The big issue facing Houston today are the Addicks and Barker dams.
On a map of Houston, the
George Bush Park and
Bear Creek Pioneers Park are in fact large reservoirs built to protect the city from flooding.
Currently, Addicks is at 107.62 feet, at 108 feet water will start uncontrollably spilling around the edge of the dam, at 111 feet it will start overtopping parts of the dam. At 119 feet it starts overtopping the main dam. Overtopping leads to erosion which leads to breeches.
Sensors at Barker dam appear to have broken at around 100 feet as the gauge structure began to flood, but extrapolations have Barker at around 102' right now, with overtopping starting at 104'
Most experts do not expect the dams to breech, but uncontrolled spillage appears to be inevitable. Uncontrolled spillage seems to mean flooded neighborhoods, while a major breech means downtown Houston gets swept into the Gulf of Mexico.
Both Addicks and Barker reservoirs are not expected to crest until Friday morning, even if the rain stops, as much of the Houston area drains into
them.