A drainage system is the pattern formed by the streams, rivers, and lakes in a particular watershed. They are governed by the topography of the land, whether a particular region is dominated by hard or soft rocks, and the gradient of the land.
Types of drainage system
There are several different types of drainage system:
Dendritic drainage system
Dendritic drainage systems are the most common form of drainage system in the world. They consists of a main river with tributaries with their own tributaries. From above, it looks like a tree or a
river delta in reverse. Examples include the
Amazon River and the
Mississippi River and the Ganga (Ganges) River. The pattern occurs in a V- shaped junction, sort of like a leaf, with its veins representing the tributaries, and the stem representing the main channel. Rivers that flow in a dendritic drainage system usually are on a gentle slope.
Parallel drainage system
A parallel drainage system is a pattern of rivers caused by steep slopes with some
relief. Because of the steep slopes, the streams are swift and straight, with very few tributaries. Regions with
mountain ranges sometimes have this drainage system.
Trellis drainage system
Rectangular drainage system
Rectangular drainage systems are arranged around faulted ground.
Annular drainage system
Annular drainage systems are arranged in ring-shaped patterns around a central basin.
Deranged drainage system
A deranged drainage system is a drainage system in
watersheds where there is no coherent pattern to the rivers and lakes. It happens in areas where there has been much geological disruption. The classic example is the
Canadian Shield. During the last
ice age, the topsoil was scraped off, leaving mostly bare rock. The melting of the glaciers left land with many irregularities of elevation, and a great deal of water to collect in the low points, explaining the large number of lakes which are found in Canada. The watersheds are young and are still "sorting themselves out". Eventually the system will stabilize.
Geomorphology | Hydrology
水系 | 水系