The Physics of Memory
In 1935, the Comal rose seven feet in three hours, swallowing the lower plaza. In 1998, it rose five feet in four, sparing the library but taking the oak grove. Between these events, our elders learned: the river does not lie. It speaks in inches and hours, and we must learn its tongue.
Today, Austin has issued a waterway ban as the Colorado swells—a reminder that the rivers of Texas are singing the same song their ancestors knew. We listen, we calculate, and we prepare.
Δh = (α × R × 0.85) − (β × t)
Where:
• Δh = rise in river level (feet)
• α = aquifer response coefficient = 0.047 ft/inch
• R = accumulated rainfall upstream (inches)
• β = base recession rate = 0.12 ft/hour
• t = hours since peak inflow
Flood Threshold: Bench elevation = 3.2 ft above mean low water.
Safe Zone: When Δh < 3.2, the elders' benches remain dry.
Coefficients derived from
USGS gauge data (Station 08235500),
the June 2007 Texas flooding record,
and current alerts from
Austin waterway bans.
Machine-readable constants in comal-flood-predictor.json.
Predict the Rise
Example: After 6 inches of rain with 4 hours elapsed,
Δh = (0.047 × 6 × 0.85) − (0.12 × 4) = 0.2406 − 0.48 = −0.24 ft
Result: River receding. Benches safe.
A Note on Imperfection
This tool assumes the aquifer behaves as it has for three centuries. It does not account for the sudden breach of a dam upstream, nor the whimsical choice of a cloud to linger over Landa Park. But it accounts for what we know: the limestone breathes, the springs pulse, and the river remembers every inch we give it.
Use it wisely. And if the numbers seem wrong—bring your grandmother to the bank. She will know better than any equation.
Download Machine-Readable Constants (.json)