353 
Plot y along the X axis, ^3 along the Y axis. The intersection of the horizontal 
and vertical will give us point P. Following the curved line through P towards 
the left will give us the true slope along the Y axis. In this way dip slope measure 
ments can be made. 
DRAINAGE ANALYSIS FROM MONOSCOPIC AND STEREOSCOPIC RADAR 
INTERPRETATION 
Drainage analysis for basemap construction can be carried out from single strip 
imagery or from overlapping strips making use of the stereo effect. McCOY (1969) 
has compared drainage systems as interpreted from Ka band single strip radar 
images with that obtained from 1 : 24, 000 topographic maps, in a number of 
drainage basins in the USA. In general he found a relationship between the drainage 
pattern derived from radar with that from the topographic maps, although this 
relationship varied from system to system. Fewer details were obtained from the 
Ka band radar, the difference being less than 1 order streams (classification ac 
cording to STRAHLER). 
Fig. 11 
Second and higher order drainage channels 
in Baudo area, Colombia 
KOOPMANS (1973) has compared drainage patterns derived from (1) monoscopic 
radar, (2) stereoscopic radar, (3) stereoscopic aerial photography, and (4) 
topographic maps in an area near Baudo, Choco, Colombia. In the low relief