The evolution time scale of macro-tidal estuaries: Examples from the Pacific Rim

The evolution of shallow, macro-tidal estuaries is a process that has been taking place since the last glaciation. It is site-specific and dependent on tides, wave climate and relative fluvial dominance. It is suggested that, because of the increased efficiency of the tidal pumping effect with decreasing water depth, these estuaries are geomorphologically unstable and may evolve much faster in the future than in the past as a result of human disturbances in the catchment, principally the damming of rivers and increasing erosion from poor land-use practices. These estuaries may become further destabilised by a sea level rise.