Coastal Morphology

Tidal Bedform Surveys

Jetyak has proven utility for tracking medium-scale bathymetric changes, and conducting ADCP surveys of the flow over these bedforms, and has become an invaluable tool in understanding coastal ecosystems. An overlay of temporal Jetyak surveys conducted over several months have demonstrated bedform migration of up to 15 m per month in coastal Massachusetts.

Jetyak was the only vessel capable of operation in these shallow water, highly energetic flow conditions. The closest alternative was a jet ski, which would not have had the precise line following needed and would have elevated operator risk during deployment. The Jetyak also simplified launch and recovery with no flat-water boat launch required.

Multiple Scale Bedforms in Tidally Energetic Environments

Superimposed bedforms - where smaller bedforms exist on larger ones, common in tidally energetic environments. Their complex interactions makes the generation of accurate sediment transport models difficult, and a significant component to further their understanding is an agile shallow water survey vehicle.

A Jetyak equipped with a wide-swath bathymetric sidescan sonar, a downward facing ADCP and dual PPK GNSS form an important tool, allowing for the collection of novel data that greatly contributes to understanding the characteristics of such features. This includes the revealing small, superimposed bedforms reversing their asymmetry with the flow while larger bedforms on which they reside remain oriented in the direction of the dominant flow.

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Radioactive Sediment Transport

The Jetyak's basic ability to safely navigate and map the coastal zone to aid in the developing sediment transport models is particularly useful in predicting the storage and release of radionuclides into the ocean.

Data from Fukushima in Japan support a process of storage and release, where high levels of radioactive Cs-137 released in 2011 were transported along the coast by ocean currents. Days and weeks after the accident, waves and tides brought the cesium in these highly contaminated waters back to the coast, with cesium stuck on the surface of sand grains. Several years later, waves and tides brought in salty seawater from the ocean, and the brackish water underneath the beaches became salty enough to release the cesium from the sand, where it was carried back into the ocean. As a result of this process, the highest levels of cesium in ocean water today are found not in the harbor of the nuclear power plant, but in the groundwater many miles away below the beach sands.

In this and similar applications, a Jetyak provides the operator safety and efficiency in collecting the multi-sensor data required to construct near-shore sediment transport models, which can provide actionable data in planning and monitoring the over 400 operational nuclear power plants worldwide.

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