. 1) Martin (Word doc, click to open), and 2) BW Response to 22 Oct questions (pdf, click to open.)


10 December 2013 Responses from B&NES & the EA to questions raised by Chew Valley Flood Forum concerning Chew Stoke (pdf, click to open) Following the flooding in Chew Stoke in 2012 Bath and North East Somerset Council (B&NES) and the Environment Agency (EA) commissioned an investigation into the floods. The results of the investigation were published during September 2013. This joint document with B&NES and the EA forms a response to questions raised by members of the public and the Chew Valley Flood Forum regarding the contents of the reports and other related issues. The EA have also provided the following document Chew Stoke Flood Risk Workshop Property Level Protection (PLP) Frequently Asked Questions (pdf, click to open).

4 December 2013 Responses to questions raised by Chew Magna Flood Forum (pdf, click to open) Response from B&NES, Bristol Water and the Environment Agency to the questions raised at the Flood Forum meeting on 1 October and also at the Public Meeting on 8 October.

28 November 2013 Report (click to open) on the meeting (attended by the Co-Chairs of the Flood Forum) of the B&NES Planning, Transport and Environment Scrutiny Panel on 20 November to discuss progress. Also, the Response from B&NES (click to open) to the questions which the Flood Forum sent to B&NES before the Public Meeting on 8 October.

23 November 2013 Bristol Water have prepared for the Flood Forum a Technical note (click to open) on the operation, capacity and management of the Chew Magna Reservoir. This restates the point made, e.g. on page 20 in the Chew Magna Flood Investigation Final Report (see below) that this reservoir has limited capacity to cope with high levels of flooding. This aspect is to be looked at in more detail when the modelling software becomes available (hopefully by the Spring).


4 November 2013 In early October we posted an email to Rachel Wilson, Co-Chair, from the Environment Agency about river/brook maintenance of is attached as a Word document (click to open).  Associated with that email we posted EA maps and other information concerning river maintenance for the Winford Brook and River Chew at Dumpers Lane. The Environment Agency have now provided revised maps because they felt that the previous ones were not clear enough.  They have also provided details of their 'check rounds'. The EA states that check rounds are undertaken when they are expecting heavy rain and high flows in the rivers, and that they check bridges, culverts, weirs, etc to ensure they are free from debris and blockages. The new documents are: Chew Magna Annual Maintenance (Dumpers Lane) (pdf click to open); Chew Magna Check Rounds (Dumpers Lane) (pdf click to open); Chew Magna Annual Maintenance (Winford Brook) (pdf click to open); Chew Magna Check Rounds (Winford Brook) (pdf click to open). Finally, the EA also state that "It is important to note that our current maintenance activities in Chew Magna are not guaranteed and can change depending on economic justification and our funding allocation from central government. In addition, as with all our work, maintenance has to be prioritised and justified technically, environmentally as well economically."