A drainage pattern refers to the river network and depends very much on the topography of the land where the river is found and the nature of the underlying rock.
Dendritic: branching tree-like pattern with tributaries that join at small angles. This pattern usually forms on gentle sloping topography, in V-shaped valleys and on non-eroding rock.
Parallel: fewer tributaries than with the dendritic drainage pattern with all rivers flowing int the same direction. This is seen on steep slopes where rivers run straight down.
Trellis: the main rivers run parallel and have short tributaries that join at 90˚ angles. This pattern forms in fold mountains, on homoclinal ridges and where soft and hard rock alternate.
Rectangular: main river and its tributaries have elbows or right-angled bends. This pattern forms in jointed rock following the lines of the joints.
Radial: a star-like pattern in which all rivers run out and down from a single high point. This pattern forms where there are isolated, high-lying features such as buttes, mesas, conical hills, domes and volcanoes. A centripetal pattern is the inversion of a radial pattern with all rivers flowing in towards a central basin to form a pan or marsh. Usually this happens in a hollow or depression in a landscape.
A deranged drainage pattern has no obvious pattern and the streams do not link up. This often occurs in flat areas like newly exposed coastal plains or areas recently uncovered by glaciers.
The river is essentially still ‘finding its way’ and in the process of cutting and establishing river beds. The deranged drainage pattern is often associated with lakes and marshes.