Rainwater harvesting
How Practical Action are helping the people feeling the effects of climate change
Climate change is disrupting the world’s rainfall patterns, meaning some parts of the developing world are suffering from a drastic drop leading to a fall in water levels in many reservoirs and rivers. In sub-Saharan Africa, 90% of agriculture is rain-fed, making it even more vulnerable to changing weather patterns.
The solution is harvesting rainwater as it falls and retaining it in the soil or in tanks below ground so it can be later used as a source of clean water.
Rainwater for irrigation
By constructing ridges of soil along the contours of fields, rainfall is held back from running off the hard-baked soils too quickly, so that crops have enough water to grow. Even when rainfall levels are low, families can harvest enough food.
Precious rainwater can also be captured and stored in tanks so that even on the driest of days, there will always be a water source for the important irrigation of crops.
Facilities installed have included both above and below ground rainwater catchment tanks, with the water collected from roofs of buildings, dams and channels for irrigation purposes, and improvement of ponds used for storing water.
Rainwater for drinking
The villagers themselves have usually expressed a clear need for improving water collection and storage provision. The water facilities are usually largely built by the villagers themselves with some assistance from trained masons or builders. People consider obtaining improved access to water well worth the building effort.
Tias Sibanda is Chairman of the Rainwater Harvesting coordinators in Ward 17, South Matebeleland, Zimbabwe. He is also one of the 100 farmer trainers.
He cultivates 4.5 hectares of maize and also has a homestead plot of 2 hectares for sorghum. Before he was introduced to water harvesting techniques by Practical Action, he used to plant maize on the 4.5 hectares but frequently harvested nothing because of the drought. He was able to grow sorghum at h\is homestead, as the crop needs little water, but this provided insufficient food for himself and his family and they could only survive by buying food with the proceeds from selling livestock.
He was one of the first farmers in the ward to build contours for conserving rainwater. This led to a big improvement in food supplies: last year, he had two crops of maize, the first producing 1.5 tonnes and the second 0.75 tonnes. He retained all of this for food and sold nothing. As a result, he no longer had to buy food and has sufficient stocks at home to last until next season. He calculates that he has avoided having to spend money on food equivalent to 12 goats. With a goat selling at some Z$300,000 (about £17), this means that he saved over £200.
"Thanks to the water harvesting techniques shown to us by Practical Action," says Tias, "and with the contour field structures, we are now more ‘food secure’ and have no worries about soil loss. I am confident of further improvements in the future and, if the drought eases, would soon be able to sell some of my maize crop".
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You can download further information on rainwater harvesting from Practical Answers, the technical information service of Practical Action, or you can ask a technical enquiry to the Practical Action staff via the online form.
Rainwater Harvesting
This technology is used in places where conventional water supply systems are not provided, are too expensive, or fail to meet people's needs.
Infiltration Pits for Rainwater Harvesting
This brief describes the context of dryland farming in Chivi District, Zimbabwe and how a technology for rainwater harvesting was developed with the community.
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...
Underground Rainwater Harvesting
Rainwater storage tanks can make an important contribution to water supplies in semi arid regions. This technical brief describes some of the techniques adopted in Zimbabwe.
Run-off Rainwater Harvesting
Run-off rainwater harvesting developed in Sri Lanka to enhance rural livelihoods.
The Sri Lankan Pumpkin Tank: A Case Study
A small scale roof water harvesting tank promoted in Sri Lanka by the World Bank.
Domestic Rainwater Harvesting Tank: Training Module
A manual on how to train people in the construction of a ferrocement "pumpkin" water tank.
Building small-scale water harvesting dams: the experience of Practical Action (ITDG) in North Darfur State, Western Sudan
The manual reflects Practical Action experiences of water harvesting dams in western Sudan, and demonstrates the quick impact that dams can make on people's livelihoods