100-year Flood Event
A 100-year event equates to 13.5 inches of rain within a 24 hour period.
There have been 7 of these events since 1976 in Clear Lake City.
500-year Flood Event
A 500-year event equates to 19 inches of rain within a 24 hour period.
There have been 3 of these events since 1979 in Clear Lake City.
Flooding is a result of storm water run-off. Flooding increases as development covers the ground with impervious surfaces and the ground can no longer soak up the rain.
Over the last 30 years, flooding has grown to be a top issue for the Clear Lake City area. For example, TSARP (Tropical Storm Allison Recovery Project) study found that the "100 year" peak flow rate in Horsepen Bayou watershed increased by 20% during the 1980's