Concrete fuse plugs are simple massive blocks placed side by side on a spillway sill. They are free standing and stable until the water level in the reservoir reaches a certain elevation and they start tilting when this elevation is exceeded.
The need in Asia of water storage for irrigation and drinking waters is as important in flat areas as in steep areas. The relevant design criteria may be very different. Examples are suggested below for a typical storage of 1 hm3 with a dam height under 10 m, i.e. with an average reservoir depth of 2 or 3 m, a reservoir area of 0,3 or 0,5 km². The banks slope is few % and the dam length in the range of 1 000 m.
Most European dams have been built fifty years ago: corresponding design criteria were based upon knowledge and solutions which did prevail and were far from present knowledge and available solutions. Old criteria which remain used in many countries may thus deserve an in depth review and using them for official regulations is much questionable. Two examples are analysed: spillways and floods control during construction.
Concrete Fuse Plugs may be used for new dams. In such case, it is possible, with about the same quantity of concrete and cost as for creager weirs, to double the flow of the extreme flood discharged through the spillway or to increase the storage for a same safety.
Concrete fuse plugs are simple massive blocks placed side by side on a spillway sill. They are free standing and stable until the water level in the reservoir reaches a certain elevation and they start tilting when this elevation is exceeded. They may be designed to tilt before being overtopped and, in such a case, will have a significant height compared to their thickness.
Most dams, and especially the great majority of irrigation dams, have free flow spillways. This solution is economical for catchments areas of few km2 with extreme floods under 100 m3/s ; but it is in fact expensive in most Asia and particularly in India for irrigation dams with catchments areas over 5 km2 for 3 reasons.