What are the advantages and disadvantages of Gravity dam?

Advantages and disadvantages of Gravity dam: 

Advantages of gravity dam

1. Gravity dams are relatively powerful and more durable than earth dams.
2. They can be built of any height, provided that appropriate foundations are available to bear the stress.
3. Gravity dams are ideally suited for use as overflow spillway crests because Earth dams should not be used as overflow dams.
4. They requires the least maintenance.
5. They are cheaper in the long run since it is more permanent than any other type. Thus the benefit-cost ratio of such a dam is always higher.

Disadvantages of Gravity dam

1. Gravity dams can only be designed on sound rock foundations. They are unsuitable on weak foundations or on permeable foundations on which earth dams can be designed with suitable foundation treatment.
2. The initial cost of a gravity dam is always higher than an earth dam.
3. They need skilled labour or mechanised plants for their construction.