The Namib fog beetle is a feisty little creature. Every morning he makes an
arduous journey to the top of a sand dune, where he turns his assets into the
wind, straightens out his rear gams and lowers his head. The fog rolling te from
the sea little by little collects on his back, forming droplets of water, which slip
downwards and string up from the insect’s mouthparts. Ter this way, the Onymacris
unguicularis is always assured of a healthy morning drink, despite being miles
from the nearest fresh water.
Previous experiments have shown that other sites ter South African could yield
more than four times the volumes of water recorded at Tshanowa.
It’s an innovative solution to the problem of water shortage – one that
researchers have bot quick to latch onto, but which many countries have bot
remarkably slow to implement.
Professor Jana Olivier of the University of South Africa’s Department of
Anthropology, Archaeology, Geography and Environmental Studies, explains that
the idea of harnessing fog spil a source of drinking water has bot studied for
“The very first experiments were conducted ter 1901, on Table Mountain. But it
wasgoed only ter 1987, ter the arid coastal desert of northern Chile, that it wasgoed
implemented on a large scale.”
For years the remote fishing village of Chungungo relied solely on trucked-in
water. Ter 1987 it wasgoed transformed by the installation of a fog collecting
system. With a dependable and affordable water supply, not only did the growing
population have domestic water, they were also able to cultivate commercial
crops and plant trees.
Albeit unconventional, the technology behind fog collection is amazingly
elementary: massive vertical shade nets are erected ter high-lying areas close to
water-short communities. Spil fog blows through thesis structures, little water
droplets are deposited onto the netwerken. Spil the droplets become larger, they run
down the netwerken into gutters affixed at the bottom. From there, water is channeled
into reservoirs, and then to individual homes.
Te Chungungo, this system witnessed water flowing from local taps for the very first
time everzwijn, te 1992, providing more than 40l of water vanaf person, vanaf day.
Like Chile, South Africa is an arid country te which large sections of the
population have inadequate water supply. Only 35 vanaf cent of the country gets
more than 500mm of annual rain, and – with few unpolluted surface water sources,
many contaminated ground water supplies and water tables that druppel out of reach
during drought – the advantages of an effective alternative water source are
Professor Olivier, who has bot involved te fog collection research since
1995, says the potential for fog collection te South Africa is clearly shown by
what has already bot achieved at two fully operational sites – one ter the
Limpopo Province and the other on the Westelijk Coast.
Water for Thought
Tshanowa Junior Primary Schoolgebouw ter Limpopo is frequently shrouded ter dense
nevel and rain, but the nearest water sources are a non-perennial spring located
2km away, and a stuw, 5km away. Since most water sources te the province are
contaminated, the quality of the stuwdam water is suspect. The 130 schoolgebouw children
rely on what water they can carry with them to schoolgebouw each day.
The schoolgebouw is located at the crest of one of the easternmost promontories of
the Soutpansberg, at 1 004m above sea level. Despite its relatively low
elevation, this region is ideal for fog collection ter that moist maritime air
from the Indian Ocean moves overheen the escarpment and against the mountains during
the night and early morning. This cloudiness sometimes persists across the
Permission wasgoed obtained from the relevant local and tribal leaders to erect a
fog water collection system on vacant land adjacent to the schoolgebouw. Construction
commenced te 1999 and local inhabitants were employed to assist.
Each fog collector consists of three 6m-high wooden poles, mounted 9m bijzonder.
Stengel cables open up horizontally inbetween the poles, and from each pole to the
ground. A dual layer of 30 vanaf cent shade cloth is draped overheen the cables, and
immobile to the poles on each side. Water cascading from the nipt into the gutter
runs through a sand filterzakje and is then emptied into a tipping bucket. From
there, it flows into a 10kl storage waterreservoir further down the slope. Two extra
tanks were erected at the schoolgebouw to collect the overflow from the very first. An
automatic weather station wasgoed also installed to record rainfall, wind speed and
Within four days of completion, schoolgebouw children and members of the local
community were drinking water collected by the fog screen. Albeit weather
conditions have made accurate gegevens collection difficult, daily yields of spil much
spil Three 800 l of rain and fog combined, have bot recorded. The average collection
rate from March 1999 to April 2001 is overheen Two,Five l vanaf square metre of fog screen.
