{
  "schema_version": "1.0",
  "last_updated": "2026-09-03",
  "product": "TerrainLogic",
  "validation_framework": ["implementation verification", "reference-model parity", "independent observational validation"],
  "erosion_reference_model_parity": {
    "reference_model": "USDA RUSLE2",
    "scope": "749 completed United States legacy-climate cases",
    "completed_cases": 749,
    "within_20_percent": { "count": 600, "percent": 80.1 },
    "within_20_percent_or_0_25_ton_acre_year": { "count": 707, "percent": 94.4 },
    "outside_both_limits": 42,
    "pearson_r": 0.9993,
    "r_squared": 0.9986,
    "mean_bias_error_ton_acre_year": 0.475,
    "limitation": "Reference-model parity is not independent measured-plot erosion validation."
  },
  "locked_erosion_regression_suite": {
    "cases": 199,
    "within_20_percent": { "count": 176, "percent": 88.4 },
    "within_practical_tolerance": { "count": 195, "percent": 98.0 },
    "outside_both_limits": 4,
    "mean_bias_error_ton_acre_year": -0.433,
    "pearson_r": 0.9973,
    "r_squared": 0.9946
  },
  "nutrient_endpoints": [
    { "endpoint": "Strict paired grain nitrogen removal", "dataset": "Transforming Drainage", "n": 112, "mbe_kg_n_ha": 9.33, "pbias_percent": 6.60, "rmse_kg_n_ha": 19.53, "spearman": 0.850, "nse": 0.790, "status": "independent domain-specific validation" },
    { "endpoint": "Soil-derived total phosphorus", "dataset": "MANAGE, harmonized no-application subset", "n": 15, "pbias_percent": -12.61, "correlation": 0.860, "nse": 0.580, "status": "independent domain-specific validation", "limitation": "Applied-P validation remains incomplete where required drivers are absent." },
    { "endpoint": "Surface-urea ammonia volatilization", "scope": "complete winter-wheat site-years", "n": 18, "mbe_kg_n_ha": 0.52, "pbias_percent": 3.77, "mae_kg_n_ha": 6.01, "rmse_kg_n_ha": 7.14, "pearson": 0.732, "spearman": 0.761, "nse": 0.485, "status": "input-limited candidate; not universal validation" }
  ],
  "preliminary_engineering_verification": {
    "frozen_equation_and_invariant_checks": { "passed": 50, "total": 50 },
    "waterway_neh_example_2_depth_difference_percent": 1.73,
    "terrace_matrix_cases": 6,
    "largest_terrace_equation_difference_percent": 0.11,
    "claim_level": "planning calculations only",
    "not_validated": ["peak-discharge hydrology", "DEM-derived drainage area or alignment", "outlet adequacy", "state-specific FOTG compliance", "utilities", "constructability", "as-built performance", "long-term maintenance"]
  },
  "canonical_human_reference": "https://contourstack.com/science-validation.html"
}