Rainfall

The flow in the River Ver is dependent on rainfall to recharge the aquifer, from which water is pumped to supply the needs of the district. Recharge largely happens in the winter and early spring; any rainfall during the summer has little effect as surface water evaporates and is used up by growing vegetation. Although after heavy rains, at any time of year, the run-off can cause short-term improvement in flow, it takes many weeks for any effect to be measured in aquifer levels or to have any long-term effect on the river.

It is therefore important for the Ver Valley Society to monitor rainfall figures regularly throughout the year and we do this with the help of Rothamsted Research Station (see tables below). 2008 was the wettest year since 2000. In 2009 rainfall was nearly 10% above average and as the Bow Bridge Pumping Station was shut down until August good flows were recorded in the first half of that year and the aquifer came back to average values.

Subsequent rainfall in 2009 and 2010 generally fell below average but flows remained moderate. However poor winter rains in 2011 mean the river was exceptionally low by the end of 2011. However the total rainfall for 2012 was the highest ever recorded at Rothamsted and their records go back to 1870. Unusually the aquifer level increased over the summer months. At the end of 2012 it was over 3 metres above average and the river was flowing north of Redbourn.

2013 rainfall was just above average with storms in December and in 2014 January rainfall was highest monthly total ever recorded since Rothamsted started recording in 1870. That summer saw a very high aquifer and good flows as a result but the winter of 2014/2015 had poor rainfall and the subsequent dry warm summer and autumn meant the aquifer dropped to well below average and poor flows resulted. Early winter 2015 was very warm with only poor rainfall but better rainfall at the beginning of 2016 helped some recovery of the aquifer and reasonable flows have been maintained through the summer after a wet June. 2017 has been relatively dry particularly in the winter months and with the very low aquifer the Ver has been dry for many months north of Redbourn.

See rainfall figures below. We are grateful to Rothamsted Research who supply these figures to the Society each month. If you wish to use these figures you should seek permission from Rothamsted Research.

Month 2018 Actual Rainfall Millimetres Average Rainfall In Millimetres +/- mm Average Percent Average
January 76.1 69.6 6.5 109.4%
February 48.4 50.1 -1.7 96.5%
March 78.5 50.8 27.7 154.5%
April 74.8 55.1 19.7 135.8%
May 61.9 54.7 7.2 113.2%
June 3.7 53.3 -49.6 6.9%
July 15.1 49.9 -34.8 30.2%
August 64.0 63.7 0.3 100.4%
September 51.0 57.6 -6.6 88.5%
October        
November        
December        
         
TOTALS 473.5 504.9 -31.4 93.8%

Month 2017 Actual Rainfall  Millimetres Average Rainfall In Millimetres +/- mm Average Percent Average
January 70.2 70.0 0.2 100.3%
February 38.7 50.1 -11.4 77.2%
March 40.4 50.8 -10.4 79.5%
April 10.9 55.1 -44.2 19.8%
May 70.5 54.7 15.8 128.9%
June 39.1 53.2 -14.1 73.5%
July 72.6 49.9 22.7 145.5%
August 66.6 63.7 2.9 104.5%
September 86.9 57.6 29.3 150.8%
October 31.2 81.8 -50.6 38.1%
November 53.6 76.7 -23.1 69.9%
December 110.8 69.6 41.3 159.3%
         
TOTALS 691.5 733.2 -41.7 94.3%

Month 2016 Actual Rainfall  Millimetres Average Rainfall In Millimetres +/- mm Average Percent Average
January 92.3 70.0 22.3 131.9%
February 46.9 50.2 -3.3 93.5%
March 84.3 50.8 33.5 166.0%
April 62.0 55.0 7.0 112.6%
May 39.4 54.7 -15.3 72.0%
June 84.8 53.2 31.6 159.3%
July 27.1 49.9 -22.8 54.3%
August 30.1 63.7 -33.6 47.3%
September 70.3 57.6 12.7 122.0%
October 30.1 81.7 -51.6 36.9%
November 85.7 76.7 9.0 111.8%
December 26.2 69.5 -43.3 37.7%
         
