Houston flood transitions from meteorology to hydrology

The story of the massive Houston flood disaster is about to make a scientific transition.

The good news? Rainfall tapers off in Houston over the next 24 hours. The not-so-good news? Over 40 inches of rain has fallen and all that water is still moving around trying to get to the Gulf of Mexico.

That means the flood focus going forward over the next few days changes from the rain falling from the sky, to the water flowing in watersheds around metro Houston.

The story of the Houston flood is shifting from meteorology to hydrology.

A year’s worth of rain

Several locations around Houston are now recording rainfall totals higher than 40 inches. That’s nearly a year’s worth of rain in a city that averages 50 inches a year. Harvey delivered on forecast rainfall totals.

Addicks and Barker

The hydrology of Houston is complicated. Two major reservoirs in the western part of the city are now at record highs, topping capacity. Water is now flowing from the spillway at the north end of the Addicks Reservoir.

Now the challenge for hydrologists is to accurately predict where all that water will go. Here’s a clip from the Harris County Flood Control District briefing this morning.

Houston area flood managers are playing a delicate game now. It’s a balancing act between releasing water from stressed reservoirs into already flooded bayous and neighborhoods in Houston. Adding insult to injury, many flood gauges have been washed away or are underwater.

The magnitude of this disaster is still unfolding. Severe flooding reports are still flowing in. There’s no way the news media can cover everything that’s happening in the nation’s fourth largest city.

So while the rain may ease in the next 24 hours in Houston, this flood story may not yet be at peak in many areas. This slow-motion flood disaster continues.

Stay tuned.