Living Shorelines

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Shoreline Monitoring

Shoreline Monitoring

In order to assess the effects and structural integrity of living shorelines, PDE, together with our tri-state partners, developed standardized monitoring methods to track performanace over time, and to compare them to hardened and untreated areas. The core and supplemental metrics developed in the monitoring framework outline a series of physical, chemical, biological, and spatial attributes which can be applied to any system both in and outside of the Delaware Estuary. The picture to the left shows the application of a feldspar marker horizon to measure sediment accretion behind a living shoreline installation. For more information, read the “Framework for Standardization Monitoring of Living Shorelines.”

An example of a plot layout for one of PDE’s planned 2014 projects is shown in the figure below. A control area is matched with each of three treatment areas because this site has an energy gradient where Treatment 1 experiences less wave and current energy than Treatment 3. We plan to install a hybrid living shoreline at the higher energy treatment (oyster reef breakwaters paired with intertidal logs), whereas Treatments 1 and 2 will consist of just intertidal treatments, but Treatment 1 will be smaller and linked to existing rip rap, making it different from Treatment 2. For each treatment and control, five parallel transects will be established perpendicular to the shoreline, and various core and supplemental metrics will be assessed along these transects extending from approximately MLLW to MHHW. Baseline (pre?installation) conditions will be assessed at this site at least once prior to installation and then will be monitored for at least two years, contingent on funding. The supplemental metrics selected for this site will focus on water quality and ecological enhancement to gauge performance relative to the priorities of the funder in this case.

Core versus Supplemental Metric Types

The monitoring framework distinguishes between core and supplemental metrics (Figure 2). Core metrics consist of parameters that we recommend monitoring for all projects. Core metrics include basic measures to gauge general performance, helping implementers and funders assess project success in a consistent manner and to facilitate adaptive management of the existing or new project designs. Core metrics should be collected using the same methods among studies and projects (i.e., use standard operating procedures, SOPs). Supplemental metrics are those that are tailored to assess whether a project is meeting its  specific goals (Fig. 2).

Physical, Chemical and Biological Attributes

For both core and supplemental types of metrics, we classify them as assessing physical, chemical or biological attributes. For example, a recommended core physical metric is sediment capture, whereas an optional supplemental physical metric is wave height. A recommended core biological metric is vegetation robustness, whereas an optional supplemental biological metric is below ground biomass. See Section IV for lists of metrics.

BACI Statistical Design

For all living shoreline monitoring, we recommend use of the same statistical approach, the Before?After?Control?Impact (BACI) design. This is a straightforward two?way comparative approach whereby the shoreline that is treated (Impact Area) is directly contrasted with an untreated shoreline that is nearby and in a similar initial state (Control Area); i.e., the Control is representative of prevailing conditions at the treatment (Impact) sites. This design will identify any significant impacts of the living shoreline on the metrics that are assessed.