Remote sensing of grassland with contaminated soil using the spectral red-edge

In most cases contaminants are concealed in soil and under vegetation and therefore can<br/>not be measured directly by remote sensing. However, soil contaminants were detected<br/>using the spectral red-edge to indicate vegetation stress caused by the presence of<br/>the contaminants. An improved red-edge position (REP) was developed and gave a<br/>slight improvement in the predictive capability over existing indices and an effective<br/>additional diagnostic indicator of soil contamination was found to be the spatial pattern<br/>of the REP. Where an area had high levels of hydrocarbon in the soil it also had a<br/>high level of variation. The indication was that spatial variation of spectral indices<br/>(especially the REP) may be more useful than the spectral index value for the detection<br/>and mapping of soil contamination.<br/><br/>Field analysis and radiative transfer modelling (using a coupled leaf and canopy model,<br/>LIBSAIL) showed the influence of vertical layering in the grassland canopy. The influence<br/>of a vegetated under-storey on the red-edge was found to be greatest when<br/>different absorption spectra were present and high within-the-leaf scattering. The former<br/>defined wavelength positions of features while the later determined if they were<br/>resolvable in a spectrum. This greater understanding of the grassland canopy identified<br/>the importance of fully surveying vegetation canopy structure, especially in complex,<br/>multi-layered canopies such as those found with contamination. With this understanding<br/>of what the red-edge can reveal, remote sensing is an effective tool for the detection<br/>of contamination.

Name dc:type.qualificationname

Ph.D.

Level dc:type.qualificationlevel

doctoral

Grantor dc:publisher.institution

University of Southampton

Year dc:date.issued

2009

Author dc:creator

• Llewellyn, Gary Michael

Advisors dc:contributor.advisor

• Curran, Paul
• Milton, Edward J.