The deciding factor, it was concluded, is the extent of the saucer-shaped basin extending beyond the pond itself: the large basin would collect more rainfall than a pond created without such a surrounding feature. Dew ponds are still common on the downlands of southern England, the North Derbyshire and Staffordshire moorlands and in Nottinghamshire.
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In 2014, the traditional technique was verified by means of modern building material at reproductions of dew ponds in East Friesland. In this context, various techniques were tried in two terrestrial hollows. Commercially available PVC- film was used for the sealing and foam glass gravel for the insulation. The construction was carried out by craftsmen and the climatological analysis by Werner and Coldewey.
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Typical example of downland dew pond near Chanctonbury Ring, West Sussex. A dew pond is an artificial pond usually sited on the top of a hill, intended for watering livestock. Dew ponds are used in areas where a natural supply of surface water may not be readily available. The name dew pond (sometimes cloud pond or mist pond) is first found in the Journal of the Royal Agricultural Society in 1865.
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Other species of interest on Salisbury Plain include the great crested newt (Triturus cristatus). This newt occurs in dew ponds across the plain and in pools along the Bourne River, together with smooth newt (Triturus vulgaris), common frog (Rana temporia) and common toad (Bufo bufo). Barred grass snake (Natrix helvetica) are also often seen near pools, and common lizard (Lacerta vivipara), slowworm (Anguis fragilis) and adder (Vipera berus) are present.
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The name dew pond (sometimes cloud pond or mist pond) derives from the widely held belief that the pond was filled by moisture from the air.Oxford English Dictionary: "dew-pond" In fact, dew ponds are primarily filled by rainwater. A stone mulch can significantly increase crop yields in arid areas. This is most notably the case in the Canary Islands: on the island of Lanzarote there is about of rain each year and there are no permanent rivers.
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In the past the village used to be nicknamed "Dry Docking", as it had no water supply of its own except rainwater. This was owing to its elevation, which meant that the water table was deep and wells difficult to dig. A feature of the village landscape are several large surviving dew ponds, created as reservoirs into which rainwater was channeled. In the 1760s a single well was sunk some 230 feet down, which provided domestic water for the village at a farthing per bucket (the money went to pay an attendant who worked the windlass, since there was no pump).
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To retain more of the rainfall, the clay layer could be extended across the catchment area of the pond. A method of constructing the base layer using chalk puddle was described in The Field 14 December 1907. A Sussex farmer born in 1850 tells how he and his forefathers made dew ponds: If the pond's temperature is kept low, evaporation (a major water loss) may be significantly reduced, thus maintaining the collected rainwater. According to researcher Edward Martin, this may be attained by building the pond in a hollow, where cool air is likely to gather, or by keeping the surrounding grass long to enhance heat radiation.
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The hill dominates adjoining parts of the South Downs ridge, and particularly the much lower ground to the north (where the villages and towns of Mid Sussex are now located) in the Lower Weald. This represented an excellent position for defensive purposes, and is known to be the site of an early Iron Age hill fort. A single defensive bank and ditch enclosed an area of approximately 5.5 hectares (13.6 acres). Relatively little excavation of the fort has been carried out, however, and the existence of dew ponds, paths and tracks, as well as regular ploughing activity over the years, reduces the likelihood of any significant discoveries in the future.
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Several man-made devices such as antique, big stone piles in Ukraine, medieval "dew ponds" in southern England, or volcanic stone covers on the fields of Lanzarote have been thought to be dew-catching devices, but could be shown to work on other principles. At present, the International Organisation for Dew Utilization (OPUR) is working on effective, foil-based condensers for regions where rain or fog cannot cover water needs throughout the year. Large-scale dew harvesting systems have been made by the Indian Institute of Management Ahmedabad (IIMA) with the participation of OPUR in the coastal, semiarid region of Kutch. These condensers can harvest more than 200 litres (on average) of dew water per night for about 90 nights in the October-to-May dew season.
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The geological formation consists of alluvium overlying limestone formations of the coastal plateau, with distinct soil characteristics. In these meadows, the marshy grassland's special feature is that it is rich in plant life with 30 species reported for every square metre. Its faunal species consist of insects, birds such as lapwings which breed here, and mammals. Wick, Vale of Glamorgan SSSI has urged the private owners of these meadows to continue to conserve this area with special emphasis on permitting grazing to maintain a sward of height to control the land from becoming scrub and woodland, manage hay as practiced in the past, creating “dew ponds” at suitable locations as watering holes for cattle stock during winter and maintaining soil moisture by controlled cleaning of ditches and drains.
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The organized collection of dew or condensation through natural or assisted processes is an ancient practice, from the small-scale drinking of pools of condensation collected in plant stems (still practised today by survivalists), to large-scale natural irrigation without rain falling, such as in the Atacama and Namib desert. The first man made fog collectors have origins stretching back as far as the Inca Empire, where buckets were placed under these trees to take advantage of this natural phenomenon. Several man- made devices such as antique stone piles in Ukraine, medieval "dew ponds" in southern England or volcanic stone covers on the fields of Lanzarote have all been thought to be possible dew-catching devices. One of the first recordings of fog collection occurred in 1969 in South Africa as a water source for an air force base.
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However, there remains controversy about the means of replenishment of dew ponds. Experiments conducted in 1885 to determine the origin of the water found that dew forms not from dampness in the air but from moisture in the ground directly beneath the site of the condensation: dew, therefore, was ruled out as a source of replenishment. Other scientists have pointed out that the 1885 experiments failed to take into account the insulating effect of the straw and the cooling effect of the damp clay: the combined effect would be to keep the pond at a lower temperature than the surrounding earth and thus able to condense a disproportionate share of moisture. In turn these conclusions were disproved in the 1930s, when it was pointed out that the heat-retaining quality of water (its thermal capacity) was many times greater than that of earth, and therefore the air above a pond in summer would be the last place to attract condensation.
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