The safeguarding structure provided in the dam to relieve the reservoir of excess water when the water level in the reservoir rises, is known  as:

Explanation:

Spillways

Definition: A spillway is a structure built into or near a dam to safely discharge excess water from a reservoir when it reaches or exceeds a certain level. The primary purpose of a spillway is to prevent overtopping of the dam, which could lead to structural failure and catastrophic downstream flooding. By providing a controlled pathway for excess water, spillways ensure the safety and integrity of the dam while also protecting downstream areas.

Working Principle: When the water level in the reservoir rises beyond the designed maximum level, it flows into the spillway. The spillway channels the water away from the reservoir and releases it downstream. Spillways are designed to handle specific maximum flow rates based on the dam's capacity and the potential inflow during extreme weather events, such as heavy rainfall or rapid snowmelt.

Types of Spillways:

• Ogee Spillway: This is the most common type of spillway, with a curved profile that allows water to flow smoothly over the crest and down the spillway.
• Chute Spillway: A steep channel that carries water away from the reservoir, designed to handle high flow rates.
• Side Channel Spillway: Positioned parallel to the dam, it diverts water to a channel leading away from the dam.
• Shaft Spillway: Also known as a "morning glory" spillway, it features a vertical shaft that leads to a horizontal tunnel for water discharge.
• Stepped Spillway: Includes steps that dissipate energy as water flows down, reducing erosion and turbulence.