Question

Why western coastal plains are devoid of alluvial soil?

Answer 1

The two main west flowing rivers Narmada and Tapti flows in the fault region created by the mountains Vindhy and Satpura, which is very rocky and also devoid of any alluvial material. So, they do not carry much sediments to form any delta. Also the coastal plains between western ghats and Arabian sea are very narrow, that is why the course of west flowing rivers is very short and the deltas are spread over a vast area. So, the western coastal plain is devoid of alluvial soil.

Answer 2

Explanation:

There are two main rivers that flow through the western coastal plain. They are the Narmada and the Tapi rivers.  

The course of these two rivers is through the region of fault between the Vindhya and the Satpura mountain ranges. This fault region is devoid of any alluvial soil because it is mostly rocky in nature.  

So they do not have many sediments to carry, that can form a delta, which makes the western coastal plains to be devoid of alluvial soil.