Fluvial Geomorphology

River channel morphology and pattern must adjust to major flood events on tropical Pacific islands, generated by extreme rainfall during tropical cyclones. Alluvial rivers often exhibit large changes in their channels, especially in terms of geometry and position, because they are sensitive to the erosive power of huge river discharges during cyclones. Riverbanks are undercut and collapse (Fig. 10.1), meander bends are cut off and abandoned and riverbeds scour and fill. Yet considering the importance of cycloneinduced floods and related river channel instability for human occupancy and activities on floodplains, it is a pity that little quantitative information exists on the nature and rates of river channel change in the South Pacific.