River Parrett Dredging: Northmoor to M5

Management System

Download Management System document: Management System Document 

Download referenced documents: Design Cross Sections   HR Wallingford Opportunities for Dredging    Halcrow Modelling Dredging Assessment     Ambios Dredging Trials Monitoring Report    Northmoor to M5 Hydraulic Assessment    Northmoor to M5 Management System    Parrett WID Maintenance Protocol    UAV Vegetation Survey Locations    Vegetation Survey Area 1      Vegetation Survey Area 2    Vegetation Survey Area 3    Vegetation Survey Area 4 


The Parrett Internal Drainage Board is acting on behalf of, and as a partner member of, Somerset Rivers Authority to maintain flood conveyance of the river Parrett in order to retain the flood risk reduction benefits achieved and carry out additional works forming parts of the Somerset 20 Year Flood Action Plan.

The Somerset Levels and Moors Flood Action Plan includes a programme of dredging to reduce flood risk. These were presented in the October 2016 report by HR Wallingford “Opportunities for further dredging in Somerset” and included five locations for dredging relating to the River Parrett catchment.

Three of these reaches have been dredged: Northmoor to confluence, Parrett up-river of confluence and the Tone. The Environment Agency will be undertaking works on the Sowy (River Parrett Relief Chanel) imminently. Channel enlargement of the Parrett downriver from Northmoor, which is the principal subject of this report, is the final reach identified in the HR Wallingford report to be dredged.

There is also a continuing need to maintain channel capacity on previously dredged parts of the Parrett.  Experience to date indicates that Water Injection Dredging (WID) is the most cost effective and environmentally acceptable method currently available. This Management System proposes and seeks support for continued use WID for maintenance and new dredging on the Northmoor to M5 reach.

The download links above access the Management System document that describes the scheme design process and to reports and other documents referenced in it.