Surfrider Foundation A-Z: The Letter 'C'

The Letter 'R':

"Red Tide" and Harmful Algal Blooms article
Riffle: Stream habitat having a broken or choppy surface (white water), moderate or swift current and low depth. The comparable feature in a river would be called Rapids.
Rill: Small channels formed by water running over the surface of the ground. Water collecting in these small channels may then concentrate and join to form larger channels as they move down slope, which in turn meet to form still larger channels. The smallest channels, rills, meet to form creeks, runs or streams; then these features meet and grow until, at some undefined size, they are termed rivers.
Riparian: Of or pertaining to the banks of a natural watercourse. This term is most of ten used to describe the transition zone between aquatic habitats in streams and upland areas. The particular habitat that is supported in this zone is extremely valuable as wild life nesting, forage, cover and migration corridors , provides favorable conditions within the adjacent aquatic habitat (shade for cool water temperatures and clear channels, cover, nutrients, woody debris), and stabilizes stream and river banks.
River: A large, natural stream of water emptying into an ocean, lake or another water body, and usually fed along its course by converging tributaries.
Riverbank: The land bordering a river, sloping up from its bed to meet the adjacent land.
Riverbed: The lower portion of a river channel, between its banks, and ordinarily at least partially covered by water.
River Mouth: The outlet of a river, where it flows into the ocean or another body of water.
Runoff: Water from irrigation, snowmelt or rain that flows from the land surface into streams, creeks, wetlands or the ocean. Read much more on runoff.