Statement 1: It is incorrect. Jayakwadi dam is an Earthen Dam on Godavari river. There are various types of dams based on either structure and design or function or material, such as gravity dam, arch dam, buttress dam, earth dam, rockfill dam, storage dam, diversion dam, detention dam, debris dam, coffer dam, steel dam, timber dam, etc.
Statement 2: It is incorrect. Koyna Hydroelectric project is the largest completed hydroelectric power plant in India. It is a complex project involving four dams where Koyna dam on Koyna river is the largest among the four.
Hence, the correct option is 4.