{
  "context": "This evaluation criteria assesses how well the engineer uses FloPy's Buoyancy (BUY) package and related MODFLOW 6 packages to implement variable-density flow simulation for saltwater intrusion. The focus is entirely on correct package usage and API calls.",
  "type": "weighted_checklist",
  "checklist": [
    {
      "name": "Simulation creation",
      "description": "Uses flopy.mf6.MFSimulation to create a MODFLOW 6 simulation object with a specified simulation name and workspace",
      "max_score": 5
    },
    {
      "name": "Time discretization",
      "description": "Uses flopy.mf6.ModflowTdis to add time discretization package with 1 stress period, 1 time step, and appropriate time units",
      "max_score": 5
    },
    {
      "name": "Model creation",
      "description": "Uses flopy.mf6.ModflowGwf to create a groundwater flow model and add it to the simulation",
      "max_score": 5
    },
    {
      "name": "Grid discretization",
      "description": "Uses flopy.mf6.ModflowGwfdis to define structured grid with nlay=20, nrow=1, ncol=50, and cell dimensions delr=10, delc=10, top=20, botm (0 to -19)",
      "max_score": 10
    },
    {
      "name": "Initial conditions",
      "description": "Uses flopy.mf6.ModflowGwfic to set initial head conditions (strt parameter) to 5.0 m",
      "max_score": 5
    },
    {
      "name": "Node property flow",
      "description": "Uses flopy.mf6.ModflowGwfnpf to add hydraulic conductivity with k=10 m/day",
      "max_score": 7
    },
    {
      "name": "Storage package",
      "description": "Uses flopy.mf6.ModflowGwfsto to add storage properties (steady_state or transient with ss and sy values)",
      "max_score": 4
    },
    {
      "name": "Constant head boundaries",
      "description": "Uses flopy.mf6.ModflowGwfchd to add constant head boundaries on left (10.0 m) and right (0.0 m) sides with proper stress period data format",
      "max_score": 10
    },
    {
      "name": "Buoyancy package addition",
      "description": "Uses flopy.mf6.ModflowGwfbuy to add the Buoyancy package to the model",
      "max_score": 20
    },
    {
      "name": "Reference density",
      "description": "Configures denseref parameter in ModflowGwfbuy to 1000 kg/m³ for freshwater reference density",
      "max_score": 10
    },
    {
      "name": "Density slope",
      "description": "Configures density slope parameter in ModflowGwfbuy (typically drhodc or similar) to relate concentration to density (value around 0.025 or 25 for saltwater)",
      "max_score": 10
    },
    {
      "name": "IMS solver",
      "description": "Uses flopy.mf6.ModflowIms to add iterative model solution with appropriate complexity level and convergence criteria",
      "max_score": 4
    },
    {
      "name": "Output control",
      "description": "Uses flopy.mf6.ModflowGwfoc to configure output control for saving head output",
      "max_score": 3
    },
    {
      "name": "File writing",
      "description": "Calls simulation.write_simulation() method to write all model files to disk",
      "max_score": 2
    }
  ]
}