gwt.f90

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! Groundwater Transport (GWT) Model
! The following are additional features/checks to add
!   * Add check that discretization is the same between both models
!   * Consider implementation of steady-state transport (affects MST, IST)
!   * Check and handle pore space discrepancy between flow and transport (porosity vs specific yield)
!   * UZT may not have the required porosity term
 
module gwtmodule
 
  use kindmodule, only: dp, i4b
  use constantsmodule, only: lenftype, lenmempath, dzero, done, &
                             lenpakloc, lenvarname, lenpackagetype
  use numericalmodelmodule, only: numericalmodeltype
 
  use basemodelmodule, only: basemodeltype
  use bndmodule, only: bndtype, addbndtolist, getbndfromlist
  use gwtdspmodule, only: gwtdsptype
  use gwtmstmodule, only: gwtmsttype
  use budgetmodule, only: budgettype
  use transportmodelmodule
  use matrixbasemodule
 
  implicit none
 
  private
  public :: gwt_cr
  public :: gwtmodeltype
  public :: castasgwtmodel
  public :: gwt_nbasepkg, gwt_nmultipkg
  public :: gwt_basepkg, gwt_multipkg
  character(len=LENVARNAME), parameter :: dvt = 'CONCENTRATION   ' !< dependent variable type, varies based on model type
  character(len=LENVARNAME), parameter :: dvu = 'MASS            ' !< dependent variable unit of measure, either "mass" or "energy"
  character(len=LENVARNAME), parameter :: dvua = 'M               ' !< abbreviation of the dependent variable unit of measure, either "M" or "E"
 
  type, extends(transportmodeltype) :: gwtmodeltype
 
    type(gwtmsttype), pointer :: mst => null() ! mass storage and transfer package
    type(gwtdsptype), pointer :: dsp => null() ! dispersion package
    integer(I4B), pointer :: inmst => null() ! unit number MST
    integer(I4B), pointer :: indsp => null() ! DSP enabled flag
 
  contains
 
    procedure :: model_df => gwt_df
    procedure :: model_ac => gwt_ac
    procedure :: model_mc => gwt_mc
    procedure :: model_ar => gwt_ar
    procedure :: model_rp => gwt_rp
    procedure :: model_ad => gwt_ad
    procedure :: model_cf => gwt_cf
    procedure :: model_fc => gwt_fc
    procedure :: model_cc => gwt_cc
    procedure :: model_cq => gwt_cq
    procedure :: model_bd => gwt_bd
    procedure :: model_ot => gwt_ot
    procedure :: model_da => gwt_da
    procedure :: model_bdentry => gwt_bdentry
    procedure :: allocate_scalars
    procedure :: get_iasym => gwt_get_iasym
    procedure :: create_packages => create_gwt_packages
    procedure, private :: create_bndpkgs
    procedure, private :: package_create
 
  end type gwtmodeltype
 
  !> @brief GWT base package array descriptors
  !!
  !! GWT6 model base package types.  Only listed packages are candidates
  !! for input and these will be loaded in the order specified.
  !<
  integer(I4B), parameter :: gwt_nbasepkg = 50
  character(len=LENPACKAGETYPE), dimension(GWT_NBASEPKG) :: gwt_basepkg
  data gwt_basepkg/'DIS6 ', 'DISV6', 'DISU6', '     ', '     ', & !  5
                  &'IC6  ', 'FMI6 ', 'MST6 ', 'ADV6 ', '     ', & ! 10
                  &'DSP6 ', 'SSM6 ', 'MVT6 ', 'OC6  ', '     ', & ! 15
                  &'OBS6 ', '     ', '     ', '     ', '     ', & ! 20
                  &30*'     '/ ! 50
 
  !> @brief GWT multi package array descriptors
  !!
  !! GWT6 model multi-instance package types.  Only listed packages are
  !! candidates for input and these will be loaded in the order specified.
  !<
  integer(I4B), parameter :: gwt_nmultipkg = 50
  character(len=LENPACKAGETYPE), dimension(GWT_NMULTIPKG) :: gwt_multipkg
  data gwt_multipkg/'CNC6 ', 'SRC6 ', 'LKT6 ', 'IST6 ', '     ', & !  5
                   &'SFT6 ', 'MWT6 ', 'UZT6 ', 'API6 ', '     ', & ! 10
                   &40*'     '/ ! 50
 
