Why does the Chota Nagpur plateau receive more rain than some of Jharkhand’s plains?

The Chota Nagpur plateau receives higher precipitation than the surrounding plains primarily due to the interaction of the two branches of the southwest monsoon. Over the northeastern portion of peninsular India, these branches—originating from the Arabian Sea and the Bay of Bengal—intermittently collide.1

These collisions create weak weather fronts that generate sufficient rainfall to produce patches of relatively high precipitation, often exceeding 60 inches (1,520 mm), across the plateau region. While the state of Jharkhand experiences annual rainfall ranging from about 40 inches in the west-central areas to over 60 inches in the southwest, the elevated nature of the plateau generally facilitates this heavier rainfall compared to the lower-lying plains that flank the region in the northwest and northeast.123