Houston storm history · August 25 – September 1, 2017

Hurricane Harvey

The wettest storm in Houston's modern history: days of rain, record reservoir pools, and flooding across nearly every watershed in Harris County.

Every bayou, hour by hour

0 ft 20 ft 39.4 ft (this storm's peak) no reading Every cell is a real archived USGS reading for that bayou, that hour — nothing is interpolated between gauges. Color scale is calibrated to this storm alone; it is not comparable across different storms. Hover a cell for the exact value.

Harvey came ashore near Rockport as a Category 4 hurricane on the night of August 25, 2017. Houston's problem was not the wind. The storm stalled over southeast Texas for four days and kept feeding rain bands into the region. Parts of Harris County measured more than 40 inches of rain, and some Harris County Flood Control District gauges recorded close to 50 inches over the event.

The heaviest flooding came overnight on August 26 into August 27, when training rain bands dumped several inches an hour across the city. Bayous that normally sit well inside their banks rose past record levels. Brays, Buffalo, White Oak, Greens, Halls, Hunting, Sims, Cypress Creek, Clear Creek and the San Jacinto River all flooded, which is what set Harvey apart. It was not one watershed in trouble. It was all of them at once.

West Houston faced a second, slower disaster. The Addicks and Barker reservoirs, which are normally dry, filled to record pools. Water backed into neighborhoods inside the reservoirs, and on August 28 the U.S. Army Corps of Engineers began controlled releases into Buffalo Bayou to protect the dams. Those releases kept homes along Buffalo Bayou, including parts of Memorial and the Energy Corridor, underwater for days and in some places close to two weeks.

The Harris County Flood Control District estimates that more than 150,000 homes in Harris County flooded. Many were outside the mapped 100-year floodplain. Tens of thousands of people were rescued from homes and vehicles, often by neighbors in private boats, and the George R. Brown Convention Center became one of the largest shelters in the city.

Harvey reshaped how Houston plans for floods. In 2018 Harris County voters approved a $2.5 billion flood control bond. Floodplain maps were redrawn with higher rainfall assumptions, new building rules followed, and the county added more than a hundred new rain and stream gauges to the flood warning network.

In the replay on this map, the columns and labels show how far each bayou rose at its USGS gauge between the start of the storm and the crest of Buffalo Bayou in the early hours of August 28. The blue glow grows with the measured rise. It is not a mapped flood outline.

Sources

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