  ! -- size of supported model package arrays
  integer(I4B), parameter :: niunit_gwt = gwt_nbasepkg + gwt_nmultipkg
 
contains
 
  !> @brief Create a new groundwater transport model object
  !<
  subroutine gwt_cr(filename, id, modelname)
    ! -- modules
    use listsmodule, only: basemodellist
    use basemodelmodule, only: addbasemodeltolist
    use constantsmodule, only: linelength, lenpackagename
    use memoryhelpermodule, only: create_mem_path
    use memorymanagerextmodule, only: mem_set_value
    use gwtnaminputmodule, only: gwtnamparamfoundtype
    use budgetmodule, only: budget_cr
    ! -- dummy
    character(len=*), intent(in) :: filename !< input file
    integer(I4B), intent(in) :: id !< consecutive model number listed in mfsim.nam
    character(len=*), intent(in) :: modelname !< name of the model
    ! -- local
    integer(I4B) :: indis
    type(gwtmodeltype), pointer :: this
    class(basemodeltype), pointer :: model
    !
    ! -- Allocate a new GWT Model (this)
    allocate (this)
    !
    ! -- Set memory path before allocation in memory manager can be done
    this%memoryPath = create_mem_path(modelname)
    !
    ! -- Allocate scalars and add model to basemodellist
    call this%allocate_scalars(modelname)
    !
    ! -- set labels for transport model - needed by create_packages() below
    call this%set_tsp_labels(this%macronym, dvt, dvu, dvua)
    !
    model => this
    call addbasemodeltolist(basemodellist, model)
    !
    ! -- Call parent class routine
    call this%tsp_cr(filename, id, modelname, 'GWT', indis)
    !
    ! -- create model packages
    call this%create_packages(indis)
    !
    ! -- Return
    return
  end subroutine gwt_cr
 
  !> @brief Define packages of the GWT model
  !!
  !! This subroutine defines a gwt model type. Steps include:
  !!  (1) call df routines for each package
  !!  (2) set variables and pointers
  !<
  subroutine gwt_df(this)
    ! -- modules
    use simmodule, only: store_error
    ! -- dummy
    class(gwtmodeltype) :: this
    ! -- local
    integer(I4B) :: ip
    class(bndtype), pointer :: packobj
    !
    ! -- Define packages and utility objects
    call this%dis%dis_df()
    call this%fmi%fmi_df(this%dis, 1)
    if (this%inmvt > 0) call this%mvt%mvt_df(this%dis)
    if (this%inadv > 0) call this%adv%adv_df()
    if (this%indsp > 0) call this%dsp%dsp_df(this%dis)
    if (this%inssm > 0) call this%ssm%ssm_df()
    call this%oc%oc_df()
    call this%budget%budget_df(niunit_gwt, this%depvarunit, &
                               this%depvarunitabbrev)
    !
    ! -- Check for SSM package
    if (this%inssm == 0) then
      if (this%fmi%nflowpack > 0) then
        call store_error('Flow model has boundary packages, but there &
          &is no SSM package.  The SSM package must be activated.', &
          terminate=.true.)
      end if
    end if
    !
    ! -- Assign or point model members to dis members
    this%neq = this%dis%nodes
    this%nja = this%dis%nja
    this%ia => this%dis%con%ia
    this%ja => this%dis%con%ja
    !
    ! -- Allocate model arrays, now that neq and nja are assigned
    call this%allocate_arrays()
    !
    ! -- Define packages and assign iout for time series managers
    do ip = 1, this%bndlist%Count()
      packobj => getbndfromlist(this%bndlist, ip)
      call packobj%bnd_df(this%neq, this%dis)
      packobj%TsManager%iout = this%iout
      packobj%TasManager%iout = this%iout
    end do
    !
    ! -- Store information needed for observations
    call this%obs%obs_df(this%iout, this%name, 'GWT', this%dis)
    !
    ! -- Return
    return
  end subroutine gwt_df
 
  !> @brief Add the internal connections of this model to the sparse matrix
  !<
  subroutine gwt_ac(this, sparse)
    ! -- modules
    use sparsemodule, only: sparsematrix
    ! -- dummy
    class(gwtmodeltype) :: this
    type(sparsematrix), intent(inout) :: sparse
    ! -- local
    class(bndtype), pointer :: packobj
    integer(I4B) :: ip
    !
    ! -- Add the internal connections of this model to sparse
    call this%dis%dis_ac(this%moffset, sparse)
    if (this%indsp > 0) &
      call this%dsp%dsp_ac(this%moffset, sparse)
    !
    ! -- Add any package connections
    do ip = 1, this%bndlist%Count()
      packobj => getbndfromlist(this%bndlist, ip)
      call packobj%bnd_ac(this%moffset, sparse)
    end do
    !
    ! -- Return
    return
  end subroutine gwt_ac
 
