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Municipal Coastal Wetland Maps

The Narragansett Bay study area encompasses 26 coastal municipalities in Rhode Island and Massachusetts. The study area is divided into 11 map units to display the project information by the individual municipality or group of municipalities. The following series of five hard copy maps were created for each municipal map unit. They include:
1. Potential Coastal Wetland Restoration Sites
2. Land Use/Land Cover Within 500-Foot Buffer of Coastal Habitats
3. Hardened Shorelines, Coastal Habitats, and Field Sites
4. Potential Coastal Wetland Restoration Sites and Open Space Lands
5. Potential Coastal Wetland Restoration Sites Sorted By Size

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Map Descriptions

Map 1. Potential Coastal Wetland Restoration Sites

Potential coastal restoration sites were identified and mapped using aerial photointerpretation and field work. They include Type I sites or former estuarine wetlands which are potentially restorable; and Type II sites which are existing estuarine wetlands subject to various impacts and potential sources of degradation (Huber, 2000). Type I sites can be filled, drained, or farmed areas, or exist freshwater wetlands and impoundments. Type II sites are potentially degraded estuarine wetlands due to on-site alterations such as tidal restrictions and ditching. Potential off-site impacts to wetlands can occur from the surrounding upland in the form of runoff from agricultural land and impervious surfaces. The sources of the coastal wetland information are true color aerial photography (transparencies) at 1:40,000-scale taken on August 11, 1996 in accordance with NOAA C-CAP protocol (Dobson et al., 1995), and field investigations. The 1:12,000-scale photography taken on July 6, 1996 was reviewed as a collateral source of information. The target minimum mapping unit for potential restoration sites is 0.5 acre, except for monocultural stands of Common reed, Phragmites australis, which is 0.25 acre. The target minimum mapping unit for linear restoration areas is approximately 125 linear feet. This map is intended for planning purposes.

Map 2. Land Use / Land Cover Within the 500-Foot Buffer of Coastal Habitats

The land within a 500-foot buffer zone around the coastal wetlands was inventoried and classified using the Anderson (1976) land use and land cover classification system (Huber, 2000). The classification system was modified to: 1) characterize natural buffers functioning as wildlife habitat, mitigation of potential erosion and sedimentation, mitigation of potential runoff and leachate, and bank stabilization; 2) characterize man-made sources of potential external impacts to coastal wetland resources; and, 3) document land development in the proximity of tidally restricted wetlands where tidal hydrology may be restored. Freshwater wetlands and water bodies in the buffer zone were classified according to Cowardin et al. (1979). The sources of the coastal wetland information are true color aerial photography (transparencies) at 1:40,000-scale taken on August 11, 1996 in accordance with NOAA C-CAP protocol (Dobson et al., 1995) and field investigations. The 1:12,000-scale photography taken on July 6, 1996 was reviewed as a collateral source of information. The target minimum-mapping unit for surrounding land use/land cover is 0.5 acre. This map is intended for planning purposes only.

Map 3. Hardened Shorelines, Coastal Habitats and Field Sites

The hardened shorelines of Narragansett Bay were identified and mapped using true color aerial photography (transparencies) at 1:12,000-scale taken on July 6, 1996 (Huber, 2000). They include bulkhead, seawall, jetty, groin, revetment, breakwater, permanent pier, and other significant pier. The target minimum mapping unit is approximately 125 to 250 linear feet. Codes for hardened shorelines were developed for this project with reference to the following definitions in the Rhode Island Coastal Resources Management Program (1979):

Bulkhead: “…a wood, steel, or concrete structure built to retain or prevent wasting and collapse of a bluff into the sea...provides limited protection from waves.”
Seawall: “…a massive, stand alone structure of placed or dumped stone, concrete or steel sheetpile…often have curved or stepped face designed to withstand the direct onslaught of ocean waves.”
Jetty: “…usually of dumped stone (rubble mound) that retard the migration of a tidal inlet (breachway) in order to provide safer passage for boats in and out of coastal lagoon and estuaries.”
Groin: “…the structure built of rock, steel, timber or concrete that extends across a beach into tidal waters and is used to entrap sand in the longshore transport system, generally perpendicular to shoreline’s coastal trend.”
Revetment: “…built to armor a sloping shoreline face usually composed of one or more layers of stone or concrete riprap…blankets and generally conforms to contours or a coastal feature.”
Breakwater: “…either exposed or submerged. Protects a shore, harbor, anchorage or basin by intercepting waves…sometimes placed parallel to open shoreline to retard force of incoming waves to headland and barrier beaches.”
Additional definitions were developed for this project: Permanent pier: “solid stone or concrete piers not suspended by piles and blocking water circulation.” Other significant piers: “large piers or wharves supported by either solid fill or large piles; type of support cannot be verified through photointerpretation.”

