Lately I’ve been going through lots of little half-finished analyses and trying to write them up in some form. Today it’s my attempt to answer the question “how long does a river stay in spate?”. The primary motivation of this being that when the water level on the Clyde is high it’s not safe to row on it. Clubs, such as Clyde ARC might want to have an idea of how long it will be before the water level is low enough that it’s safe.
This is a very simplistic look at this problem, and I imagine I’ll revisit it in order to do some proper analysis in the future.
I had a look at data from SEPA regarding the height of the river during 2022, which had an exceptionally dry summer, and when the river levels spent a long period of time very low (and sometimes were almost dangerously low for boating).
The real question for me is how long it will take for the river to drop below around 1.6-metres once it’s exceeded that. That’s normally a reasonable rule of thumb for what produces a managable stream on the stretch further down the river where we row. Looking at the data, without doing any serious analysis it seems like the time to half the height of the river is around 24 hours once the rain stops. In this post I’ve included a plot of a four day period after heavy rain in September showing how the level gradually declines once the rain stops.
A more complete analysis would be useful for making a stronger prediction alongside rain data however, so I’ll add that to the to do list!