100
So why is a Geographic Information System (GIS) useful? Imagine randomly
visiting ~30 locations across the entire NY metropolitan area and then trying to
estimate the total number of cars in the City. Without knowing the number of roads
or parking lots, this would be impossible. In my study, GIS enabled me to map all
of the similar environments (waterways, shallow areas) and identify areas similar to
where I sampled. Using this information, coupled with analyses from the cores,
river morphology and bathymetry offshore, I estimated the sediment being trapped
in the study area vs the total amount coming into the ocean. This work is fundamental to determining how materials from land are dispersed in the sea. My doctoral
work also highlighted the importance of mangroves in storing sediment and carbon,
another topic receiving much attention as nations grapple with too much carbon
dioxide in the atmosphere.
Mapping the Coast with Lasers, Acoustics, and Robots
Today there is a lot of cool technology that we can use to better understand Earth
surface dynamics and history. The most widely used tool for studying the seafloor
is sonar. Developed during World War I and used heavily during World War II, the
technology has come a long way. Now we have sophisticated acoustic systems that
can measure depths over a swath of the seafloor using a fan of sound propagating
below a ship or other device. It is with these systems that we can now “see” the
seafloor and use this invaluable information to measure and determine governing
processes, such as submarine landslides or wave-reworking by storms.
During my time at East Carolina University (ECU), a couple colleagues, Drs.
Reide Corbett and David Mallinson, and I obtained a grant from the National
Science Foundation to obtain state-of-the-art tools for studying the coastal areas.
The problem with mapping the seafloor with fancy, expensive equipment is that one
does not know the depths prior to the first mapping. Often the information on nautical chart is decades old. For testing of our ~$150,000 new seafloor mapping instrument, we went to Washington, North Carolina, where we could use an ECU vessel
as a survey platform. After getting the system set up and going, we were thrilled by
the results and wanted to see more in harbor. We passed under an old bridge and
could see individual pilings and other structures to the side of the vessel, but as we
came out the other side, the depths got shallower … and shallower… and shallower.
The seafloor quickly came within inches of the sensor, and we scrambled to tilt up
the device and slow the boat. Thankfully before any impact, the water began to
deepen. It is terrifying to think that we almost destroyed the costly system on the
first day. But this is ocean science. Conditions are dynamic and often dangers are
unknown.
It was this same multibeam system that we used aboard the R/V Cape Hatteras
to map seafloor change after Hurricane Katrina and civil war wreckage in coastal
North Carolina (Fig. 6.5). More and more vessels have this type of technology integrated with their navigation and other systems. As a result, new data are being
J. P. Walsh
So why is a Geographic Information System (GIS) useful? Imagine randomly
visiting ~30 locations across the entire NY metropolitan area and then trying to
estimate the total number of cars in the City. Without knowing the number of roads
or parking lots, this would be impossible. In my study, GIS enabled me to map all
of the similar environments (waterways, shallow areas) and identify areas similar to
where I sampled. Using this information, coupled with analyses from the cores,
river morphology and bathymetry offshore, I estimated the sediment being trapped
in the study area vs the total amount coming into the ocean. This work is fundamental to determining how materials from land are dispersed in the sea. My doctoral
work also highlighted the importance of mangroves in storing sediment and carbon,
another topic receiving much attention as nations grapple with too much carbon
dioxide in the atmosphere.
Mapping the Coast with Lasers, Acoustics, and Robots
Today there is a lot of cool technology that we can use to better understand Earth
surface dynamics and history. The most widely used tool for studying the seafloor
is sonar. Developed during World War I and used heavily during World War II, the
technology has come a long way. Now we have sophisticated acoustic systems that
can measure depths over a swath of the seafloor using a fan of sound propagating
below a ship or other device. It is with these systems that we can now “see” the
seafloor and use this invaluable information to measure and determine governing
processes, such as submarine landslides or wave-reworking by storms.
During my time at East Carolina University (ECU), a couple colleagues, Drs.
Reide Corbett and David Mallinson, and I obtained a grant from the National
Science Foundation to obtain state-of-the-art tools for studying the coastal areas.
The problem with mapping the seafloor with fancy, expensive equipment is that one
does not know the depths prior to the first mapping. Often the information on nautical chart is decades old. For testing of our ~$150,000 new seafloor mapping instrument, we went to Washington, North Carolina, where we could use an ECU vessel
as a survey platform. After getting the system set up and going, we were thrilled by
the results and wanted to see more in harbor. We passed under an old bridge and
could see individual pilings and other structures to the side of the vessel, but as we
came out the other side, the depths got shallower … and shallower… and shallower.
The seafloor quickly came within inches of the sensor, and we scrambled to tilt up
the device and slow the boat. Thankfully before any impact, the water began to
deepen. It is terrifying to think that we almost destroyed the costly system on the
first day. But this is ocean science. Conditions are dynamic and often dangers are
unknown.
It was this same multibeam system that we used aboard the R/V Cape Hatteras
to map seafloor change after Hurricane Katrina and civil war wreckage in coastal
North Carolina (Fig. 6.5). More and more vessels have this type of technology integrated with their navigation and other systems. As a result, new data are being
J. P. Walsh