Hyperspectral remote sensing of peat humification

The ability to estimate the spatial variability in the degree of humification in exposed and eroding peats is important for carbon budget studies as well as having implications for water quality and drinking water supplies. This paper examines the potential of using hyperspectral remotely sensed data to estimate peat humification in exposed peats in the southern Pennines, UK. Hyperspectral HyMap images were acquired as art of the BNSC/NERC SAR and Hyperspectral Airborne Campaign (SHAC). Spectra were extracted for selected sample sites where ground-based spectra had been acquired with a spectro-radiometer and peat samples had been collected. The peat samples were analysed in the laboratory to determine their physico-chemical properties, including moisture content, organic content and the degree of humification. A number of candidate indices were investigated by testing the strength of correlation between the remotely sensed data and humification. The effect of water content was also investigated by comparing the results from in situ wet peat and samples that had been dried and measured using a spectro-radiometer with a contact probe. The index most strongly correlated with humification across a range of moisture content was the normalised gradient of the NIR plateau, especially the normalised slope of the shoulders of the absorption feature at 1200 nm. The results suggest that such indices could be used to estimate the spatial variability of peat humification, although further work is required to test the spatial and temporal stationarity of the results and further understand the relationships between peat properties and reflectance, especially for burned peat.