The notch – necessary to allow an outflow so as to avoid the erosion of the banks of the river-bed near the weir – is defined with reference to the following figure:
Geometrical diagram of the notch
LG [m]
Width of the notch lesser base
IS [°]
Inclination of the chutes on the side of the notch (Angle measured as positive clockwise)
FRS [m]
Safety freeboard to be guaranteed in the most unfavourable case, measured as the vertical distance between the notch bottom and the highest point of its chutes.
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