online_contraction_scour_live_bed:  Contraction scour under live bed conditions using modified Laursen 1960 equation Modified Laursen formula ys / y1 = ( Q2 / Q1 ) 0.86 (W1 / [W2) k1  -  ( yo / y1 ) [ yo, y1, Q and W in any consistent set of units ] [ S1 in m/m or ft/ft ] [ T in °C or °F ] [ D50 in mm or ft ] Reference: Evaluating Scour at Bridges, FHWA Hydraulic Engineering Circular No. 18, Fifth Edition, 2012. SAMPLE INPUT:      [Main Page]     [Description] Mean flow depth below the bridge, before scour yo =  1.0 m Mean flow depth upstream of the bridge y1 =  2.0 m/s Discharge upstream of the bridge (only in the main channel) Q1 =  10.0 m3/s Discharge in the contracted section Q2 =  8.0 m3/s Bottom width in the section upstream of the bridge W1 =  2.0 m Bottom width in the contracted section, excluding piers W2 =  1.0 m Energy slope in the main channel upstream S1 =  0.002 m/m Median diameter of the bed material D50 =  2.0 mm Water Temperature T =  20oC SAMPLE OUTPUT               Contraction scour depth under live bed conditions ys =   1.57 m