Dike Restoration Monitoring

How fast is the beach and dike recovering after the timber sill repairs, rock seawall repairs and other recovery efforts? Where were sills or the seawall damaged by floating logs during last winter's storm surges? Did any shoreline properties adjacent to the dike have significant damage? Currently, where are the weakest and lowest points along the seawall?

Annual programmed scan flights and high-accuracy 3D geospatial models over the next 15 years enable detailed measurements of the volumes of sand along the base of the dike and along the repaired timber sills. The data and imagery in the progression of models provides evidence of sand accumulation and erosion from the previous year, and detailed visualization of any damage to the dike and homes from winter storms. Each year, the current elevations along the top of the dike indicate the lowest areas or weakest points where there is potential for a sustained breach of the dike during extreme winter weather conditions. The dike currently prevents flooding of over 700 acres of residential properties, farm lands, recreational lands (a golf course), wetlands, livestock grazing lands, and freshwater aquifers tapped by the wells of several local, residential water supply systems.

This project is being coordinated with the WA State Department of Ecology, the US Army Corps of Engineers, other regulatory agencies, local tribes, and property owners in and near the dike. As contracted by the local Diking District, Aerial Whidbey authored the long-term Monitoring and Adaptive Management Plan for the project, and is responsible for developing the annual progress reports based primarily on georeferenced aerial imagery and data from high-accuracy 3D geospatial models. Aerial Whidbey was among the first to acquire a proven, high-accuracy system from Klau Geomatics, based in Australia. Aerial Whidbey developed additional capability by adapting industry-leading software from Switzerland and Belgium. Extensive field and office procedures have been developed to reduce operational risks and enable rapid training and assumption of contractual responsibilities. Outcome: A complete system with procedures for high-accuracy geospatial modeling and monitoring of changes in the visible state of a property, and without placing and retrieving any ground targets. The 3D models are readily explorable by project participants and stakeholders without extensive photogrammetry, land surveying or civil engineering background, and without significant software training or cost.

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