ShoreZone Inventory1

Introduction

Between 1994 and 2000, the Nearshore Habitat program inventoried Washington's saltwater shorelines statewide. The resulting ShoreZone Inventory describes the physical and biological characteristics of intertidal and shallow subtidal areas. It can be used to better understand and manage Washington's coastal ecosystem.

The inventory covers all of Washington's saltwater shorelines, from the Canadian border to the mouth of the Columbia River. It describes the geomorphic and biological resources of the intertidal and nearshore habitats. Features such as eroding cliffs, sand and gravel beaches, sandflats and wetlands are some of the geomorphic forms mapped. Visible macrobiotic vegetation, such as wetland grasses, intertidal algae, and subtidal vegetation such as eelgrass or kelp, are also mapped.

The ShoreZone Inventory systematically characterizes shoreline morphology, substrate, wave exposure, and biota. The inventory divides the shoreline into homogenous stretches called units. Within each unit, the shoreline is further divided into a series of across-shore components. Units are usually represented spatially by line segments, but can be polygons or points. Information on the unit and on its components is recorded in tables. These tables are then linked to spatial data, allowing a wide range of feature information to be illustrated on maps or analyzed numerically.

Inventory information was collected from a helicopter during low tides. Video imagery of the shoreline was recorded, along with locational information (GPS). From the helicopter a geomorphologist and a marine ecologist recorded continuous commentary on the physical and biological features along the shoreline. Following the survey, the videotapes were taken back to the office for interpretation and classification. The geomorphologist divided the shoreline into units on orthophoto maps and described each unit. Next the marine ecologist added information on the living resources in each unit.

The ShoreZone Mapping System was developed in British Columbia, where it has been used extensively. The Nearshore Habitat Program adapted it in Washington State to include additional features of interest, but it remains compatible with the original BC system. Many people and organizations helped to produce the Washington data set, including the Washington Department of Natural Resources, the Washington State Department of Fish and Wildlife, and the Puget Sound Water Quality Action Team.

Two agencies worked primarily on the Washington State ShoreZone Inventory. The Washington State Department of Fish and Wildlife (WDFW) began mapping in 1994 as a pilot project. WDFW collected survey data and completed data analysis for San Juan Island in 1994, and for the outer coast and the Strait of Juan de Fuca in 1995. In 1997, WDFW collected survey data for a portion of Puget Sound.

In 1998, the Nearshore Habitat Program in the Washington State Department of Natural Resources (DNR) adopted the ShoreZone Inventory project. It collected survey data for the remaining portions of the shoreline in 1999 and 2000, and completed data analysis for all of the surveys. The Nearshore Habitat Program altered the data structure of the ShoreZone Inventory slightly to increase ease-of-use. A series of fields were also added that describe anthropogenic features, translate codes for biota, form, and material fields, and convert the BC CLASS shoreline classification into two local classification systems (the Natural Resource Damage Assessment [NRDA] Classification System and Washington State Marine and Estuarine Classification System).

The coastal zone is an intrinsic part of the northwest culture. For Native Americans, the coast has been a provider of food and a transportation zone for millennia. European settlement also concentrated along the state's shorelines. These trends continue today: the coastline is an economic, esthetic, and geographic focal point for residents of Washington. It is the window between uplands and the world for transportation; it provides recreation, residential amenities, and sites for waste disposal; and it continues to be an important Tribal harvest and cultural resource.

Use of the shoreline is more intense than ever. Humans directly and indirectly impact the coast everywhere. These impacts include degradation of water quality from urbanized watersheds, pollution of shellfish beds, loss of coastal wetlands, loss of coastal riparian vegetation, and invasion of exotic plants and animals. Fortunately there is an increasing awareness of the importance and fragility of coastal ecosystems. Programs are now in place to restore habitat, to improve water quality, and to conserve rare and endangered habitats.

The coastal zone is a unique part of this planet's ecosystem. It is the interface between land, air, and ocean, and shares elements of the terrestrial, marine and atmospheric environments. The ecological processes controlling coastal ecosystems are complex. Basic inventories of the location and abundance of abiotic and biotic coastal resources contribute immeasurably to our understanding of these processes. Such an inventory for the entire marine and estuarine shoreline has never been completed. By carefully mapping our resources, we can increase our knowledge of where features and organisms occur, and build an understanding of complex coastal processes.

The challenge of a mapping system is to characterize features of interest into simple, discrete, and useful classes of information. For example, a good road map directs travelers by depicting roads, cities, and other prominent features. Similarly, a useful shoreline map depicts important littoral features such as landforms, substrate, and biota. In both cases, the mapping system must identify and describe the features of interest. Unfortunately, variations in landforms and biota are often gradational, so a "system" or "methodology" is consistently required to identify and summarize important features. The ShoreZone Inventory System provides an efficient methodology for systematically characterizing shore-zone features from visual observations over large areas.

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ShoreZone Units

The basic concept underlying the ShoreZone Inventory System is that a shoreline can be subdivided into smaller pieces, and the characteristics of each piece can be described and recorded. The primary data division is the unit (See Figure 1a and Figure 1b). Units are alongshore stretches of beach with similar geomorphologic characteristics. In Washington State, the average unit length is 0.5 miles.

