Under what conditions should engineers consider using stilling basins?

Stilling basins are usually introduced to convert supercritical flow to subcritcal flow before it reaches downstream. A typical stilling basin consists of a short length of channels located at the source of supercritical flow (e.g. end of spillway). Certain features are introduced to the basins like baffles and sills to provide resistance to the flow. As such, a hydraulic jump will form in the basin without having conducting significant amount of excavation for the stilling basin if baffles are installed.

This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.