TOTALS 679.2 732.9 -53.7 92.7%

Month 2015 Actual Rainfall  Millimetres Average Rainfall In Millimetres +/- mm Average Percent Average
January 81.9 70.0 11.9 117.1%
February 54.6 50.2 4.4 108.8%
March 26.1 50.8 -24.7 51.4%
April 31.0 55.1 -24.1 56.3%
May 68.4 54.7 13.8 125.2%
June 26.7 53.3 -26.6 50.1%
July 132.6 49.9 82.7 265.8%
August 83.2 63.7 19.5 130.6%
September 45.5 57.7 -12.2 78.9%
October 64.6 81.6 -17.0 79.1%
November 84.0 76.6 7.4 109.7%
December 81.8 69.5 12.3 117.7%
         
TOTALS 780.4 732.9 47.5 106.5%

Month 2014 Actual Rainfall  Millimetres Average Rainfall In Millimetres +/- mm Average Percent Average
January 176.2 69.9 106.3 252.1%
February 141.9 50.1 91.8 283.2%
March 28.2 50.8 -22.6 55.5%
April 31.5 54.1 -22.6 58.3%
May 82.8 54.7 28.1 151.5%
June 30.5 53.3 -22.8 57.3%
July 36.9 49.9 -13.0 73.9%
August 113.3 63.7 49.6 177.8%
September 14.8 57.6 -42.8 25.7%
October 95.7 81.7 14.1 117.2%
November 108.2 76.6 31.6 141.2%
December 64.0 69.6 -5.6 92.0%
         
TOTALS 924.0 731.8 192.2 126.3%

Month 2013 Actual Rainfall  Millimetres Average Rainfall In Millimetres +/- mm Average Percent Average
January 62.8 70.0 -7.2 89.8%
February 43.4 50.1 -6.7 86.6%
March 83.1 50.8 32.3 163.6%
April 32.8 55.1 -22.3 59.5%
May 56.0 54.7 1.2 102.4%
June 24.6 53.3 -28.7 46.2%
July 47.4 50.1 -2.5 94.6%
August 57.5 63.7 -6.2 90.2%
September 50.2 57.6 -7.4 87.2%
October 108.8 81.7 27.1 133.1%
November 59.5 76.6 -17.1 77.6%
December 123.1 69.5 53.6 177.1%
         
TOTALS 749.2 733.1 16.1 102.2%

Month 2012 Actual Rainfall Millimetres Average Rainfall In Millimetres =+/- mm Average Percent Average
January 58.0 70.0 -12.0 82.9%
February 24.7 50.3 -25.6 49.1%
March 34.7 50.8 -16.1 68.3%
April 168.6 55 113.6 306.4%
May 52.6 54.7 -2.1 96.2%
June 166.5 53.3 113.2 312.4%
July 128.4 49.8 78.6 257.7%
August 54.9 63.7 -8.8 86.2%
September 40.4 57.7 -17.3 70.1%
October 115.8 81.7 34.1 141.8%
November 100.4 76.6 23.8 131.1%
December 114.2 69.5 44.7 164.2%
         
TOTALS 1059.2 733.1 326.1 144.5%

Month 2011 Actual Rainfall Millimetres Average Rainfall In Millimetres =+/- mm Average Percent Average
January 84.6 70.0 14.6 120.9%
February 56.8 50.1 6.7 113.3%
March 10.0 50.8 -40.8 19.7%
April 5.2 55.1 -49.9 9.4%
May 23.6 54.7 -31.1 43.2%
June 83.0 53.3 29.7 155.8%
July 44.6 49.9 -5.3 89.4%
August 81.2 63.7 17.5 127.4%
September 38.4 57.6 -19.2 66.6%
October 25.2 81.7 -56.5 30.9%
November 36.4 76.6 -40.2 47.5%
December 82.4 69.5 12.9 118.5%
         
TOTALS 571.4 732.9 -161.5 78.0%

Month 2010 Actual Rainfall (2010) Millimetres Average Rainfall In Millimetres =+/- mm Average Percent Average
January 47.3 69.7 -22.4 67.9%
February 77.2 48.8 28.4 158.2%
March 45.2 53.9 -8.7 83.8%
April 18.7 53.4 -34.7 35.0%
May 38.4 49.7 -11.3 77.3%
June 23.5 60.2 -36.7 39.0%
July 31.6 42.1 -10.5 75.1%
August 127.6 53.5 74.1 238.3%
September 59.7 61.0 -1.3 97.9%
October 84.9 74.7 10.2 113.7%
November 54.9 66.3 -11.4 82.8%
December 35.3 70.1 -34.8 50.4%
         
