1999 – Towards Total Acceptance of Fully Automated Spillway Gates

Peter Townshend

Ungated spillways offer the safest form of spillway but they are more costly than gated spillways for the volume of water stored. Gated spillways offer a more cost-effective use of water by maximizing the storage capabilities of the dam. Gated spillways also lead to more cost effective new dams as well as increasing storage of existing dams. They can therefore offer considerable advantages but must not jeopardize dam safety. Most commonly used spillway gates are mechanically driven by electric or hydraulic systems reliant on external power supply and instrumentation, and usually require operators to control the systems. Unfortunately there is already a substantial record of these types of gates not operating when required, thereby placing the dam’s safety in jeopardy. The ideal is to have automatic gates which do not suffer the problems associated with mechanically-driven gates.

A number of automatic gates exist, some with differing degrees of success but most are not truly automatic in operation and suffer some limitations. A range of fully automatic water control equipment has been developed and has operated for more than 20 years in South Africa. Out of experience gained from this equipment, a new generation of spillway gates has been developed which meets nearly all the requirements of an ideal spillway gate.
This paper introduces the gates and examines their features and safety devices. Other benefits are also mentioned.

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