By: Dim Siawns

The Severn bore is actually somewhat endangered; the proposed barrage which would generate (roughly) an absolute shitload of power would put an end to it, which some conservationists are sub-thrilled about. The Government announced late last year that the barrage would receive no public funding, but the word on the street is that it might still go ahead if private investors are willing to stump up. Bores are really quite cool, actually, they basically crop up when a river is roughly aligned with the direction of a tidal flow. Tidal waves (by which I mean waves generated by tidal variation, not really big waves) can be standing or moving, and with moving waves you have a peak and a trough. If you care to work through the shallow water wave equations (do not do this, it's really boring), you'll see that shallow water flows slower than deep water, so with a sufficiently long distance to go - up a river, for instance - eventually the peak catches up with the trough and we get a tidal bore.