standing wave

Whitewater rapids break a river’s smooth flow into descent and chaos, then restore a civilized flow line again. Waves express the energy of motion through each stage of this passage. From silken tongue to runout, you can follow this sequence through a rapid: lateral, or diagonal waves, when the river constricts and its energy is poised between slow and swift flow; a roiling, erratic turbulence in the rapid’s frothing heart; then stationary, standing waves formed as the river’s current slows over deep water. A rollercoaster series of standing waves is known as a wave train. Elongated standing waves, with spray peeling off their crests, are called rooster-tails. Large, symmetrical standing waves are haystacks. In big water their slopes can rise steeply enough to block out the downriver view and your boat will slide right off their face.

Ellen Meloy