A typical simple delta is commonly made of three layers of which only top layer may be sub aerial, that is exposed on surface.

Cavitation is a distinct and rare type of hydraulic action performed by running water. It is particularly observed where river water suddenly acquires exceptionally high velocity such as at location of a waterfall.

Velocity is defined as distance water travels in a unit time within its channel.

Kickpoints are actually places of steep drops in elevation in course of a river. These are very often caused due to presence of rocks of unequal hardness at those places.

The velocity of a stream itself depends on: gradient of channel; roughness of channel along base and sides; volume of load in stream at a given place.

Littoral currents are bodies of seawater of considerable volume moving along and parallel to shore.

Translatory waves are typically of shallower depths in sea and abound along seashore. They are commonly produced after oscillatory waves break and rush forward.

Convex flood plains are most common type and are associated with many major rivers of world.

It is known that where stream velocity exceeds 12m/sec, water pressure developed at impinging points equals vapour pressure and re is spontaneous change from liquid to vapour state and back to liquid state at that point.

The barrier reefs are most common type of reefs and occur at a distance from shore or island running in form of parallel, flat-topped ridges.