subroutine et_act !! ~ ~ ~ PURPOSE ~ ~ ~ !! this subroutine calculates potential plant transpiration for Priestley- !! Taylor and Hargreaves ET methods, and potential and actual soil !! evaporation. NO3 movement into surface soil layer due to evaporation !! is also calculated. !! ~ ~ ~ INCOMING VARIABLES ~ ~ ~ !! name |units |definition !! ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ !! canstor(:) |mm H2O |amount of water held in canopy storage !! ep_max |mm H2O |maximum amount of transpiration (plant et) !! |that can occur on current day in HRU !! esco(:) |none |soil evaporation compensation factor !! ihru |none |HRU number !! ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ !! ~ ~ ~ OUTGOING VARIABLES ~ ~ ~ !! name |units |definition !! ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ !! canev |mm H2O |amount of water evaporated from canopy !! |storage !! ep_max |mm H2O |maximum amount of transpiration (plant et) !! |that can occur on current day in HRU !! es_day |mm H2O |actual amount of evaporation (soil et) that !! |occurs on day in HRU !! snoev |mm H2O |amount of water in snow lost through !! |sublimation on current day !! ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ !! ~ ~ ~ SUBROUTINES/FUNCTIONS CALLED ~ ~ ~ !! Intrinsic: Exp, Min, Max !! ~ ~ ~ ~ ~ ~ END SPECIFICATIONS ~ ~ ~ ~ ~ ~ use basin_module use organic_mineral_mass_module use hru_module, only : hru, canstor, ihru, canev, ep_max, & es_day, pet_day, snoev use soil_module use plant_module use climate_module use hydrograph_module use water_body_module use reservoir_data_module implicit none integer :: j = 0 !none |HRU number !! real, parameter :: esd = 500., etco = 0.80, effnup = 0.1 real :: esd = 0. !mm |maximum soil depth from which evaporation ! |is allowed to occur real :: etco = 0. ! | real :: effnup = 0. ! ! real :: no3up = 0. !kg N/ha |amount of nitrate moving upward in profile real :: es_max = 0. !mm H2O |maximum amount of evaporation (soil et) ! |that can occur on current day in HRU real :: eos1 = 0. !none |variable to hold intermediate calculation ! |result real :: xx = 0. !none |variable to hold intermediate calculation ! |result real :: cej = 0. ! | real :: eaj = 0. !none |weighting factor to adjust PET for impact of ! |plant cover real :: pet = 0. !mm H2O |amount of PET remaining after water stored ! |in canopy is evaporated real :: esleft = 0. !mm H2O |potenial soil evap that is still available real :: evzp = 0. ! | real :: eosl = 0. !mm H2O |maximum amount of evaporation that can occur ! |from soil profile real :: dep = 0. !mm |soil depth from which evaporation will occur ! |in current soil layer real :: evz = 0. ! | real :: sev = 0. !mm H2O |amount of evaporation from soil layer real :: sev_st = 0. !mm H2O |evaporation / soil water for no3 flux from layer 1 -> 2 real :: cover = 0. !kg/ha |soil cover real :: wetvol_mm = 0. !mm |wetland water volume - average depth over hru integer :: ly = 0 !none |counter integer:: ires = 0 !Jaehak 2022 integer:: ihyd = 0 !Jaehak 2022 j = ihru pet = pet_day !! added statements for test of real statement above esd = 500. !soil(j)%zmx etco = 0.80 effnup = 0.05 ires= hru(j)%dbs%surf_stor !Jaehak 2022 !! evaporate canopy storage first !! canopy storage is calculated by the model only if the Green & Ampt !! method is used to calculate surface runoff. The curve number methods !! take canopy effects into account in the equations. For either of the !! CN methods, canstor will always equal zero. canev = 0. pet = pet - canstor(j) if (pet < 0.) then canstor(j) = -pet canev = pet_day pet = 0. ep_max = 0. es_max = 0. else canev = canstor(j) canstor(j) = 0. endif if (pet > 1.0e-6) then !! compute potential plant evap for methods other that Penman-Monteith !if (bsn_cc%pet /= 