Things today are very different along Rapid Creek, including the greenway with no business or homes. Many advancements to the warning process have been made since 1972 as well.
45 years ago at around this time, things started to go downhill rapidly. Heavy rain falling on already saturated ground that had received rain in the days before.
USGS Hydrologist Janet Carter says, "That led to saturated soil conditions, and when you have saturated soil conditions, the soil can't absorb any more water."
That, combined with the steep terrain drop leading from the Black Hills along Rapid Creek and eventually into Rapid City led to catastrophe.
Carter says, "The foothills area of the eastern Black Hills is very steep. We also traditionally get a lot of intense thunderstorms in the eastern part of the Black Hills, and when you combine that with the steep topography, it's a recipe for flash flooding."
Many things have changed from then to now. During the flood event, there were far fewer stream gauges along Rapid Creek and other tributaries that flow in, and that is one reason why warning time would be drastically lower if a similar event were to occur today.
Carter says, "When they meet a certain threshold, then it will trigger a warning that is sent to Pennington County Emergency Management and the National Weather Service, so they can get warnings out to folks and warn them that flood is imminent."
This network of gauges is scattered throughout the hills, giving us data around the clock. Research has been, and continues to be done to this day.
USGS Hydrologist David Bender says, "She's actually measuring the velocities of the stream, calculated by the area that she's measuring, and she gets a discharge, or a flow in cubic feet per second going down the stream."
The comparisons between the Flood of '72 with today are off the charts.
Carter says, "The flow was about 50,000 cubic feet per second, and that would be equivalent to filling an Olympic size swimming pool 30 times in the course of a minute, and the bridge behind us, the flow of Rapid Creek would actually have been above the top rail of the bridge by about a couple feet anyway."
Bender says, "What's coming down the creek right now is about 57 cubic feet per second. So what is coming down the creek right now, needs to be multiplied by about a thousand to get what was coming down the creek in '72."