A word about water

September 5, 2017

The famous white chalk of the South Downs hills acts like a giant sponge, soaking up and storing water for 1.2 million people in the south east. The Brighton ChaMP project aims to protect this precious resource.

Words by Aimee Felus

The chalk aquifer of the South Downs gives us the water we drink and wash in, and feeds winterbourne streams and local rivers. But, like many aquifers and rivers across the world, it is polluted with nitrates – from fertilisers, manure heaps and road run-off. If nitrate levels rise above 50mg per litre then water no longer meets the Drinking Water Standard and can’t be supplied to our homes.

The project I work on is called Brighton ChaMP (Chalk Management Partnership) for Water. The South Downs National Park Authority is working together with other organisations to protect the aquifer. Winter is a particularly vulnerable time as bare fields and higher rainfall allow the nitrates in the soil to leach through into the aquifer. We can detect these nitrate spikes at the boreholes which supply our fresh water.

This autumn we’ll be trialling a new method for helping to protect our drinking water from pollution, working with two farmers on the Brighton chalk block to see whether cover crops can reduce nitrate leaching through soils and into the aquifer.

It’s a simple idea. Plant cover crops on otherwise bare winter fields which will take up excess nitrates and use them to grow. These plants will hopefully also provide cover for birds, small mammals and invertebrates, reduce erosion and improve the health of the soil. We’re working with a local crop sampling company and a volunteer from the University of Brighton to monitor the success of this approach. Other organisations have seen a reduction in nitrate leaching of up to 59% so we hope ours will perform just as well. In some European member states cover crops are now compulsory in areas where drinking water is particularly vulnerable.

There have been some indications that cover crops can increase slug numbers which would be bad news for water too – more slugs may mean that farmers need to use more pesticides – but there are some reports which suggest that cover crops help to increase numbers of natural slug predators. The jury is out so we hope that our trial will help to provide this much needed evidence. We don’t want to see a situation where one type of pollution is swapped for another so we will also be monitoring slug and snail numbers in the trial plots.

The Brighton ChaMP partnership is made up of the South Downs National Park Authority, the Environment Agency, Southern Water, Natural England, University of Brighton, Brighton and Hove City Council and the Living Coast; all striving together to protect the aquifer.

Visit brightonchamp.org.uk for more news about the project