How Edge-of-Field Flows Can Change Due to Rain Events

The USGS has posted an excellent video of how the discharge can vary widely over a short period of time at an edge-of-field site.

The site uses a H flume provided by Openchannelflow to measure and analyze the discharge off a field near Fort Wayne, IN.

The 2.5-foot H flume goes from almost no flow to 1.9-feet of head in about 90 minutes before the flow starts to gradually decline. By daylight, the level is down to about 0.45-feet and by 11 AM, the level is down to about 0.5-feet.

This rapid change in flow highlights the need to remote, continuous flow monitoring – if the manual inspection of the flume and recording of the flow rate was required, it is most likely that this rain even would have been substantially missed.

Also, note the use of paving stones and geotextile to reduce downstream scour.