Would Dew Ponds be a help in climate change?

A panoramic view of all seven sisters from the Beachy Head cliffs near Birling Gap, looking back towards the River Cuckmere and Seaford Head in the background.

These shallow concave scrapes found high in the chalk Downs or grasslands of southern England, particularly the eastern parts – Kent, East and West Sussex, Hampshire, Wiltshire and into Dorset are an enigma .. but they could be a useful enigma in this day of climate warming.

These small ponds, some survived, some revived, some left to sediment and grass, have a huge wealth of hidden knowledge ... they do not seem to run dry. Why? They should do, as most are situated on the chalky Downs – that soft white porous sedimentary rock that does not allow rainwater to run off, but absorbs the rain releasing it slowly into aquifers below.

Cowlink Dew Pond, near Eastbourne on the Downs

Early settlements were situated on high land to provide protection from the marauding animals roaming the forests and thicketed land below, but they lacked one essential – water.

These dew ponds – also known as ‘mist ponds’ or ‘fog ponds’ lie on the Downs far above the level at which streams begin to form, or springs are found, and romance has attributed certain of the older ones to the work of Stone Age men.

Archaeological evidence has revealed that the Downs have been inhabited and worked for thousands of years. Neolithic flint mines and settlements; Bronze Age burial mounds; and Iron Age forts are all in evidence. It is also thought that the tree cover of the Downs was cleared some 2,500 years ago, and the present closely-grazed turf is the result of continual grazing by sheep.

The fact that most dew ponds are at the top of the hill make them strategically positioned to get the most from the mist and rainclouds billowing up from the nearby coast to the chilly heights of the Downs, where any water that collects is less likely to evaporate. There is no catchment area for the rain when it does fall, but the Downs are quite often enshrouded in mist or low cloud, and where trees have been replanted then there will be extra moisture from the dripping branches.

Some dew ponds will also collect rain water from the surrounding land, as they are normally situated in a slight depression, but a great many are at the high point and need to obtain their moisture in other ways. The water retention properties of these ponds lay in their making and the appreciation of the margins of the pond as a catchment area.

An ancient method of obtaining a watertight material based on chalk, clay and straw is by ‘puddling’ - layering the pond bottom with these materials, which were then trodden and beaten flat, providing a bound waterproof bottom liner. The ‘puddle’ needed to be about 25 cm (ten inches) at the edge, and about a metre (three feet) thick at the bottom.

This ‘puddling’ is done in layers and has to be kept wet in order to remain waterproof. The process took some days, and at night the work done had to be covered with straw to ensure the frost did not get in and damage the lining. Once completed the base is lined with flints, pebbles and small stones – providing a protection from animal hooves damaging the lining surface as they quench their thirst.

On warm summer days the pond will remain cooler from the stone layer taking longer to warm up, the non-conducting nature of the layers of straw, when night comes and the air cools, the cooler water will attract more moisture from the atmosphere, and so counteracts the evaporation on the hottest of days.

High 'N Over: a rising Down looking back down the Cuckmere basin towards the English Channel

We have a dew pond on the coast road at the high point, where the herders would have rested their animals on their way to market before the days of transport, or when the animals were moved from one part of the lands to another; these coast roads were the main stay of prehistoric man as they provided access to the beaches and sea – a major source of food., and I have always wondered about them.

It is a credit to our ancestors that these dew ponds were able to exist, found high up on the hills, far from the shade of trees or protecting copse, where no streams have ever flowed, they seldom if ever dry up even when the valleys are parched and the springs reduced to mere trickles.

Dew Pond on top of Downs at Beachy Head, above Eastbourne

This enigma could be used today – new dew ponds being dug to retain water, old ones revived. In 1922 it was estimated that the life of a dew pond was 100 to 150 years, at this stage as long as it was renewed and cleaned – then its life would be indefinite .. there are records of ponds being in existence today that were recorded in Saxon times around 825AD. These could provide a lifeline or back up where a supply of water is required in times of drought – will the art of dew ponds be revived?

Dear Mr Postman .. these pictures and these ponds must resonate with you - as a Sussex man. My mother loves these old stories remembering her history and the old ways that she heard as a child - though she was mostly brought up in Cornwall - she'll be interested to see the Sussex content .. it's great to see you and thank you for our letter ...

Hilary Melton-Butcher

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