Arroyo
A wash is another term for a gully, an arroyo or a wadi. It is a usually a dry stream bed in a desert formed by occasional heavy rains.
A stream bed is the bottom (floor) of the stream.
A playa is a dried lake bed in a desert. It only has water after a substantial rain.An arroyo is a wash or gully - a dry stream bed in the desert that only has flowing water during a substantial rain.
A wady is another term for a wadi - a valley or stream bed which remains dry except during the rainy season.
Bed Load
The bed of the stream.
Bed
Sediment that is carried by a stream along the bottom of its channel.
A stream bed is the bottom sediment layer of the stream channel which is constantly inundated with water. It is a saturated layer of sediment inhabitated by macroinvertibrates, algae, macrophytes, and microbes. The particle size of the stream bed material (fine clay vs large rock and boulders) is dependent on geologic region, size of the stream, and stream velocity. The stream bank is the adjacent sloping walls that confine the stream on either side. They are typically not wet except in times of high flows. Banks typically can grow more terrestrial vegetation such as reeds, grasses, and trees.
wide and steep
The measure of the largest particles that a stream can carry is typically determined by its stream power, bed material size, and flow velocity. Streams with higher stream power and flow velocity are able to transport larger particles. The largest particles a stream can carry before they settle to the streambed are usually referred to as the stream's "bedload" particles.
bed