EcoSLIM

EcoSLIM is a Lagrangian, particle-tracking code that simulates advective and diffusive movement of water parcels. This code can be used to simulate age, diagnose travel times, source water composition and flowpaths. It integrates seamlessly with ParFlow-CLM.

Development Team

• Reed Maxwell rmaxwell@mines.edu
• Laura Condon lecondon@email.arizona.edu
• Mohammad Danesh-Yazdi danesh@sharif.edu
• Lindsay Bearup lbearup@usbr.gov

Citation

For more details on the model and if you use EcoSLIM in published work please cite the following reference:
Maxwell, R.M., L.E. Condon, M. Danesh-Yazdi and L.A. Bearup, Exploring source water mixing and transient residence time distributions of outflow and evapotranspiration with an integrated hydrologic model and Lagrangian particle tracking approach, Ecohydrology, doi: 10.1002/eco.2042, 2018.

Building and Running

To build EcoSLIM simply type make in the directory with the main directory where EcoSLIM.f90 sits.

To set the number of parallel threads use either export OMP_NUM_THREADS=16 for bash or setenv OMP_NUM_THREADS 16 for t/c-shell.

To run you will need to have a completed ParFlow simulation and an EcoSLIM input file that must be named slimin.txt and follow the format described below. Note that the slim input file does not need to be co-located with the ParFlow simulation.

To run simply execute EcoSLIM.exe from the directory that contains the slimin.txt input file.

Refer to the Examples directory described below for example workflows running ParFlow and EcoSLIM

Inputs

Mandatory File Inputs

1. EcoSlim driver file: The main EcoSLIM input file that includes information on domain geometry, ParFlow timing and input, and particle options. This file must be named slimin.txt. Refer to the Settings section for a complete description of this file.
2. ParFlow outputs: The following ParFlow outputs for at least one time must be provided as pfbs.
   • Velocity - In x, y, and z directions. Used for particle advection
   • Saturation - Used to determine the volume of water in a cell for determining particle mass
   • Porosity - Used to determine the volume of water in a cell for determining particle mass

Optional File Inputs

1. Elevation: DEM file for ParFlow domain in pfb format. If no DEM is provided all elevations are set to zero.
2. Evapotranspiration: Evapotranspiration files in pfb format (i.e. out.evaptrans.filenumber.pfb) that specifies the vertical water flux across the land surface. This is normally generated from by CLM calculations and written in ParFlow but can also be generated by ParFlow or even externally by the user. If evaptrans is less than zero particles will be added to the domain if evaptrans is greater than zero particles are removed through ET.
3. CLM single file output: Single file CLM output files (i.e. .C.pfb files). These are used to distinguish between rain and snow particles. NOTE: By default EcoSLIM assumes the CLM outputs have 10 soil layers but this may be changed in the code to be any number of soil layers. If the user wants to change the number of soil layers they can modify nCLMsoil in EcoSLIM.f90 and recompile.
4. Indicator File: A pfb format file with integer values assigning every grid cell in the domain to an indicator unit. If this file and a positive nind value are provided in the EcoSLIM driver file, EcoSLIM will summarize age and path length for every particle across each of the 1 to nind units in the indictor file. Cells with values of 0 or greater than nind specified in the EcoSLIM driver file will not be included in the indicator summaries but will still be included in the overall EcoSLIM particle tracking domain.

Settings

The slimin.txt file contains all of the settings for an EcoSLIM Simulation. An example of this file is provided below and other examples are also provided in the Examples folder. Inputs must be provided in the oder they appear in the template shown here.

Here we describe each parameter and what they do:

