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. From 2017 through  to March 2019 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.

With above average rainfall through the 2019/20 winter the aquifer was high enough to get flow through Redbourn for the first time since the summer of 2016. 

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.