MERGING REMOTE-SENSING IMAGES FOR GEOLOGICAL-ENVIRONMENTAL MAPPING - APPLICATION TO THE CABO-DE-GATA-NIJAR NATURAL PARK, SPAIN

The Cabo de Gata Nijar Natural Park in Spain presents certain unique c haracteristics which make it of great geological, ecological and envir onmental interest. As a prior step to the environmental study of the p ark and the impact produced by the mining activities carried out up un til ten years ago, the mining and waste-tip areas were defined and a l ithological discrimination carried out. For this purpose, various remo te-sensing techniques were employed to create high-resolution image do cuments on which the geological and environmental mapping of the area would be based, with special attention being paid to the areas of form er mining activity because of its implications for the environment. Th e merging of remote-sensing es with different spatial/spectral resolut ions has become a highly useful tool, due to their increasing availabi lity. Such is the case of the SPOT panchromatic and Landsat Thematic M apper multispectral images, which are two of the most commonly used im ages in geological and environmental es based on remote sensing. Of th e numerous techniques described for merging remote sensing image data, this paper analyses those based on Intensity-Hue-Saturation, Principa l Component Analysis-Spherical Coordinates, High-Pass Filters and ur N ormalized transform, using SPOT palingenetic and Landsat TM data. The research goals (1) to analyse and compare some of the most commonly us ed methods; (2) to select the most appropriate method for a detailed g eological-environmental study, and (3) to apply the methodology to Cab o de Gata-Nijar area, the site of one of the distinctive natural parks in the country.