  !> @brief Map the positions of the GWT model connections in the numerical
  !! solution coefficient matrix.
  !<
  subroutine gwt_mc(this, matrix_sln)
    ! -- dummy
    class(gwtmodeltype) :: this
    class(matrixbasetype), pointer :: matrix_sln !< global system matrix
    ! -- local
    class(bndtype), pointer :: packobj
    integer(I4B) :: ip
    !
    ! -- Find the position of each connection in the global ia, ja structure
    !    and store them in idxglo.
    call this%dis%dis_mc(this%moffset, this%idxglo, matrix_sln)
    !
    if (this%indsp > 0) call this%dsp%dsp_mc(this%moffset, matrix_sln)
    !
    ! -- Map any package connections
    do ip = 1, this%bndlist%Count()
      packobj => getbndfromlist(this%bndlist, ip)
      call packobj%bnd_mc(this%moffset, matrix_sln)
    end do
    !
    ! -- Return
    return
  end subroutine gwt_mc
 
  !> @brief GWT Model Allocate and Read
  !!
  !! This subroutine:
  !!   - allocates and reads packages that are part of this model,
  !!   - allocates memory for arrays used by this model object
  !<
  subroutine gwt_ar(this)
    ! -- modules
    use constantsmodule, only: dhnoflo
    ! -- dummy
    class(gwtmodeltype) :: this
    ! -- locals
    integer(I4B) :: ip
    class(bndtype), pointer :: packobj
    !
    ! -- Allocate and read modules attached to model
    call this%fmi%fmi_ar(this%ibound)
    if (this%inmvt > 0) call this%mvt%mvt_ar()
    if (this%inic > 0) call this%ic%ic_ar(this%x)
    if (this%inmst > 0) call this%mst%mst_ar(this%dis, this%ibound)
    if (this%inadv > 0) call this%adv%adv_ar(this%dis, this%ibound)
    if (this%indsp > 0) call this%dsp%dsp_ar(this%ibound, this%mst%thetam)
    if (this%inssm > 0) call this%ssm%ssm_ar(this%dis, this%ibound, this%x)
    if (this%inobs > 0) call this%obs%tsp_obs_ar(this%ic, this%x, this%flowja)
    !
    ! -- Set governing equation scale factor. Note that this scale factor
    ! -- cannot be set arbitrarily. For solute transport, it must be set
    ! -- to 1.  Setting it to a different value will NOT automatically
    ! -- scale all the terms of the governing equation correctly by that
    ! -- value. This is because much of the coding in the associated
    ! -- packages implicitly assumes the governing equation for solute
    ! -- transport is scaled by 1. (effectively unscaled).
    this%eqnsclfac = done
    !
    ! -- Call dis_ar to write binary grid file
    !call this%dis%dis_ar(this%npf%icelltype)
    !
    ! -- set up output control
    call this%oc%oc_ar(this%x, this%dis, dhnoflo, this%depvartype)
    call this%budget%set_ibudcsv(this%oc%ibudcsv)
    !
    ! -- Package input files now open, so allocate and read
    do ip = 1, this%bndlist%Count()
      packobj => getbndfromlist(this%bndlist, ip)
      call packobj%set_pointers(this%dis%nodes, this%ibound, this%x, &
                                this%xold, this%flowja)
      ! -- Read and allocate package
      call packobj%bnd_ar()
    end do
    !
    ! -- Return
    return
  end subroutine gwt_ar
 
  !> @brief GWT Model Read and Prepare
  !!
  !! Call the read and prepare routines of the attached packages
  !<
  subroutine gwt_rp(this)
    ! -- modules
    use tdismodule, only: readnewdata
    ! -- dummy
    class(gwtmodeltype) :: this
    ! -- local
    class(bndtype), pointer :: packobj
    integer(I4B) :: ip
    !
    ! -- In fmi, check for mvt and mvrbudobj consistency
    call this%fmi%fmi_rp(this%inmvt)
    if (this%inmvt > 0) call this%mvt%mvt_rp()
    !
    ! -- Check with TDIS on whether or not it is time to RP
    if (.not. readnewdata) return
    !
    ! -- Read and prepare
    if (this%inoc > 0) call this%oc%oc_rp()
    if (this%inssm > 0) call this%ssm%ssm_rp()
    do ip = 1, this%bndlist%Count()
      packobj => getbndfromlist(this%bndlist, ip)
      call packobj%bnd_rp()
      call packobj%bnd_rp_obs()
    end do
    !
    ! -- Return
    return
  end subroutine gwt_rp
 
