Identify the type of drainage pattern on the basis of the given characteristics : 1. It represents the most common pattern of streams and their tributaries. 2. It occurs in areas of uniform rock type and regular slope. 3. A map, or aerial photograph, shows a pattern like the veins on a leaf—smaller streams join the main stream at an acute angle. Select the correct answer.
- (a)Dendritic
- (b)Radial
- (c)Trellis
- (d)Centripetal
Correct — A, Dendritic. Every clue in the stem is a dendritic marker. It is the most widespread drainage pattern on Earth, it develops where the underlying rock is uniform in resistance and the slope is regular so that no structural line steers the water, and its plan view is the branching, tree-like or leaf-vein form in which small tributaries meet the trunk stream at acute angles pointing downstream. The word itself comes from the Greek dendron, a tree.
- (b)Radial — A radial pattern has streams flowing outward in all directions from a central high point such as a volcanic cone or a structural dome. It is neither the commonest pattern nor a product of uniform rock and regular slope — it needs a conical relief to exist at all.
- (c)Trellis — A trellis pattern forms precisely where the rock is not uniform: alternating bands of hard and soft strata in folded country steer the tributaries along strike valleys so that they join the main stream at nearly right angles, not acute ones.
- (d)Centripetal — In a centripetal pattern the streams converge inward from all sides into a basin, depression or lake — the reverse of radial. CDS asked exactly that definition in the 2021-I paper, and it does not describe a leaf-vein plan.
A drainage pattern is the plan-view arrangement a river and its tributaries take on the land, and it is read as evidence of the rock structure and slope beneath. Where the bedrock offers the same resistance in every direction and the ground slopes evenly, water simply follows the steepest available line and the network branches freely — that is the dendritic pattern, and it is the default. Departures from it are informative: trellis reveals alternating hard and soft folded strata, radial reveals a central dome or cone, centripetal reveals an enclosed basin, and rectangular reveals a joint or fault grid.
The three clues in the stem are three independent routes to the same answer, which is unusual generosity in a CDS item. 'Most common' alone settles it, because dendritic is the pattern textbooks name as the commonest. 'Uniform rock type and regular slope' settles it again, because structural control is what produces every other pattern in the list. And the leaf-vein image with acute-angle junctions is the standard textbook description of dendritic. In India, the pattern is well shown by the tributary networks of the Ganga in the northern plains, where the alluvium is homogeneous and the slope is gentle and even.
- Dendritic drainage is described in standard geomorphology as the most common form of drainage system.
- It develops on rock of uniform resistance where no structural line steers the streams, and tributaries join the trunk at acute angles.
- Trellis drainage forms in folded country with alternating hard and soft beds; tributaries join at about right angles.
- Radial drainage flows outward from a central high point; centripetal drainage converges inward into a basin or depression.
Every pattern except dendritic needs a structural reason to exist; dendritic is what you get when there is none.
- Picking trellis because the phrase 'main stream and tributaries' suggests structure — trellis needs alternating hard and soft rock, which the stem rules out.
- Reading 'acute angle' loosely; the right-angle junction is the trellis signature and is the clearest discriminator here.
- Confusing radial with centripetal — the first flows outward from a high point, the second inward into a basin.
Asked as a three-clue identification item; CDS also asks the same set of patterns as a one-line definition and as a match-the-list item.
The rivers of North-West Europe are good examples of
- (a) parallel pattern of drainage.
- (b) radial pattern of drainage.
- (c) barbed pattern of drainage.
- (d) trellis pattern of drainage.
Answer(a) parallel pattern of drainage.
Extends the same list with a fifth pattern and a real region, which is how these items usually escalate once the four basic patterns are assumed known.
CDS_GK_2021_I_Q422021When the rivers discharge their waters from all directions into a lake or depression, the pattern is known as
- (a) Trellis
- (b) Dendritic
- (c) Radial
- (d) Centripetal
Answer(d) Centripetal
The same four patterns, tested on the one this item lists last. Learning the pair centripetal and radial together closes off two of the three distractors here at a stroke.
CDS_GK_2022_II_Q902022Match List I with List II and select the correct answer using the code given below the Lists: List I (Drainage Pattern of River) A. Insequent B. Consequent C. Subsequent D. Resequent List II (Feature) 1. Whose direction of flow is controlled by the rock structure 2. No apparent reason why it follows the path it takes 3. Flow in the same direction as the consequent stream but at a lower level 4. Whose course is determined by the original slope of the land Code:
- (a) A-2 B-1 C-4 D-3
- (b) A-2 B-4 C-1 D-3
- (c) A-3 B-4 C-1 D-2
- (d) A-3 B-1 C-4 D-2
Answer(b) A-2 B-4 C-1 D-3
The stream-type vocabulary behind the patterns. An insequent stream is defined as one with no apparent structural reason for its path, which is exactly the condition that produces a dendritic network.
- practice — not a real PYQ
A drainage pattern in which tributaries join the main river at nearly right angles in a region of folded strata is called
- (a)Dendritic
- (b)Trellis
- (c)Radial
- (d)Annular
Answer(b) Trellis — alternating resistant and weak beds steer the tributaries along strike, giving right-angle junctions.
- practice — not a real PYQ
Streams flowing outward in all directions from a central volcanic cone form which drainage pattern?
- (a)Centripetal
- (b)Rectangular
- (c)Radial
- (d)Parallel
Answer(c) Radial — outward from a central high point; centripetal is the inward-converging opposite.