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spectral aspects. Karst and mass movement phenomena are usually best 
recognized on their morphology, so MSS imagery is not usefull for their 
detection (23). Macro-tectonic lineaments may sometimes show up on 
Landsat imagery, even when unknown from the field or invisible on 
aerial photography of a large scale. 
5.3 Use of MSS during the various stages of an engineering project 
For the preliminary investigation phase of engineering projects MSS 
  
Landsat images may be used in areas, where aerial photography is not 
available for projects of extremely large dimensions, such as the planning 
of long roads (24), selection of harbour sites. Especially when a high 
temporal resolution is needed for the monitoring of water (flooding), or 
snow (melt water abundance) or ice (coastal areas), Landsat imagery may 
provide good information. Large scale lineaments on Landsat imagery can 
be related to fault patterns, which may be accompanied by seismic events. 
As these events can endanger sensitive structures such as dams or 
nuclear power plants a carefull comparison of these patterns with the 
available seismic epicenterdata should be made. 
For the subsequent phases of reconnaissance, main investigation, 
  
construction as well as operation of engineering projects the scale of 
Landsat imagery is inadequate, with a possible exception for the 
estimation of the amount of water for à hydro-electrical power scheme or for 
a flood control project. The high cost of MSS imagery from an aeroplane 
and the limited information to be expected (compared with stereo aerial 
photography in black and white or colour) rules out this technique for 
reconnaissance or more detailed investigation phases. 
6. Radar 
6.1 Introduction 
Side looking airborne radar (SLAR) and synthetic aperture airborne radar 
(SAAR) are "active" remote sensing techniques. Radio pulses are emitted 
from an aeroplane and the return signals are recorded with an antenna. 
The range in the electromagnetic spectrum, which can be used is from 8 mm 
to several meters, but usually 0.8 — 15 cm is applied. 
The technique can be used night and day and using longer wavelengths, as 
in SAAR, even heavy rainshowers can be penetrated, which makes the 
application of this technique independent from meteorological conditions. 
The intensity of the return signal is translated to greytones and after