The Emm Brook River Walk

The Emm Brook river walk was arranged by the Loddon Valley Residents’ Association in response to concerns about flooding from the Emm Brook.  Ian Watson represented  emmbrok walk 1 20120120 1787115298LFCC.  The EA was out in force with representatives from FRM, OPs and biodiversity functions.  In addition to local residents, there were also local councillors present together with local press and radio.  The walk was led by Brian Roberts (EA FRM) who took us on a walk along the stretch near the Morrisons’ store.

The flood risk management engineered into the developments was inadequate; the area which was designed to flood is in a public park area which has relatively steep land either side which protects the adjacent housing. This area floods as expected and provides some buffering capacity. There are also some balancing ponds built into surface drainage but opinion was that these did not work well enough and that more buffering is needed. When the developments began in the 1970s, it was common practice to have large, impermeable surfaces with surface water being drained as quickly as possible. One way or another, most of the surface drainage of Wokingham and the surrounding area ends up in the Emm Brook, although some of it takes a while to work its way through the system. Unsurprisingly, this has led to flooding. We did not get the chance to see the properties which have been flooded in the past. Residents reported problems with sewage backing up after heavy rain, although this is probably not anything to do with levels in the Emm Brook.

The Emm Brook does not look its best in January and was too muddy for much to be seen (the result of overnight rain) but photos provided by OPs showed that in summer it has a good growth of submerged macrophytes with what is probably an excess of plant growth on the banks. There is a twice yearly maintenance for the Emm Brook carried out by OPs where much of the bankside and instream vegetation is removed. Up to 80% of instream vegetation can be removed. At least one section appears to be heavily overgrown in summer with considerable encroachment into the river channel. Tree trimming is also carried out and any woody debris is removed.

Not all the flood risk is due to the Brook and its vegetation. On the stretch visited there are two bridges, one of which narrows the channel by an appreciable amount. Not only that, but the narrowed channel is prone to being blocked by things dumped in the Brook such as supermarket trolleys and even a Grundon bin. When the bridges are due for replacement, there would be a good opportunity to fix the problems they have caused but that may not be for a good few years.

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Trying to fix the extensive drainage from the developments is not feasible but there are some prospects for improving flood storage without compromising the environment. The one thing that FRM were quick to rule out as a fix was dredging which is now only carried out where no other option is available. In the case of the Emm Brook dredging would not have any impact on flood risk so other options have to be considered. The good news is that options may include re-meandering the river to slow down the progress of floodwater which could help to restore the Brook to a more natural channel. Another option would be to re-profile the Brook to provide a higher level flood channel with the current river channel maintained inside it. Consideration is also being given to removal of a weir which probably no longer serves any useful purpose. Although the Emm Brook is not a high quality fishery, any measures to restore ecological function are welcome.

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It would be a good idea to continue contacts with such groups as they often have limited understanding of flooding and how various factors contribute to it. If nothing else, it could help to persuade people that the heavy engineering option is no longer appropriate, especially given the need for WFD compliance. LFCC should continue to attend such residents’ meetings to ensure out views are heard and we should invite them to our meetings, whether they have a flood-related talk or not, simply to encourage them to take a more holistic views or rivers and their ecology