Question

Dams have broad foundations. Why is it so?

Answer 1

Dams must hold back water of a certain depth, determined by the height of the dam. The pressure exerted by this water on the dam is dependent in part by its depth since the base of the dam must be able to hold pressures exerted by the weight of all the water above the base. Since the pressure is greater at the base, the dam is broader at the base.

Answer 2

The broad base of dams reduces downward pressure of the huge amount of water, as greater is the area, lesser is the pressure.