The correct matches are Vajrai Waterfall- Urmodi river (Maharashtra), Barehipani Falls- Budhabalanga River (Odisha), Dhuandhar Falls- Narmada (Madhya Pradesh), Kunchikal Falls- Varahi river (Karnataka).
The useful steps to prevent soil erosion are Afforestation, Contour Ploughing, Prohibition of shifting cultivation, Flood control, Restoration of long fallow, reclamation of alkaline and saline soil.