Climate-dependent iron-bearing morphological units around lake marshes (Tablas de Daimiel, Spain) using hyperspectral DAIS 7915 and ROSIS spectrometer data

Emerged areas around open-system lakes developing marshes are sensitive environments to climate changes. Under a semi-arid climate the sediments oxidize and dehydrate developing red colours due to iron bearing minerals. Mineral climate-dependent mixtures are spatially traced using hyperspectral imagery. Iron oxide mixtures have been mapped along differentially dehydrated units in the past 2000 years using DAIS spectrometer data. Spectral behaviour interactions and masking from iron and carbonate mixtures suffering desiccation on the sands are described on the imagery and laboratory spectra. Four morphological sandy units can be distinguished, located at different height from the lake coast-line. These units are related to terraces, eolian deposits and desiccated areas, and appear as both continuous and remnant sparse encased surfaces showing different stages of landscape development. Mineralogical variations on iron oxides and hydroxides developed when sediments are exposed to the atmosphere are easily recorded in the visible and thermal infrared wavelength range in the imagery. Quantitative evaluation of soil colour and related mineralogy is attempted.