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WELL FACTSHEET - Regional Annex

Rainwater Harvesting in Southern Africa

Author: Sibonginkosi Moyo and Takura Nyimo, IWSD, February 2006

Quality Assurance: Jo Smet and Kristof Bostoen

Summary

Rainwater harvesting is rapidly being recognised as a primary or alternative source of water in Southern Africa, a region prone to droughts and unreliable rainfall. In the 1970s and 1980s, the potential of rainwater harvesting to improve crop production received great attention due to widespread droughts (Critchley and Reji, 1989). Despite its apparent potential use, rainwater remains relatively unexplored in the region. Although there are no clear policies to fully support rainwater harvesting, farmers in the region are using traditional techniques such as rock catchment, dead level contours, roof catchment, infiltration pits and road catchment to harvest rainwater. There are associations in the various countries formed to promote rainwater harvesting. These associations fall under a regional network called ‘SEARNET’.

In Zimbabwe, farmers practising rainwater harvesting now enjoy increased yields with 2 to 3 harvests in a planting season. Institutional support for rainwater harvesting from Government and donor agencies is increasing. In Botswana households practise homestead catchment with channels leading to underground tanks. Gender issues are taking a centre stage in the unfolding momentum of rainwater harvesting as women are the major users of rainwater systems. They are involved in decision making on how to practise farming, maintenance of the systems and distribution of income.

The benefits from rainwater harvesting include improved access to water, income generation as well as improved health and quality of life among others. Problems associated with the practice presently are limited capacity, financial constraints and the HIV/AIDS pandemic that is wiping out the able bodied.

Introduction

Frequent droughts in Southern Africa are threatening availability of food and food security in the region. Much of the response by governments of the countries in this region have tended to be on developing water resources mainly through construction of dams and irrigation schemes. This option often involves water transfer from one catchment to another, which besides being expensive to implement and to maintain, has a negative effect on the environment. One answer to the current crisis might lie in the promotion of rainwater harvesting techniques, especially as a source of water for domestic use and for agriculture between dry spells.

Rainwater has been harvested and used since ancient times in Southern Africa. The San people in Africa used to collect and store water in ostrich eggs (Gould, 1999). Rainwater harvesting activities are also documented from southern Tunisia ((Pacey and Cullis, 1986).

Despite its apparent use and advantages rainwater has not been fully exploited in the region. Its use has been sidelined by the use of protected wells, boreholes, piped water supplies and other ‘modern’ systems. In particular, the majority of countries in Southern Africa do not have policies to support rainwater harvesting . Most rainwater harvesting activities are being promoted by NGOs. In Botswana, government policies recognise the role of rainwater harvesting in promoting sound use of natural resources and enhancing agricultural production. However rainwater harvesting has not yet been accepted by the government as a reliable and safe water supply source, with water quality being an important concern. In Zimbabwe, a few NGOs have successfully introduced rainwater harvesting for crop production with small farmers in a few pilot areas. Most recent rainwater harvesting activities have been for crop production. Intermediate Technology Group (ITDG) has for a number of years been promoting rainwater harvesting as part of a broader land use and crop production programme. In Zambia, rainwater harvesting activities are primarily agricultural, and are co-ordinated by the Ministry of Agriculture, Food and Fisheries. Techniques such as graded terraces, tied ridges and potholing are commonly employed .

Countries from East and Southern Africa have formed country associations to coordinate activities and promote rainwater harvesting initiatives namely; Botswana, Ethiopia, Kenya, Malawi, Rwanda, Tanzania, Uganda Zambia and Zimbabwe. The country associations form a regional network for Eastern and Southern Africa (SEARNET); www.searnet.org. The network promotes rainwater harvesting in the region and has affiliations in Eritrea, Mozambique, Somaliland and South Africa.

Rainwater Harvesting Technologies

A number of technologies are being used in the region. These include brick tank, road runoff harvesting, spring development and protection, water pans runoff water harvesting, rock catchment harvesting, subsurface dams built of soil in sandy riverbeds and plastic lined underground pits . In roof catchment, gutters are positioned under the eaves of the roof to collect rainwater. The gutters are then directed and connected to a storage tank. However, some debris from leaves and other substances that may be on the roof affects the water quality especially during the first rains. A mesh may be placed to exclude the debris form the storage tank but this does not guard against the micro-organism content of the water. The water collected is basically used for domestic purposes like cooking, washing, bathing and watering home gardens. For details, see the WELL Global Fact Sheet on Rainwater Harvesting, http://www.lboro.ac.uk/well/resources/fact-sheets/fact-sheets-htm/drh.htm. Roof catchment is widely practised in parts of Zimbabwe like Matabeleland South province, Chipinge, Zvishavane, Binga and Chiredzi. In rock catchment the water is harvested from a rock (Box 1).

In road catchment rainwater is harvested from the perches of the road. Contour ridges on the perches of the road capture and collect rainfall run-off. The run-off is immediately directed to the fields that consist of dead level contours designed to collect water that has been captured by the road catchment.