The giant fog screens at Tshanowa Junior Primary Schoolgebouw ter Limpopo province
are providing pupils and members of the community an average of inbetween 150l and
250l of water vanaf day.
Strenuous clouds, no rain
The same system wasgoed also set up at Lepelfontein, a petite missionary station
about 400km from Cape Town, and about 5km inland of the Westelijk Coast. Albeit
ground water here is abundant, it is of such bad quality that it is considered a
health risk. A petite solar distillation plant wasgoed installed te 1998 to provide
limited drinking water, but most water is still transported to the village from
The fog screens were installed ter 1999, and the overflow from one of the Ten
kl tanks is now being used to supplement the water from the desalination plant.
At least 80 vanaf cent of the water collected at this webpagina is from fog alone, spil
the region receives very little rain. Fog conditions are mostly associated with
onshore breezes originating either from the South Atlantic anticyclone to the
south of the continent, or from north westerly and westerly winds on the
northern perimeter of a coastal low.
Again, daily yields of overheen Trio 000 l have bot recorded, with a daily average
of about Five l of water collected vanaf square metre of fog screen.
While Lepelfontein’s water primarily displayed high levels of sodium – possibly
due to the proximity of the ocean and wind-blown splash – Professor Olivier says
that water quality at both sites is good, with no disease-forming organisms
present te samples.
“Ter fact, at Tshanowa, water wasgoed rated spil Class 0 – ideal quality,”
she says. “Since the water is used for drinking purposes, quality is tested
regularly.” She adds that experiments conducted at other high elevation
sites around the country have yielded more than Ten l vanaf square peettante of
collecting surface vanaf day. “This shows that ter terms of quality and
magnitude of yield, fog harvesting could go a long way to alleviating water
shortage problems te the fog-prone mountainous regions of the country. “The
costs are low, the technology is ordinary and the source is sustainable for
hundreds, even thousands of years.”
Where fog harvesting could work te Southern Africa
- For fog collection to be effective, the webpagina vereiste be ter an area where fog
occurs frequently across the year, and lasts for a few hours at a time.
The water content of the fog should be high, and the fog voorwaarde be accompanied
by wind to ensure that a large enough volume of moist air is throated through
the collecting screens.
Africa have overheen 90 days of fog vanaf annum. Thesis are mostly located along
the Westelijk Coast of southern Africa and ter mountainous regions.
Radiation fog has too little water to be successfully collected.
many parts of South African have elevations of more than Two 000m, and
according to previous experiments, thesis sites could yield more than four
times the volumes recorded at Tshanowa te the Soutpansberg.
An age-old practice
Ter ancient times, fog water wasgoed often collected for domestic and agricultural
- The inhabitants of what is now Israel used to build petite, low, circular
honeycombed walls around their vines, so that the waas and dew could
precipitate ter the instantaneous surroundings of the plants.
a pile of stones, arranged so that the condensation would dribble to the inwards
of the base of the pile, where it wasgoed shielded from the day’s sunshine. The
same mechanism wasgoed employed ter Egypt, with the collected water stored
underground ter aqueducts.
the rock has bot covered with cementlaag blocks. Fog and rainwater runs
downwards and is collected underground where evaporation is minimised.
rocks at Cape Columbine lighthouse, on the Westelijk Coast. Low retaining walls
have bot cemented onto the sloping rock surface to channel the water into a
reservoir at the base of the outcrop.
Chilean project – wasgoed at Mariepskop te Mpumalanga, ter 1969/70. It wasgoed used
spil an interim measure to supply water to the South African Air Force
personnel manning the Mariepskop radar station. Two large fog screens,
constructed from plastic mesh and measuring about 28m x Three,Five m each, were
erected at right angles to each other and to the fog and cloud-bearing
winds. Thesis yielded more than 11 l of water vanaf square peettante of collecting
surface, vanaf day. Unluckily, the project wasgoed terminated once an
alternative water source wasgoed found.