By Sarah de Sainte Croix, Contributing Reporter
RIO DE JANEIRO - For most of us in the Southern hemisphere the autumnal equinox on March 20th signifies little more than the gentle shifting of seasons. For the residents of the Amazon basin however, it announces the arrival of a much more ominous threat - the indomitable pororoca or ‘mighty roar’.
The pororoca is a massive wave (or ‘tidal bore’) that happens when the force of the tide overpowers the force of the water discharging at the mouth of a river. A huge swell forms which advances up-stream from the mouth of the . . .