Water and soil variability of internal peninsular wetlands from Landsat images (TM and ETM)

Some wetlands from the central part of Spain have been here studied. There are big differences between field work and images taken by some sensors of environmental satellites. Usually, on summer, when these ponds dry up, the seasonal wetlands exhibit a whitish surface due to salt precipitation, contrasting with the bluish colour displayed in images. It has been suggested that this apparent paradox results from the fact that sensor records data from an three-dimensional earth and not only from a simple surface. Therefore, in Mediterranean semiarid region satellite images can be used to discriminate wetlands fed by groundwater from other ones having a non sub-surface water contribution.