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MID-TERM CONFERENCE CREST
23 November 2017
Innovation in Coastal Monitoring
Alain De Wulf (Ugent, Geography Dept.)
Innovation in coastal monitoring
Outline
23/11/2017
• Why ?
• How ?
• What (tools do we use to assess) ?
• Conclusion
Innovation in coastal monitoring
Outline
23/11/2017
• Why ?
• How ?
• What (tools do we use to assess) ?
• Conclusion
Why monitor the coast ?
23/11/2017
Sand particles move !
• Dry transport (wind)
• Wet transport (tides, currents, waves)
Why monitor the sand particles
on the coast ?
23/11/2017
• Coastal Safety (flooding)
• Tourism (spatious sand beaches)
• Habitat preservation
Therefore the erosion/accretion balance must
be monitored and understood.
Classical assumption:
• Erosion during storm events
• Accretion in standard weather situations
23/11/2017
If erosion/accretion volumes are not in balance => beach
nourishment = reclamation of the beach areas (quite expensive)
Why monitor the sand particles on the coast
Innovation in coastal monitoring
Outline
23/11/2017
• Why ?
• How ?
• What (tools do we use to assess) ?
• Conclusion
How ? 1. By measuring the geometric changes
Comparison of different techniques
• Aerial
• Lidar
• Drone survey
• Terrestrial
• Static GNSS
• Kinematic GNSS
• Static Lidar
• Kinematic Lidar
• Hydrographic
• Single beam echosounder
• Multi beam echosounder
23/11/2017
23/11/2017
How: 2. By measuring the sand transport “in the dry” (Aeolian campaigns)
• By measuring the
spatial and temporal
variability of
sediment transport
on the beach with
acoustic sensors and
sand traps and sand
catchers
• By measuring
surficial moisture
content changes
• By measuring the wind conditions: wind speed and wind
direction at different heights above the surface with
meteorological stations
How ? 2. By measuring the sand transport “in the dry” (Aeolian campaigns)
How ? 2. By measuring the sand transport “in the dry” (Aeolian campaigns)
How ? 3. By measuring the sand
transport “in the wet”
• Near shore wave and
current conditions
(e.g. with ADCP,…)
• Sediment
concentration,…
23/11/2017
Innovation in coastal monitoring
Outline
23/11/2017
• Why ?
• How ?
• What?
• Conclusion
Innovation in coastal monitoring
Outline
23/11/2017
• Why ?
• How ?
• What is the innovation in monitoring techniques ?
• Conclusion
Innovation in coastal monitoring
What is the innovation in geometric
monitoring techniques ?
23/11/2017
• Speed of acquisition- Terrestrial Lidar: 0.25 till 1 million points/s (<> 20 p/s).
• Quantity of acquisition (point density)- 1 cross-section per 5 cm (<> 50 m). - interval distance in the cross-section: 1-5 cm (<> 5m).
• Quality of acquisition- Accuracy on sub cm level in x,y,z (<> 1 dm).
Innovation in coastal monitoring
What is the innovation in geometric
monitoring techniques ?
23/11/2017
Speed, density, quality =>
• Detailed 3D model instead of small set 2D profiles
• 4D (1 model per hour) with static long-range terrestrial laser scanner
=> Small (sub cm) changes and very short time ( 1 hour) changes can now be monitored.
Innovation in coastal monitoring
What is the innovation in monitoring
techniques ?
23/11/2017
• Dry aeolian transport: detection of sand particle movement with automated electronic devices.
• Wet transport: • automated density and current sensors.• multi beam in intertidal zone (even in extremely
shallow water < 1 m).
Innovation in coastal monitoring
Outline
23/11/2017
• Why ?
• How ?
• What tools do we use to evaluate the topographic / morphologic changes ?
• Conclusion
Software development of high precision analysis tool
• High precision digital terrain modelling tool (PC: maximum up to 8 billion grid cells with 32 Gb RAM).