Field sites were selected to collect reference wetland data from accessible coastal wetlands within four categories of disturbance (Huber, 2000). The categories are relatively undisturbed or near pristine, moderately disturbed, severely disturbed, and severely tidally restricted. They were determined based upon presence/absence and severity of disturbance factor(s), the presence / absence of buffering vegetation, and disturbance categories within the context of the overall development in the estuary. This map is intended for planning purposes only.

Map 4. Potential Coastal Wetland Restoration Sites and Open Space Lands

The potential coastal wetland restoration sites data layer was joined with the public lands data layer as method to help sort and prioritize restoration projects. The sources of public lands information are Rhode Island Geographic Information System and Massachusetts Geographic Information System. The sources of the coastal wetland information are true color aerial photography (transparencies) at 1:40,000-scale taken on August 11, 1996 in accordance with NOAA C-CAP protocol (Dobson et al., 1995), and field investigations. The 1:12,000-scale photography taken on July 6, 1996 was reviewed as a collateral source of information. This map is intended for planning purposes only.

Map 5. Potential Coastal Wetland Restoration Sites Sorted by Size Category

The potential coastal wetland restoration sites data layer was sorted by size category as method to help prioritize restoration projects. The sources of the coastal wetland information are true color aerial photography (transparencies) at 1:40,000-scale taken on August 11, 1996 in accordance with NOAA C-CAP protocol (Dobson et al., 1995), and field investigations. The 1:12,000-scale photography taken on July 6, 1996 was reviewed as a collateral source of information. This map is intended for planning purposes only.

References:

Anderson, J.R., E.E. Hardy, J.T. Roach, and R.E. Witmer. 1976. A Land Use and Land Cover Classification System for Use with Remote Sensor Data. U.S. Geological Survey Professional Paper 96A. U.S. Government Printing Office, Washington, D.C. 28 pp.
Cowardin, L.M., V. Carter, F.C. Golet, and T. Laroe. 1979. (Reprinted 1992). Classification of Wetlands and Deepwater Habitats of the United States. U.S. Fish and Wildlife Service, Washington DC. FWS/OBS-79/31. 103 pp.
Dobson, J.E., E.A. Bright, R.L. Ferguson, D.W. Field, L.L. Wood, K.D. Haddad, H. Iredale III, J.R. Jensen, V.V. Klemas, R.J. Orth, and J.P. Thomas. 1995. NOAA Coastal Change Analysis Program (C-CAP): Guidance for Regional Implementation. U.S. Department of Commerce, NOAA National Marine Fisheries Service Technical Report 123. Seattle, Wash. 92 pp.
Huber, I. 1999. Report on the Analysis of True Color Aerial Photographs to Map Submerged Aquatic Vegetation and Coastal Resource Areas in Narragansett Bay Tidal Waters and Nearshore Areas, Rhode Island and Massachusetts. Natural Resources Assessment Group, Department of Plant and Soil Sciences, University of Massachusetts, Amherst, Mass. Narragansett Bay Estuary Program Report No. 99-117, Providence, R.I. 16 pp.+ Appendices.
Huber, I. 2000. Photointerpretation of Buffer Zones, Coastal Wetland Potential Restoration Sites and Hardened Shorelines in the Narragansett Bay Estuary, R.I. and Mass. Narragansett Bay Estuary Program Report No. 01-119. Providence, R.I.17 pp.+ Appendices.
Olsen, S. and G. Seavy. As amended, 1990. The State of Rhode Island Coastal Resources Management Program. University of Rhode Island Publications Office, Kingston, R.I.
Tiner, R.T., I.J. Huber, T. Nuerminger, and A.L. Mandeville. 2003. An Inventory of Coastal Wetlands, Potential Restoration Sites, Wetland Buffers, and Hardened Shorelines for the Narragansett Bay Estuary. U.S. Fish and Wildlife Service, Northeast Region, Hadley, Mass. In cooperation with the University of Massachusetts-Amherst and University of Rhode Island. National Wetlands Inventory Cooperative Interagency Report.