Rain is supposed to continue through part of Saturday. With the already saturated ground, the Ohio River is rising. What are the local communities doing in response?
Some waterways have stream gages
Throughout Indiana, the U.S. Geological Survey (USGS) has a network of stream gages. There are a couple hundred of these gages in various streams, which can provide real-time data of the water elevation and discharge (flow moving through). In Jeffersonville, there are three gages that I keep tabs on:
- Ohio River McAlpine Upper
- Ohio River McAlpine Lower (lock and dam)
- Silver Creek in Jeffersonville, near Sellersburg
What does the graph show?
The National Weather Service gathers data from the USGS stream gages to create forecasts for flooding. Right now, the graph in the image is indicating that the gage is experiencing minor flooding from the Ohio River. It is also showing the Ohio River (at that gage) is expected to crest at about 28.1 ft. on Sunday / Monday. The gage is currently showing the flood height as 25.22 ft. The future forecast will change as more data becomes available. On the website, you can get a ton of additional information, such as historical flood elevations.
How is the information useful?
The local communities use this information to determine if there is a need to close roads, evacuate residents, close up the flood wall, or enact our flood plan for our utilities. We collect data about flood events and try to improve the process of when to close roads and talk to people about leaving their homes. People in the community generally know which roads are closed if we get lots of rain, but we are attempting to make the process somewhat more scientific than just saying “that road over there near the water needs closed soon”.
During this particular flood event, we have been out monitoring our local waterways that receive flood waters from the Ohio River, such as Silver Creek. The bridge over Silver Creek on Blackiston Mill Road may end up closed by the end of the weekend. We are also checking out the roads and bridges that are adjacent to the Ohio River, such as at Duffy’s Landing. Utica Pike may also end up closed if the Ohio River continues to flood.
On a positive note, the Ohio River does not have an impact on all the of streams in the area, so they are not currently flooded (several are close to the top of the banks). If we continue to have sustained rain, water in several local streams will start to leave the floodway and enter the flood fringe (see my last post for more information on this topic).
To wrap up
While stream gage data looks boring, it is a super useful tool for floodplain administrators and emergency response professionals to figure out if they should be concerned about an upcoming flood event. We desire to keep people safe and their property undamaged, and stream gages play an important role in this effort.