A new method, called hybrid modelling was developed, which dynamically couples physical and mathematical models of various regions of an estuary. The method is used to predict possible changes the development for tidal power would have on the Bay of Fundy/Gulf of Naine existing tides. Fundy Tidal Power Canada is a country of abundant natural resources. One such resource, so far unexploited, is tidal energy. Some of the largest tidal ranges in the world are to be found in Ungava Bay, in Northern Quebec, and of course in the Bay of Fundy in the tlaritimes. This potential energy could be converted using almost conventional technology: dams and turbines.In additiorl strong tidal currents exist, for example in the Strait of Georgia between Vancouver Island and the mainland, the kinetic energy of which could be converted using water mill analogous to windmills. As everyone knows, tides are the result of the gravitational attraction of the moon, and to a lesser degree the sun, and the fact that the sun, moon and earth are always moving. This sets the waters of the oceans in motion in tile form of waves of a very long period, more than 12 hours. ' ' ' Fl-i-w+ GULFoFMAlitEl I I NW-GULF M-1 Fiq.2: Nurlerical discretizaticn of tk Say of Fund/ and the Gulf of Maine and extent of the %ysical Yodel.