[Ccpg] PERU: IRRIGATING WITH FOG, looking for ways that are simple but effective, a story of reading and observing the landscape

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G r e e n T e c h n o l o g i e s I V

PERU: IRRIGATING WITH FOG

Although they were not always so, the Andean foothills surrounding Lima are 
today a terrain practically empty of trees or other plants. Between May and 
November a little rain turns the tops of the hills green. Aver- age annual 
rainfall here -- as along the entire Peruvian coast -- is a meagre 1-2 cm.

"A hundred years ago, these hills and valleys would have been covered by 
forests," says Barbara Leon, sweeping her arm across a bare -- save for a 
few hardy cacti -- landscape in the rural community of Collanac, about 30 
km southeast of Lima. Leon, an industrial engineer, is executive director 
of TECNIDES, a Peruvian NGO. She attributes the loss of the original 
forests to years of overgrazing by livestock and excessive har- vests of 
wood for household use or to fuel steam locomotives.

In order to encourage residents of Collanac to reintroduce trees and plants 
to this area, Leon is leading an IDRC-supported project that is testing a 
novel irrigation system for peri-urban agriculture. About 2,000 people live 
in Collanac, a community without electricity, water or sewage services. The 
average monthly income of $US190 per family is less than half the official 
poverty level for a family in Lima. With a view to improving family incomes 
and restoring vegetation, the project is promoting cultivation of two 
valuable plants: the prickly pear cactus or tuna (Opuntia ficus indica) and 
the tara tree (Caesalpinea tinctoria). The prickly pear is the host for the 
cochineal insect, from which car- mine -- a valuable natural colorant used 
in the food and textile indus- try -- can be extracted. In addition, fruit 
from the prickly pear fet- ches between 50 cents to a dollar [$Can.] per 
kilo, depending on the season. As for the tara tree, it is excellent for 
reforestation in arid lands owing to its low demands in water and soil 
quality. Moreover, its fruit can be powdered to produce a natural tannin 
for leather tanning or exported to developed countries as a raw material 
for the production of gallic acid, a high-value commodity used in the 
leather, cosmetic and pharmaceutical industries.

Trapping moisture from clouds

An important obstacle to cultivation of tara and prickly pear along the 
Peruvian coast has been extremely low rainfall. But plenty of water reg- 
ularly passes by overhead in moisture-laden fog heading from the Pacific 
Ocean into the Andes. The vanished coastal forests used to trap some of 
this moisture naturally.

The Collanac project reproduces this water-trapping process artificially 
using a technology applied in an earlier IDRC project on the Chilean coast. 
The technology, known as fog collectors, consists of large panels (about 12 
m by 4 m) of fine mesh positioned along hilltops. Some of the incoming fog 
condenses on the mesh, drips into plastic troughs and flows to storage 
tanks at the foot of the hill. "In principle, each collector should provide 
enough water to cultivate one hectare," says Barbara Leon.

The fog collectors at Collanac were built using low-cost materials 
available locally such as bamboo posts treated with a tar preservative, 
notes Javier Blosier, an agricultural engineer with TECNIDES. Five col- 
lectors have been installed (at an altitude of 500 metres), with 15 more 
collectors partially constructed or planned.

The Collanac community has worked alongside TECNIDES to manage the pro- 
ject and in the construction, maintenance and use of the water from the 
collectors. "We have a committee that decides how to share the water we 
capture, depending on things like who is planning on planting," says Cesar 
Palacios, the president of La Meseta sector.

Norma Verastegui, a social worker with TECNIDES, has been encouraging 
different forms of community participation in the project. There are some 
57 families in the La Meseta sector, migrants from every corner of Peru in 
flight from economic hardship and the violence sparked by the Shining Path 
during the past decade. "Their customs are quite different depending on 
where they are from, which can pose problems when it comes to working 
together," says Norma Verastegui.

Nonetheless, this diverse community has succeeded in forming womens' and 
youth clubs. The womens' club is planning to build a community kitchen 
because it is more economical for them to prepare meals together. They have 
also begun growing vegetables. It is primarily the women, children and 
elders who shoulder all the work of gardening and raising livestock. The 
men leave the community every day to look for work in Lima.

Some families have created productive oases in the dry soil, growing a 
variety of trees including tara, licuma and Schinus molle, cultivating 
fruits and vegetables, and raising chickens and guinea pigs. A portion of 
the water for the family and community gardens comes from the fog 
collectors already installed. Until the other collectors are in service, 
the rest of the water must be purchased from tanker trucks at a cost of 
about $US3 per cubic metre.

Making every drop count

Minimizing the amount of water needed for cultivation is the purpose of the 
second major technology being applied in the project: pottery dis- pensers 
that allow just enough water to seep through their porous walls to satisfy 
the needs of each plant. This technology finds its antecedent in ceramic 
pots used by the Incas in Peru's arid hills. The modern pot- tery 
dispensers are about 6 inches [15 cm] deep, with spouts at each end that 
allow them to be linked by hose beneath the growing plants.

Dispensers of varying rates of seepage -- to match the water needs of 
different plants -- have been designed for TECNIDES by Ernesto Huayta, an 
engineer specializing in ceramics. They save enormous amounts of water. 
Based on tests with all the different types of trees involved in the 
project, "the average amount using this system is 4 litres per month per 
tree," says Huayta. "This is very little water."

Collanac resident Apolinario Crispen says he uses 60 litres of water per 
month for each tuna plant when he waters by bucket. But the dispenser 
system requires a mere 4 litres of water monthly to do the same job.

"The dispenser system is an important saving of water, which represents 
income," says Cirilo Vasquez, the president of Collanac community. Once the 
dispensers go into full-scale production, they will be sold for less than 
10 cents each. Although not many residents have bought pottery dis- 
pensers, or the tara seedlings (along with other tree species) that the 
project raises at a community nursery, Vasquez believes more will. "I think 
with the dispenser system everyone will buy taras. It was a desert when we 
arrived, but now it is getting better every year -- the people are becoming 
convinced."

In one dry valley, Leon and Blosier are pursuing experiments to grow tara 
trees with little or no irrigated water, using various soil mix- tures. 
These experiments also allow them to select the best tara trees: "We have 
to carry out research to choose the right genetic material for the area 
that will survive in these difficult conditions," says Leon.

If the combination of fogcatchers and pottery dispensers proves a suc- cess 
in tuna cultivation and tara afforestation, it is a model of sus- tainable 
development that could be adapted to innumerable similar com- munities 
along the dry Pacific coast of Peru and Chile and to other countries such 
as Namibia, Oman and Yemen. Apart from helping improve the incomes of poor 
rural residents, this system may lead one day to fulfilling a dream of 
Barbara Leon, one no doubt shared by many Peruvi- ans: a coastal region 
whose valleys are once again carpeted in green forests.

Reproduced from: Neale MacMillan, 1995. "Pottery Irrigation on Peru's Arid 
Coast." IDRC Reports, Volume 23, no. 1 (April), pages 8-9; with kind 
permission of International Development Research Centre (IDRC) of Canada. 
Also at gopher://gopher.idrc.ca .