Because those places have less water resources and rainfall is very less the part of Rajasthan,Gujarat etc are drought prone because they have less rainfall.
The part of rajasthan,gujarat and western side ghats are drought prone because :-

1) In western side of India where rajasthan and gujarat situated they have less water sources.

2) the water is situated so much deep of the earth around 700 feet deep water is found in gujarat and rajasthan.

3) t
he monsoon winds which are completely drained by the time they reach them. the leeward side of the western ghats is drought prone as the western ghats block the rain bearing winds from reaching it.

Rajasthan and gujarat have less rainfall in a year that's why they have less water sources.

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