Up on the side of Plynlimon, near the source of the River Severn, you wouldn’t expect to find much evidence of human interaction with the river.
There’s a path to the source…
…and a track within the first mile, but then there’s one of these!
A gauging station.
The entire river is channelled through a vertically-sided gap and sensors measure the depth of the water.
A measurement is taken every 15 minutes, but it’s all automatic so there is no need to sit by the river all day!
The first gauging station is located just before the river enters Hafron Forest and just downstream of the first obvious confluence on the River Severn.
A confluence is the point where a tributary river joins the main river bringing in a flow of extra water.
Many streams in the Hafren Forest make their way down the slopes to join the River Severn and there are gauging stations on some of the tributaries as well as the main river.
So what’s the point of all this data? Well apart from monitoring for flood warnings, there’s a lot of research being carried out in the area. I’ll tell you more next week.