The hydraulic design of spillways has been done using the guidelines and the design criteria of the United States Bureau of Reclamation. Normally, the design must be supported by studies in hydraulic models, one three-dimensional and another two-dimensional. The hydraulic design of the spillway basically consists of determining the width and height of the hydraulic head on the crest to safely discharge the design flood. The initial crest forms were usually based on a simple parabola designed to fit the trajectory of a projectile. Tests performed by Rouse showed that the spillway designed in this way will produce a nappe that is not affected by the presence of a fixed lower boundary, provided the spillway shape has the same shape of the nappe for the same discharge. Labyrinth spillways are particularly advantageous in situations where it is necessary to discharge a large amount of water with a small charge on the crest.