The diagram shows a cross-section of a dam holding back water in a reservoir. The dam wall is constructed with a wider base and tapers towards the top.

The diagram shows a cross-section of a dam holding back water in a reservoir. The dam wall is constructed with a wider base and tapers towards the top.

This design is based on the principle that fluid pressure increases with depth. The pressure exerted by the water on the dam wall is greatest at the bottom of the reservoir and least at the surface. To withstand the immense force from the water at greater depths, the dam wall is built significantly thicker at its base, providing the necessary strength and stability.