Which of the following statements are true with regard to energy dissipation below a dam?

(i) If the upper conjugate depth of a hydraulic jump is below the tailwater, little energy will be dissipated

(ii) An upturned bucket will protect the dam from scour by moving material toward the dam.

(iii) A secondary dam may increase tailwater height, thereby causing a hydraulic jump to form at the toe of the main dam.

(v) A slopping apron above streambed level may be used to control the hydraulic jump so that it occurs on the apron.