{
  "title": "Comal River Floodline Predictor Constants",
  "author": "Amy Coates",
  "location": "New Braunfels, Texas",
  "date": "2026-07-18",
  "source_citations": [
    {
      "id": "usgs-gauge-08235500",
      "description": "USGS Streamflow Gauge Station 08235500 - Comal River at New Braunfels",
      "url": "https://waterdata.usgs.gov/tx/nwis/uv?site_no=08235500"
    },
    {
      "id": "june-2007-texas-flooding",
      "wikidata": "Q6312080",
      "description": "Historical precedent: June 2007 Texas flooding event",
      "url": "https://www.wikidata.org/entity/Q6312080"
    },
    {
      "id": "austin-waterway-ban-2026",
      "description": "Current event: Austin issues waterway ban due to recent floods",
      "url": "https://www.fox7austin.com/news/texas-flooding-austin-issues-waterway-ban-due-recent-floods"
    },
    {
      "id": "nbhs-1935-memoirs",
      "description": "New Braunfels Historical Society: 1935 flood oral histories",
      "archive": "local"
    }
  ],
  "constants": {
    "alpha": {
      "value": 0.047,
      "unit": "ft_per_inch_rainfall",
      "description": "Aquifer response coefficient: limestone transmissivity factor",
      "derivation": "Mean of 1935, 1998, 2007 discharge curves normalized to rainfall input"
    },
    "beta": {
      "value": 0.12,
      "unit": "ft_per_hour",
      "description": "Base recession rate: spring-fed baseline drainage",
      "derivation": "Spring flow decay curve from Edwards Aquifer recharge zones"
    },
    "efficiency": {
      "value": 0.85,
      "unit": "dimensionless",
      "description": "Aquifer transmission efficiency: percentage of rainfall reaching river via conduit flow",
      "notes": "Accounts for evaporation loss during summer months (July-September)"
    },
    "flood_threshold": {
      "value": 3.2,
      "unit": "ft_above_mean_low_water",
      "description": "Historic bench elevation: 1935 plaza marker level",
      "validation": "Verified against 1998 flood watermark on library cornerstone"
    }
  },
  "equation": {
    "formula": "Δh = (α × R × ε) − (β × t)",
    "variables": {
      "Δh": "predicted river rise (ft)",
      "α": "aquifer response coefficient",
      "R": "accumulated rainfall upstream (inches)",
      "ε": "transmission efficiency",
      "β": "recession rate",
      "t": "hours since peak inflow"
    }
  },
  "usage_notes": [
    "Valid for July-October flood season when aquifer saturation exceeds 78%",
    "Does not account for sudden structural failures or upstream dam breaches",
    "Calibrated to mean annual discharge of 850 cfs at station 08235500",
    "For emergency evacuation decisions, always consult official NWS alerts"
  ],
  "machine_legible": true,
  "format_version": "1.0",
  "linked_pages": [
    "/comal-flood-predictor.html",
    "/comal-heritage-map.html",
    "/new-braunfels-roots.html"
  ]
}