Challenges with Propeller Wash
Vessel traffic (propeller wash or “propwash”) has been shown to be closely related to increases in sediment resuspension. One such study conducted in San Diego Bay showed that berthing/docking at only three naval piers resuspended a total of 26 tons per day of sediments into the water column (Wang et al., 2000).
Propwash has also been attributed to be the main cause of scour around quay structures; such scour may result in structural instability, or even failure (PIANC, 2015). A study of ferry vessel propwash effects on scour at the Kingston Ferry Terminal in Washington state (Kastner et al., 2019) found that vessel arrivals and departures are associated with 10 to 30 times higher water velocities and 10 to 100 times higher resulting shear stresses than ambient conditions.
Modeling water and sediment transport patterns due to propwash in near shore areas is critical to planning successfully preventing resuspension, and designing structures to avoid development of scour holes. Unfortunately, limited availability of field data, computing capabilities, and other resources have hampered efforts to model propwash-related sediment resuspension. The available propwash models are empirical models that only address velocity and shear at the sediment interface; these are decoupled from far field transport and ignore propeller velocities in the water column.
Solutions Provided by EEMS
EEMS provides a fully integrated propwash module that is able to predict sediment resuspension using ship information, position, and speed, dynamically combined with a three-dimensional model of the waterbody. Optionally, the propeller energy can be incorporated into the three-dimensional flow field behind the ships. The EEMS propwash module may be a game changer for contaminated sediment remediation teams in their efforts to properly consider the role of propwash in their evaluations and designs, and for port and harbor engineers evaluating foundation and bulkhead impacts due to propeller action. Learn more about propwash by viewing our blog series.
Examples of Studies Done with EEMS
San Diego Bay, CA (in progress)
Kingston Ferry, WA (in progress)
Download Example EE Models
This module is currently in beta testing for EEMS10.3. Please contact us if you are interested in using this feature.
Use EFDC_Explorer (EE) and EFDC+ to simulate the impact of ship propellers on bed erosion and suspended solids. This is an important element in the development of plans for improvement and optimum utilization of waterways. This model was originally developed by DSI for testing this feature.