Back on the evening on 21st October we had our last Ruscombe Brook Action group meeting - I've still not gone round to catching up on what we talked about. Here below is a brief summary of some of the stuff - it is also worth noting that the road at Acres Place flooded twice over the weekend....
Photo: a rather poor photo of Alistair's drawings of before and after to show an example of what attenuation pond could look like - this would hold back water in times of heavy rainfall and reduce flooding - see more below - but please note this is a sketch and not to scale at all.
-I fed back issues relating to my meeting with Wessex Water
- a report on the digging party at Pucks Hole plus a discussion about next steps - culvert, silt retrieval, attenuation, landowners etc. The work opened up the brook and encouraged flow, but already leaf fall has blocked the grating. We hope to have Ian Kear from the District Council to our next meeting - he has already made a site visit to Pucks Hole and discussed issues with residents. He has reported that SDC will be exploring upstream connections that flow into the brook, and may be able to make some funds available for a grille to be installed at the culvert, although there are then issues about responsibility for maintenance. There was also a discussion on the merits of a restrictor to control water flow down to Pucks Hole from Wheelers Walk, the question of a bond to ensure that the developer of Wheelers Walk should complete the sewer work and of the silting at the Charley’s lake.
- a Stroud Valleys Project re floods - I had been in discussion with SVP who are talking to the EA and others re some mini-projects. We agreed to pursue some possibly joint working.
- DIY Flow monitoring - check actions and plan next stage. The student Adam Broadhead had produced the most excellent instructions for conducting flow-monitoring. These are copyright for Water 21 but we have copies for use locally.
- discussed the brook's bank erosion on fields in the Ruscombe valley - it is damaging the field and the stream, and is a danger to livestock and people. There are various approaches to repairing the bank. If used, tyre gabions would be planted up and be visually acceptable. Information on Willowbank – river protection systems was also discussed.
- the next stage of the Biodiversity study was planned. A worksheet is beingt put together for use with students at Marling.
- Julian Jones from Water 21 reported that MSc student Ilaria Pretto’s work on the Slad Brook last summer is significant as it demonstrates that it is possible to control flooding through upstream attenuation (see previous blogs on this). Her work confirms that the old millponds were essential in alleviating flooding in the past. Ilaria worked with the EA and her approach has influenced their thinking on these issues. Adam Broadhead has also produced a report following his work last summer with the Bridgend Action Group on possible approaches to flooding in that area. This report's summary is below - it is an excellent clear study outlining the main issues. Julian reports that general points from both reports are relevant to Ruscombe Brook. There are funding offers for Water21 which may mean that Ismaila (the previous student) and Ilaria can be employed full-time.
- Discussion on way forward - all agreed it would be useful to meet other Action groups and develop a more shared approach. There was debate about who should call this conference, and how the water action groups should co-ordinate and work together with Stroud Valleys Project. It was agreed for RBAG to contact SVP and explore possibilities and discuss their Flood Project mentioned above. Also, a separate meeting should be held about the details of planning the conference outside of the main RBAG meeting.
Bridgend Report Summary (Review of Flooding) - by Adam Broadhead from Water 21
Loss of local natural, ecological water management function and the abandonment of former extensive water power and water meadow facilities has caused increased flood risk in the Stroud Valleys. Hydrographic modelling indicates these features can be restored at low cost to prevent all flooding while benefiting biodiversity, energy & food production.
Bridgend lies on the narrow floodplain of the Frome, nearby Stonehouse, with 5 river sub catchments upstream.
Historically, the upper Stroud Valleys catchments comprised impenetrable woodlands and marshy wetlands. This landscape would have better retained rainfall, controlled runoff, promoting aquifer recharge and slowed the drainage into water courses.
Stroud Valleys’ complex hydrogeology is now disrupted by artificial modification, urbanisation and intensification of agriculture. Infiltration zones such as fields and woodlands have been covered with paved, impermeable surfaces. Local water resources were once usefully exploited for milling and irrigation. Creation of historic mill ponds and water meadows partly compensated for loss of natural water function, providing both significant water storage and watercourse control.
Flood water control functions have been abandoned, with no consideration of, or planning for, the consequences - which includes widespread neglect of watercourses.
This is symptomatic of also of a local decline in land and aquatic ecology, siltation and pollution effects from agricultural and urban runoff, just part of a wider loss of local “ecological capital‟ and failure to use local renewable resources.
The water cycle in the Stroud Valleys has thus been disrupted, with rivers rising higher and faster, leading to greater risk of flooding at choke points such as culverts, bridges etc., whilst also being more prone to drought.
The permanent full solution to Stroud-wide watercourse flooding is to restore the local hydrological cycle, and ensure floodplains function correctly. As suggested by “Making Space for Water” (Defra 2005), in line with Agenda 21, EU Water Framework Directive etc.
The economic benefits (energy & food productivity) could in many situations meet costs of providing flood relief. Economic benefits should be evaluated and discussed with landowners; who mostly indicate a favourable attitude to soft (agricultural) engineered working wetlands on their property.
Water 21, working with the Environment Agency during summer 2008, has developed a hydrographic model which demonstrates the feasibility of storing in excess of 1/150 year flood events within the Slad Valley; this appears practical for all local rivers and provides the clear focus for any strategic planning to protect Bridgend.