TOTALS 644.3 703.4 -59.1 91.6%

Month 2009 Actual Rainfall (2009) Millimetres Average Rainfall In Millimetres +/- mm Average Percent Average
January 70.4 69.7 0.7 101.0%
February 73.9 48.8 25.1 151.4%
March 37.3 53.9 -16.6 69.2%
April 46.7 53.5 -6.8 87.3%
May 24.8 49.7 -24.9 49.9%
June 68.1 60.2 7.9 113.1%
July 73.3 42.1 31.2 174.1%
August 63.4 53.7 9.7 118.1%
September 15.9 61.0 -45.1 26.1%
October 39.1 74.7 -35.6 52.4%
November 146.1 66.2 79.9 220.6%
December 105.2 70.1 35.1 150.0%
         
TOTALS 764.2 703.6 60.6 108.6%

Month 2008 Actual Rainfall (2008) Millimetres Average Rainfall In Millimetres =+/- mm Average Percent Average
January 103.2 69.7 33.5 148.1%
February 21.9 48.8 -26.9 44.9%
March 108.5 53.9 54.6 201.3%
April 53.5 53.5 0.0 100.0%
May 87.0 49.7 37.3 175.1%
June 35.3 60.2 -24.9 58.6%
July 90.3 42.0 48.3 215.0%
August 107.8 53.7 54.1 200.7%
September 66.2 61.0 5.2 108.5%
October 74.3 74.7 -0.4 99.5%
November 91.1 66.2 24.9 137.6%
December 42.0 70.1 -28.1 59.9%
         
TOTALS 881.1 703.5 177.6 125.2%

Month 2007 Actual Rainfall (2007) Millimetres Average Rainfall In Millimetres =+/- mm Average Percent Average
January 91.6 69.7 21.9 131.4%
February 97.44 48.6 48.84 200.5%
March 57.6 53.9 3.7 106.9%
April 2.8 53.5 -50.7 5.2%
May 135.8 49.7 86.1 273.2%
June 72.4 60.2 12.2 120.3%
July 86.8 44.6 42.2 194.6%
August 64.6 53.9 10.7 119.9%
September 29.2 61.0 -31.8 47.9%
October 57.1 74.7 -17.6 76.4%
November 80.0 66.2 13.8 120.8%
December 67.1 70.1 -3.0 95.7%
         
TOTALS 842.44 706.1 136.34 119.3%

Month 2006 Actual Rainfall (2006) Millimetres Average Rainfall Millimetres =+/- mm Average! Percent Average
January 29.2 69.7 -40.5 41.9%
February 41.4 48.8 -7.4 84.8%
March 49.5 53.9 -4.4 91.8%
April 51.0 53.5 -2.5 95.3%
May 89.0 49.7 39.3 179.1%
June 15.0 60.2 -45.2 24.9%
July 35.6 42.1 -6.5 84.6%
August 110.0 53.7 56.3 204.8%
September 54.2 61.0 -6.8 88.9%
October 105.0 74.7 30.3 140.6%
November 104.4 66.2 38.2 157.7%
December 95.0 74.1 20.9 128.2%
         
TOTALS 779.3 707.6 71.7 110.1%

Month 2005 Actual Rainfall (2005) Millimetres Average Rainfall In Millimetres =+/- mm Average Percent Average
January 33.8 69.7 -35.9 48.5%
February 36.2 48.8 -12.6 74.2%
March 43.2 53.4 -10.2 80.9%
April 65.6 53.5 12.1 122.6%
May 44.4 49.7 -5.3 89.3%
June 44.0 60.2 -16.2 73.1%
July 39.0 42.1 -3.1 92.6%
August 58.6 53.7 4.9 109.1%
September 65.0 61.0 4.0 106.6%
October 88.4 74.7 13.7 118.3%
November 53.8 66.8 -13.0 80.5%
December 53.0 74.5 -21.5 71.1%
         
TOTALS 625.0 708.1 -83.1 88.3%