• EcoSLIM Runname (runname): The runname for all of the file outputs
• ParFlow Runname (pname): The runname used for the ParFlow simulations. If the ParFlow outputs are not located in the same directory as the EcoSLIM run this should also include the directory path to the ParFlow simulation as shown in the example below.
• DEM File Name (DEMname): The name of the DEM file for the ParFlow simulations. If this line is left blank all elevations will be set to zero. The DEM is used for VTK writing and does not ajust the Z values reported in outputs #.
• ParFlow nx (nx): Number of grid cells in the x-direction for ParFlow domain
• ParFlow ny (ny): Number of grid cells in the y-direction for ParFlow domain
• ParFlow nz (nz): Number of grid cells in the z-direction for ParFlow domain
• Number of Initial Particles (np_ic): If a positive integer is provided this will be the number of particles placed in every grid cell at the start of the simulation. To start from a previous EcoSLIM output set this value to -1. In this case particles will be initialized from the runname_particle_restart.bin file (refer to the outputs section for details on this file). If a negative integer less than <-1 is provided this number of particles will be placed in every grid cell in the top layer of the model.
• Total Particles (np): The total number of particles allowed in the simulation. If the particle count exceeds this at any point (i.e. through particle addition with initial conditions or rainfall events) the simulation will exit.
• ParFlow dx (dx): ParFlow grid cell size in the x-direction
• ParFlow dy (dy): ParFlow grid cell size in the y-direction
• ParFlow dz (dz): ParFlow grid cell size in the x-direction. This should be a list separated by comas that is nz long (refer to example below).
• ParFlow time step (pfdt): The time step used for the ParFlow simulation. The time units of this are determined by the ParFlow simulation and all EcoSLIM outputs will have the same units. Currently EcoSLIM assumes a constant time step so this is not compatible with growth times steps in ParFlow
• Starting ParFlow File Number (pft1): The file number for the ParFlow output to start the EcoSLIM simulation from. Note that the initial conditions will be set from the file number before this (i.e. the pressure and saturation files used to calculate particle masses for the initial particle assignment).
• Ending ParFlow File Number (pft2): The file number for the ParFlow output to stop the EcoSLIM simulation at.
• EcoSLIM Output Start Counter (tout1): This initializes the file numbering for the EcoSLIM outputs. If this is set to zero then the first EcoSLIM output number will be set to match starting ParFlow file number specified above.
• Particle Start Time Counter (part_tstart): This sets the start time that will be used for recording the particle input times in the exited particle logs. Generally this would be set to 0.0 but a non-zero number should be used for restarts to properly record the input time for particles inserted after the restart.
• Time Sequence Repeat (n_cycle): If the time sequence repeat is greater than one the ParFlow inputs from pft1 to pft2 will be repeated the specified n_cycle times. (i.e. the total number of time steps simulated will be n_cycle(pft2-pft1+1))
• ASCII 3-D Particle File Output Frequency (ipwrite): Controls ASCII output of particle locations and ages. This output format is not recommended for performance reasons. Refer to the Outputs section for the details on this output. If frequency is set to 0 this output will not be written at all, 1 will write the output every timestep, n>1 will write the output every n timesteps (i.e. n=2 writes outputs every other step). If n<0 then all outputs will be written to one file; useful for truly steady state simulation. (Transient outputs files: runname_transient_particle.filenum.3D, static output files: runname_total_particle_trace.3D)
• Particle VTK Output Frequency (ibinpntswrite): Controls VTK, binary output of particle locations and attributes (runname_pnts_filenum.vtk). Refer to the Outputs section for the details on this output. If frequency is set to 0 this output will not be written at all, 1 will write the output every timestep, n>1 will write the output every n timesteps (i.e. n=2 writes outputs every other step)
• Gridded ASCII ET Output Frequency (etwrite): Controls ASCII grid based ET output (runname_ET_summary.filenum.out.txt). Refer to the Outputs section for the details on this output. If frequency is set to 0 this output will not be written at all, 1 will write the output every timestep, n>1 will write the output every n timesteps (i.e. n=2 writes outputs every other step)
• Gridded VTK Output Frequency (icwrite): Controls VTK, binary grid based output (runname_cgrid_filenum.vtk). Refer to the Outputs section for the details on this output. If frequency is set to 0 this output will not be written at all, 1 will write the output every timestep, n>1 will write the output every n timesteps (i.e. n=2 writes outputs every other step)
• Velocity Multiplier (V_mult): Set to 1.0 for forward particle tracking and -1.0 for backward particle tracking
• CLM Evapotranspiration Flag (clmtrans): Logical flag (1=True, 0=False) indicating whether evapotranspiration outputs should be read (pfrunname.out.evapotrans.filenum.pfb). These files are normally generated by CLM but can also be generated by ParFlow (refer to examples for ParFlow and ParFlow-CLM test cases) or externally by the user. If this is set to false then no particles are added or removed through recharge and ET.
• CLM Variable Read Flag (clmfile): Logical flag (1=True, 0=False) indicating whether CLM variables should be read to classify recharge events as rain and snow. If false then all recharge events are assumed to be rain. #
• Number of Flux Particles (iflux_p_res): The number of particles to be added per grid cell per ParFLow time step when there is a positive flux into the domain.
• Density of Water (denh20): Density of water [M/L3], used for mass calculations. The units should match the mass and length units set by the ParFlow simulation.
• Molecular Diffusivity(moldiff): Molecular diffusivity
• Numerical Stability Scaler (dtfrac): Controls on the maximum timestep a particle can take to ensure numerical stability (i.e. in one dimension: Particle Timestep= min[(pfdt)( dtfrac), (dtfrac)(dx/Vpx)], where Vpx is the velocity in the x direction)
• Number of units in the indicator file (nind): An integer value indicating the number of units included in the indicator file. If this value is greater than 0, EcoSLIM will provide summary outputs for units 1 through nind. Therefore, nind should be the maximum integer value present in the indicator file. If this is set to 0 no indicator summaries will be created.
• Indicator File Name (Indname): The name of a pfb indicator file that will be used to summarize flow path lengths and ages. If this line is left and nind is set to zero then no indicator summaries will be provided.

