Thursday 23 January 2014

A bad spate of affairs

I really feel for people in this area whose homes were affected by the recent flooding. On the other hand, it has made for some pretty good photo opportunities...

River Mole to the north of the airfield, North West Zone (Jan 2014)

Gatwick Airport operations were disastrously impacted over the Christmas period when an electricity substation flooded out in an unprecedented event. A lot of urgent work then had to be done to save several of the airfield regulators. Many people in surrounding areas such as Charlwood, Horley and Crawley were also badly affected, with some properties being flooded out on several occasions over the past month.

Airfield Engineering had a rather challenging time over the Christmas period (photo by David Maurice, Dec 2013). A contender for next year's airport greeting card, perhaps?

Apparently, a weather station at Reigate Grammar School measured 70mm (2.8") of rainfall over 23rd and 24th December, the highest ever recorded for (modern county) Surrey over a 24 hour period. With so much water falling so quickly in a largely concreted and industrialised area, the water drainage systems were severely pushed to their limits. In our woodlands and grasslands, the already saturated ground just couldn't take anymore and water was soon running off in torrents along paths and roads. The unseasonably warm weather means we probably have more heavy rain to come!

No training today at the Fire Training Ground (David Maurice, Dec 2013) 

Gatwick Stream and the cycle path (underwater) along the A23 at City Place (David Maurice, Dec 2013) 

The A23 by the South Terminal (David Maurice, Dec 2013) 

Although we might call this a '1 in 100 year' flood, we tend to have rather short memories when it comes to the weather. Apparently back in 1968 after an extreme rainfall (apparently in one area about 100mm fell in 24 hours), the water was halfway up these crash barriers as well as the South Terminal baggage system ending up under water. 

River Mole north of the airfield - March 2013. Here the river is in-channel

River Mole floodplain last week (Jan 2014)

The floodplain from the diverted River Mole section to the north of the airfield was created in 2000 and designed to hold a vast amount of water. The large meanders and natural pooling areas of the lower ground help to slow down the flow, hold more water and relieve some of the pressure further downstream in urban areas of Horley. This is a good example of an important ecosystem service which floodplains provide us.

River Mole Culvert Corner - December 2012

River Mole Culvert Corner - Jan 2014

For some wildlife, such as wetland birds, this is all rather fun with those pesky humans spending more time indoors and plenty of extra wetland about for foraging in. For other wildlife however, this amount of water could be devastating, particularly for ground hibernating animals such as harvest mice, bats, reptiles and invertebrates. There have been strange reports of whole armies of leatherjacket grubs (Cranefly larvae) marching out from saturated lawns. Those which cannot get away will die off, possibly meaning depleted food sources for other wildlife in the months to come.

River Mole netted section - April 2013

River Mole netted section - January 2014

This has all been rather interesting for the Surrey Wildlife Trust's RiverSearch project, which is building up a profile of the River Mole and associated streams as part of a catchment-wide scheme. At times like this, we can really see how these waterways are functioning: their attributes, limitations and what work needs to be done to ensure they keep functioning.

Finally, another trusty Gatwick coconut has made an appearance. I am currently tracking down the full story on these!

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