High Resolution Marsh Mapping

During 2021, Whiteout Solutions, LLC conducted a series of drone flights to collect remotely-sensed elevation and landcover data at five tidal marshes in Connecticut, USAPilots flew drones at all sites to collect RGB imagery, multispectral imagery, high density return LiDAR, and thermal imagery. Two flights were conducted at each site, one at low tide (July 13th or 14th) and one at high tide (August 16th, 17th, or 18th).

The viewer is for exploring the five small study sites the many layers available for each including aerial imagery, elevation like hillshade and indices. The data download section provides the GIS formatted files for those who can use them.

Background

Tidal marshes worldwide [1], and in coastal New England [2], are rapidly declining. Major causes of tidal marsh loss include sea level rise and reduced sediment in the water [3], and tidal marsh declines are often punctuated by losses in elevation relative to sea level (marsh ‘drowning’). Species that rely on tidal marsh habitat are therefore threatened by this ecosystem degradation and understanding how species respond both to ongoing degradation and to restoration efforts designed to reverse the losses, is key to their persistence.

Bird species such as saltmarsh sparrow and clapper rail are already declining, and declines of other species are expected as marshes flood more frequently and marsh vegetation changes. Because habitat transitions occur along a very shallow elevation gradient in tidal marshes, and because sea level rise is predicted to occur at rates of ~3 mm per year in coastal New England [4], elevation data needs to be of high precision to understand how future sea level conditions may alter the plant communities of tidal marshes, and the animals that depend on them.

Implications

The areas flown at Great Meadows Marsh, Sluice Creek, and Bride Brook contain patches of degraded tidal marsh where there are plans for marsh restoration through the addition of a thin layer placement of sediment. These flights therefore serve as pre-management data collection efforts. The areas flown at Hammonasset Beach State Park and Barn Island Wildlife Management Area include patches of habitat that have been surveyed for the tidal marsh breeding birds since 2002. These flights therefore serve as benchmark data collection efforts to relate future changes in habitat composition to future changes in saltmarsh bird populations at each site.

Purpose

Data collected during these drone flights will be used to understand how habitat changes manifest in Connecticut’s tidal marshes as sea levels continue to rise. These data will also be used to inform our understanding of the fine scale elevation and habitat responses following restoration activities that use thin-layer sediment placement. The dataset provides elevation data for sections of five tidal marshes through a variety of remote sensing products including point cloud, DEM, and DSM products. It also contains thermal imagery data and multispectral imagery, which can be used to estimate aboveground plant species composition and biomass. These data will be valuable to all individuals interested in tidal marsh elevation, landcover, or future changes in coastal Connecticut.

Literature Cited

1. C. J. Mcowen et al., A global map of saltmarshes. Biodiversity Data Journal e11764 (2017).
2. E. B. Watson et al., Anthropocene survival of southern New England’s salt marshes. Estuaries Coast 40, 617–625 (2017).
3. S. Fagherazzi, et al., Numerical models of salt marsh evolution: Ecological, geomorphic, and climatic factors. Reviews of Geophysics 50 (2012).
4. J. A. Church, N. J. White, Sea-level rise from the late 19th to the early 21st century. Surveys in Geophysics 32, 585–602 (2011).

Study Sites

Barn Island Wildlife Management Area, Stonington

Bride Brook, Rocky Neck State Park, East Lyme

Hammonasset Beach State Park, Madison

Sluice Creek, Guilford

Great Meadows, Stewart B. McKinney National Wildlife Refuge, Stratford

Download and Connect

Imagery - Orthomosaic
Site Dataset Date Format Download Link and File Size
Barn Island August 17, 2021 tif download zip (2.2Gb)
Bride Brook August 17, 2021 tif download zip (349Mb)
Hammonasset July 13, 2021 tif download zip (749Mb)
Sluice Creek August 18, 2021 tif download zip (851Mb)
Stratford Great Meadows August 18, 2021 tif download zip (2.2Gb)

Image Service

Layer Name:
Orthomosaics

Imagery - Aerial (5 bands)
Site Dataset Date Format Download Link and File Size
Barn Island (eastern section) August 17, 2021 tif section 1 - download zip (617Mb)
Barn Island (western section) August 17, 2021 tif section 2 - download zip (1.6Gb)
Bride Brook August 17, 2021 tif download zip (879Mb)
Hammonasset July 13, 2021 tif download zip (551Mb)
Hammonasset August 16, 2021 tif download zip (2.2Gb)
Sluice Creek August 18, 2021 tif download zip (1.9Gb)
Stratford Great Meadows August 18, 2021 tif download zip (4.32Gb)

Image Service

Layer Name:
Aerial_5band

Elevation - Digital Surface Model (DSM)
Site Dataset Date Format Download Link and  File Size
Barn Island August 17, 2021 tif download zip (178Mb)
Barn Island August 17, 2021 kml download (1kb)
Barn Island August 17, 2021 asc download zip (108Mb)
Bride Brook August 17, 2021 tif download zip (18Mb)
Bride Brook August 17, 2021 kml download (1kb)
Bride Brook August 17, 2021 asc download zip (19Mb)
Hammonasset July 13, 2021 tif download zip (61Mb)
Hammonasset July 13, 2021 kml download (1kb)
Hammonasset July 13, 2021 asc download zip (58Mb)
Hammonasset August 16, 2021 tif download zip (61Mb)
Hammonasset August 16, 2021 kml download (1kb)
Hammonasset August 16, 2021 asc download zip (57Mb)
Sluice Creek August 18, 2021 tif download zip (38Mb)
Stratford Great Meadows August 18, 2021 tif download zip (69Mb)

Image Service

Layer Name:
Marshes_DSM

Elevation - Digital Terrain Model (DTM)
Site Dataset Date Format Download Link and File Size
Barn Island August 17, 2021 tif download zip (167Mb)
Barn Island August 17, 2021 kml download (1kb)
Barn Island August 17, 2021 asc download zip (100Mb)
Bride Brook August 17, 2021 tif download zip (16Mb)
Bride Brook August 17, 2021 kml download (1kb)
Bride Brook August 17, 2021 asc download zip (17Mb)
Hammonasset July 13, 2021 tif download zip (57Mb)
Hammonasset July 13, 2021 kml download (1kb)
Hammonasset July 13, 2021 asc download zip (55Mb)
Hammonasset August 16, 2021 tif download zip (56Mb)
Hammonasset August 16, 2021 kml download (1kb)
Hammonasset August 16, 2021 asc download zip (53Mb)
Sluice Creek August 18, 2021 tif download zip (34Mb)
Stratford Great Meadows August 18, 2021 tif download zip (61Mb)

Image Service

Layer Name:
Marshes_DTM

Elevation - Lidar Point Clouds

Elevation – Lidar Point Clouds

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