Deltaic responses to changes in river regimes

Deltas form at the mouths of rivers, where sediments are supplied to the marine system at a rate faster than coastal currents are able to remove them. Within the time frame of the last 6000 years, with relatively stable sea level, the relationship between the river, the longshore drift and the receiving basin, permitted variations in the rate of growth of the landform. The principal features and known histories of sedimentation, together with its controls in a selection of 10 of the best-known deltas of the world, are outlined. The changes are related, as far as possible, to known developments in land use, of river conditions, or other controls (as appropriate). These observations apply principally to sediment transport, but the variability of the freshwater discharge also has significant impact on the receiving waters; this leads to habitat modification during times of channel abandonment, as new depositional lobes are created.