Geoscience Reference
In-Depth Information
Surface
7 m
2.8 km
fIGURe 26.3
Raw ground-penetrating radar (GPR) data of a single spiral track unscrolled (2.5 km long by
8 m deep). Arrow at right margin points to a water perching horizon 2 m beneath surface of which Figure 26.7
and Figure 26.8 are top-down views.
50 m
40
30
20
Water
applied
within ring
10
0
-50 m
-40
-30
-20
-10
0
10
20
30
40
50 m
-10
-20
-30
-40
-50 m
fIGURe 26.4
Course guidance layout design showing flag placement, top-down view.
Odhiambo et al. (2004) and to spatially map these similarity identifiers by corresponding geospatial
position.
Figure 26.4 illustrates the survey layout of one such spiral plot, central to which a double-ring
infiltrometer is installed. The operator of the mobile GPR platform follows an outwardly spiraling
traverse from the infiltrometer as guided by survey flags and tracked in real time by differential
GPS (DGPS) (Figure 26.5). Tests are conducted during seasonal extended dry soil conditions such
that baseline “dry” condition radar imagery can be registered. After which, water application to the
infiltrometer begins at controlled application rates (Figure 26.6). The traverse taken by the mobile
platform about the spiral is continuously traveled until a saturated equilibrium state within the sub-
surface is detected (Figure 26.7).
26.2.2 d
a t a
P
R o c e s s i n g
Field data sets are stored in two linkable files: one a traditional GPR-format binary matrix of dig-
itized waveform scans (scans x samples), and a second GPS data file containing 1 sec interval
