The Cahermore Situation

The following article looks at the flooding situation in Cahermore which was badly affected by flooding in 1995, 2013,  2009 and again in winter 2015.

Cahermore is located close to Kinvara between Cahermore cross and Kinvara.  Cahermore Cross connects Kiltartan to Kinvara as well as Labane/Ardrahan and Garryland-Tierneevin.   It is therefore a very important area for access in South Galway which was compromised a great deal with roads blocked for 110 days in the 2015 winter floods.  The Cahermore area has close to 20 households in or directly around it but from an access point of view it would have a substantial impact when blocked.

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What is the hydrology of Cahermore?

Cahermore contains a dry Turlough which means that in the summertime there is rarely any standing water except for a few ponds that are used to water cattle.   As you can see from the diagram below, there is no water body in Cahermore in summer levels  sometimes even in normal winters.

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This site also has a connection with Caherglassaun and when Caherghassaun lake starts to rise Cahermore will also rise through many small springs.   In and 1846 map you can seen  McInerney’s old farm from and a small path to a well in the South.  (This used to have steps down into it)

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Severe Winter Rains

In the past 20 years, during severe winter rains, the situation in Cahermore becomes critical. The Turlough rises initially through springs but when Caherglassaun starts to overflow,  the levels of Cahermore starts to threaten roads, homes and farms.

The critical aspect of Cahermore is that it is one of the last of the South Galway basins to fill with no major connection to the sea and is effectively land-locked meaning water will continue to rise and cause chaos in the community

History of Flooding

From a historical perspective McInerney’s farm has never had a history of flooding, and only since 1995 has flooding become an issue here.

Martin McInerney clarifies the history of flooding. “This farm has been in our family for 10 generations and in those 10 generations, I’m the only one that has had to deal with flooding.   The floods came in 1990 into the sheds and we relocated them to higher ground but the flooding is getting worse and worse and last winter it flooded not only my farm and farm buildings but also my home. The water was never as high.   Imagine that the recent flood levels would have been up the thatch in my grandfathers house – having never been flood in any of that time.   I’ve heard stories of the the ‘night of the big wind‘ in winter 1911 but never a mention of a bad flood.   This situation has to be man-made  since 199 and something needs to be done about this.

When you look at older maps e.g. 1836 there is a section of Cahermore that has been marked ‘Liable for flooding‘. This is an area of about 20 acres and consistently floods in wet winters for 4 to 6 weeks (at the longest).  This is shown in the dotted lines.  This line constitutes a ‘regular’ flood and this is the actual Turlough boundary.

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During the Winter of 2015 the flooding extent was approximately the following:

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As you can see the Turlough levels were way above the 1846 levels and this caused the flooding of homes, farms and roads.    The levels reached in Cahermore were 13.51m above sea level .The following pictures summarize the Cahermore Story (Courtesy of Sean Brady Aerial Photography)

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Why is Cahermore flooding

The easy to say answer is ‘global warming’ but there a lot more at play here.  As we have seen in previous blogs water is getting off the Slieve Aughty’s quicker that before and flood remedial work done in Gort (and channeled to culvert at Kiltartan)  is filling the lower basins much faster and with greater volume of water (Coole, Caherglassaun and Cahermore) – This is  a real threat to the Cahermore community.

The Emergency Channel

In winter 2015, as the water continued to rise, the only potential outlet was around Adrian Glynn’s house was in Cahermore.  Water was already seeping under the ground at the back of Glynn’s making its way to Caherawooneen and the sea at Kinvara.  There was a mound of rock though beside the house that was holding back water.

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A lot of credit has to be given to Adrian Glynn to allow work to be done on this channel. He, and his family were very accommodating  with allowing a channel to be dug right at the back of this house, through his land. A gentleman!

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The Cahermore Channel  in full flow – Courtesy of Sean Brady Aerial Photography

Cahermore was rising several inches per day but this channel tapered it and eventually the levels stabilized within 5 days and around 2 weeks it started dropping.  There is no doubt in my mind that this channel had a significant impact on the saving of a complete community from flooding.

Impacts of Flooding

Cahermore was one of the communities affected the most seriously as the level of the Turlough impacted directly on the area.

  • There were 4 houses flooded and an additional 5 houses under water (but protected with sandbags and pumps etc) . A further  5 house were badly threatened.
  • Over 14 septic tanks flooded
  • Several farm buildings with slurry tanks were flooded and over 240 acres of farm land was flooded and over 17 farmers affected
  • Consequently the water in the area was contaminated
  • The road was closed for 106 days. This had a severe impact on parents with kids going to Northampton school and Seamount College and the community of Kinvara  as a whole and farmers having to make their way to get access to lands on the far side of the flood

Also Cahermore is a SAC (Special area of conservation) which, due to the flooding of roads, septic tanks and farmyards, would have had considerable pollution.  (you can see the slurry from the farmyard below flowing into the Turlough.

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Community response

One thing that I wanted to highlight is the Cahermore community response to the flooding.  The level help and support for people in crisis was incredible.   From Adrian Glynns selfless attitude to digging through this land to alleviate floods to the youth of the community – filling sandbags, manning pumps, helping neighbours – Cahermore – It’s a credit to ye!

Solutions

From the moment that we got the storms, Cahermore was always in trouble and the trouble starts several weeks after the rains. There is simply no way for the amount of water to get to the sea underground and it swells the Turloughs and spills overgound. The key solution is simple – Keep the maximum turlough level to a safe level (for all concerned) and get the water safely to the sea. The implementation of that solution may be more complex but still not rocket science.

What is a safe Level for Cahermore?

A safe level for Cahermore would be a level that doesn’t threaten homes, farms or access (and consequently the environment). In winter 2015, the maximum level of Cahermore was 13.51m and this is too high.  For instance, if we look at an OS map you can see a 10m contour (highlighted in red) . It doesn’t come near any house. (It still comes near a road but this may be a special case)

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From an environmental point of view, the NPWS, were of the opinion that if the Turlough was kept within this boundary, it wouldn’t have an adverse affect on the integrity of the Turlough, consequently, maintaining this at a maximum level would have positive benefit  on this SAC and other downstream areas.

Channel to the sea

The complex part of the solution is that in order to maintain this type of a level there needs to be a dedicated overflow channel to the sea, through Caherawooneen and there needs to be a proper sizing and overflow levels.  E.g.  the road at Caherawooneen is at 11.12 m.  So maintaining Cahermore at e.g. 10m would mean deeper and more costly channel.   There would need to be  balance between a deep (and expensive and disruptive channel) and cost efficient, but not very flow-efficient channel.   This balance is what we will need to keep an eye on as a solution progresses.

Today a temporary emergency channel is in place that can be opened to let some small flow out of Cahermore but this should not be seen as a long-term solution – it’s simply not big enough.

Summary

In severe winter flooding, Cahermore gets very badly affected as it takes overflow from Coole and Caherglassaun and there is no dedicated outlet.  The flooding has had a significant impact on homes, farms, access, health and the environment.   This situation is exacerbated by more recent upstream flood alleivation work and cannot be allowed to repeat.  The maximum Turlough level for Cahermore needs to be maintained at a level that eliminates these threats and the only way this will happen is to provide a dedicated ‘storm drain’ from Cahermore to the sea.  This is the first thing that needs to happen in overall South Galway Flood relief scheme

 

David Murray

 

 

 

 

 

 

 

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