  !> @brief GWT Model Time Step Advance
  !!
  !! Call the advance subroutines of the attached packages
  !<
  subroutine gwt_ad(this)
    ! -- modules
    use simvariablesmodule, only: isimcheck, ifailedstepretry
    ! -- dummy
    class(gwtmodeltype) :: this
    class(bndtype), pointer :: packobj
    ! -- local
    integer(I4B) :: irestore
    integer(I4B) :: ip, n
    !
    ! -- Reset state variable
    irestore = 0
    if (ifailedstepretry > 0) irestore = 1
    if (irestore == 0) then
      !
      ! -- copy x into xold
      do n = 1, this%dis%nodes
        if (this%ibound(n) == 0) then
          this%xold(n) = dzero
        else
          this%xold(n) = this%x(n)
        end if
      end do
    else
      !
      ! -- copy xold into x if this time step is a redo
      do n = 1, this%dis%nodes
        this%x(n) = this%xold(n)
      end do
    end if
    !
    ! -- Advance fmi
    call this%fmi%fmi_ad(this%x)
    !
    ! -- Advance
    if (this%indsp > 0) call this%dsp%dsp_ad()
    if (this%inssm > 0) call this%ssm%ssm_ad()
    do ip = 1, this%bndlist%Count()
      packobj => getbndfromlist(this%bndlist, ip)
      call packobj%bnd_ad()
      if (isimcheck > 0) then
        call packobj%bnd_ck()
      end if
    end do
    !
    ! -- Push simulated values to preceding time/subtime step
    call this%obs%obs_ad()
    !
    ! -- Return
    return
  end subroutine gwt_ad
 
  !> @brief GWT Model calculate coefficients
  !!
  !! Call the calculate coefficients subroutines of the attached packages
  !<
  subroutine gwt_cf(this, kiter)
    ! -- modules
    ! -- dummy
    class(gwtmodeltype) :: this
    integer(I4B), intent(in) :: kiter
    ! -- local
    class(bndtype), pointer :: packobj
    integer(I4B) :: ip
    !
    ! -- Call package cf routines
    do ip = 1, this%bndlist%Count()
      packobj => getbndfromlist(this%bndlist, ip)
      call packobj%bnd_cf()
    end do
    !
    ! -- Return
    return
  end subroutine gwt_cf
 
  !> @brief GWT Model fill coefficients
  !!
  !! Call the fill coefficients subroutines attached packages
  !<
  subroutine gwt_fc(this, kiter, matrix_sln, inwtflag)
    ! -- modules
    ! -- dummy
    class(gwtmodeltype) :: this
    integer(I4B), intent(in) :: kiter
    class(matrixbasetype), pointer :: matrix_sln
    integer(I4B), intent(in) :: inwtflag
    ! -- local
    class(bndtype), pointer :: packobj
    integer(I4B) :: ip
    !
    ! -- call fc routines
    call this%fmi%fmi_fc(this%dis%nodes, this%xold, this%nja, matrix_sln, &
                         this%idxglo, this%rhs)
    if (this%inmvt > 0) then
      call this%mvt%mvt_fc(this%x, this%x)
    end if
    if (this%inmst > 0) then
      call this%mst%mst_fc(this%dis%nodes, this%xold, this%nja, matrix_sln, &
                           this%idxglo, this%x, this%rhs, kiter)
    end if
    if (this%inadv > 0) then
      call this%adv%adv_fc(this%dis%nodes, matrix_sln, this%idxglo, this%x, &
                           this%rhs)
    end if
    if (this%indsp > 0) then
      call this%dsp%dsp_fc(kiter, this%dis%nodes, this%nja, matrix_sln, &
                           this%idxglo, this%rhs, this%x)
    end if
    if (this%inssm > 0) then
      call this%ssm%ssm_fc(matrix_sln, this%idxglo, this%rhs)
    end if
    !
    ! -- packages
    do ip = 1, this%bndlist%Count()
      packobj => getbndfromlist(this%bndlist, ip)
      call packobj%bnd_fc(this%rhs, this%ia, this%idxglo, matrix_sln)
    end do
    !
    ! -- Return
    return
  end subroutine gwt_fc
 
  !> @brief GWT Model Final Convergence Check
  !!
  !! If MVR/MVT is active, call the MVR convergence check subroutines to force
  !! at least 2 outer iterations. The other advanced transport packages are
  !! solved in the matrix equations directly which means the solver is
  !! completing the necessary checks thereby eliminating need to call package
  !! cc routines.  That is, no need to loop over active packages and run:
  !! call packobj%bnd_cc(iend, icnvg, hclose, rclose)
  !<
  subroutine gwt_cc(this, innertot, kiter, iend, icnvgmod, cpak, ipak, dpak)
    ! -- dummy
    class(gwtmodeltype) :: this
    integer(I4B), intent(in) :: innertot
    integer(I4B), intent(in) :: kiter
    integer(I4B), intent(in) :: iend
    integer(I4B), intent(in) :: icnvgmod
    character(len=LENPAKLOC), intent(inout) :: cpak
    integer(I4B), intent(inout) :: ipak
    real(DP), intent(inout) :: dpak
    ! -- local
    ! -- formats
    !
    ! -- If mover is on, then at least 2 outers required
    if (this%inmvt > 0) call this%mvt%mvt_cc(kiter, iend, icnvgmod, cpak, dpak)
    !
    ! -- Return
    return
  end subroutine gwt_cc
 