1) then if (pcom(j)%lai_sum <= 3.0) then ep_max = pcom(j)%lai_sum * pet / 3. else ep_max = pet end if if (ep_max < 0.) ep_max = 0. !end if !! compute potential soil evaporation cej = -5.e-5 eaj = 0. es_max = 0. eos1 = 0. cover = pl_mass(j)%ab_gr_com%m + rsd1(j)%tot_com%m if (hru(j)%sno_mm >= 0.5) then eaj = 0.5 else eaj = Exp(cej * (cover + 0.1)) end if es_max = pet * eaj eos1 = pet / (es_max + ep_max + 1.e-10) eos1 = es_max * eos1 es_max = Min(es_max, eos1) es_max = Max(es_max, 0.) if (wet(j)%flo > 0.) then !wetlands water evaporation reduced by canopy Jaehak 2022 if (pcom(j)%lai_sum <= 4.0) then ihyd = wet_dat(ires)%hyd es_max = wet_hyd(ihyd)%evrsv * (1.-pcom(j)%lai_sum / 4.) * pet !adapted from Sakaguchi et al. 2014 else es_max = 0. endif else !! make sure maximum plant and soil ET doesn't exceed potential ET if (pet_day < es_max + ep_max) then es_max = pet_day - ep_max if (pet < es_max + ep_max) then es_max = pet * es_max / (es_max + ep_max) ep_max = pet * ep_max / (es_max + ep_max) end if end if end if !! adjust es_max and ep_max for impervous urban cover !es_max = 0.5 * es_max !ep_max = 0.5 * ep_max !! initialize soil evaporation variables esleft = es_max !! compute sublimation if (w%tave > 0.) then if (hru(j)%sno_mm >= esleft) then !! take all soil evap from snow cover hru(j)%sno_mm = hru(j)%sno_mm - esleft snoev = snoev + esleft esleft = 0. else !! take all soil evap from snow cover before taking from soil esleft = esleft - hru(j)%sno_mm snoev = snoev + hru(j)%sno_mm hru(j)%sno_mm = 0. endif endif !! compute evaporation from ponded water wet_wat_d(j)%evap = 0. if (wet(j)%flo > 0.) then wetvol_mm = wet(j)%flo / (10. * hru(j)%area_ha) !mm=m3/(10.*ha) !! take all soil evap from wetland storage before taking from soil if (wetvol_mm >= esleft) then wetvol_mm = wetvol_mm - esleft wet_wat_d(j)%evap = esleft * (10. * hru(j)%area_ha) esleft = 0. else esleft = esleft - wetvol_mm wet_wat_d(j)%evap = wetvol_mm * (10. * hru(j)%area_ha) wetvol_mm = 0. endif wet(j)%flo = 10. * wetvol_mm * hru(j)%area_ha hru(j)%water_evap = wet_wat_d(j)%evap / (10. * hru(j)%area_ha) !mm=m3/(10*ha) endif !! take soil evap from each soil layer evzp = 0. eosl = esleft do ly = 1, soil(j)%nly !! depth exceeds max depth for soil evap (esd) dep = 0. if (ly == 1) then dep = soil(j)%phys(1)%d else dep = soil(j)%phys(ly-1)%d endif if (dep < esd) then !! calculate evaporation from soil layer evz = eosl * soil(j)%phys(ly)%d / (soil(j)%phys(ly)%d + & Exp(2.374 - .00713 * soil(j)%phys(ly)%d)) sev = evz - evzp * (1. - hru(j)%hyd%esco) evzp = evz if (soil(j)%phys(ly)%st < soil(j)%phys(ly)%fc) then xx = 2.5 * (soil(j)%phys(ly)%st - soil(j)%phys(ly)%fc) / & soil(j)%phys(ly)%fc sev = sev * exp(xx) end if sev = Min(sev, soil(j)%phys(ly)%st * etco) if (sev < 0.) sev = 0. if (sev > esleft) sev = esleft !! adjust soil storage, potential evap if (soil(j)%phys(ly)%st > sev) then esleft = esleft - sev soil(j)%phys(ly)%st = Max(1.e-6, soil(j)%phys(ly)%st - sev) else esleft = esleft - soil(j)%phys(ly)%st sev = soil(j)%phys(ly)%st soil(j)%phys(ly)%st = 0. endif endif !! compute no3 flux from layer 2 to 1 by soil evaporation if (ly == 2) then if (soil(j)%phys(2)%st > 1.e-3) then sev_st = sev / (soil(j)%phys(2)%st) else sev_st = 0. end if sev_st = amin1 (1., sev_st) no3up = effnup * sev_st * soil1(j)%mn(2)%no3 no3up = Min(no3up, soil1(j)%mn(2)%no3) soil1(j)%mn(2)%no3 = max(0.0001,soil1(j)%mn(2)%no3 - no3up) soil1(j)%mn(1)%no3 = max(0.0001,soil1(j)%mn(1)%no3 + no3up) endif end do !layer loop !! update total soil water content soil(j)%sw = 0. do ly = 1, soil(j)%nly soil(j)%sw = soil(j)%sw + soil(j)%phys(ly)%st end do !! calculate actual amount of evaporation from soil es_day = es_max - esleft if (es_day < 0.) es_day = 0. end if return end subroutine et_act