Harvesting rainwater using traditional techniques

 

http://answers.practicalaction.org/our-resources/item/building-on-a-tradition-of-rainwater-harvesting

BUILDING ON A TRADITION OF RAINWATER HARVESTING

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.

See the text: Practical Action

Published by

Willem Van Cotthem

Honorary Professor of Botany, University of Ghent (Belgium). Scientific Consultant for Desertification and Sustainable Development.