Example format for the EcoSLIM input file

SLIM_hillslope   ! SLIM run name, path to ParFlow files follows, then DEM file
"/EcoSLIM/hillslope_clm/hillslope_clm"
"ER_dem.pfb"
20          !nx
5           !ny
5           !nz
20          !particles per cell at start of simulation (-1 = use restart file)
11000000    !np Total
5.0         !dx
0.2         !dy, dz follows
0.1, 0.1, 0.1, 0.1, 0.1
1.0         ! ParFlow DT
1          ! ParFlow t1: ParFlow file number to start from (initial condition is pft1-1)
1752       ! ParFlow t2: ParFlow file number to stop at
1          ! EcoSLIM output start counter 0=pft1
0.0          ! Particle start time counter (for recording particle insert times)
2          ! Time Sequence Repeat (n_cycle) Total number of time steps = [n_cycle*(pft2-pft1+1)]
0         ! ipwrite frequency, controls an ASCII, .3D particle file not recommended due to poor performance
0         ! ibinpntswrite frequency, controls VTK, binary output of particle locations and attributes
0         !  etwrite frequency, controls ASCII ET output
24        ! icwrite frequency,controls VTK, binary grid based output where particle masses, concentrations
1.0d0       ! velocity multiplier 1.0=forward, -1.0=backward
True         ! CLM Evap Trans Read logical
True           ! CLM Variables Read logical
10          ! number of particles per Evap Trans IC
1000.0      ! density H2O
0.00000414   ! Molecular Diffusivity
0.5d0       ! fraction of Dx/Vx for numerical stability
5           ! Number of indicators provided. If this value is greater than 0 an indicator file must be included
"../Indicator.1s.pfb" ! Name of the indictor file to use set to '' if not using an indicator file

Outputs

Single File Outputs

• EcoSLIM log: A log of the settings used for the simulations and any warnings that occur.
  • File name: runname.out.log
• Restart: Binary file containing all the particle information for all active particles at the end of the simulation.
  • File name: runname_particle_restart.bin
  • The first entry gives the number of particles in the restart file
  • Variables: X, Y, Z, Age, Saturated_Age, Mass, Source, Status, Particle_Concentration, Exit_Status, ParticleID, InitialX, InitialY, InitialZ, InsertTime, Path_Length, Saturated_Path_Length, IndicatorUnit_Path_Length(1:nind), IndicatorUnit_Age(1:nind)
• Exited Particles Log:
  • File name: runname_exited_particles.bin
  • Variables: Time, X, Y, Z, Age, Saturated_Age, Mass, Source, Exit_Status, ParticleID, InitialX, InitialY, InitialZ, InsertTime, Path_Length, Saturated_Path_Length, IndicatorUnit_Path_Length(1:nind), IndicatorUnit_Age(1:nind)
• ET summary: Spatially aggregated summary of ET flux composition
  • File name: runname_ET_output.txt
  • Variables: Time (TIME), mass weighted mean ET age (ET_age), mass fraction of ET from initial condition particles (ET_comp1), mass fraction of ET from rain particles (ET_comp2), mass fraction of ET from snow particles (ET_comp3), total ET mass (ET_mass), total number of ET particles (ET_NP)
• Outflow summary: Spatially aggregated summary of outflow composition
  • File name: runname_flow_output.txt
  • Variables: Time (TIME), mass weighted mean outflow age (Out_age), mass fraction of outflow from initial condition particles (Out_comp1), mass fraction of outflow from rain particles (Out_comp2), mass fraction of outflow from snow particles (Out_comp3), total outflow mass (out_mass), total number of outflow particles (Out_NP)
• Precipitation - ET summary: Spatially aggregated summary of total precipitation and ET mass fluxes calcualted from the ParFlow intputs.
  • File name:runname_PET_balance.txt
  • Variables: Time (TIME), total precipitation mass (P[kg]), total evapotranspiration mass (ET[kg])
• Particle ASCII: Detailed output of every particle in ascii FORMAT written to a single file.
  • File name:runname_particletrace.3D
  • Variables: X, Y, Z, Age, ParticleID
  • Note: This format is very slow in parallel and is NOT advised for large particle numbers. This file is only written if ipwrite is less than zero in slimin.txt

