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Florida Sandcastles

Southeast Florida’s buildings as toy houses, one per million m³, piled up in four clusters. With the sea 2.1 m (7 ft) higher, 54% of the Miami area’s building volume lies in flooded areas.

4 November 2026 · Day 4: Clusters

Questions, something to add, or a thought you’d like to talk through? Write to me, I’d love to hear it.

A 3D scene of Florida’s southeast coast seen from the south. A toddler sits in shallow blue-green water beside a large pile of small toy houses on the coast, labeled Miami. Smaller piles further up the coast are labeled Fort Lauderdale, West Palm Beach and Port St. Lucie, fading into haze. A tipped bucket and a toy shovel full of houses lie in the water. Title: Florida Sandcastles. Miami: 2,907 toy houses, 54% of built-up volume in areas inundated at +2.1 m. Legend: 1 toy house = 1 million cubic meters of built-up volume.
One toy house stands for 1 million m³ of building volume. Full resolution

The Clusters theme made me think of sand: cities pile up at the water’s edge. Each toy house here is 1 million m³ of building volume, about one Empire State Building. The Miami area, from Homestead to Hollywood, is 2,907 of them, Fort Lauderdale 1,823, West Palm Beach 1,423 and Port St. Lucie 674.

Clusters of building volume

The building volume comes from the EU’s Global Human Settlement Layer (2020, 100 m cells). I smoothed it with a 5 km kernel and gave every cell to the density peak it climbs to, which is mean-shift clustering on a grid. A simple density threshold doesn’t work here: South Florida’s suburbs are so even that you get either one 140 km city or dust. Each cluster became one pile, dropped at its peak and settled by a physics engine.

Sea level 2.1 m above high tide

The water sits 2.1 m (7 ft) above mean higher high water, from NOAA’s Sea Level Rise Viewer. At that level, 54% of the Miami area’s building volume is in flooded areas, 35% of Fort Lauderdale’s and 7% of West Palm Beach’s. It is a scenario with no year attached, and only ocean-connected flooding counts, so the shares are on the low side.

A flat map of the coast from Miami to West Palm Beach, built from small square cells colored by inundation level. Three pie charts show each cluster’s built-up volume split into shares inundated at +0.9 m, +2.1 m and +3.0 m. Miami: 2.91 km³ of built-up volume, 54% inundated at +2.1 m. Fort Lauderdale: 1.82 km³, 35%. West Palm Beach: 1.42 km³, 6.6%. A side panel explains the method in three steps: built-up volume per cell, smoothed density with its peaks, and each cell assigned to the peak it climbs to.
Built-up volume inundated at 0.9, 2.1 and 3.0 m, and how the clusters are found. Full resolution

At 0.9 m the Miami share is 2%, at 3.0 m it is 88%. Along the whole coast at 2.1 m, 2.35 of 6.83 billion m³ of buildings would be in flooded areas, about a third.

From one toy house to the whole coast, in 46 seconds.

Data and method

GHS-BUILT-V R2023A, epoch 2020; Gaussian kernel with a standard deviation of 5 km; gridded mean shift. NOAA ocean-connected inundation extents at 3, 7 and 10 ft above MHHW, without storm surge, groundwater or flood defenses. No generative AI imagery.

References

Questions, something to add, or a thought you’d like to talk through? Write to me, I’d love to hear it.