Geography Reference
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on the western rim of Kenya's Rift Valley—can extend for tens of kilometers, some-
times including channels that have been blasted from rock faces, or are made of planks
suspended around cliffs. The most complex are the underground systems— qanat or
khettara —a technology probably first developed about 2,500 years ago in Iran, then
spread eastward to Afghanistan and westward through North Africa and across the
Mediterranean to Cyprus (Cech 2009). They include water collection systems, storage
reservoirs and cisterns, and underground pipes that carry the water to the fields. While
these systems minimize evaporation, they also require high inputs of labor to build and
maintain. Though many, some centuries old, are still in use in Iran, the Middle East, and
North Africa, many others have fallen into disrepair because the required manpower is
no longer available, or pumped groundwater is more easily acquired. Another tradition-
al technology is spate irrigation, using floodwater from seasonal rainfall in mountains
to irrigate fields in the piedmont areas, as practiced in Baluchistan in southwestern
Pakistan, and in Yemen and Eritrea (Mehari et al. 2004).
A much more recent technology, fog water collection or fog harvesting, is used to
harvest water in some of the world's driest mountain areas, such as Chile's Atacama
Desert (Suau 2010). The water contained in the clouds rising over such mountains, es-
pecially in the afternoon and at night, does not always condense into rain, especially
where there is little vegetation. However, by erecting high fences of polypropylene
mesh, or “fog catchers”—or by planting stands of trees—this water can be harvested,
stored, and piped to villages (Gischler and Fernandez 1984). Installation and mainten-
ance costs are low. Similar projects have been installed in Cape Verde, Ecuador, Peru,
Namibia, Oman, Yemen, and Eritrea. In other dry areas, drip irrigation—another mod-
ern technology, though not mountain-specific—can increase the efficiency of water use
and expand the cultivated area, so that smallholders can increase their food security
and also grow crops for sale.
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