remote sensing data are most important. Consider a Landsat image of the 
Mackenzie River Delta and the Beaufort Sea (Figure 9). On this image, by tracing 
the sediments carried by the Mackenzie River, we can follow the currents far out 
into the sea, indicating the potential dispersal patterns of oil slicks. On other 
images we have seen clear boundaries between zones within a water body: this is 
well documented where tidal action is strong. We can now draw the line between 
this image of the Beaufort Sea and the conclusions of Klemas, Davis, Wang, Whelan 
and Tornatore (1975) reached after research in Delaware Bay: an integrated 
system using satellites, aircraft, a drogue and observations on the ground allows the 
FIGURE 9. Portions of Landsat images of the Beaufort Sea showing the estuary 
of the sediment-laden Mackenzie River. Note the differences between 
Band 6, right, and Band 5, left, of this September 1, 1975 scene. 
(Canada Centre for Remote Sensing).