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The March Floods

The floodwaters which tore down the tributaries of the Rye and flooded Malton, Norton and Stamford Bridge at the beginning of March 1999 also provided an example of what seems to have become a national habit - finding someone to blame. In this case the target was the Environment Agency (the old Rivers Authority), which was accused of giving inadequate warning and of allowing bankside vegetation to run wild. I myself feel that if you plant crops on what used to be water meadows, or build on land known to be subject to flooding, you accept the risks involved. I also believe that if the river channels had been as smooth and bare as some farmers seemed to wish more flood water would have reached Malton sooner, and would have done greater damage.

The floods were caused by exceptionally heavy and persistent rainfall over the moors: a low pressure system over the North Sea became blocked, and fronts moved east to west between February 28th and March 9th, bringing first snow, then rain, so that melting snow added to the run-off. Church Houses in Farndale had over 250 mm (10 inches) of rain between 28th February and 11th March, and other stations recorded similar figures. Rainfall of this intensity and duration is a very rare event - it would be expected to happen only once in a thousand years.

Station March 1999 rainfall Long-term March average

ins mms ins mms
Westerdale 8.15 207 2.99 76
Randymere (nr. Goathland) 7.83 199 2.83 72
Ruswarp 5.31 135 2.00 51
Scarborough 4.88 124 2.05 52
Cold Moor (Upper Bilsdale) 7.05 179 2.68 68
Farndale (top of valley) 11.89 302 3.31 84

The response of the rivers can be imagined. The Rye at Shaken Bridge rose to more than 2 metres (well over the limit of the gauge); the Seven at Normanby reached 3.5 metres (around 10ft) three times between the 5th and the 9th; Pickering Beck rose 1.27 metres (over 4 ft) above its normal level. By contrast the upper Derwent at Ayton barely rose - almost all the flood water was diverted by the weir at Everly and went down the Sea Cut to Scalby.

The normal level of the river at Malton is 14.52 metres above sea level, and it rose to 18.90 on the 8th March - 4.38 metres or 14ft 4ins above normal. It has quite often risen more than 12 ft in the past - in 1930, 1947, 1960, 1963 and 1982 - and in 1931, said to be the worst flood in Maltonís history, the level reached 18.70 metres. So 1999 was, it seems, the biggest flood ever recorded.

The Environment Agency has responded to farmersí accusations of neglect - it quickly issued the hydrologistís report (1) from which I have quoted above, and also commissioned an independent review (2) of its river management. This concludes that flood embankments were adequately maintained, and that silting of the river channels was not responsible for the flooding - though it is recognised that the extension of arable farming has led to increased silt loads.

But along many reaches trees had been allowed to grow into the channel to such an extent that when the rivers rose debris was trapped and the flow was impeded: and when this happens the water can only escape laterally, flooding the adjacent lowlands. Understandably the farmer whose fields are flooded will blame the Agency, and it does seem that willows in particular had been allowed to encroach - though the report makes it quite clear that this had no influence on the floods in Malton.

The review concludes that balancing the various interests involved in the management of the river system is an enormous task. The wildlife value is recognised by the designation of part of the river as an SSSI; at the same time arable farming in the Vale of Pickering is dependent on elaborate systems of drainage into the rivers, which are in effect the ímain drainsí.

It would be very sad if a backlash from the floods were to result in miles of sterile embanked channels, regularly shaved and cleaned out. As naturalists we wish to see our rivers in their natural state, supporting a wide range of wildlife, and we deplore the loss since 1945 of almost all our carrs and ings as a result of land drainage: Wheldrake south of York is the only survivor. One of the Countryside Agencyís Stewardship Schemes helps farmers to return riverain land to something more like the old water meadows, but take up has been small, and the payment on offer is probably too little. Letís hope that one of the new ideas about rural policy will be the restoration of flood plains to their natural function of retaining winter rainfall. I am sure that a policy which allowed a greater area to flood after exceptional rainfall, and compensated farmers for reduced income, would not only be cheaper, but better for wildlife too.

References:

  1. 1999 Derwent Flood Hydrological Report. Michael Stokes. Environment Agency Dales Area, York.
  2. River Derwent Review. David Noble and Associates High Street Huntingdon July 1999

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