Yesterday there was a good comment on our post about the Zumbro River falling and the flood stage. The comment asked what that nitty gritty hydrology info meant. So, for those of you wondering what exactly flood stage, and the classifications mean, here you go!

Stage:  the level of the water surface of a river or stream above an established gage at a given location. It’s a horizontal surface and used as a zero point for measuring the water’s level.

Action Stage – when water rises on a stream or river, this is the level where the National Weather Service starts to take some type of  action to prepare for possible flooding. The type of action taken differs for each gage location. For those living in the area, the flooding should be monitored.

Flood Stage – This is a set gage height for a given location that water must rise above in order to create a hazard to life & property. Flood advisories and/or warnings are usually issued at this flood stage.

After the flood stage, the flood is placed in a category. These categories describe the observed and expected severity of flooding impacts in a given stream segment or nearby stream segment.  Differences with the channel and bank characteristics on portions of the stream will alter the severity of flooding at a given stage.

Minor flooding: some water affecting roads and buildings. Some evacuations may be necessary.

Moderate flooding: more extensive flooding – water has partially inundated roads and buildings. A greater amount of evacuations may be necessary.

Major flooding: severe flooding – water has significantly inundated roads and buildings. Massive evacuations become necessary.

Posted under flooding