the reaction of a system to a given action on that system, typically in accordance with Newton=s 3rd Law of Motion. In process modeling, the response is the system=s reaction to the forcing functions that act on the system through boundary conditions.


the gradual retreat of the sea from the land, usu during sea level lowering associated with glacial epochs.

rill erosion

the removal of soil from the land surface in small channels (rills). It is the second stage in water erosion, following sheet erosion and preceding gullying.

rip channel

channel cut by the seaward flow of rip currents, usu across a longshore bar.

rip current

relatively narrow currents that flow seaward through the breaker zone. They are the seaward return flow from longshore currents.

rip feeder channel

seaward curving channel in the surf zone where the longshore current curves seaward to form a rip current.

rip head

the seaward extent of a rip current, usu about one surf zone width beyond the breakpoint of the waves.


pertaining to or formed by a river, or situated along the banks of a river; eg a riverine harbor.


an aggregate of one or more minerals as in granite, shale, marble, etc; any rocky mass lying at or near the surface; any prominent peak, cliff or promontory, usu bare.


the landward migration of the beach-dune ridge system due to overwash and dune migration.


general term for movement of water and associated dissolved/suspended load across the relatively flat surfaces of land, usu before the flow becomes channelized. Syn: overland flow.


the maximum vertical height attained by the uprush of the swash on a beach or structure, usu taken as the height above still water level (SWL).

runup level

the vertical height of the runup above some established datum such as mean sea level (MSL).