Esempi di
applicazioni
Marine Consultants map Eelgrass in
Puget Sound with GPS receiver and WinWedge
Minimizing the environmental effects
of our expanding population presents one of today’s most difficult
challenges. How do we balance economic growth and environmental
safety? The problem is particularly acute for booming coastal
communities where waterfront development threatens critical marine
environments, such as eelgrass meadows.
In the Pacific Northwest’s Puget
Sound area, global positioning systems (GPS) and geographic
information systems (GIS) are supplying a way for development and
scientists to meet this challenge. The Washington State Department
of Transportation (WSDoT) is relying on GPS and GIS to help protect
critical nearshore marine habitats -- primarily eelgrass -- while
the agency expands and improves its ferry system. The ferry system,
which in 1995 transported more than 24 million passengers and
vehicles across the Puget Sound, is consistently overloaded,
resulting in two to three hour waits during the peak summer tourist
season. WSDoT is addressing the overcrowding by constructing three
new jumbo ferries, adding two more passenger-only boats, and
expanding several terminals to accommodate the additional demand.
However, WSDoT had to find a way to provide these improved services
while also satisfying local residents’ desires to protect the
natural environment they moved there to enjoy.
In fact, the State of Washington is
so serious about environmental preservation, that in 1989 the
Washington Department of Fish and Wildlife adopted a "no net loss"
program for all marine habitats. Any waterfront construction project
that might cause a loss of eelgrass must get a Hydraulic Project
Approval. The ferry system expansion falls under this policy since
it calls for the construction of new docks, which can threaten
eelgrass by blocking the light the vegetation needs to survive.
Eelgrass Mapping System
The first step in protecting eelgrass
is mapping where it is. Marine Resources Consultants developed a
creative, low-cost, real-time mapping solution to chart the proposed
expansion areas. The consulting company’s solution utilizes a
GPS-based underwater video graphic mapping system that is plotted in
a Microsoft Excel version 5.0. The basic idea is pretty simple, the
crews’ helmsman monitors the underwater video camera on a TV screen
in the boat. The GPS Receiver (manufactured by Trimble, Sunnyvale,
CA) is connected to NMEA multiplexer, which is connected to a
computer running Microsoft Excel and the Software Wedge for Windows
(WinWedge). WinWedge parses and filters the output from the GPS
Receiver and directs it to the spreadsheet program.
The spreadsheet plots three data
series. The first is the current longitude and latitude plotted in
red with a black cross-hair in the middle, indicating the current
vessel position. The other two data series consist of longitude and
latitude coordinates for the vessel track line when eelgrass is
present, indicated by a thick green line, or absent, indicated by a
thin black line. The helmsman simply clicks on a eelgrass ON/OFF
button embedded in the spreadsheet when eelgrass appears or
disappears on his monitor. The result is a real-time plot of the
area sampled that indicates where eelgrass is present.
The system has been used to help
WSDoT expand its ferry system with no negative effects to the area
eelgrass. The system is so impressive that on Earth Day in 1997, the
US Department of Transportation awarded one of the terminal
expansion projects the Distinguished Environmental Achievement Award
for Research.
Before discovering WinWedge, data
was collected by hand and charts were created on a PC back at the
office. Users of the system noted that the process was significantly
more time consuming and tedious before development of the real-time
system.
Benefits
- 50% time reduction in data
collection and analysis
- Accurate correlation of location
and "eelgrass visibility" data from the GPS Receiver and video
camera
- Real time remote data collection
and immediate access to survey data
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