Spectral Characteristics of some Saline Playa Surfaces and their Application toMultispectral Imagery Analysis

摘要

Playas, commonly formed in arid basins, can have surface conditions ranging fromhard and dry to soft and moist. These surfaces result from the relation between the hydrologic environment and the mineralogy of the surrounding basin. Surfaces composed of soluble salts deposited by capillary action from saline ground water can be found on playas in structurally closed basins. To determine methods of discriminating different saline mineral deposits using multispectral imagery, spectral reflectance data (400 to 2500 nm range) of selected saline playas in the Mojave Desert were collected using a portable spectroradiometer. Reflectance data included field spectra of salt crusts and laboratory spectra of pure compounds and salt mixtures. Results show that while certain common soluable materials such as potassium chloride and sodium chloride are spectrally featureless in the Landsat Thematic Mapper (TM) visible and near infrared bands, others such as calcium sulfate and calcium chloride have absorptions in TM bands 5 and 7 which allow their discrimination from other salts. Knowledge of the spectral characteristics of these materials allows selection of band combinations and ratios which maximize discrimination of different surfaces using TM multispectral imagery.