Understanding Storm Surge

Storm surge is the abnormal rise of water generated by a storm's winds. During hurricanes, this surge can inundate coastal communities, causing devastation far beyond the immediate impact of wind and rain. The surge height depends on storm intensity, coastal topography, and the timing of tides. Emergency managers use complex models, but this simplified calculator offers a quick estimate based on hurricane category, tide level, and how steeply the seabed rises near shore.

Simple Surge Formula

For educational purposes, we approximate surge depth with:

where $C$ is the Saffir–Simpson hurricane category (1-5), $k$ is a coastal slope coefficient reflecting how gradually the seafloor rises, and $T$ is the tide level in feet. A steeper slope or lower tide reduces flooding potential, while intense storms and high tide increase it. The exponent of 1.3 fits typical empirical curves but does not capture all local variations.

Using the Calculator

Select the expected hurricane category, then enter the tide level and your coastal slope factor. Values between 0.5 and 2 work for most beaches, with larger numbers indicating gently sloping shorelines prone to deeper surge. After pressing Estimate, the tool displays an approximate surge depth. If the number seems high, consider evacuation planning well in advance of landfall.

Limitations and Local Factors

This calculator simplifies a complex phenomenon. Real surge predictions include storm size, forward speed, angle of approach, and geographic features like bays or barrier islands. Inland waterways can funnel water much higher than open coasts. Always defer to official forecasts from meteorological agencies and emergency managers. The tool is best used for awareness and rough planning, not precise floodplain analysis.

Example Scenario

Assume a Category 3 storm approaches during high tide (3 feet) and the coastal slope factor is 1.4. Plugging those numbers into the formula gives:

≈ 8.8 ft