  !> @brief GWT Model calculate flow
  !!
  !! Call the intercell flows (flow ja) subroutine
  !<
  subroutine gwt_cq(this, icnvg, isuppress_output)
    ! -- modules
    use sparsemodule, only: csr_diagsum
    ! -- dummy
    class(gwtmodeltype) :: this
    integer(I4B), intent(in) :: icnvg
    integer(I4B), intent(in) :: isuppress_output
    ! -- local
    integer(I4B) :: i
    integer(I4B) :: ip
    class(bndtype), pointer :: packobj
    !
    ! -- Construct the flowja array.  Flowja is calculated each time, even if
    !    output is suppressed.  (flowja is positive into a cell.)  The diagonal
    !    position of the flowja array will contain the flow residual after
    !    these routines are called, so each package is responsible for adding
    !    its flow to this diagonal position.
    do i = 1, this%nja
      this%flowja(i) = dzero
    end do
    if (this%inadv > 0) call this%adv%adv_cq(this%x, this%flowja)
    if (this%indsp > 0) call this%dsp%dsp_cq(this%x, this%flowja)
    if (this%inmst > 0) call this%mst%mst_cq(this%dis%nodes, this%x, this%xold, &
                                             this%flowja)
    if (this%inssm > 0) call this%ssm%ssm_cq(this%flowja)
    if (this%infmi > 0) call this%fmi%fmi_cq(this%x, this%flowja)
    !
    ! -- Go through packages and call cq routines.  cf() routines are called
    !    first to regenerate non-linear terms to be consistent with the final
    !    conc solution.
    do ip = 1, this%bndlist%Count()
      packobj => getbndfromlist(this%bndlist, ip)
      call packobj%bnd_cf()
      call packobj%bnd_cq(this%x, this%flowja)
    end do
    !
    ! -- Finalize calculation of flowja by adding face flows to the diagonal.
    !    This results in the flow residual being stored in the diagonal
    !    position for each cell.
    call csr_diagsum(this%dis%con%ia, this%flowja)
    !
    ! -- Return
    return
  end subroutine gwt_cq
 
  !> @brief GWT Model Budget
  !!
  !! This subroutine:
  !!  (1) calculates intercell flows (flowja)
  !!  (2) calculates package contributions to the model budget
  !<
  subroutine gwt_bd(this, icnvg, isuppress_output)
    use constantsmodule, only: dzero
    ! -- dummy
    class(gwtmodeltype) :: this
    integer(I4B), intent(in) :: icnvg
    integer(I4B), intent(in) :: isuppress_output
    ! -- local
    integer(I4B) :: ip
    class(bndtype), pointer :: packobj
    !
    ! -- Save the solution convergence flag
    this%icnvg = icnvg
    !
    ! -- Budget routines (start by resetting).  Sole purpose of this section
    !    is to add in and outs to model budget.  All ins and out for a model
    !    should be added here to this%budget.  In a subsequent exchange call,
    !    exchange flows might also be added.
    call this%budget%reset()
    if (this%inmst > 0) call this%mst%mst_bd(isuppress_output, this%budget)
    if (this%inssm > 0) call this%ssm%ssm_bd(isuppress_output, this%budget)
    if (this%infmi > 0) call this%fmi%fmi_bd(isuppress_output, this%budget)
    if (this%inmvt > 0) call this%mvt%mvt_bd(this%x, this%x)
    do ip = 1, this%bndlist%Count()
      packobj => getbndfromlist(this%bndlist, ip)
      call packobj%bnd_bd(this%budget)
    end do
    !
    ! -- Return
    return
  end subroutine gwt_bd
 
  !> @brief Print and/or save model output
  !!
  !! Call the parent class output routine
  !<
  subroutine gwt_ot(this)
    ! -- dummy
    class(gwtmodeltype) :: this
    ! -- local
    integer(I4B) :: icbcfl
    integer(I4B) :: icbcun
    !
    !
    ! -- Initialize
    icbcfl = 0
    !
    ! -- Because mst belongs to gwt, call mst_ot_flow directly (and not from parent)
    if (this%oc%oc_save('BUDGET')) icbcfl = 1
    icbcun = this%oc%oc_save_unit('BUDGET')
    if (this%inmst > 0) call this%mst%mst_ot_flow(icbcfl, icbcun)
    !
    ! -- Call parent class _ot routines.
    call this%tsp_ot(this%inmst)
    !
    ! -- Return
    return
  end subroutine gwt_ot
 
