Radial gate as a part of dams , What are the advantages and disadvantages of it?

Radial gates are the most frequently used movable water control structures. ... Their advantages are: (a) Absence of gate slots, because side seals are used. ... The disadvantages of radial gates are: (a) The flume walls must extend ...

Radial Spillway/Tainter Gates

Advantages

• Quick operation as they move in an arc.
• The entire water load is transferred radially through the arms to the pivots which reduces hoist capacity compared to a Wheel Gate.
• Gate bottom lip gives good hydraulic discharge profile.
• Hydraulic cylinder or rope hoist options.
• Flush side and sill sealing faces.
• Crest or culvert type 
• Disadvantages
• Gate aesthetics, visible when raised
• Civil loads concentrated on piers
• Long piers.

Radial gates are designed for wide and unobstructed waterways where a light-weight economical gate with minimal hoist effort to open and close is required. A radial gate consists of a curved gate leaf, rubber seals, support arms, seal rubbing embedment and embedded pivot points. The gate leaf is of a welded construction varying in width and height as required by the size of the opening. Embedded rubbing seats are mounted flush with the wall to provide a smooth flat surface for the seals to slide on as the gate opens and closes.

Water pressure applied against the curved gate leaf is transmitted through the support arms into the pivot points, which are embedded in the concrete wall. Since the gate leaf is curved, the water also applies a pressure upward, thereby lowering the lifting force required. A smaller hoist is therefore necessary as compared to other types of gates. Radial gates are used primarily for upstream level control in open-channel installations. Flow is always one-way, against the face of the gate. Low lifting forces are required for radial gate operation, which is normally by cable hoists.

First of all Mr. Mohamed, I am not an expert in "concrete, civil engineering" because I am a Mechanical Engineer, but all I know is....

Radial Gate,  like other gates are sliding or rolling against guides, but are curved in vertical section to better resist water pressure ( advantage ). One of disadvantage is the cost civil works.

Here at National Power Corporation (Philippines) Angat Hydroelectric Power Plant, we are using three (3) radial gates for our spillway.

Thank you mr. Al Yazouri