Box 1: Some rainwater harvesting techniques in Southern Zimbabwe

Mr. Phiri, a farmer in Zvishavane a district in Southern Zimbabwe practises rock catchment. The rock collects water, which is directed to two collecting tanks. There is a ‘half moon’, which is a curved pit that has been dug. The pit is 8 meters wide and 3 meters deep. It is found at the edge of the rock catchment. Run-off from the rock catchment is captured and stored in the half moon pit. Since the half moon pit is not lined, water infiltrates into the soil. Mr Phiri reported that if the pit fills three times he is guaranteed a good harvest from his agricultural plot 300 meters downstream. Further, it guarantees him 3 harvests in one year.

Mr Phiri also makes use of another underground unlined pit which is 2.5m by 2.5m and 2m deep. Rocks have been placed inside the pit so that there is enough storage of water between the rocks. A plastic sheet was placed on the rocks before the pit was covered with soil. A drainage furrow collects water from the rock catchment into the pit. From the pit, the water infiltrates into the soil and downstream to the fields.

In the fields there are dead level contours on the perches of the fields and a small dam to store the water that has been harvested by the rock catchment. Mr Phiri successfully grows bananas, vegetables, maize, beans, paprika, mangoes and pigeon peas. Through rainwater harvesting he has managed to expand the area under cultivation form 3 hectares to 7 hectares.

Other Issues

Community participation and gender relations have been identified as key to the successful implementation of the water harvesting techniques. For example as women are the main users of rainwater harvesting systems, they must be involved in the planning, design and operation of the systems to ensure sustainability.

The Benefits of Rainwater Harvesting

Some of the benefits being realised from rainwater harvesting in the region are:

Improved access to water

Rainwater harvesting reduces the pressure on other water resources. It makes water available throughout the year. In urban areas, it can provide a means to lower the water bills. The walking distances to water sources are greatly reduced.

Food security

The use of rainwater is allowing more food production per unit of water (Box 2: Rainwater for irrigation). All over the region, small-scale farmers are employing the various techniques to increase their yields. Communities are increasingly being assured of adequate supplies of food.

Income generation

Some income can be realised from the sale of the agricultural produce.

Benefits to the environment

It nourishes the landscape; improvements in vegetative cover reduce soil erosion.

Box 2: Rainwater for irrigation

The successful implementation of rainwater harvesting projects in Zvishavane District in Zimbabwe has seen farmers like Mr. Phiri, Mr. Mawara and Mr. Banda catapulted into middle scale farming. Zvishavane is characterised by high temperatures and low rainfall patterns. Self-motivation and experimentation led the farmers to develop and establish traditional techniques of rainwater harvesting. The farmers have changed their cropping pattern and they have embarked on growing cash crops like rice, wheat and beans. They also grow crops such as millet sorghum, maize, pigeon pea sweet potatoes, vegetables chilli, watermelons, bananas and orchards with mangoes, guavas granadilla, oranges and lemons.

The farmers are now selling their agricultural produce to lucrative markets in Zvishavane and other surrounding places. Their levels of income have been substantially uplifted. These farmers formed a group called “Upenyu Ivhu” (Soil is Life). This group shares information through exchange visits with other established farmers around Zimbabwe, Africa and international organizations. Some of these farmers were once invited to Kenya, Australia and England respectively to learn more about rainwater harvesting as well as to share and exchange ideas with other farmers.

Other farmers in Gwanda, one of the driest areas in Zimbabwe are reaping positive agricultural outputs through practising rainwater harvesting using dead level contours. The contours are also found on the perches of the field and the again stretch the same size as the fields;. they are 1m deep and 1.5m wide. They yield 2-3 harvest in one season, which are known locally as and include maize, sorghum and millet. In April 2004 trials for wheat growing commenced.

Problems associated with Rainwater Harvesting

Limited capacity

Some of the farmers practising rainwater harvesting lack the agricultural knowledge and expertise to maximise the benefits from the water that they collect. It has been suggested that some of the implementation plans/ designs may be too technical for the users.

Financial constraints

Some rural farmers, although aware of the advantages of rainwater harvesting, are constrained by lack of funds to buy equipment.

The HIV/AIDS pandemic

Southern Africa is carrying the greatest burden of the world’s HIV/AIDS crisis. The pandemic is killing the able bodied who are able to practise rainwater harvesting, that is dig contours, build tanks etc.

References

Critchley, W.R.S. and Reji, C. (1989) Water harvesting for plant production: Part 2. Case studies and conclusions from sub-Saaharan Africa
Gould, J. and Nissen-Petersen, E. (1999). Rainwater Catchment Systems for Domestic Supply
Gould, J. (1999). Rainwater Harvesting Information Resources Booklet for Southern Africa.
Pacey, A. and Cullis, A. (1986). The Collection of Rainfall and Runoff in Rural Areas. London.

For further information

Contact Sibonginkosi Moyo or Takura Nyimo

Institute of Water and Sanitation Development (IWSD)

P O Box MP422

Mount Pleasant

Harare

Zimbabwe

Tel.: +263-4-250522/ 753026/ 735017

E-mail: smoyo@iwsd.co.zw/ takuranyimo@yahoo.co.uk

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