With reference to river meanders, consider the following statements: 1. They are formed when the river enters the plain. 2. No erosion or deposition…

The correct option is (a).

Explanation

Meanders are loop-like channel patterns that develop over floodplains and delta plains where river gradients are gentle. They are dynamic features resulting from the interplay of lateral erosion and deposition by running water.

Statement 1: Correct
Meanders typically form when a river leaves the mountainous region and enters the plains (mature and old stages). In these areas, the slope is gentle, and the water velocity decreases. The river loses its ability to erode vertically and instead begins to erode laterally (sideways), causing the channel to swing back and forth.

Statement 2: Incorrect
Meanders are characterized by active erosion and deposition along their sides. Erosion occurs on the outer bank (concave side) where the water flows fastest, creating a steep "cut bank." Deposition occurs on the inner bank (convex side) where the flow is slower, forming a "point bar" or slip-off slope.

Statement 3: Incorrect
As erosion continues on the outer banks and deposition on the inner banks, the meander loops become more pronounced. The ends of the meander loop (the neck) come closer to each other, not further apart. Eventually, the river cuts through the narrow neck during a flood, straightening its course and leaving the loop behind as an oxbow lake.

Key Takeaway:
Meanders are formed in the plains due to lateral erosion on the outer bank and deposition on the inner bank. Over time, the neck of the meander narrows until the loop is cut off to form an oxbow lake.