With freshwater resources and population densities unevenly distributed worldwide, water demands already exceed supplies in regions with more than 40% of the world’s population. As a result, agriculture has been yielding its share gradually to non-agricultural uses. As the use of freshwater for non-agricultural activities generates wastewater, the volume of wastewater has been increasing, commensurate with rapidly growing population, urbanization, improved living conditions, and economic development.
Irrigation with wastewater supports agricultural production and the livelihoods of millions of smallholder farmers in many parts of the world.
Many farmers in water scarce developing countries irrigate with wastewater because:
- It is the only water source available for irrigation throughout the year,
- Wastewater irrigation reduces the need for purchasing fertilizer,
- Wastewater irrigation involves less energy cost if the alternative clean water source is deep groundwater, or
- Wastewater enables farmers in peri-urban areas to produce high-value vegetables for sale in local markets.
While recycling of treated wastewater and optimization of nutrient input to wastewater-irrigated soils need to be developed as a common practice in the water scarce areas, most wastewater in developing countries is being used in untreated and inadequately treated forms to grow a range of crops. Therefore, the protection of public health and environment are the main concerns associated with reuse of untreated or inadequately treated wastewater. This situation warrants rethinking of the ways through which wastewater is handled and used for crop production systems in developing countries. The implementation of research-based technical options for wastewater treatment and reuse, supported by pertinent policy level interventions, offers great promise for environment and health protection as well as livelihoods resilience.
Despite the importance of irrigation with wastewater in supporting the livelihoods of smallholder farmers, information regarding the quantity of wastewater generated, treated, and used at national scale is unavailable, limited, or outdated in numerous countries. A comprehensive search, published in an international journal ‘Agricultural Water Management’ identifies a global dearth of data on the generation, treatment and use of wastewater. Another piece published in ‘News & Views of Nature‘ (31 October 2013) states that remedying this situation will help policy-makers to better legislate for the management of this precious resource.
In addition, there would be need for site-specific and cost-effective approaches to water reuse, but the data gap must be closed before such policies can be effectively designed. This has been emphasized in the report, Catalyzing Water for Sustainable Development and Growth, produced by United Nations University Institute for Water, Environment and Health (UNU-INWEH) and the UN Office of Sustainable Development, in collaboration with Stockholm Environment Institute .
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World Soil Day!