Transient File Outputs

Transient files outputs are written at the frequencies specified in the slimin.txt file (see: ibinpntswrite, icwrite, etwrite, ipwrite)

• Particle VTK: Detailed output of every particle in VTK format
  • File name: runname_pnts_filenum.vtk
  • Variables: *X, Y, Z, Age, Saturated_Age, Mass, Source, Status, Particle_Concentration, Exit_Status,ParticleID, InitialX, InitialY, InitialZ *
• Gridded VTK : Gridded summary of model outputs in VTK format
  • File name: runname_cgrid_filenum.vtk
  • Variables: Grid_Particle_Concentration, Mean_Age, Grid_Mass, Mean_Source, Grid_Concentration, ET_Particles, ET_Mass, ET_Age, ET_Source
• Gridded ASCII ET: Gridded summary of ET composition
  • File name: runname_ET_summary.filenum.out.txt
  • Variables: i, j, k, ET_Particles, ET_Mass, ET_Age, ET_Source, Saturation, Porosity
  • Note: ET variables are defined below, saturation and porosity are from the ParFlow inputs.
• Particle ASCII: Detailed output of every particle in ascii FORMAT
  • File name: runname_transient_particle.filenum.3D
  • Variables: X, Y, Z, Age, ParticlID
  • Note: This format is very slow in parallel and is not advised for large particle numbers

Output Variable Definitions

Particle Variables: Variables for individual particles

• ParticleID = Unique particle identifier [-]
• X = X coordinate [L]
• Y = Y coordinate [L]
• Z = Z coordinate relative to the bottom of the domain (i.e. not taking the DEM into account) [L]
• InitialX = X coordinate where particle was inserted [L]
• InitialY = Y coordinate where particle was inserted [L]
• InitialZ = Z coordinate relative to the bottom of the domain where particle was inserted(i.e. not taking the DEM into account) [L]
• InsertTime = The time the particle was added to the domain. This will be set to part_tstart for particles initialized in the domain.
• Age = Particle Residence Time [T]
• Saturated_Age= Total time that particle spends in saturated cells [T]
• Path_Length = Distance traveled [L]
• Saturated_Path_Length= Distance traveled in saturated cells [L]
• Mass= Particle Mass [M]
• Source = Particle source type (1= particles initialized in the domain, 2=particles added by a rain event, 3= particles added by a snow event) [-]
• Status = Flag indicating whether particle is currently active (1=active, 0=inactive) [-]
• Particle_Concentration= Placeholder, currently set to 1
• Exit_Status = Flag indicating how inactive particles left the domain (1=outflow, 2=ET) [-]
• IndicatorUnit_Path_Length= The portion of a particle's path length spent in indicator i [L].
• IndicatorUnit_Age= The portion of a particle's total age spent in indicator i [T].

Gridded Variables: Variables aggregated to the ParFlow grid cells at every ParFlow time step

• i = grid cell location in X (counting starts with 1) [-]
• j = grid cell location in Y (counting starts with 1) [-]
• k = grid cell location in Z (counting starts with 1) [-]
• Grid_Particle_Concentration = Total active particle mass in cell divided by the mass of water in cell [-]
• Mean_Age = Mass weighted average age of active particles in a cell [T]
• Grid_Mass = Active particle mass in a cell [M]
• Mean_Source = Mass weighted average source of active particles in a cell [-]
• Grid_Concentration = Mass weighted Particle_Concentration
• ET_Particles = Number of particles leaving as ET from a cell [-]
• ET_Mass = Total mass of particles leaving as ET from a cell [M]
• ET_Age = Mass weighted average age of particle leaving as ET from a cell [T]
• ET_Source = Mass weighted average source of particles leaving as ET from a cell [-]

Note: All Length [L] and Time [T] units are set by the ParFlow simulation and spatial coordinates start from the lower left hand corner of the bottom layer consistent with ParFlow.

Examples and tests contained in the repo

The Examples folder contains the following test cases. A short description is provided here. For more details on how to run the examples refer to the readme files in that directory. Note that the testing folder contains tests that were used for development purposes and which are not necessarily maintained with updated versions. User should refer only to the Examples folder.

1. ParFlow_SteadyFlux: A hillslope domain with constant recharge and ET applied at the top and bottom of the hill respectively. Example is setup to run EcoSLIM on transient ParFlow outputs without CLM. The documentation for this example includes all the steps for running ParFlow and EcoSLIM
2. Hillslope_Simulations/paper_cases:Hillslope Cases Run in Maxwell et al. Ecohydrology, see readme file for more details