Q.Why is the western coastal plain devoid of any delta?

The western coastal plain is devoid of deltas primarily due to the tectonic tilting of the Indian peninsular block. This geological event caused the western margin of the peninsula to subside, while simultaneously uplifting the Western Ghats.

As a result:

• Rivers originating in the Western Ghats and flowing westwards have a steep gradient.
• These rivers are short, swift, and flow at high velocities.
• Their high velocity prevents significant sediment deposition at their mouths. …

Deltas are landforms created by the deposition of sediment that is carried by a river as its flow leaves its mouth and enters slower-moving or stagnant water, such as an ocean, sea, or lake. For a delta to form, several conditions are generally necessary: a significant sediment load carried by the river, a relatively gentle gradient near the river mouth allowing the water to slow down, and a shallow, calm body of water where sediments can accumulate without being dispersed by strong currents or tides.

The western coastal plain of India, stretching along the Arabian Sea, presents a stark contrast to these conditions, which explains the absence of deltas. The primary reasons are rooted in the geological history and geomorphology of the region.

• Origin from Western Ghats: The rivers flowing westwards into the Arabian Sea originate from the Western Ghats. The Western Ghats are not true mountains in the conventional sense but rather a fault-scarp, formed by the rifting and subsequent uplift of the western edge of the Indian subcontinent. This tectonic activity created a steep escarpment facing the Arabian Sea.
• Steep Gradient and Short Course: Due to the proximity of the Western Ghats to the coast, these rivers have extremely short courses and flow down a steep gradient. This results in high velocity and significant erosive power, but very little time or opportunity for the rivers to accumulate and transport large quantities of fine sediment over long distances.
• Hard Rock Terrain: The Western Ghats are composed predominantly of hard, resistant igneous and metamorphic rocks. While these rocks are subject to erosion, they do not easily break down into the fine, abundant sediment required for delta formation, unlike the softer alluvial plains found in other regions. …