Storm Surge Height & Inland Hazard (SLOSH Simplified) – Cyclone Inundation Tool

Storm Surge Height & Inland Hazard (SLOSH Simplified)

Saffir‑Simpson categories • Landfall surge • Coastal topography • Inundation depth • Evacuation zones

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📐 1. Storm Surge & Inland Flooding – SLOSH Method

Storm surge is the abnormal rise of water generated by a cyclone. The NOAA SLOSH (Sea, Lake, and Overland Surges from Hurricanes) model is the standard for surge prediction. This simplified tool uses empirical relationships from SLOSH to estimate:

• Maximum surge height (H_surge) based on Saffir‑Simpson category and coastal geometry.
• Inland inundation distance using a shallow water decay formula.
• Hazard classification for emergency planning.

Simplified surge formula: H_surge = H_base(cat) · (1 + 0.1·B) · (1 – 0.02·Δz) where B = bay/shore enhancement factor, Δz = mean ground elevation (m).

🚀 2. Storm Surge & Hazard Estimator

Saffir‑Simpson CategoryCategory 1 (74-95 mph) – MinimalCategory 2 (96-110 mph) – ModerateCategory 3 (111-129 mph) – ExtensiveCategory 4 (130-156 mph) – ExtremeCategory 5 (≥157 mph) – Catastrophic

Landfall coastal typeOpen coast (straight shoreline)Bay or estuarine (amplification)Funnel‑shaped bay (extreme amplification)

Mean ground elevation (m above MSL) – inland

Distance from coast (km)

Tide contribution (m) – astronomical tide

Batch CSV (category, coastType, elev, dist)

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CSV Template

📊 3. Cross-shore Inundation Profile

📈 4. Surge Height vs Category & Historical Records

📘 5. How to Use the Simulator

1. Select hurricane category (1–5).
2. Choose coastal type (open, bay, or funnel bay) – this amplifies the surge.
3. Enter ground elevation (m MSL) and distance from coastline.
4. Optionally add astronomical tide contribution.
5. Click "Compute" – maximum surge, inland flood depth, inundation extent, and hazard level are displayed.
6. 2D profile shows water surface, ground elevation, and flood depth.
7. Batch CSV: process multiple scenarios for planning.
8. PDF report includes all parameters and the profile.

❓ Frequently Asked Questions

❓ What surge heights are typical for each category?

Cat 1: 1.2–1.7m; Cat 2: 1.8–2.7m; Cat 3: 2.7–3.7m; Cat 4: 3.7–5.5m; Cat 5: >5.5m. Our tool uses mid‑range values.

❓ How does bay shape affect surge?

Funnel‑shaped bays (e.g., Bay of Bengal) can amplify surge by 30‑50% compared to open coast. The tool adds an amplification factor.

❓ What does "inundation distance" mean?

It's the horizontal distance inland where flood depth becomes zero, assuming a linear decay of surge height.

🌐 References

NOAA SLOSH Model Documentation | FEMA Coastal Flood Hazard Analysis | Bangladesh Cyclone Preparedation (IWM)

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© ERH Simplified SLOSH – For educational and preliminary planning. Always refer to official surge forecasts.