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Hatfield Marine Science Center Dynamic Revetment Project DSL Permit # 45455-FP. Monitoring Report. February, 2016
Citation:
Nelson, Walt AND C. Folger. Hatfield Marine Science Center Dynamic Revetment Project DSL Permit # 45455-FP. Monitoring Report. February, 2016. Oregon State University, Corvallis, OR, 2016.
Impact/Purpose:
A Dynamic Revetment (gravel beach) was installed in November, 2011 on the shoreline along the northeastern edge of the Hatfield Marine Science Center (HMSC) to mitigate erosion that threatened HMSC critical infrastructure. The report provides details of a multiagency effort to conduct shoreline topographic and biological monitoring for the narrow purpose of compliance to requirements of a dredge and fill permit needed to protect EPA infrastructure at HMSC. Differences observed between the project and reference areas have tended to reflect the pre-project differences in two areas rather than the gravel beach installation. The study is not a part of and has no impact on ORD research under current RAPs.
Description:
Stabilization of the Yaquina Bay shoreline along the northeastern edge of the Hatfield Marine Science Center (HMSC) campus became necessary to halt erosion that threatened both HMSC critical infrastructure (seawater storage tank) and public access to the HMSC Nature Trail. A Dynamic Revetment (gravel beach) was installed in November, 2011 on 260 feet of shoreline to mitigate erosion. Shoreline topographic and biological monitoring was initiated before and has continued after the project completion. Monitoring of beach profiles indicated that as of January 2016 the 2011 Dynamic Revetment Project (DRP) has generally successfully stabilized the shoreline in the project area. Beach profile data also indicated that the 2007 DRP continued to be successful in stabilizing further retreat of the shoreline. In both areas, some loss of gravel at the top of the shore profile due to overtopping of the beach during highest tides was noted, and some additional placement of gravel at these locations is recommended. As a result of the rapid erosion that continued through much of 2015 in the adjacent Reference beach area, an extension of the 2011 DRP project to the south was completed during October 2015, at the very end of the agreed on monitoring period. This converted the Reference area used for monitoring during the project into an additional gravel beach area (DRP 2015), which clearly differed from its previous characteristics. However, the bulk of the fish sampling was completed prior to this project, and as described below, this transition probably had minimal impact on the wrack invertebrate or vegetation monitoring.Monitoring of beach wrack invertebrates, fish, and vegetation was conducted in 2015. The Reference (DRP 2015) area had significantly higher abundance per unit dry wt versus both the DRP (2011) and DRP Reference (2007) samples. In contrast to previous years when the total amount of beach wrack was much sparser in the Reference area due to the eroded shore profile, there was little apparent difference in wrack accumulation along the shoreline. As has been a consistent pattern, fish were significantly more abundant in the Reference area compared to the DRP. However, this pattern was present in the pre-project sampling, and the Reference area may have a higher degree of physical habitat complexity. This was certainly true after the completion of the DRP 2015, where in addition to the root masses of trees that have been eroded onto the shore, six additional tree root masses were emplaced along the shoreline as an experiment. As has consistently been observed, vegetation coverage was significantly greater and presence of non-living substrata was significantly less in the Reference (DRP 2015) area as compared to the DRP. These differences are consistent with the pre-DRP 2011 project site differences, probably resulting from a low area of the shoreline which allows increased flooding and associated disturbance in the DRP back shore area. Fish and wrack invertebrates, such as beach hoppers, continue to utilize the DRP project area. Biological differences in fish and vegetation observed in the monitoring in 2015 tended to reflect differences in habitat that were present before the DRP 2011 project was implemented.
URLs/Downloads:
Hatfield Marine Science Center Dynamic Revetment Project DSL Permit # 45455-FP. Monitoring Report. February, 2016