When 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
Correct — D, Centripetal. The stem is the NCERT definition almost unaltered — the school text reads 'When the rivers discharge their waters from all directions in a lake or depression, the pattern is know as centripetal', printing 'in' where the paper prints 'into' and carrying a typographical slip of its own in 'is know as'. The name says the mechanism: centripetal means centre-seeking, so the streams converge inward on a low point instead of spreading outward. The landform that produces it is an enclosed basin with no outlet to the sea — a crater, a caldera, a structural depression or a rift-floor lake — and the drainage of the Loktak lake basin in Manipur and of the inland basins of Rajasthan and of Central Asia are the standard illustrations.
- (a)Trellis — Trellis is the pattern where the primary tributaries flow parallel to one another and the secondary tributaries join them at right angles, produced by alternating bands of hard and soft rock in folded country.
- (b)Dendritic — Dendritic is the pattern that resembles the branches of a tree, formed where the underlying rock offers uniform resistance and the slope is gentle. The rivers of the northern plain are the textbook example.
- (c)Radial — The mirror image and the intended trap. In a radial pattern the rivers originate from a hill and flow outward in all directions, as those rising on the Amarkantak range do; centripetal has them flowing inward from all directions.
A drainage pattern is the plan view that a river and its tributaries make on the ground, and it is read as evidence of the slope and the rock structure beneath. Uniform rock and a gentle regional slope give a dendritic pattern; a dome or a volcanic cone gives radial; alternating resistant and weak strata in folded rocks give trellis; an enclosed basin gives centripetal. Other named patterns include rectangular, formed on strongly jointed rock, and deranged, left behind by glaciation.
Radial and centripetal are a matched pair, and every question on either one is really testing whether the candidate can tell the direction of flow. The word itself carries the answer — centripetal, centre-seeking, inward — so the safe habit is to translate the name before reading the options. It helps to attach each pattern to the landform that makes it rather than to a picture: a hill gives radial, a basin gives centripetal, folded ridges give trellis, a uniform plain gives dendritic. Centripetal drainage is also the pattern of inland or endorheic basins, which do not reach the sea and therefore tend to accumulate salt — which is why the saline lakes of the Nagaur-Sikar belt of Rajasthan and the playas of arid regions sit in exactly this drainage setting.
- Centripetal drainage forms where rivers converge inward on a lake or a depression from all directions.
- Radial drainage is its opposite: rivers rise on a hill and flow outward in all directions, as on the Amarkantak range.
- Dendritic drainage resembles the branches of a tree and is the pattern of the rivers of the northern plain.
- In trellis drainage the primary tributaries run parallel and the secondary tributaries join them at right angles.
- Basins with centripetal drainage are usually endorheic — they have no outlet to the sea, which is why their lakes often turn saline.
- Reading centripetal and radial as the same word; they describe opposite directions of flow.
- Assuming a drainage pattern tells you the size of a river; it describes plan geometry, not discharge.
- Matching trellis to any right-angle bend; trellis needs parallel main streams with tributaries entering at right angles, which is a structural signature.
Asked as a definition-to-name item like this one, or as a match-the-following pairing four patterns with four descriptions or four regions.
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.
The same topic extended past the standard four. Parallel and barbed patterns turn up once the basic set is assumed known, so it is worth adding them to the dendritic, radial, trellis and centripetal group.
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
Answer(a) Dendritic
The same four patterns three years later, with the definition moved into the stem as a set of clues. CDS asks this block repeatedly and always from the same list, so learning all four definitions together answers both papers.
- practice — not a real PYQ
The drainage pattern in which streams flow outward in all directions from a central elevated area is called
- (a)Centripetal
- (b)Radial
- (c)Trellis
- (d)Rectangular
Answer(b) Radial — the pattern of streams rising on a dome or volcanic cone, such as those of the Amarkantak range.
- practice — not a real PYQ
A drainage pattern in which the primary tributaries flow parallel to each other and the secondary tributaries join them at right angles is known as
- (a)Dendritic
- (b)Radial
- (c)Trellis
- (d)Centripetal
Answer(c) Trellis — produced where alternating bands of resistant and weak rock in folded country guide the main streams along the weak bands.