subroutine ero_pkq !! ~ ~ ~ PURPOSE ~ ~ ~ !! this subroutine computes the peak runoff rate for each HRU !! and the entire subbasin using a modification of the rational formula !! ~ ~ ~ INCOMING VARIABLES ~ ~ ~ !! name |units |definition !! ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ !! hru_km(:) |km^2 |area of HRU in square kilometers !! ihru |none |HRU number !! tconc(:) |hr |time of concentration for HRU !! ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ !! ~ ~ ~ OUTGOING VARIABLES ~ ~ ~ !! name |units |definition !! ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ !! qp_cms |m^3/s |peak runoff rate !! ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ !! ~ ~ ~ SUBROUTINES/FUNCTIONS CALLED ~ ~ ~ !! Intrinsic: Log, Exp !! ~ ~ ~ ~ ~ ~ END SPECIFICATIONS ~ ~ ~ ~ ~ ~ use hru_module, only: hru, tconc, ihru, qp_cms, qday use hydrograph_module use climate_module use basin_module implicit none integer :: j = 0 !none |HRU number real :: altc = 0. ! | real :: qp_cfs = 0. !ft3/s |peak flow rate integer :: iob = 0 ! | real :: xx = 0. j = ihru iob = hru(j)%obj_no iwst = ob(iob)%wst xx = (2. * tconc(j) * Log(1. - wst(iwst)%weat%precip_half_hr)) altc = 1. - exp(xx) qp_cms = altc * qday / tconc(j) !! mm/h qp_cms = qp_cms * hru(j)%km / 3.6 !! m^3/s !! NRCS dimensionless hydrograph with PRF !! convert ha-mm * mi2/259ha * in/25.4mm to mi2-in --> 1/6578.6 qp_cfs = bsn_prm%prf / 6578.6 * hru(j)%area_ha * qday / tconc(j) qp_cms = qp_cfs / 35.3 return end subroutine ero_pkq