  !> @brief Deallocate
  !!
  !! Deallocate memory at conclusion of model run
  !<
  subroutine gwt_da(this)
    ! -- modules
    use memorymanagermodule, only: mem_deallocate
    use memorymanagerextmodule, only: memorylist_remove
    use simvariablesmodule, only: idm_context
    ! -- dummy
    class(gwtmodeltype) :: this
    ! -- local
    integer(I4B) :: ip
    class(bndtype), pointer :: packobj
    !
    ! -- Deallocate idm memory
    call memorylist_remove(this%name, 'NAM', idm_context)
    call memorylist_remove(component=this%name, context=idm_context)
    !
    ! -- Internal flow packages deallocate
    call this%dis%dis_da()
    call this%ic%ic_da()
    call this%fmi%fmi_da()
    call this%adv%adv_da()
    call this%dsp%dsp_da()
    call this%ssm%ssm_da()
    call this%mst%mst_da()
    call this%mvt%mvt_da()
    call this%budget%budget_da()
    call this%oc%oc_da()
    call this%obs%obs_da()
    !
    ! -- Internal package objects
    deallocate (this%dis)
    deallocate (this%ic)
    deallocate (this%dsp)
    deallocate (this%ssm)
    deallocate (this%mst)
    deallocate (this%adv)
    deallocate (this%mvt)
    deallocate (this%budget)
    deallocate (this%oc)
    deallocate (this%obs)
    !
    ! -- Boundary packages
    do ip = 1, this%bndlist%Count()
      packobj => getbndfromlist(this%bndlist, ip)
      call packobj%bnd_da()
      deallocate (packobj)
    end do
    !
    ! -- Scalars
    call mem_deallocate(this%indsp)
    call mem_deallocate(this%inmst)
    !
    ! -- Parent class members
    call this%TransportModelType%tsp_da()
    !
    ! -- NumericalModelType
    call this%NumericalModelType%model_da()
    !
    ! -- Return
    return
  end subroutine gwt_da
 
  !> @brief GroundWater Transport Model Budget Entry
  !!
  !! This subroutine adds a budget entry to the flow budget.  It was added as
  !! a method for the gwt model object so that the exchange object could add its
  !! contributions.
  !<
  subroutine gwt_bdentry(this, budterm, budtxt, rowlabel)
    ! -- modules
    use constantsmodule, only: lenbudtxt
    use tdismodule, only: delt
    ! -- dummy
    class(gwtmodeltype) :: this
    real(DP), dimension(:, :), intent(in) :: budterm
    character(len=LENBUDTXT), dimension(:), intent(in) :: budtxt
    character(len=*), intent(in) :: rowlabel
    !
    call this%budget%addentry(budterm, delt, budtxt, rowlabel=rowlabel)
    !
    ! -- Return
    return
  end subroutine gwt_bdentry
 
  !> @brief return 1 if any package causes the matrix to be asymmetric.
  !! Otherwise return 0.
  !<
  function gwt_get_iasym(this) result(iasym)
    class(gwtmodeltype) :: this
    ! -- local
    integer(I4B) :: iasym
    integer(I4B) :: ip
    class(bndtype), pointer :: packobj
    !
    ! -- Start by setting iasym to zero
    iasym = 0
    !
    ! -- ADV
    if (this%inadv > 0) then
      if (this%adv%iasym /= 0) iasym = 1
    end if
    !
    ! -- DSP
    if (this%indsp > 0) then
      if (this%dsp%ixt3d /= 0) iasym = 1
    end if
    !
    ! -- Check for any packages that introduce matrix asymmetry
    do ip = 1, this%bndlist%Count()
      packobj => getbndfromlist(this%bndlist, ip)
      if (packobj%iasym /= 0) iasym = 1
    end do
    !
    ! -- Return
    return
  end function gwt_get_iasym
 
  !> Allocate memory for non-allocatable members
  !!
  !! A subroutine for allocating the scalars specific to the GWT model type.
  !! Additional scalars used by the parent class are allocated by the parent
  !! class.
  !<
  subroutine allocate_scalars(this, modelname)
    ! -- modules
    use memorymanagermodule, only: mem_allocate
    ! -- dummy
    class(gwtmodeltype) :: this
    character(len=*), intent(in) :: modelname
    !
    ! -- allocate parent class scalars
    call this%allocate_tsp_scalars(modelname)
    !
    ! -- allocate additional members specific to GWT model type
    call mem_allocate(this%inmst, 'INMST', this%memoryPath)
    call mem_allocate(this%indsp, 'INDSP', this%memoryPath)
    !
    this%inmst = 0
    this%indsp = 0
    !
    ! -- Return
    return
  end subroutine allocate_scalars
 