• Allows:
• Sub-cm grid intervals (e.g. 300 m by 160 m grid of 1 cm cells => ca. 0.5 billion cells)
• Visualisation
• Filtering (outlier removal)
• Correlation computation
CREST meeting – January 20, 2016
How: tools to evaluate the topographic / morphologic changes
Depth Analysis
CREST meeting – January 20, 2016
How: tools to evaluate the topographic / morphologic changes
Slope Analysis
SeArch meeting – January 14, 2016
• Maximal Slope (%)
How: tools to evaluate the topographic / morphologic changes
Slope Analysis
SeArch meeting – January 14, 2016
• Maximal Slope (%)• Direction of maximal slope
How: tools to evaluate the topographic / morphologic changes
Slope Analysis
SeArch meeting – January 14, 2016
• Maximal Slope (%)• Direction of maximal slope• Slope in specified direction
How: tools to evaluate the topographic / morphologic changes
SeArch meeting – January 14, 2016
• Maximal Slope (%)• Direction of maximal slope• Slope in specified direction• Slope curvature (second derivative model)
Slope Analysis
How: tools to evaluate the topographic / morphologic changes
SeArch meeting – January 14, 2016
• Intensity values of the backscatter
Intensity Analysis
How: tools to evaluate the topographic / morphologic changes
SeArch meeting – January 14, 2016
• Maximum slope of intensity values
Intensity Analysis
How: tools to evaluate the topographic / morphologic changes
SeArch meeting – January 14, 2016
• Maximum slope of intensity values• Direction of maximum intensity slope
Intensity Analysis
How: tools to evaluate the topographic / morphologic changes
SeArch meeting – January 14, 2016
• Intensity of the backscatter signal• Direction of maximum intensity slope• Slope in specified direction
Backscatter intensity Analysis
How: tools to evaluate the topographic / morphologic changes
SeArch meeting – January 14, 2016
• Intensity of the backscatter signal• Direction of maximum intensity slope• Slope in specified direction• Slope curvature (second derivative model)
Backscatter intensity Analysis
How: tools to evaluate the topographic / morphologic changes
CREST meeting – January 20, 2016
• Without noise elimination and intensity correction => almost no correlation
• Geometric model can be improved by optimal noise filtering
• Backscatter model can be improved by corrections for distance, angle (and humidity ?)
• In the near future significant higher correlation can be expected between the improved geometry and the improved backscatter model
Correlation analysis height <> backscatter
How: tools to evaluate the topographic / morphologic changes
SeArch meeting – January 14, 2016
• Local Relief (absolute difference value)• Standard Deviation (n*SD)• Boxplot (1.5 * (Q3-Q1))
Noise removal: outlier elimination
Can be applied to:
Geometric model• Depths• Slopes• Curvature
Backscatter model• Intensity• Slopes• Curvature
How: tools to evaluate the topographic / morphologic changes
SeArch meeting – January 14, 2016
• Local Relief (absolute difference value)• Standard Deviation (n*SD)• Boxplot (1.5 * (Q3-Q1))
Noise removal: outlier elimination
How: tools to evaluate the topographic / morphologic changes
Innovation in coastal monitoring
Outline
23/11/2017
• Why ?
• How ?
• What (tools do we use to assess) ?
• Conclusion
Innovation in coastal monitoring
Conclusion
23/11/2017
• Safety, tourism and habitat protection requires accurate and frequent beach monitoring.
• Nowadays significantly more fast and accurate technologies are available as well for geometry modelling of the beaches as for dry (aeolian) and wet transport of sand particles.
• A combination of these techniques combined with simultaneous measurements allows a new and deeper insight in the mechanisms of sand transport and will connect the “small scale” observations with the “big scale” observations.
In samenwerking met
23/11/2017
Met dank aan
Monitoring wind-blown sandGlenn Strypsteen
Mid-term Conference CREST, 23/11/2017Conference Room Planet Ocean
Study area
Measurement positions
A variety of instruments are used
Sand traps capture the wind-blown sand at different heights
Saltiphones record grain impacts every second
A horizontal sand trap captures sand in downwind direction
Laser scanner measures the topography from a fixed position (TU Delft)
Or on a mobile all-terrain vehicle (Ughent)
Meteorological stations measure the wind conditions and
temperature
A typical campaign
A typical campaign
Thank you!
Glenn StrypsteenKU Leuven
Campus BrugesFaculty of Engineering
Technologyglenn.strypsteen@kuleuven.be
MID-TERM CONFERENCE CREST
23 November 2017
Beach topography: measuring techniques
14/05/2018
• 2D
• Profiles
• RTK-GNSS
Topography: traditional survey
14/05/2018
• 2D
• Profiles
• RTK-GNSS
Topography: traditional survey
3D survey
• Platform: mobile
4x4 with
• Laserscanner
• RTK-GNSS
• Motion sensor
14/05/2018
• MTLS (Lidar): Own system:
3D survey
3D survey
• Acquisition similar
to multibeam set-
up
• Boresight offsets
• Calibration
14/05/2018
3D survey
• Acquisition on site
• Survey lines
• Approx. 2-3 hours
14/05/2018
3D survey
• Challenges
14/05/2018
3D survey
14/05/2018
Result: after cleaning
Comparing techniques
• Drone survey
• Long distance
laser
• Lidar
14/05/2018
Comparing techniques
• Drone survey
• Long distance
laser
• Lidar
14/05/2018
Comparing techniques
• Drone survey
• Long distance
laser
• Lidar
14/05/2018
In samenwerking met
14/05/2018
Met dank aan
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