I’m posting to share a hydrograph from a channel in Houston to show how fast this flood happened, and why I think it may have left so many drivers stranded in the roads. Below is a hydrograph and rain data from Buffalo Bayou in Houston, from before the major rain to this evening (the day after). Buffalo Bayou is a largely engineered channel which means it conveys water much faster than a natural channel — this explains the really abrupt rise in the hydrograph. But why did it leave so many drivers stranded? Simple!
The Rockets Conference finals game began at 8:00pm, just before the rain started. Everyone ignored warnings to stay home and watched the game (I don’t blame them) and then when the game ended ~11:30pm, all the rain had flooded the streets (not yet into the bayou) and stranded drivers. The bayou overtopped its banks at about 2:00am this morning, and continued to rise through the morning. This led to vehicles remaining stuck and becoming even deeper submerged. Luckily, the water has began to recede.