Hey radhika, Athirappilly Falls in Kerla is something that you can give a try to visit.
In Karnataka, Shivanasamudra Fall which I would recommend you to visit.
If you wanna visit something near Karnataka i would suggest Jog falls, Shivanasamudra falls, Hebbe falls, Irupu falls, Hogenakkal, Shivaganga falls or you can travel a few hours and visit these beautiful falls Athirapally , Soochipara falls, meenmutty falls.
These are the some of the must visit waterfalls in karnataka.Pick your favorite and enjoy your holiday.
Jog Falls
Iruppu Falls
Abbey Falls
Hebbe Falls
Sathodi Falls
Unchalli Falls
Kalhatti Falls
Kalhatti Falls
Godchinamalaki Falls
Shivanasamudra Falls