Meandering between Pennsylvania, Delaware and New Jersey, the fresh water of the Delaware River winds its way southward to meet the salt water in the Atlantic Ocean. The transition zone, known as the Delaware Estuary, is a vital resource for the region’s five million people, who rely on the channel for drinking water, food production, shipping, recreation and power. The estuary is also an essential habitat for fish and wildlife, hosting more than 130 species of finfish along with clams, oysters and crabs, and 15 different species of waterfowl. The world’s largest population of spawning horseshoe crabs is found here, as is the second largest concentration of migrating shorebirds in the Western Hemisphere. It’s a tidal wetland worth protecting.
In 1994, PSEG Power’s Salem Generating Station in Salem County, N.J., in response to its New Jersey Pollutant Discharge Elimination System (NJPDES) permit, began an ambitious effort to help restore and safeguard a portion of the estuary by creating the Estuary Enhancement Program (EEP). Relying on experts in land management, salt marsh restoration, ecology, biology and a number of other disciplines, the program focused on restoring and enhancing an area encompassing approximately 20,000 acres of salt marsh and uplands along the Delaware Bay in the states of New Jersey and Delaware. The overall goals of the program were to provide long-term benefits to the environment and improve the habitat for naturally occurring flora and various aquatic species. By creating channels and breaching dikes, the EEP sought to restore natural tidal inundation. In addition, efforts were undertaken to improve re-vegetation by the beneficial Spartina and the reduction of invasive Phragmites.
Extensive monitoring programs were put in place to gather information about habitat structure, species abundance and biological productivity. The EEP also conducted fisheries surveys and other in-field testing programs. However, tracking the success of wetland restoration required a bird’s eye view--a perspective that could only be achieved through an overall vegetation survey of the wetlands.
Working for PSEG, the URS Corp. teamed with BAE Systems in 1996 to provide a comprehensive geospatial solution for monitoring this massive mitigation effort. The goal was to capture aerial data and produce both natural color and color infrared (CIR) orthoimagery for change detection, thematic vegetation mapping and detailed photo interpretation to determine the width, length and depth of channels. Tidal shifts, changing water temperatures and seasonal differences posed significant challenges to the project. The areas of interest had to be flown at a specific time of year, during specific tidal windows and at midday, requiring complex and continuous flight planning by BAE Systems, while incorporating NOAA tide predictions and sun angles as well as local weather conditions.
After acquiring the imagery, BAE Systems used its trademarked SOCET SET Automatic Terrain Extraction (ATE) system to classify elevation signatures in the terrain, with enhanced spot elevations and breaklines added for greater detail. The resulting digital terrain models were used to generate orthoimagery. The team carefully compared imagery datasets to detect and monitor invasive and native species.
“Vegetative and hydrogeomorphic monitoring included peak growing season (August) sampling at two reference marshes in New Jersey and four wetland restoration sites in New Jersey and Delaware,” says Ray Hinkle, vice president and principal ecologist for URS. “False color infrared and true color aerial imagery was also acquired of the reference marshes and wetland restoration sites, and utilized to prepare orthoimagery for use in the mapping of vegetation for each of the sites as well as quantification of the changes in geomorphological characteristics related to new channel formation and expansion.”
These and other datasets were used in the development of detailed GIS basemaps used to assess the health of the wetlands over time. Gradually, through improvements implemented as a result of having access to comprehensive data, evidence of restoration, enhancement and preservation could be seen throughout the region.
Recognizing that real change must be monitored long term, PSEG has continued its comprehensive assessment and improvement efforts through the EEP. In 2010, BAE Systems was tasked with acquiring new imagery in support of the project. Once again, the aerial imagery had to be acquired during a specific monitoring period and timed to the correct tidal activity. In addition, the firm had to ensure that the radiometric quality for the orthophotography would be consistent with past years so that accurate vegetation analysis could be performed.
To meet these goals, the BAE Systems team developed new image classification techniques and deployed new tone balancing processes. According to Hinkle, the radiometrically consistent orthoimagery produced by BAE Systems, in conjunction with some field work, allowed URS to verify a reduction in the unwanted Phragmites and an increase of the Spartina (a desirable marsh vegetation). Channel density also improved, indicating better wetland health.
After completing the flights and processing the imagery, BAE Systems performed thematic mapping to determine changes and additions to new channels and expansions to existing channels. The channel mapping provides URS with a valuable product for the firm’s annual analysis of the wetland areas. Vegetation mapping is also performed to evaluate the success of reintroductions of native species along with efforts to eradicate invasive species.
Using remote sensing to help monitor the impact of the EEP has proven invaluable. The 2010 project helped demonstrate the program’s success, showing that PSEG’s methods can be used on many other restoration programs around the country and the world.
As a result of actions taken by the EEP, more than 1,600 acres of aquatic habitat has been restored in the Delaware Estuary and more than 800 acres of Phragmites-dominated wetlands has been replaced with desirable native vegetation. The EEP has been recognized with numerous awards, including the Coastal America Special Recognition Award, the N.J. Audubon Society Corporate Leadership Award, the Wildlife Habitat Council Site Certification and many others.
Innovative remote sensing and geospatial monitoring efforts have helped PSEG accomplish its goals. Based on the implementations of the 2010 project, the EEP will continue to provide long-term benefits to the environment, ecology, natural resources, economy and the people of the Delaware Bay estuaries.
BAE Systems was honored with a 2011 MAPPS Geospatial Products and Services Excellence Award in the Remote Sensing category for its work on this project.
URS Corporation’s website is www.urscorp.com. For more information about the EEP, visit www.pseg.com/info/environment/estuary.jsp.