When and where rivers meet the sea

River mouth areas provide one of the most desired locations for human habit ation. Although occupying only a small portion of the total length of the w orld's shoreline, river mouths are dynamic and complex with highly variable physical and chemical characteristics.. The size, shape, and position of a river's mouth are dependent on its geolo gic and hydrologic history. Further, the processes that operate in a river' s mouth are affected by the sea and its currents, tides, and salinity; the river and its discharge and sediment characteristics; and wind generated wa ves and storm surges. Present-day locations are, geologically speaking, of recent origin because of the rise in sea level that accompanied deglaciatio n and the sedimentation that followed drowning.