GeoIS-EM Home         Bogue Island monitoring data processing

Helena Mitasova, NCSU
Chris Freeman, UNC, David Bernstein, CMWS CCU

GIS data processing is performed for the Bogue Island renourishment project:
a) stopped nourishment section May 2002
b) same section in August 2002

a b

Data were imported into GRASS5 and interpolated at various resolutions using s.surf.rst with tension (20,30,90 depending on the density of points which was 15m,7m and 2m), smoothing 0.7 and anisotropy 0.2/10 deg. LIDAR data from 2000 were imported and compared with the current measurements.
Click on the image to get the full size.

Renourished beach 2002: comparison with 2000 LIDAR

a)Elevation in 2000 based on LIDAR b)Elevation in 2000 overlayed with elevation 2002 from RTK-GPS

a b b

Section without new sand

a) LIDAR surface overlayed with 2002 RTK survey - new sand is missing here and the elevation surface is at 2000 level
b,c,d) Crossections comparing the 2000 (LIDAR) and 2002(RTKS) elevation, 10x exagerrated elevation

a b c d

High resolution (2m) comparison of small subarea

a) LIDAR 2000 elevation at 2m resolution
b) LIDAR 2000 (transparency) overlayed with RTK-GPS 2002 surface. Note that RTK data are smoothed out too much - needs re-interpoltation with higher tension and less smoothing
c) RTK-GPS 2002 surface with slope draped as color shown with LIDAR 2000 transparent surface

a b c

Entire 38km beach: 20m resolution analysis

a) Elevation and sampling pattern. Diamonds mark the sections 1 through 12.
b) Slope showing three areas with increased nearshore slope (red: 4-5deg)
c) Profile curvature with 3 paralel convex lines: top of the beach and two sandbars

a b c

Renourished area A: 10m resolution analysis

a) Elevation
b) Slope and 0m contour shown as blue line
c) Slope with overlayed subarea studied at higher resolution in the next section
d) Profile curvature blue line is 0m contour, some "features" are subtle interpolation artifacts

a b c d

Beach at the steeper bathymetry area: 2m resolution analysis

a) Elevation
b) Slope and 0m contour shown as blue line
c) Elevation surface shown as block with color representing slope

a b

Preliminary results for May and August 2002 data

Overlayed elevation surfaces 2000 LIDAR and RTK-GPS May and August 2002, 2m resolution, in the disrupted nourishment area (see photo above)

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In the next images, LIDAR is blue, May 2002 orange and August 2002 green

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This project is supported by Army Research Office and National Research Council

Processed and visualized
by GRASS5