Drainage Patterns and their Interpretation

The knowledge and interpretation of drainage patterns is very important to carry out studies of mining exploration, oil exploration, in geography, for risk management and many other activities, because they are associated with different types of rocks, with various processes and important geological structures such as geological faults.

Dendritic drains

The dendritic drainage has an extended tree-like pattern with irregular branching of tributaries in many directions and at almost any angle.

It occurs mainly in horizontal and uniformly resistant strata and unconsolidated sediments and in homogeneous igneous rocks where there are no structural controls.

Learn about igneous rocks by clicking here.

Parallel drains

Parallel drainage shows regularly spaced and more or less parallel main streams with tributaries joining at sharp angles.

Dipping parallel currents dominate the pattern.

They develop where the strata are uniformly resistant and the regional slope is marked, or where there is strong structural control exerted by a series of closely spaced geological faults, monoclines or isoclines.

Lattice drains

Lattice drainage has a dominant drainage direction with a parallel secondary direction, so that primary tributaries join the main streams at right angles and secondary tributaries run parallel to the main streams.

It is associated with alternating bands of hard and soft bed or folded beds or recently deposited and aligned glacial remnants.

An example is the Appalachian Mountains in the Northeastern United States, where alternating weak and strong strata have been truncated by erosion from running water.

Radial drains

The radial drain has currents flowing outward in all directions from a central elevated tract.

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It is found in topographic domes, such as volcanic cones and other types of isolated conical hills.

On a large scale, radial drainage networks form in torn continental margins over mantle plumes, creating lithospheric domes.

Rectangular drains

The rectangular drainage shows a perpendicular network of streams with tributaries and main streams joined at right angles. It is less regular than trellis drainage and is controlled by joints and fault lines.

The rectangular drain is common along the Norwegian coast and in parts of the Adirondack Mountains, USA.

Angular drains

Angular drainage is a variant of rectangular drainage and occurs when geological joints or faults join each other at acute or obtuse angles rather than right angles.

Annular drains

The annular drain has main streams arranged in a circular pattern with subsidiary streams meeting at right angles to them.

It evolves into a broken or dissected dome or basin in which erosion exposes concentrically arranged bands of hard and soft rock.

Centrifugal drains

Centrifugal drainage is similar to radial drainage and occurs where, for example, channels develop inside meanders.

Centripetal drains

Centripetal drainage has all currents flowing toward the lowest central point on a sedimentary basin floor.

It occurs in calderas, craters, sinkholes, and tectonic basins. A large area of ​​internal drainage is found on the central Tibetan plateau.

Distributed drains

Distributed drainage typifies rivers that empty into narrow mountain gorges and run over plains or valleys, particularly during occasional floods when they overflow their banks.

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