near-real time and time-critical scour monitoring at the irib
DESCRIPTION
Near-Real Time and Time-Critical Scour Monitoring at the IRIB. Objectives: Investigate hydrodynamic tidal forcing in the inlet that plays a role in scour hole development Monitor orientation of the bridge piers Monitor riprap and scour hole edge in near-real time - PowerPoint PPT PresentationTRANSCRIPT
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Near-Real Time and Time-Critical Scour Monitoring at the IRIB
Objectives:
1) Investigate hydrodynamic tidal forcing in the inlet that plays a role in scour hole development
2) Monitor orientation of the bridge piers3) Monitor riprap and scour hole edge in near-real time4) Collect higher temporal resolution bathymetry
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1994 1996
19992004
IRIB SCOUR PROBLEM
Images courtesy of Jeff Gebert, USACE
Over the last 12 years, scour hole depths and spatial extent have increased dramatically
Will scour holes begin to undermine protective riprap and interfere with pier stability?
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IRIB PIER ORIENTATION MONITORING
Use a dual axis tilt sensor to monitor long-term pier orientation
Most appropriate pier due to potential for scour hole interference
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IRIB PIER ORIENTATION MONITORING
Cabling
•One 8-conductor cable spans two piers
•This cable transmits data and powers sensor
•Limits electrical access needs to land
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Powering and data collection
Waterproof Enclosure Power unit
Dataq DI-710 stand alone logger
D-Link Pocket Router
Omega Power Converter (sends power to sensor)
•Box secured to top of land-based concrete pier
•Logger and router plug into box power unit
•Sensor receives power from converter
•Will need power access from land only!
Router connects to ethernet port on logger so data can be downloaded without opening box
IRIB PIER ORIENTATION MONITORING
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IRIB TIDAL CURRENT MONITORING
Use boat mounted acoustic Doppler Current Profiler to collect data over a tidal cycle.
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TIMELINE
January, 2006
Install tilt sensor on bridge pier
Spring, 2007 Collect ADCP current meter data over a tidal cycle
Summer, 2007
Analyze tilt and current meter data to investigate variability
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Spring, 2007
Install rotary sonar and ADCP to monitor stability of pier riprap armoring, inlet bottom, scour hole edge and to measure tidal currents
Spring, 2007
Begin high temporal resolution bathymetry collection using GPS and echo-sounder equipped wave runner
Summer, 2007
Initiate physical model study of scour hole development using current meter data for scaling
DETAILED MONITORING EFFORTS PENDING FUNDING
Do we want to include physical model study? Might be difficult for a student to complete in allotted time? However, would be a nice complement to study
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WHY CONDUCT A THOROUGH INVESTIGATION?
Can answer questions such as:
1) What is the spatial and temporal variability of the scour hole?
2) What is the spatial and temporal variability of the riprap protecting the pier?
3) How are variations in riprap armament and scour hole morphology related to tidal forcing conditions?
4) How does the scour hole respond to storm events?
5) Is the rate of scour hole development increasing or decreasing?
To answer these important questions, it is necessary to collect the response AND the forcing conditions simultaneously.
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3D PROFILING SONAR
Advantage: System does not need to be engineered in-house. Can be cabled to logger for near-real time internet access.
3D XYZ elevation data
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Bridge mounting: Top view
Pier
East pier of North pier pair
3D PROFILING SONAR
Scanned area below sensor
sensor
Pier
Routinely image (X,Y,Z coordinates) the area directly below and adjacent to the pier
~120 ft
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3D PROFILING SONAR LAYOUT
pier
Electronics Package
PierOnland
Edge of inlet
Comms cable attached to bridge deck
PC, logger
Network connected PC at Coast Guard Station
sensor
Power
Wireless connection
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TIDAL CURRENT MEASUREMENT
Tidal currents must play a role in scour hole evolution and migration
Use Acoustic Doppler Current Profiler (ADCP) to obtain the time dependent tidal flow.
Communications layout is the same as the sonar
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TIDAL CURRENT PROFILING
Show some example image of tidal or wave ADCP data if we can get it.
pierpier
Edge of inlet
Edge of inlet Measure current velocity
Pretty lame schematic and probably not needed
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SCOUR HOLE AND RIPRAP BATHYMETRIC MAPPING
Arm
y C
orps
, 20
04
• Army corps data collected roughly every 2-3 years• Shows that the scour holes have deepened and migrated, particularly seaward holes• No indication as to the high frequency evolution of holes (tidal, storm, seasonal)• Requires more frequent and targeted monitoring
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BATHYMETRIC MAPPING USING A WAVERUNNER
Will survey roughly monthly, but also some targeted surveying pre- and post-storm and surrounding a tidal cycle
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BATHYMETRIC MAPPING USING A WAVERUNNER
•Example wave runner bathymetric data from the surf zone.
•Lack of waves in the inlet may simplify data collection
•Will be able to quantify scour hole variability
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ITEM YEAR1 (Cost in $k)
YEAR2(Cost in $k)
3D Profiling Sonar 60 0
Computers (1 for student, 1 for data acquisition, 1 for received telemetry)
10 0
ADCP (including cables) (can we collect via other computer (how long of a cable can we use?)
35 0
Wave runner with GPS 65 0
Miscellaneous (cables, mounts, power wireless connection, NEMA enclosures)
10 2
Life vests, wet suits, wave runner upkeep 1 1
COSTS
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ITEM YEAR1 (Cost in $k)
YEAR2 (Cost in $k)
Student Salary (could be less depending on start date, since Jesse presently funded)
20 20
PI Salary (Puleo; 1.5 mo, 1.5mo, Macmahan; 1.5mo, 1.5mo, Righman?)
30 30
Tech Salary 5
Travel 2.5 2.5
Fringe 12 10
Overhead 42.5 35
Total 293 100.5
COSTS Continued
This is HUGE, but necessary to get work done. They may decide they are only interested in certain aspects or not at all
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BUDGET DESCRIPTION
•Large initial investment in the first year to acquire instrumentation
•Expenses in year 2 are significantly reduced and cover the salary for PI’s and the student to continue the monitoring effort and data analysis.
•In situ equipment has a lifespan of at least 5 years and can be extended if cleaned and serviced regularly
•Waverunner lifespan is roughly 10 years with adequate upkeep
•Lifespan of instruments means they can be in service until the new IRIB is completed. Monitoring can continue after old bridge is removed
•Monitoring can be modified to occur at other locations of interest to DelDot (e.g. C&D Canal Bridge) as necessary.