Dutch Student Visiting USGS Pacific Coastal and Marine Science Center

Above: Visiting M.S. student Jeroen Stark at a beach near Santa Cruz, California, March 2011. Jeroen is studying how dredging at the Columbia River mouth affects the long-term morphological development of the littoral system—the nearshore area where sediment is moved by waves. [larger version]

Dutch student Jeroen Stark is visiting the U.S. Geological Survey (USGS) Pacific Coastal and Marine Science Center in Santa Cruz, California, for 2½ months, from February 26 to May 10, 2012. He is working with Guy Gelfenbaum and Andrew Stevens on long-term morphological modeling of the mouth of the Columbia River, Oregon/Washington, with a particular focus on factors that cause accretion or erosion of sediment at the river mouth and along the coast to the north and south. Jeroen is currently working on his M.S. thesis in the field of coastal engineering at the Delft University of Technology, the Netherlands. The project he is working on is part of a cooperative agreement between the USGS and Deltares, a Dutch research institute in the field of water management and building in deltaic regions.

Jeroen’s thesis focuses mainly on how dredging at the Columbia River mouth affects the long-term morphological development of the littoral system—the nearshore area where sediment is moved by waves. Because much of the sand dredged from the Columbia River mouth is placed at deep-water disposal sites, entrance-channel dredging has removed a significant amount of material from the littoral system. Strategic placement of dredged material at the mouth of the Columbia River, however, could help solve coastal-erosion problems. The long-term effects of historical sediment-disposal practices, as well as future disposal strategies, are therefore part of this study.

A process-based numerical model (Delft3D) originally developed by Edwin Elias (coastal engineer with Deltares and the USGS) and Guy Gelfenbaum is used for long-term morphological simulations of the Columbia River mouth and adjacent coastal areas. Model simulations are performed to study the influence of historical dredge and disposal activities on the littoral drift (net alongshore sediment transport) and on the morphological development of the area. Ultimately, the Delft3D model could be used for investigating or optimizing strategic placement of dredged material.

Historically, the Columbia River has supplied sediment to the littoral system, in which a general accretion trend was present during Holocene time (the past approximately 12,000 years). Sediment from the Columbia River and estuary was deposited at the ebb-tidal delta, and waves dispersed the material to the littoral cell. Jetty construction significantly disturbed this natural behavior of the morphological system. Initially, it caused accretion rates to increase rapidly. As these accretion rates are now slowing down or even reversing to erosion, it is important to study the influence of the different natural and anthropogenic processes on the littoral system.

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