Concept: Types of weirs: Types of weirs Characteristics 1. Vertical drop weir Suitable for any type of foundation Crest gate may be provided to store more water during flood period. Cut off Piles are provided at u/s and d/s ends of impervious floor. Launching apron is provided both at u/s and d/s ends of floor to safe guard against scouring action Graded filter is provided immediately at the downstream end of impervious floor to relieve the uplift pressure. 2. Sloping weir of concrete Suitable for Soft sandy Foundation Used where difference in weir crest and downstream riverbed is not more than 3m Hydraulic jump is formed when water passes over the sloping glacis 3. Parabolic Weir Similar to spillway section of dam Weir body dam is designed as low dam for this weir Cistern is provided at downstream 4. Dry stone sloping weir Dry stone or rock fill weir Body wall, downstream and upstream dry stone are laid in the form of glacis with some intervening core wall