Rainwater Harvesting for Drylands and Beyond by Brad Lancaster

August 1, 2014

Fog Harvesting with Living Systems

by Brad Lancaster © 2014

Got fog? Plant and grow living fog-harvesters or become one yourself, and you’ll end up increasing your rainfall—or at least your fogfall.

Note how much wetter the ground is below the trees than in areas where there are no trees. The tree leaves harvest the fog moisture, as it gathers on the rough/fine surface of the leaves, then rains down as fog precipitation. This effect can significantly increase the amount of water available to soil and plants. Photo credit: Erin O’Neill

Many native plants that grow in areas where fog is a regular occurrence have adapted their leaf structure to harvest fog. The fog gathers/precipitates on the rough/fine surface area of the leaves then drips/rains down to the soil as “fog precipitation.” The coastal redwood tree (Sequoia sempervirens) is an excellent example of the impact of this phenomenon; one study in northern California found that on average 34% of the annual hydrologic input was fog-drip off the redwood trees themselves, while in areas without the redwood trees, fog accounted for only 17% of the water input. These data demonstrate that the trees significantly influence the volume of fog-water entering the system.1 The study also found that in summer when fog was most frequent, and rainfall was absent, about 19% of the water within the redwoods—and about 66% of the water within the understory plants—came from fog after it had dripped from the leaves of the trees.2

Fog-drip from trees can be, and has been, harvested in cisterns to provide drinking water, as was the traditional practice with the “rain tree” (Ocotea foetens)3 of Hierro, otherwise known as the “holy tree,” or “garoe,” which grows in laurel-forest habitat at elevations between 400 and 1400 meters in Madeira, Azores, and the Canary Islands.4

Rain tree image links:

Rather than building a roof from which you can capture water, in the right fog-rich areas it is wiser to find or plant a tree—that’s a living system.

Coastal ridgeline forests—where fog gathers—are ideal for collecting fog, and the fog harvested by the vegetation typically contributes significant volumes of water to groundwater, springs, and creeks. So when these forests are removed, the inputs to groundwater, springs, and creeks are reduced—sometimes to the point that the spring and creek flows cease as groundwater levels drop.

Manufactured fog-catching sails (which mimic fog-harvesting spider webs) with gutters below are a non-living means of harvesting fog, though they can be used to capture water to irrigate and reestablish native living fog-harvesting trees. That’s the case in Bellavista, Peru, where over 800 river she-oaks have been planted and irrigated during the establishment period with fog harvested from a human-made fog-harvesting sail.5

Spider web harvesting fog, Santa Cruz, California

Spider web harvesting fog, Santa Cruz, California

The YouTube video From Thin Air features the FogQuest effort to provide drinking water from fog with manufactured fog-collecting screen sails and gutters below.

Efforts are underway to improve the efficiency of such fog sails by basing their design on the skin of fog-harvesting Namibian beetles (Stenocara gracilipes).6

There are a number of different fog-harvesting beetles in the dry, yet fog-rich, coastal area of Namibia. All the beetles climb to the top of coastal sand dunes, where some of these beetles harvest fog off their backs, while others build or dig fog-harvesting sand ridges or trenches on the dunes.7

We can mimic such adaptive behavior, either by planting or supporting fog-harvesting vegetation, adapting materials used in constructed fog-harvesting screens, or learning from the behaviors of fog-harvesting beetles and other life forms, including those that we have not yet discovered. The living natural world has more to teach us than we could ever imagine.

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
1. “Fog in the California Redwood Forest: Ecosystem Inputs and Use by Plants,” by T.E. Dawson, Oceologia, 1998. http://link.springer.com/article/10.1007%2Fs004420050683#page-2, accessed 7-21-2014.

2. “Fog in the California Redwood Forest: Ecosystem Inputs and Use by Plants,” by T.E. Dawson, Oceologia, 1998. http://link.springer.com/article/10.1007%2Fs004420050683#page-2, accessed 7-21-2014.

3. The Laurel or Bay Forests of the Canary Islands, C.A. Schroeder, Department of Biology, University of California, Los Angeles. California Avocado Society 1989 Yearbook 73:145-147. http://www.avocadosource.com/CAS_Yearbooks/CAS_73_1989/CAS_1989_145.htm, accessed 7-21-2014.

4. Ocotea foetens, Wikipedia, http://en.wikipedia.org/wiki/Ocotea_foetens, accessed 7-21-2014

5. “Fog Catchers Bring Water to Parched Villages,” National Geographic, http://news.nationalgeographic.com/news/2009/07/090709-fog-catchers-peru-water-missions/, accessed 7-21-14. Photos can also be found at http://poleshift.ning.com/profiles/blogs/photos-fog-catchers-harvest.

6. “Water Vapor Harvesting: Namib Desert Beetle,” http://www.asknature.org/strategy/dc2127c6d0008a6c7748e4e4474e7aa1#.U84AdaiySkc, accessed 7-21-2014.

7. “Fog-Basking Behaviour and Water Collection Efficiency in Namib Desert Darkling Beetles,” Thomas Nørgaard and Marie Dacke, Frontiers in Zoology 2010, 7:23, http://www.frontiersinzoology.com/content/7/1/23, accessed 7-21-2014.


Fog Harvesting in Morocco with Dar Si Hmad
Includes articles and video presentations

 “The Rain Tree of Hierro, Canary Islands. (Oreodaphne foetens)”
J. Hutchinson
Bulletin of Miscellaneous Information (Royal Botanic Gardens, Kew)
Vol. 1919, No. 3 (1919), pp. 153-164
Published by: Royal Botanic Gardens, Kew

Fog-Harvesting cactus (Opuntia microdasys)
Accessed 7-22-2014

Fog Harvesting


Dew Harvesting with air well (condenser) en.wikipedia.org/wiki/Air_well_%28condenser%29

Deflection of drying wind from grapes in Canary Islands with pits and stone walls




4 Responses to “Fog Harvesting with Living Systems”

  1. Fog Harvesting with Living Systems - Planet Experts Says:

    […] here […] to continue reading this blog post in its entirety on my website, HarvestingRainwater.com. _ _ _ _ […]

  2. Jesse Sherer Says:

    Brad, you speak to my times hahaha. I’ve been visiting the Bay Area and have been cringing at all of the bare hill tops throughout this region of fog. Especially marked is Mt. San Bruno in South San Francisco, to which there is perhaps a single tree growing on top of. I believe that the native oaks (what are left of them) probably do their fair share of fog condensing, and perhaps Bay Laurels fulfill certain niches of their Macronesian counterparts in California’s biome, but I’m terribly interested in whether Til will grow along the Pacific Coast. With the depth of the drought being this intense, and no knowledge of how intensely it will continue to be, it seems like a grand opportunity to make some Garoe of our own in the states.

    To that end I’ve actually begun looking for some Ocotea foetens seeds to start some experiments, but I have yet to find a source. I found your article through my search, and was wondering if you would have any leads? =]

  3. Episode 1502: Water Harvesting with Brad Lancaster | The Permaculture Podcast Says:

    […] resource of interest: Brad’s blog post on Fog Harvesting David Eisenberg and the Development Center for Appropriate Technology Zephaniah Phiri […]

  4. Creating Water Resilience Says:

    […] to the point that the spring and creek flows cease as groundwater levels drop.” writes Brad […]

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