Rain vs. Rivers in South Galway

We have an OPW based website that tracks many river levels (known as metering ‘stations’) and some of these monitor levels in South Galway –  The web address is simply www.waterlevel.ie. I got an email this morning from the OPW after I requested that they create a ‘group’ for the western Slieve Aughty drainage and this can give a picture of what happened a week or so ago during storm Gertrude.  The address is http://waterlevel.ie/group/28/ . So now you we can get a picture of how river water levels behaved over the past month, something like this [Note plenty of disclaimers on the data accuracy on the website].

levels

These relate to the levels of the rivers at these stations:

And this show you where they are:

Water Levels

So what can it tell us? It can give some insight into the water dynamics

strormGert.JPG
River Levels in with Storm Gertrude : Jan 26th/27th 2016

e.g. the rainfall we got during Storm Gertrude

  • The Owendalulleegh/Derrywee river (into Lough Cutra) rose over 1.2 M in 6 hours : peaking at 2pm. [Killafeen station]
  • The Bolleyneendorish river @Ballycahalan rose over 1 M in 6 hours ,peaking at 11am
  • The Owenshree @Kilcheest rose 0.5Min 6 hours, peaking at 11am
  • The Beagh River (Orange) rose over 0.5 M, but took 26 hours to rise (The wonderful dampening affect of lough Cutra) but was sustained for several days)

The 1-2 hour difference timing peak in river levels is probably to do with the distance from catchment area.

Rainfall

It’s also possible to get rainfall here http://www.met.ie/climate/daily-data.asp

I looked up Athenry stations (one of the nearest to Slieve Aughty) for the 24 hours around the 26th Jan and its profile looked like this:

rain1.JPG

Assuming Athenry was a good indicator (It seems like a good approximation as winds were in an easterly direction and Slieve Aughty is ~10KM eastwards)

Some notes:

  • Rainfall was ~22 mm (~1 inch) in 7 hour 1am to 8am with a peak of 6am-7am
  • Rainfall was ~8mm @9m that night

If we correlate this to the river levels then we can roughly say that heavy rainfall in the Slieve Aughty will be in the Kilchreest & Peterswell 3-4 hours later.

Of course – the easiest way to find out this is to ask the locals – they agree that it’s down of a shot but it’s also good to get some numbers behind it.

‘Slow the Flow!’

This rapid run-off the mountain is a dynamic that the downstream swallow holes simply cannot handle. We’ve heard from other sources that there are viable techniques to ‘slowing the flow’

We have to seek these type of solutions – It’s working with nature and it’s not rocket science!

-David Murray

 

 

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