Introduction
Background
Historical
loss of coastal wetlands from natural and human disturbances is
significant. These actions have resulted in the loss of important
wetland values and functions that include fish, shellfish, and
wildlife habitat, water quality improvement, and shoreline erosion
control. As a result, there is growing interest in assessing the
status and trends of coastal wetlands in Rhode Island. Such studies
help measure the effectiveness of Federal and State wetland protection
programs and laws, raise public awareness of wetlands, and create
science-based plans to alter these trends. Recognizing the value
of these resources, the Narragansett Bay Estuary Program (NBEP)
secured the funding for and coordinated a series of three cooperative
mapping projects to assess the Bay's coastal habitats.
Inventory
of Narragansett Bay Coastal Habitats
In 1995, the
NBEP formed partnerships with the University of Massachusetts-Natural
Resources Assessment Group (UMass), R.I. Department of Environmental
Management, Save the Bay, and the City of Warwick to characterize
the Bay's estuarine habitats. Environmental scientists and planners
from Federal and State agencies, local universities, and nonprofit
organizations, provided technical support on the project. The
following year, new aerial photographs of the Bay were taken to
identify, classify, and map the coastal habitats. The project
identified approximately 2,924 acres of salt marsh, 1,466 acres
of beach, 582 acres of rocky shore, 569 acres of tidal flat, 656
acres of brackish/Phragmites marsh, 160 acres of salt shrub wetland,
100 acres of eelgrass beds, 46 acres of panne and pool, 43 acres
of dune, 9 acres of oyster reef, and 3 acres of streambed habitats
(Huber, 1999) The inventory provides baseline information on the
Bay’s habitats from which to measure historical and future
change.
Inventory
of Narragansett Bay Coastal Wetland Restoration Sites, Wetland
Buffers, and Hardened Shorelines
In 1998, building on this new information, the NBEP partnered
with the U.S. Fish and Wildlife Service (USFWS), UMass., University
of Rhode Island Environmental Data Center (URI-EDC), and Save
The Bay to identify and map degraded coastal wetlands and potential
restoration sites in the Bay. The methodology was modeled after
a watershed-based approach to restoration planning work in Massachusetts
performed by the USFWS and UMass. They further tailored the methodology
to apply to estuarine wetlands in Narragansett Bay. Using aerial
photo-interpretation and field investigations, the UMass. personnel
identified, delineated, and classified the land use/land cover
surrounding the Bay's coastal wetlands within a 500-foot buffer
area, hardened shorelines, and two categories of potential coastal
wetland restoration sites. The URI-EDC personnel then converted
the photo-interpreted information into digital coverages and a
geospatial database using GIS technology. Maps were created for
the 26 Narragansett Bay coastal municipalities in Rhode Island
and Massachusetts.
The study identified
over 4000 acres or a total of 236 potential coastal wetland restoration
projects. Most (78%) of the acreage consisted of Type 2 degraded
wetlands with onsite impacts such as ditches, impoundments, tidal
restrictions, and excavation. The remainder of the area, 888 acres,
was represented by Type I sites that are no longer coastal wetlands
due to filling or draining, or that presently exist as submerged
or freshwater wetlands. The land use/land cover within the 500-foot
buffer of coastal wetlands was comprised of nearly evenly divided
developed land and natural cover. In addition, over 133 miles
of hardened shores (25 percent of the shoreline) were mapped with
greater that 75 percent of these represented by bulkheads, revetments,
and seawalls.
The results
of the study were incorporated into a GIS-based decision-making
tool developed by NOAA Coastal Services Center to assist resource
managers with the prioritization of coastal wetland restoration
opportunities (Coastal Resources Management Council et al., 2003).
The Tool can be used to promote a coordinated and systematic approach
to restoration planning in Narragansett Bay.
The acreage
summaries, technical reports, and downloadable spatial data from
the two projects described above are available on the Narragansett
Bay Coastal Wetland Restoration Analysis-Inventory of Potential
Restoration Sites, Wetland Buffers, and Hardened Shorelines CD-ROM.
The digital data is also available through the Rhode Island Geographic
Information System (RIGIS) web site at www.edc.uri.edu/rigis.
