Notes to broadcasters on water harvesting

    | April 30, 2012

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    Water scarcity already affects more than a third of the world’s population. With climate change, this number will undoubtedly increase. But there are many practical solutions to water shortages. One solution is water harvesting. Rainwater harvesting – often with a roof to catch water and a storage tank – is used extensively, while there are many traditional and modern systems for harvesting surface water and ground water. In this week’s story, a farmer simply uses his powers of observation to note that a nearby stream carries more water at night. By taking advantage of this observation, he harvests enough water to get good harvests while his neighbour’s crops are suffering from drought.

    Other strategies to adapt to water scarcity include recycling water, enacting and enforcing laws to protect streams and rivers, and using drought-tolerant crops and crop varieties.

    While many water harvesting systems involve harvesting rainwater via roofs and gutters, harvesting surface water involves collecting runoff water after a rainstorm, or obtaining water from intermittent streams, rivers or wetlands in open ponds or reservoirs. This stored surface water is typically used for irrigation, livestock and aquaculture. For domestic use, this kind of water would require treatment.

    Surface water can be collected indirectly by diverting it to ponds and / or spreading it over a large surface area. This type of surface water spreading increases soil moisture and crop yields, and is called spate irrigation. Surface water harvesting – at a small or large scale – revives and improves the productivity of the soil and allows for crop cultivation, tree planting and raising livestock.

    Typical surface water harvesting techniques include:

    • stone or earth embankments used as contour bunds,
    • terracing,
    • traditional systems such as the Sudan trus system,
    • semi-circular bunds such as demi-lunes, and
    • pits, including zai and tassa in West Africa or chololo and ngoro in East Africa.

    Farm Radio International has produced a number of radio scripts on water harvesting, including these two:

    -Catch rain from your roof (Package 89, Script 6, December 2009)

    -Malawian farmers catches water for crops in trenches and pits (Package 75, Script 2, June 2005)

    There is a wealth of information and lists of further resources on water harvesting in this issue pack:

    Water harvesting: an issue pack (Package 89, Script 3, December 2009)

    Farm Radio Weekly has published some stories on water harvesting, including:

    -Sahel: Fighting malnutrition with local food security and water management initiatives (FRW 122 August 2010)

    Zimbabwe: Collecting rainfall in the city (FRW 141, January 2011)

    -Kenya: Rainwater harvesting improves rural livelihoods (FRW 15, March 2008)

    If you want to create programs on water harvesting, you could talk to progressive farmers, older traditional farmers, organic farmers, NGOs with an interest in water or in adapting to climate change, and governments or companies with an interest in water.

    Find out whether any farmers harvest rainwater or surface water in your listening area.

    What methods do they use? Are these methods effective when there is an extended period of low rainfall? What other changes do they make to their farming and domestic life to adapt to low rainfall?

    Do farmers plant drought-tolerant crops? Or perhaps drought-tolerant varieties of staple crops? Do farmers make collective efforts to harvest rainwater? Has the government or NGOs helped these efforts? What are the results of efforts to harvest rainwater or surface water?