function qman(x1,x2,x3,x4) !! ~ ~ ~ PURPOSE ~ ~ ~ !! this subroutine calculates flow rate or flow velocity using Manning"s !! equation. If x1 is set to 1, the velocity is calculated. If x1 is set to !! cross-sectional area of flow, the flow rate is calculated. !! ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ !! ~ ~ ~ SUBROUTINES/FUNCTIONS CALLED ~ ~ ~ !! Intrinsic: Sqrt !! ~ ~ ~ ~ ~ ~ END SPECIFICATIONS ~ ~ ~ ~ ~ ~ implicit none real, intent (in) :: x1 !m^2 or none |cross-sectional flow area or 1. real, intent (in) :: x2 !m |hydraulic radius real, intent (in) :: x3 !none |Manning"s "n" value for channel real, intent (in) :: x4 !m/m |average slope of channel real :: qman !m^3/s or m/s |flow rate or flow velocity qman = x1 * x2 ** .6666 * Sqrt(x4) / (x3 + .001) return end