Flood Defences

Public authorities everywhere are facing the challenge of climate change: unprecedented frequency of severe weather events and rising water levels combine to threaten existing river and coastal defence structures. Spot reinforcement of existing systems is proving to be a poor solution, often doing no more than moving flood impacts from one vulnerable location to another.

Large scale remediation programmes carry a huge cost and can be politically divisive. Worst of all, the basic survey data to support funding allocation decisions is often decades out of date.

Flooding image

Updated surveys and condition assessments are therefore desperately needed - but conventional survey approaches are too slow and too costly. Strat Aero has pioneered the delivery of large scale specialist flood defence surveys using a combination of fixed wing and multi-rotor UAVs and hydrographic equipment, enabling complete and accurate surveys above and below the waterline to be created quickly and cost-effectively.

The overall process is to combine multiple aerial photos to create a single georeferenced picture, which can cover several hectares. From this we then create a highly granular 3D model based on a dense point cloud. Using engineering survey techniques, sub-50mm 3D accuracy can be achieved.

Geocurve Broadlands image

Using these techniques, we have surveyed a range of flood defence systems - both river and coastal - identifying defects and vulnerabilities over multiple linear kilometres. Customer deliverables include:

  • Completed 3D models that can be "flooded" digitally to analyse the impacts of rising water levels. They can also be used for animated 3D "fly throughs" and can be printed to scale using 3D printing.

  • Tiled geo-located aerial images (1cm pixels) in JPEG/RAW format.

  • Regular cross sections through flood defence structures down to low water line (or below water bathymetric survey data), delivered as CAD drawings and PDF.

  • Flood defence structures long-section with, for example, 10m intervals, delivered as CAD drawings and PDF.

  • Ultra-High Definition (4K) geo-located video of the entire length of defence structures from both sides.

Clients receive not only final Digital Terrain Models but progress photos as the project proceeds, and final reports with analysis and interpretation.

Isle of Grain cross-section image

Input imagery and final models are held on Strat Aero's Digital Data Manager. This enables us to provide ongoing support if flood defence breaches take place - re-surveying affected areas, delivering volumetric analysis to plan flood repair work, and taking final survey imagery to help expedite sign-off of completed repairs.

Using UAV technology in combination with hydrographic systems, Strat Aero can quickly provide up-to-date, high accuracy surveying and analysis of large-scale flood defence systems. And by using remotely piloted vehicles, we minimize the need to have personnel on/adjacent to the water.