El Niño Tracker provides transparent, deterministic environmental risk assessments. We believe users deserve complete visibility into how data is transformed into risk scores.
The Deterministic Flood Risk Formula
Rather than relying on uninterpretable black-box algorithms, our platform calculates flood risk scores using a deterministic composite equation based on three physical inputs:
Input 1: 48-Hour Forecast Rainfall
The total precipitation forecast over the next 48 hours (in mm) from the Open-Meteo best-match NWP models:
Rain Score = min(100, (Rain48h / 80 mm) * 100)
Rationale: 80 mm of rain over 48 hours represents a widespread threshold for severe flash flooding and rapid stream overtopping.
Input 2: Near-Surface Soil Moisture
The volumetric water content (VWC) of the top 0–10 cm soil layer (m³/m³) from land-surface models:
Soil Score = min(100, (VWC / 0.55) * 100)
Rationale: 0.55 m³/m³ approximates complete saturation for typical soils. Saturated ground prevents infiltration and forces 100% of rain into surface runoff.
Input 3: River Discharge Ratio (GloFAS)
The ratio of peak 7-day forecast river discharge to the mean discharge over the previous 90 days, sourced from the Copernicus GloFAS model:
River Ratio = PeakForecastDischarge / MeanDischarge90d
River Score = clamp(((River Ratio - 1) / 2) * 100, 0, 100)
Rationale: A ratio of 1.0 indicates normal seasonal flow (score 0), while a ratio of 3.0 or greater indicates river discharge three times normal (score 100). This component is only included when mean flow exceeds 5 m³/s.
Composite Weighting and Tiers
When river flow data is available:
Total Score = round(0.40 * RainScore + 0.30 * SoilScore + 0.30 * RiverScore)
When river data is absent (e.g., small islands, arid plateaus):
Total Score = round(0.55 * RainScore + 0.45 * SoilScore)
| Risk Tier | Score Range | Physical Meaning & Trigger Conditions |
|---|---|---|
| Very High | 75–100% | Multiple strong signals at once: heavy forecast rain on saturated ground and/or rivers far above their recent flow. Check official warnings now and be ready to act. |
| High | 50–74% | Significant rain expected and/or wet soils or rising rivers. Localised flooding is plausible, especially in low-lying areas and along rivers. |
| Moderate | 25–49% | Some rain and moderately wet conditions. Flooding is unlikely to be widespread but drains, streams and flood-prone spots deserve attention. |
| Low | 0–24% | Little forecast rain, drier soils and normal river flow. Flash floods from intense local storms are still possible. |
Worked Example (Illustrative)
Consider a monitored river basin with the following hypothetical conditions:
- 48-Hour Forecast Rain: 40 mm → Rain Score = (40 / 80) * 100 = 50
- Current Soil Moisture: 0.44 m³/m³ → Soil Score = (0.44 / 0.55) * 100 = 80
- GloFAS River Discharge Ratio: 2.0 (double 90-day mean) → River Score = ((2.0 - 1) / 2) * 100 = 50
- Total Score: (0.40 * 50) + (0.30 * 80) + (0.30 * 50) = 20 + 24 + 15 = 59% (HIGH RISK)
Indexing Quality Control Safeguards
To avoid mass-producing low-value programmatic pages, our build system enforces strict automated checks. A programmatic page is only indexed if:
- Coordinates resolve to a verified geographic location with valid elevation and timezone data.
- Numerical weather and soil telemetry feeds return valid, complete data.
- The page provides verified local geographical, historical, and hydrological context.
Safety and Limitations Disclaimer
El Niño Tracker is an informational assessment tool. It does not replace official emergency warnings, evacuation orders, or directives issued by national meteorological and civil protection agencies. Small-scale urban drainage backups, dam breaks, and local flash floods can occur independently of regional model grids.