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Experience
in the Field
Terrain
Modeling and Dredging Analysis with ArcGIS
The U.S. Army Corps of Engineers is a worldwide organization
that provides engineering services and construction support
for a wide variety of military and civil projects. Since 1928,
the New England District of the Corps has been responsible
for the operation and maintenance of the Cape Cod Canal in
Massachusetts. The Canal, 17.4 miles long, is designed primarily
to provide safe waterway navigation between Cape Cod Bay and
Buzzards Bay, saving an average of 135 miles of coastwise
travel around the Cape's tip and outer shore. The Canal is
also operated as a federal recreation area available to the
visiting public.
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Benefits
of the Channel Management Process with ArcGIS
1. Application uses data incorporated into GIS
storehouse
2. Analysis results can be stored for historical
reference and future use
3. Data processing is a simple extension of the
existing GIS processes
4. Model and dredging information can be combined
with GIS data sets to perform detailed and complex
analyses
5. Updates to channel management data are easily
processed into the stored models
6. Analysis time is reduced from weeks to a matter
of hours
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The Army Corps of Engineers-Cape Cod Canal (CCC), a field
office of the New England District, has utilized ESRI products
for the last ten years to assist with the maintenance and
operation of the Canal. For better system management and tighter
security, the CCC recently began a migration project from
the existing system to ArcGIS Desktop. Canal personnel sought
to utilize the new functionality of ArcGIS--the Geodatabase
structure, advanced ArcGIS editing tools with multi-user capabilities,
wizard driven menus, and high-quality cartography. On the
foundation of the Geodatabase, they planned to create a GIS
model of the waterway system, developing a process and designing
specific tools that would assist them in the dredging of the
Canal. Based on hydrographic surveys of the Canal bottom,
dredging is periodically necessary to eliminate sand and other
excess material deposited due to the Canal's swift current.
The CCC currently uses manual processes to determine the amount
and location of material to dredge.
To accomplish these tasks, the CCC contracted Sewall to assist
with the Geodatabase design, interface ArcSDE and Oracle configuration,
data migration, and development of custom dredging, volumetric
analysis, and estimation tools. Sewall's shared history with
the CCC and experience with ESRI products as an authorized
ESRI software developer were essential criteria for selection
as a vendor. On previous projects, Sewall has provided the
Canal with digital orthophotography, digitally compiled photogrammetric
and facility data in ESRI Coverage format, and a customized
system using ArcView and ArcInfo.
Custom dredging tools for the Canal were programmed with
ArcObjects, utilizing ESRI extensions Spatial Analyst and
3D Analyst, and ArcScene for viewing capabilities.
PROJECT
DEVELOPMENT
Application Development.
To automate the current manual process of calculating dredge
volumes, Sewall developed two custom tools, Fish Net Filter
for creating Canal bottom contours and Cut Volume for dredging
estimation and analysis. The Fish Net Filter was originally
written for the CCC in 1995 in Avenue. For the updated process
Sewall rewrote it in Visual Basic , using ESRI's ArcObjects.
When utilized, the filter creates an even spaced grid centered
over the selected data set. Then it creates a new data set
with the same fields as the original. The highest point in
each grid cell is copied to the newly resampled data set.
This smaller resampled data set makes some analysis functions
more efficient without degrading the quality of the resulting
information. The CCC uses these results to create Canal bottom
contours. The original depth sound points are spaced about
1 foot apart.
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