Project
Description
Inventory
of the Rhode Island portion of the Narragansett Bay Coastal Wetland
and Buffer Zone Losses, Gains, and Change from the 1950s to the
1990s; and 1930s to the 1950s at Six Demonstration Sites:
In 1999, the
Estuary Program continued working with the URI-EDC, USFWS, and UMass.
to assess the changes in coastal wetlands and their buffers in the
Narragansett Bay estuary. Using aerial photointerpretation from
two time periods, the extent of loss (wetland to non-wetland), gain
(non-wetland to wetland), and change in the classification (wetland
to wetland) of coastal wetlands was identified in the Rhode Island
portion of the Narragansett Bay estuary between the 1950s and 1990s
era. The trends in land use and land cover were interpreted within
a 500-foot buffer zone of the coastal wetland. In addition, further
analysis of change was performed at six sites back to the 1930s.
The areas were selected because of their ecological value, the history
and extent of the on-site alterations, and the interests of the
communities and resource managers to restore the sites. They include:
1) Allins Cove/West Shore, Barrington, R.I.; 2) Calf Pasture Point,
North Kingstown, R.I.; 3) Jacobs Point, Warren and Bristol, R.I.;
4) Palmer River System, Warren, R.I. and Swansea, Mass.; 5) Sachuest
Point, Middletown, R.I.; and, 6) Wesquage Pond, Narragansett, R.I.
The wetland trends
information was classified according to Cowardin et al., (1979)
and follows the USFWS's National Wetlands Inventory (NWI) mapping
standards. The smallest unit of change that was mapped in the study
area was 0.25 acre. Codes were assigned to these areas to describe
the causes of change resulting from natural and human disturbances,
e.g., coastal erosion and deposition, agriculture. The land use
and land cover in the buffer zone was classified using a modified
Anderson (1976) method.
The photointerpreted
information was then converted into digital coverages and a geospatial
database using geographic information system (GIS) technology. The
database contains the acreages and NWI codes of the wetlands in
the 1990s and 1950s, and in the 1930s for those wetlands that occur
in the six demonstration sites. A code describing the cause of the
wetland trend also appears for some of the wetlands. A series of
GIS maps were developed for the bay municipalities and environmental
agencies and organizations. Project reports were then prepared to
summarize the findings of the study. It is expected that the results
of this study will be beneficial to resource managers by providing
the data to develop a comprehensive strategy for the protection,
restoration, and monitoring of coastal wetlands.
The study area
is presented in10 maps organized by municipality or groups of municipalities
at 1:24,000-scale. The six demonstration sites are displayed in
one map at the same scale.
The
municipal maps, database,
acreage statistics,
and project reports are
available on this CD.
Project
Study Area
Narragansett
Bay is defined as the waters north of a line extending from Pt.
Judith to Sakonnet Point, and includes the Sakonnet River, East
and West passages, Providence River, Warren River System, Seekonk
River, Mount Hope Bay, Taunton River, Assonet River, and Assonet
Bay. The project area encompasses the Narragansett Bay shoreline
areas in Rhode Island. This includes the following 18 municipalities:
Barrington, Bristol, Cranston, East Greenwich, East Providence,
Jamestown, Little Compton (partial-western shoreline), Middletown,
Narragansett (partial-eastern shoreline), Newport, North Kingstown,
Pawtucket, Portsmouth, Providence, South Kingstown, Tiverton, Warwick,
and Warren, Rhode Island.
Project
Purpose
The objectives
of the project are to:
- identify
coastal wetland and buffer zone trends including losses, gains,
and changes in classification in the Narragansett Bay estuary
from 1950s, and 1990s eras;
- identify
coastal wetland trends including losses, gains, and changes in
Allin's Cove, the Palmer River System, Calf Pasture Point, Jacob’s
Point, Sachuest Point, and Wesquage Pond from the 1930s, and 1950s
eras;
- develop a
GIS database and maps of wetland and buffer zone trends; and,
- promote comprehensive
and coordinated approaches to restoration, protection, and monitoring
of coastal wetlands in the Narragansett Bay estuary.
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