Projects

Sustainable Dredging Studies

Consultants collecting data for investigations into sustainable dredging.

© DEEM

One of the burning questions on the River Dart has been, 'should the sand dredging of the river that took place in the past, be recommenced?' The principal reason that the dredging ceased was because it was being done in an excessive and poorly monitored manner that led to damage to the river banks.

To carry out dredging nowadays requires rigorous control and extensive studies into the potential environmental impacts such works might have. The problem was that no-one knew how much, if any, sediment could be removed from the system without causing damage. There was no reliable knowledge base of how the estuary actually functioned in terms of physical processes.

There was also a public perception that the river was silting up and required dredging to maintain navigability.

The detailed technical surveys that needed to be undertaken are extremely expensive to conduct and beyond the technical and financial resources available locally. DEEM identified a source of financial assistance, the Aggregates Levy Sustainability Fund (ALSF) and was able to put together a comprehensive programme of studies to examine the hydrodynamics of the estuary. You can download the summary of the whole survey as a pdf (see the downloads section of this page. If you need to read the whole survey please contact us here at DEEM.

This initial work was expanded significantly under the funding of the Cycleau project. This programme looked at the whole of the tidal estuary and demonstrated clearly that although siltation is taking place and was quantified, the principal navigation channel is stable and not under threat. Based on the surveys undertaken by DEEM, a dredging policy for the river was developed and adopted by Dart Harbour in 2006. This policy can be viewed on the Dart Harbour website.