Tilshead Borehole Levels: 23rd February 2020

Another week with quite a bit of rain and the water level in the aquifer rose steadily throughout the period.  The Environment Agency has kept the Flood Warning in place, even though the borehole level has only just exceeded the level we reached on 1st January 2020, when we only had a Flood Alert.  The reason for the Flood Warning this month was the short period in which the bulk of the rain fell and the subsequent rapid rise in the borehole level.  The Environment Agency has created a bit of a conundrum though.  I monitor the raw data output by the instrumentation at Tilshead which measures to two decimal places.  In its latest Flood Warning update yesterday at 16:03, the Environment Agency said: “The groundwater level in the Tilshead borehole now appears to have peaked at 99.6m AOD.” 

My initial reaction was that the Environment Agency had simply rounded up yesterday’s measurement of 99.56m AOD to 99.6m AOD.  A little odd, but understandable perhaps.  But reading on, it then claims that: “It is currently at 99.5 and slowly falling.”  If they have been rounding up and down, then the actual reading should have dropped below 99.50m AOD.  The borehole instrumentation at Tilshead shows the water level rose to 99.56m AOD by 04:00 on 21st February and stayed there until the level rose again to 99.57m at 06:30 yesterday and again at 19:15 to its highest level, so far, of 99.58m AOD.  Since then, its wobbled up and down a bit over the last few hours and currently stands at 99.57m AOD.  So the level may be falling, or it may rise again.   Although this small difference of 1.0cm may look like splitting hairs, it is very important for those whose homes may suffer flooding.  The Environment Agency has been asked to explain the anomaly.

What does the weather have in store for next week?  Well, if you are hoping for dry weather, Wednesday might be the only day without rain.  We are expecting drizzle today, with perhaps a clearer period this afternoon before more rain arrives later.  Another weather system will track in overnight, but clear by morning and a second bout of rain will hit later on Monday.   This picture carries on towards the end of the week.  There are suggestions that a very low-pressure system will hit the country in the following week, but it is too early to say where.  The good news is that as we move into March, the weather in the south of the country looks increasingly settled and dry!

Winterbourne Stoke Parish Council