Why every dam needs a spillway to prevent catastrophic failure and manage water flow.

Dams are built to store water for power, irrigation, and flood control, but they cannot always hold everything. A spillway is a vital, often complex component that allows engineers to safely release excess water when a reservoir reaches capacity or downstream needs arise.

A spillway serves as a necessary safety valve for dam infrastructure. While the primary purpose of a dam is to impound water for human utility, the spillway provides the essential mechanism for controlled discharge. This component is frequently cited as the most intricate part of a dam's design.

The necessity for a spillway arises from two primary scenarios: when the reservoir behind the dam is at maximum capacity and requires relief, or when specific water requirements exist downstream. By managing these releases, spillways ensure the structural integrity of the dam while facilitating the practical distribution of water resources.

Source: How Do Spillways Work?