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Blessing from the sky: rainwater harvesting can enhance ecosystem productivity and livelihoods

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Wednesday, 22 April 2009 14:33

water-management3

A joint SEI/UNEP report outlines the advantages of investing in better water resource management.


Rainfall and soil water are fundamental parts of ecosystems which supply goods and services for human well-being. The availability of rain and soil water will consequently determine ecosystem productivity, both for agricultural and natural systems. However, increasing demand for water for development as well as the desire to maintain healthy ecosystems puts water resources under pressure.
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Ecosystem services suffer when rain and soil water become scarce. This in turn affects human livelihoods. The strain on water resources has led to an immediate need to find innovative opportunities that enable development and improve human well-begin without undermining ecosystem services.

A neglected opportunity
A recently published policy report entitled "Rainwater harvesting: a lifeline for human well-being" which is edited by SEI researcher Jennie Barron, highlights the potential of rainwater harvesting as a way to create synergies in landscape management and human well-being.

The report, prepared jointly for the World Water Forum by the United Nations Environment Programme and SEI , explains how rainwater harvesting can serve as an opportunity to enhance ecosystem productivity, thereby improving livelihoods, human well-being and economies.

- Rainwater harvesting has often been a neglected opportunity in water resource management because only liquid water in surface and groundwater sources (often called blue water) is usually considered. If we develop better ways of managing rainwater, we can improve water supply, enhance agricultural production and even sustain the ecosystem services we rely upon, Barron says.

Rainwater harvesting is the collective term for a wide variety of ways of collecting and storing rainfall, be it soil as storage, man-made dams, tanks or containers. The intention is to improve water management for multiple purposes. With farms being the most important ecosystem for human welfare, rainfed agriculture provides nearly 60 percent of global food value. Needless to say, rainfall variability constitutes a challenge to such agricultural systems.

- Low agricultural productivity often aggravates a negative spiral in landscape productivity, with degradation of ecosystem services through soil erosion, reduced vegetation cover and species decline, says Barron. She points to two reasons why rainwater harvesting deserves serious consideration:

- One reason is that the cost of decentralised water supply, especially in rural areas: harvesting and storage of rainfall is much lower than the cost of public water infra-structure in a hilly landscape with scattered homesteads. Secondly, rainwater harvesting reduces pressure to withdraw water from existing groundwater and/or surface water sources which could negatively impact ecosystems habitats and services.

Applicable in both rural and urban areas
In India, rainwater harvesting has been a successful starting point to put development on a positive track addressing both improved human well-being and re-generation of degraded landscapes, in particularly semi-arid and sub-humid zones. One of the most extensive rainwater harvesting programmes to date has been implemented in the Ganzu province in China.

- Through promoting small-scale storage at the household level, 15 million people now have an improved water supply. The water has also generated extra income through small-scale horticulture and increased livestock and poutry keeping. Because people’s health and income have improved, the ecosystem services have also been improved, Barron says.

Rainwater harvesting is increasingly also being promoted and implemented in urban areas. Recurrent droughts in Australia have spurred private and public establishments to invest in rainwater harvesting for their own needs. In parts of Japan and South Korea, rainwater harvesting has also been implemented as a way to reduce vulnerability in emergencies such as earthquakes or severe flooding which can disrupt public water supplies.

Not a magic bullet, but…
Barron recommends that rainwater harvesting should be better implemented in water management policies, strategies and plans in order to better recognize the valued impact of rainwater harvesting.

- Such harvesting is not a ‘magic bullet’ but it can be effective as a complementary and viable alternative to large-scale water withdrawals, and as a way of reducing the negative impacts on ecosystem services, not least in emerging water-stressed basins, Barron concludes.

Download the report from UNEP.org (pdf)

Download policy brief of the report (pdf)

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