TM4 channel of the Landsat scene

The TM4 channel is the one that gives the better contrast between water and active photosynthetic vegetation.

Nevertheless, on this image, we can see that pines in the shadow (near the fold, S1 spectrum) have the same intensity than the river (in the lower left corner, spectrum S2).

This means that it is very difficult to distinguish between water and pines in the shadow.