Towards improved dredge monitoring with seabed imagery
Type:
Presented during:
CEDA Dredging Days 2026
Authors:
S. Walby, M. Lee, N. Crossouard and D. Eccles
Abstract
The collection of visual evidence of seabed condition before and after a dredge campaign is likely to have the advantage of being more easily interpreted and accepted by some key stakeholders. Standard scientific data types such as turbidity / suspended sediment concentration (SSC) may be difficult for stakeholders to relate to their area of interest whereas seabed imagery could help to capture the interest and engagement of stakeholders, whilst also providing information which is potentially useful to them. A trial was undertaken to investigate the practicalities of collecting seabed imagery and its potential to: •Strengthen the environmental baseline of a project •Provide evidence of seabed impacts (or otherwise if no noticeable impacts are present) Four techniques were initially considered for the trial; drop down camera frames, towed camera frames, small Autonomous Underwater Vehicles (AUVs) and small Remotely Operated Vehicles (ROVs). A lightweight ROV was selected and two surveys were undertaken in the Thames Estuary. The first survey yielded useable seabed imagery, in one case allowing identification of fauna to species level. The second survey resulted in no useable imagery due to poor visibility. The trial showed that seabed imagery could readily be included in survey scopes and make use of vessels of opportunity, creating links with stakeholders. As anticipated before the trial, limited visibility is a risk to successful use of the system and therefore targeting particular tidal or weather windows may be required depending on the proposed monitoring site.