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< prev - next > Agriculture Irrigation KnO 100626_Building on a Tradition of Rainwater Harvesting (Printable PDF)
Pastoralists in sub-Saharan Africa are often part-time cultivators as well, and they manage to
make the most of irregular rainfall by harvesting rainwater, using traditional techniques. Will
Critchley argues that these methods can sustain a delicate balance between cropping and
pastoralism which is both environmentally and socially appropriate.
Development jargon is constantly changing, and new terms can quickly become fashionable.
The actual processes described may not be new - 'agroforestry' and 'rapid rural appraisal' arc
examples of basic techniques which have been around for a good long time - but the very
naming draws popular attention to the concept, and gives it respectability. 'Rainwater
harvesting' is a term which only became widely talked about in the early 1980s, despite the
fact that, according to one well-known (and nameless!) proponent, it is the world's second
oldest profession. But as is so often the case, it is much easier putting a name on a technique
than putting that system into practice.
The basic concept of rainwater harvesting for plant production is very attractive: instead of
allowing run-off to cause erosion, it is collected and concentrated in the fields for better
crops. It is, in effect, productive soil-and-water conservation. This makes very good sense for
the semi-arid areas of sub-Saharan Africa, where a third or more of the meagre rainfall is lost
through runoff. In the field, however, things are not so straightforward.
Traditional techniques
Part of the problem is that much of the well-publicized work on rainwater harvesting in the
1970s and 1980s was carried out in Israel where conditions are very different to sub-Saharan
Africa (SSA). Not only are the soils and climate dissimilar, but so, of course, are the social
and economic settings. Briefly, the direct transportation of techniques from the Negev Desert
in Israel to SSA in the heady days of the early 1980s just did not work out. Engineering
structures were commonly inappropriate, and costs often too high. A number of fingers were
burned, and rainwater harvesting lost some of its initial shine when trials did not give the
results hoped for.
What was not recognized, however, until very recently, is the wide usage of simple traditional
techniques in SSA: systems which have been used quietly to harvest rainwater for as long as
local inhabitants recall. These systems are not perfect, nor could they be automatically
replicated elsewhere, but they do represent a very useful source of information and ideas for
people with an interest in rainwater harvesting in SSA. Three examples illustrate the point.
The central rangelands of Somalia, stretching north from Mogadishu, are noted for their rich
bush which supports the largest population of camels in Africa. Scattered through this
apparently pastoral zone, however, are pockets of cultivation. In some areas, where the
average annual rainfall is less than 300mm, up to half of the families are actually growing
crops as well as herding livestock. In Hiraan District, some 200km north of Mogadishu, the
soils are mainly clayey and here the agro pastoralists make use of rainwater harvesting to
magnify the effect of the scanty rains.
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