Units can be illustrated as lines, polygons, or points (See Figure 2). However, the vast majority of the Units are represented by lines. Lines are the primary data type because Washington's shoreline is typically a long narrow feature with the alongshore length many times the across-shore width. Polygons are used to describe features with unique spatial characteristics that cannot be captured by a single line segment, such as convoluted marshes or extensive embayment mudflats. Points are used to identify features that are of interest to resource managers but are too small (in terms of alongshore length) to be represented by a line segment.

Figure 2. A typical map of shore zone information showing the three types of unit. The map is based on the Ordinary High Water line (OHW) that has been subdivided into line segments (units 452, 453, 455, 456). Points represent small features (unit 457). Polygons represent small features with unique spatial characteristics that are not captured by a single line segment (unit 454).

Information that describes the entire unit is recorded in the Unit Table. This information is then attached as attribute information to each spatial unit feature.

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ShoreZone Components

The shoreline commonly exhibits across-shore variation in sediment composition and morphology that is correlated with tidal zonation (See Figure 3). To capture this across-shore variation, we further subdivide each unit into across-shore components.

Figure 3. A conceptual diagram showing how each Unit is subdivided into across-shore Components. Shore zone features typically occur in across-shore bands that are correlated with tidal elevation. These bands are not mapped, but information about them is recorded in the Component Database.

Across-shore components are not mapped. Instead, a description of each subdivision is recorded in the across-shore (XSHR) Component table. Each across-shore component is described first according to the zone it occurs in (for example, supratidal, intertidal or subtidal), then it is numbered according to its sequence within the zone. Across-shore components are linked to units using a unique ID number. See the Data Dictionary for a list of all of the tabular data fields that describe each component.

For each unit, many associated across-shore component records describe the physical and biological features in detail. The location of each across-shore component is first described according to the zone it occurs in (A= supratidal, B=intertidal, C=subtidal). It is possible to have multiple components per zone. Within each zone, each across-shore component is numbered sequentially (for example, A1, B1, B2, and C1).

Across-shore component data is designed to capture detail about the across-shore variation. For example, along a stretch of beach, the backshore seawall is comprised of concrete, the beach berm is comprised of logs on sand, the beach face is made of sand and pebbles, and the tidal flat with channels is comprised of sand and mud. This typical sequence of features is captured within the Component Database, where each component (for example, seawall, beach berm, beach face, and tidal flat) is a separate record in the database. A coding system records details on each component as if one were walking across the shore from the land (supratidal zone) to the water (subtidal zone). The codes describe the landforms and substrates (See Table 1). In the ShoreZone system, the subtidal zone begins at approximately Mean Lower Low Water (0 feet elevation).

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Biological Information

In addition to a description of the physical characteristics of a beach, each Component record includes a description of the living resources. The living resources are cataloged in terms of 23 conspicuous assemblages of species that are visible from the air. These assemblages are referred to as Bio-Bands because the algae, plants, and animals create a well-defined series of across-shore color bands (See Figure 4). Each Bio-Band (See Table 2) is named for the most prominent species in the band, or by the general description of the species assemblage. The abundance of each band is recorded as either absent, patchy, or continuous.

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ShoreZone Themes

The Nearshore Habitat Program created Geographic Information Systems (GIS) themes or layers from the ShoreZone Inventory. The themes include information on physical and biological features. Each theme is an Environmental Systems Research Institute® (ESRI) ArcView® shapefile. The themes are summarized below.

Unit Summary: summarizes the physical and biotic ShoreZone Inventory information in its attribute table. All codes have been translated into text.

Substrate Summary: divides the shoreline into 7 basic shoreline types based on substrate type.

Shoreline Type: divides the shoreline into 15 shoreline types commonly used in British Columbia. This classification is a simplification of the BC Shoreline Classification.

Shoreline Modification: shows the percentage of anthropogenic shoreline modification in each line unit. Information on other anthropogenic features is also included in the attribute table, such as the number of docks, ramps, piers, and slips.

Floating Kelp: shows line units where canopy forming kelp (Macrocystis and Nereocystis) is continuous, patchy, or absent.

Nonfloating Kelp: shows line units where nonfloating kelp (that is, Laminaria sp., Hedophyllum sp., etc) is continuous, patchy, or absent.

All Kelp: shows line units where all kelp (both floating and nonfloating species) is continuous, patchy, or absent.

Sargassum: shows line units where the non-indigenous brown alga Sargassum muticum is continuous, patchy, or absent.

Eelgrass: shows line and polygon units where eelgrass (Zostera marina and Zostera japonica) is continuous, patchy, or absent.

Surfgrass: shows line units where surfgrass (Phyllospadix spp.) is continuous, patchy, or absent.

Seagrass: shows line and polygon units where seagrass (Zostera spp. and Phyllospadix spp.) is continuous, patchy, or absent.

Salt Marsh: shows line and polygon units where salt tolerant vascular plants (that is, Salicornia virginica, Triglochin maritima, Carex sp., Spartina sp.) are continuous, patchy, or absent.

Dune Grass: shows line units where dune grass (Leymus mollis) is continuous, patchy, or absent.

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Reference Cited

1. Washington State Department of Natural Resources. 2001. Washington State Shorezone Inventory CD. Nearshore Habitat Program. Olympia, WA.