  !> @brief Create boundary condition packages for this model
  !!
  !! Call the package create routines for packages activated by the user.
  !<
  subroutine package_create(this, filtyp, ipakid, ipaknum, pakname, mempath, &
                            inunit, iout)
    ! -- modules
    use constantsmodule, only: linelength
    use simmodule, only: store_error
    use gwtcncmodule, only: cnc_create
    use gwtsrcmodule, only: src_create
    use gwtistmodule, only: ist_create
    use gwtlktmodule, only: lkt_create
    use gwtsftmodule, only: sft_create
    use gwtmwtmodule, only: mwt_create
    use gwtuztmodule, only: uzt_create
    use apimodule, only: api_create
    ! -- dummy
    class(gwtmodeltype) :: this
    character(len=*), intent(in) :: filtyp
    character(len=LINELENGTH) :: errmsg
    integer(I4B), intent(in) :: ipakid
    integer(I4B), intent(in) :: ipaknum
    character(len=*), intent(in) :: pakname
    character(len=*), intent(in) :: mempath
    integer(I4B), intent(in) :: inunit
    integer(I4B), intent(in) :: iout
    ! -- local
    class(bndtype), pointer :: packobj
    class(bndtype), pointer :: packobj2
    integer(I4B) :: ip
    !
    ! -- This part creates the package object
    select case (filtyp)
    case ('CNC6')
      call cnc_create(packobj, ipakid, ipaknum, inunit, iout, this%name, &
                      pakname, dvt, mempath)
    case ('SRC6')
      call src_create(packobj, ipakid, ipaknum, inunit, iout, this%name, &
                      this%depvartype, pakname)
    case ('LKT6')
      call lkt_create(packobj, ipakid, ipaknum, inunit, iout, this%name, &
                      pakname, this%fmi, this%eqnsclfac, this%depvartype, &
                      this%depvarunit, this%depvarunitabbrev)
    case ('SFT6')
      call sft_create(packobj, ipakid, ipaknum, inunit, iout, this%name, &
                      pakname, this%fmi, this%eqnsclfac, this%depvartype, &
                      this%depvarunit, this%depvarunitabbrev)
    case ('MWT6')
      call mwt_create(packobj, ipakid, ipaknum, inunit, iout, this%name, &
                      pakname, this%fmi, this%eqnsclfac, this%depvartype, &
                      this%depvarunit, this%depvarunitabbrev)
    case ('UZT6')
      call uzt_create(packobj, ipakid, ipaknum, inunit, iout, this%name, &
                      pakname, this%fmi, this%eqnsclfac, this%depvartype, &
                      this%depvarunit, this%depvarunitabbrev)
    case ('IST6')
      call ist_create(packobj, ipakid, ipaknum, inunit, iout, this%name, &
                      pakname, this%fmi, this%mst)
    case ('API6')
      call api_create(packobj, ipakid, ipaknum, inunit, iout, this%name, pakname)
    case default
      write (errmsg, *) 'Invalid package type: ', filtyp
      call store_error(errmsg, terminate=.true.)
    end select
    !
    ! -- Packages is the bndlist that is associated with the parent model
    ! -- The following statement puts a pointer to this package in the ipakid
    ! -- position of packages.
    do ip = 1, this%bndlist%Count()
      packobj2 => getbndfromlist(this%bndlist, ip)
      if (packobj2%packName == pakname) then
        write (errmsg, '(a,a)') 'Cannot create package.  Package name  '// &
          'already exists: ', trim(pakname)
        call store_error(errmsg, terminate=.true.)
      end if
    end do
    call addbndtolist(this%bndlist, packobj)
    !
    ! -- Return
    return
  end subroutine package_create
 
  !> @brief Cast to GwtModelType
  !<
  function castasgwtmodel(model) result(gwtmodel)
    class(*), pointer :: model !< The object to be cast
    class(gwtmodeltype), pointer :: gwtmodel !< The GWT model
    !
    gwtmodel => null()
    if (.not. associated(model)) return
    select type (model)
    type is (gwtmodeltype)
      gwtmodel => model
    end select
    !
    ! -- Return
    return
  end function castasgwtmodel
 
