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using the reservoir close to the power plant of Almaraz, which receives cooling effluents from the plant, as a test area. 
ETM+ and TM band 6 imagery were transformed to estimates of ground temperature and then compared. The conversion 
is achieved via a straightforward manipulation of the DN values in band 6 of the TM and ETM sensors using the calibra- 
tion data supplied by the provider. Transformation of band 6 to surface temperature (EOSAT, 1986) was realized accord- 
ing to: 
SR = band6- C1 + C2 (1) 
K2 
T log(K1/SR 4 1) r291s (2) 
where: 
SR Spectral Radiance (milliwatts per square centimetre per steradian per micrometer) 
T Effective at-satellite temperatures in Celsius 
Cl Conversion parameter for DN to radiance conversion 
C2 Conversion parameter for DN to radiance conversion 
Kl1 Calibration constant for offset of detectors in Band 6 of TM and ETM+ sensors 
K2 Calibration constant for gain of detectors in Band 6 of TM and ETM- sensors 
The estimates of surface temperature may be refined to measurements of absolute surface temperature by using meteoro- 
logical data. Atmospheric effects on remotely sensed data can be accounted for by calculating a corrected radiance and 
using the black body inversion formula to determine a correct temperature. Meteorological data had been requested for 
the study area to correct the results obtained but they have not been made available at the time of analysis. The inability 
to calculate absolute surface temperatures determined that the thermal infrared data were compared on the basis of tem- 
perature variation over the course of the three data acquisitions. Thus the variability of reservoir surface temperatures 
adjacent to the industrial facility was compared with that observed within the Embalse de Valdecañas reservoir located to 
the SE of the Almaraz power plant. 
3 RESULTS 
3.1. Qualitative Analysis 
3.1.1 Geology 
Comparison of the individual LANDSAT scenes from the TM and ETM+ sensors and the products of image fusion 
between panchromatic data and multi-spectral data shows that the lithological boundaries within folded sequences of 
Ordovician-Silurian age rocks and those between intrusive rocks and adjacent alluvial deposits are more readily distin- 
guished within the multi-spectral data than within the image fusion products. 
The fused products created via the image fusion of SPOT Panchromatic data and LANDSAT TM data are unsuitable for 
the assessment of textural indicators in areas where significant mis-registration of the data sets occurs. As this mis-regis- 
tration coincides with areas of moderate relief characteristic of the intrusive segment of the stratigraphic column, the 
image fusion product created by the processing of LANDSAT ETM+ panchromatic and multi-spectral data is superior to 
that created from LANDSAT and SPOT data for the purpose of discriminating intrusive rocks. Furthermore the incorpo- 
ration of the panchromatic data and the multi-spectral data results in a reduction of the geo-botanical association of 
lithologies within the sedimentary sequence. 
The LANDSAT ETM+ and SPOT panchromatic data contained evidence of linear features that might be interpreted as 
fault lines within the major sedimentary sequences. This identification was enhanced by use of the multi-spectral data 
due to the previously mentioned geo-botanical associations. Within the recent alluvial units the correspondence between 
fault identification in the geological maps and the imagery was zero. This is partly because many of the faults occur in 
areas of agricultural development and partly due to the pixel size of the imagery. Traditionally field mapping in areas 
adjacent to river courses identifies fault lines by small displacements within the sequence of alluvial terraces adjacent to 
the rivers. Evidently in the case of the rivers studied here these features are too small to be identified within the imagery. 
  
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B7. Amsterdam 2000. 935