Plans for a new £32M tidal surge barrier at Bridgwater in Somerset will be go out for public consultation next week.
CH2M was appointed in December last year by the Environment Agency and Sedgemoor District Council to carry out detailed technical work on the construction of a tidal surge barrier in the Parrett Estuary which would be operational by 2024. It is examining possible locations, gate arrangements and operating regimes for the barrier and will assess the possibilities in terms of the management of water levels and silt.
A flood risk management review prepared for Sedgemoor District Council by Black & Veatch in 2014 confirmed the need for a major intervention in the area and supported the option of a tidal surge barrier which the council identified a preference for back in 2009, saying tidal was still the biggest flood risk. It said that this should be part of a wider programme of flood management that should tackle the different causes of flooding.
Following the 2014 flooding, the Somerset Levels and Moors Flood Action Plan was created. As part of this the Somerset Rivers Authority was established, which has an extensive dredging and de-silting, modelling, trials and monitoring programme, involving contractors such as Galliford Try and Black & Veatch. The programme includes the rivers Parrett and Tone. However, the tidal barrier plan does not cover flooding from rainfall or tackle the silt problem which caused the major 2014 floods.
A question and answer document on the review said: “Had the tidal barrier been in place in 2012 the impact on the extent and duration of flooding would have been very small. This is also likely to be the situation for the 2014 event. A reduction in peak water levels of about 100mm in severe floods may be possible on North Moor for example (depending on the event). Further modelling is ongoing to confirm the likely impact.
“The recent flood events were caused by high fluvial flows. Fluvial flooding is caused by the limited flow carrying capacity of the River Parrett and River Tone. Modelling has shown that any changes to water levels at the downstream end of the River Parrett have a limited impact upstream in the Levels and Moors.”
Local resident and member of Flag (Flooding on the Levels Action Group) Bryony Sadle said: “Our concern is half of the problems we suffer is the tidal silt. Without regular maintenance and dredging we are right back to square one.”
New Civil Engineer has contacted the Environment Agency for a response.