  !> @brief Source package info and begin to process
  !<
  subroutine create_bndpkgs(this, bndpkgs, pkgtypes, pkgnames, &
                            mempaths, inunits)
    ! -- modules
    use constantsmodule, only: linelength, lenpackagename
    use characterstringmodule, only: characterstringtype
    ! -- dummy
    class(gwtmodeltype) :: this
    integer(I4B), dimension(:), allocatable, intent(inout) :: bndpkgs
    type(characterstringtype), dimension(:), contiguous, &
      pointer, intent(inout) :: pkgtypes
    type(characterstringtype), dimension(:), contiguous, &
      pointer, intent(inout) :: pkgnames
    type(characterstringtype), dimension(:), contiguous, &
      pointer, intent(inout) :: mempaths
    integer(I4B), dimension(:), contiguous, &
      pointer, intent(inout) :: inunits
    ! -- local
    integer(I4B) :: ipakid, ipaknum
    character(len=LENFTYPE) :: pkgtype, bndptype
    character(len=LENPACKAGENAME) :: pkgname
    character(len=LENMEMPATH) :: mempath
    integer(I4B), pointer :: inunit
    integer(I4B) :: n
    !
    if (allocated(bndpkgs)) then
      !
      ! -- create stress packages
      ipakid = 1
      bndptype = ''
      do n = 1, size(bndpkgs)
        !
        pkgtype = pkgtypes(bndpkgs(n))
        pkgname = pkgnames(bndpkgs(n))
        mempath = mempaths(bndpkgs(n))
        inunit => inunits(bndpkgs(n))
        !
        if (bndptype /= pkgtype) then
          ipaknum = 1
          bndptype = pkgtype
        end if
        !
        call this%package_create(pkgtype, ipakid, ipaknum, pkgname, mempath, &
                                 inunit, this%iout)
        ipakid = ipakid + 1
        ipaknum = ipaknum + 1
      end do
      !
      ! -- cleanup
      deallocate (bndpkgs)
    end if
    !
    ! -- Return
    return
  end subroutine create_bndpkgs
 
  !> @brief Source package info and begin to process
  !<
  subroutine create_gwt_packages(this, indis)
    ! -- modules
    use constantsmodule, only: linelength, lenpackagename
    use characterstringmodule, only: characterstringtype
    use arrayhandlersmodule, only: expandarray
    use memorymanagermodule, only: mem_setptr
    use memoryhelpermodule, only: create_mem_path
    use simvariablesmodule, only: idm_context
    use gwtmstmodule, only: mst_cr
    use gwtdspmodule, only: dsp_cr
    ! -- dummy
    class(gwtmodeltype) :: this
    integer(I4B), intent(in) :: indis
    ! -- local
    type(characterstringtype), dimension(:), contiguous, &
      pointer :: pkgtypes => null()
    type(characterstringtype), dimension(:), contiguous, &
      pointer :: pkgnames => null()
    type(characterstringtype), dimension(:), contiguous, &
      pointer :: mempaths => null()
    integer(I4B), dimension(:), contiguous, &
      pointer :: inunits => null()
    character(len=LENMEMPATH) :: model_mempath
    character(len=LENFTYPE) :: pkgtype
    character(len=LENPACKAGENAME) :: pkgname
    character(len=LENMEMPATH) :: mempath
    integer(I4B), pointer :: inunit
    integer(I4B), dimension(:), allocatable :: bndpkgs
    integer(I4B) :: n
    character(len=LENMEMPATH) :: mempathdsp = ''
    !
    ! -- set input memory paths, input/model and input/model/namfile
    model_mempath = create_mem_path(component=this%name, context=idm_context)
    !
    ! -- set pointers to model path package info
    call mem_setptr(pkgtypes, 'PKGTYPES', model_mempath)
    call mem_setptr(pkgnames, 'PKGNAMES', model_mempath)
    call mem_setptr(mempaths, 'MEMPATHS', model_mempath)
    call mem_setptr(inunits, 'INUNITS', model_mempath)
    !
    do n = 1, size(pkgtypes)
      !
      ! attributes for this input package
      pkgtype = pkgtypes(n)
      pkgname = pkgnames(n)
      mempath = mempaths(n)
      inunit => inunits(n)
      !
      ! -- create dis package as it is a prerequisite for other packages
      select case (pkgtype)
      case ('MST6')
        this%inmst = inunit
      case ('DSP6')
        this%indsp = 1
        mempathdsp = mempath
      case ('CNC6', 'SRC6', 'LKT6', 'SFT6', &
            'MWT6', 'UZT6', 'IST6', 'API6')
        call expandarray(bndpkgs)
        bndpkgs(size(bndpkgs)) = n
      case default
        ! TODO
      end select
    end do
    !
    ! -- Create packages that are tied directly to model
    call mst_cr(this%mst, this%name, this%inmst, this%iout, this%fmi)
    call dsp_cr(this%dsp, this%name, mempathdsp, this%indsp, this%iout, &
                this%fmi)
    !
    ! -- Check to make sure that required ftype's have been specified
    call this%ftype_check(indis, this%inmst)
    !
    call this%create_bndpkgs(bndpkgs, pkgtypes, pkgnames, mempaths, inunits)
    !
    ! -- Return
    return
  end subroutine create_gwt_packages
 
end module gwtmodule