|By Eleanor Starkey, Dr. Geoff Parkin and Dr. Matt Perks (Newcastle University)
19th May 2014
The Haltwhistle Burn catchment (Northumberland) is predominantly rural, 42km2 in size and is situated in the centre on Britain. The catchment is elongated, which becomes particularly steep and narrow towards its confluence and outlet with the South Tyne River. The town of Haltwhistle (population of just under 5000 – Office for Statistics, 2011 census) is also located close to the outlet. The Haltwhistle Burn catchment has a history of flooding, with records dating back to at least 1892, affecting the town in numerous locations during 2007, 2012, 2013 and more recently, April and May 2014 events. As a result, the Haltwhistle Burn catchment is listed on the Environment Agency’s Rapid Response Catchment (RRC) register.
The recent flood events which occurred on Wednesday 30th April and Sunday 11th May 2014 highlight how flashy and localised rainfall and subsequent flood events are within this catchment. On both occasions there were no weather warnings issued by the Met Office and rainfall totals took locals by surprise. On each occasion, the rain storm lasted approximately 40 minutes. Many properties flooded, culverts became blocked by sediment and drains surcharged. On both occasions, the Fire Bridge was called out. A local resident commented that “the floods had been and gone within a few hours”.
A PhD project at Newcastle University (which is focussing on the Haltwhistle Burn catchment, see http://research.ncl.ac.uk/haltwhistleburn/) has collected data from members of the locals community (through a ‘community monitoring’ approach) and nearby traditional monitoring sites. The map below illustrates where rainfall has been monitored within and near the Haltwhistle Burn catchment on 30th April 2014. A total of 41mm of rainfall was observed by a local resident in Haltwhistle, yet nearby monitoring stations were far lower. The nearest national rainfall monitoring station is 3.4km away from the Haltwhistle but only measured 17.2mm of rainfall.
A comparison between 24 hour rainfall totals for 30/04/2014 event
To further emphasise how localised these heavy rainfall events were, a Flood & Coastal Erosion Risk Management Engineer from Northumberland County Council confirmed that they did not have any reports of flooding elsewhere in the county during these two days. This case study provides an excellent example of why monitoring is required on a local level to capture the nature and understand the impacts from flash flood events.