What is the primary purpose of a core trench in a principal spillway?

The primary purpose of a core trench in a principal spillway is to create a barrier that retains the dam. A core trench is typically excavated in order to help control seepage and provide stability to the dam structure. By extending the core of the dam into the underlying material, it minimizes the risk of water passing through or under the dam, thereby reducing the likelihood of erosion or structural failure.

This function is crucial in ensuring the integrity of the spillway and the overall safety of the dam. Properly constructed core trenches help manage hydraulic conditions and enhance the performance of the spillway, contributing to effective stormwater management by preventing uncontrolled overflow and allowing for a stable, controlled release of water. The effective containment of water also supports the long-term functionality of the spillway, ensuring that it can handle significant flow events without jeopardizing the dam's stability.