ERDC/CHL CETN-IV-28
September 2000
Introduction to the Diagnostic
Modeling System (DMS)
by Nicholas C. Kraus
PURPOSE: The Coastal Engineering Technical Note (CETN) described herein introduces the
methodology and technical products associated with the Diagnostic Modeling System (DMS)
that is being developed to assist U.S. Army Corps of Engineers (USACE) Divisions and Districts
in reducing the frequency and cost of dredging.
BACKGROUND: As described in CETN IV-22 (Rosati and Kraus 2000), "Shoal-Reduction
Strategies for Entrance Channels," from fiscal year (FY) 1995 through 1998 the Corps dredged
an average of 198 million m3/year from Federal channels. Maintenance dredging accounted for
an average of 89 percent of this volume, with new work and emergency dredging comprising the
remainder. A reduction in maintenance and emergency dredging represents a significant cost-
and timesaving measure for the operation and maintenance (O&M) of Corps waterways. Such
savings can be cumulative over the life of a project and can be reprogrammed to other O&M
projects.
CETN IV-17 (Pope 1997) classifies shoaling of inlet channels through consideration of
geomorphologic characteristics. CETN IV-22 discusses managerial actions that can be taken to
reduce deposition in channels and the associated dredging costs and quantities. These include
the following:
a. Be alert to existing and past shoaling patterns, coastal processes at the site, and ongoing
projects. This must occur on both local and regional scales.
b. Plan ahead for anticipated increases in dredging, rather than reacting to an emergency
situation.
c. Plan to allow modification of designs.
d. Evaluate the success or failure of each implementation so that knowledge is gained
through the process. Document and share findings.
e. Revise designs based on improved knowledge.
The present CETN describes an emerging system and selected products under development to
support engineering actions that may be taken to reduce the frequency and cost of dredging. The
DMS is intended to provide a rapid, yet reliable capability for identifying and evaluating
navigation channel operations and maintenance (O&M) alternatives based on limited information
about the hydrodynamic and sediment-transport conditions at a site. The DMS gives a diagnosis
of a problem shoaling area (in contrast to conducting expensive and time-consuming studies),
together with guidance for determining possible solutions. The DMS can also contain dredging
and associated records to document shoaling patterns and measures taken.
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