The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B7. Beijing 2008 
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pipeline is routed through a mixed sub-soil, textures ranging 
from other mineral soils with sandy loam in places, sandy soil 
which may have a sandy loam top-soil, and sand. 
Legend 
NGL 20" pipeline 
NGL pipelines 
Roads 
River 
Drains 
Buildings 
f—) Field boundaries 
Field sites 
Figure 1. Map of study area with location of test sites 05B, 05C 
and 06A annotated. 
2.2 Field spectroradiometry acquisition 
Field spectroradiometry data of barley were acquired for two 
field campaigns in 2005 and 2006 at selected transects 
perpendicular to a stretch of buried gas pipeline in 
Aberdeenshire. A spatially intensive field spectroradiometry 
experimental design for acquiring spectra under challenging 
heterogeneous field conditions was developed and implemented. 
The sampling strategy used in 2005 was refined for the 2006 
campaign (see results and discussion section). The experimental 
transect sampling design used in the 2006 field campaign 
consisted of transects extending 70 m either side of the 508 mm 
gas pipeline to encapsulate the full spatial signature of 
vegetation stress features, zones of known soil disturbance, and 
zones with no known soil disturbance (Figure 2). This enabled 
associations between soil properties measured and vegetation 
stress to be investigated. The extent of the transects was also 
determined by the practicalities of field spectroradiometry. Two 
transects were acquired at each test site above the 508 mm 
pipeline, one above an identified stress site and the other at a 
control site with no visible stress (Figure 2). The rigour and 
success of the experimental design is determined by the ability 
of the first derivative ratios evaluated to detect pipeline 
earthworks associated sub-surface soil disturbance from 
resultant surface vegetation stress. 
2.3 Field spectra analysis: derivatives and waveband ratios 
First derivatives were employed in this study to provide a 
sensitive analysis of the subtle spectral absorption and 
reflectance features associated with vegetation stress (Philpot,