The Environment Agency has developed a new guide on the assessment and management of blockage. Drawing on the latest research and international good practice, it provides guidance on screening for blockage risk, quantifying the risk of blockage and choosing a management approach.
The blockage of watercourses or structures by debris (such as man-made materials, vegetation or sediment) reduces flow capacity and raises water levels. Although well-managed blockages in the right place can reduce flood risk and restore natural processes, blockage in the wrong place can increase the risk of flooding, structural failure or embankment breach. It can also change flow patterns, causing scour and undermining structures, obstructing navigation and presenting a hazard to water users.
The appropriate management of blockage is essential to manage these risks. In recent years, environmental legislation has emphasised the need to work with natural processes, promoting a move towards more sustainable practices. The consistent economic appraisal of blockage is also necessary to allow the preparation of a business case for the full range of management measures from maintenance to capital works.