Park at the junction of the D135 and the D140 (you can park by the bridge on the D140, but there are only two or three spaces).
(S/E) From the junction, turn left and head downhill along the D140 for about 300 metres. Cross the bridge and, immediately afterwards, take a path on the right. You’ll reach a small meadow; follow the river on your right. At the end of the meadow, look out for a path on the right that leads down to the confluence of the Brette and the Roanne. Descend into the riverbed.
(1) Follow the right-hand branch to head upstream along the Roanne. The river is cut into a steep gorge at the start, but after a few bends, the view opens out as you approach Pradelle (on your right). Continue to the bridge at a place called Le Moulin.
(2) Turn round and walk back down the river in the opposite direction to return to your car (S/E).