Wastewater Use for Urban and Peri-urban Agriculture
A D V E R T I S E M E N T
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Freshwater Availability for Agriculture
As the world population increases, the competition for freshwater resources between domestic demands, industry, commerce, institutions such as hospitals, and agriculture is intensifying. Water demand has tripled since the 1950s (Brown, 2003).
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Imminent water shortages, however, are less likely to be visible than other natural resource disasters such as deforestation and soil erosion to both the public and policymakers. This is due to the fact that much of the water scarcity is induced by groundwater overdraft for agriculture, industry and domestic use made possible by increased electricity coverage, power subsidies for diesel and electricity, and the extension of cheap credit (Shah & Scott, 2004).
A huge increase in the number of wells and over-pumping with increasingly powerful diesel and electrical pumps is leading to falling water tables. Particularly serious over-pumping is occurring in China, India, USA, Pakistan, Mexico, Iran, South Korea, Morocco, Saudi Arabia, Yemen, Syria, Tunisia, Israel and Jordan.
Surface water from rivers is also tapped for freshwater and major rivers either completely dry up before reaching the sea or contain only a very small volume of water. Such over-exploited rivers include the Colorado river, the Yellow river, the Amu Darya, the Nile, the Indus and the Ganges. Currently, 70 percent of surface and groundwater is used for agriculture, however with increasing competition between agriculture, industry and domestic demand, agriculture is beginning to receive less water (Brown, 2003).
Water reuse is not a new phenomenon; it has been a worldwide practice for centuries. Agricultural wastewater, sewage wastewater (including grey water and black water) and industrial wastewater have been used directly or after treatment and/or dilution in urban and peri-urban areas for agriculture, especially in drought years.
With the dwindling supplies of fresh surface and groundwater, water reuse and recycling assumes a greater role than before to keep up with the increasing population growth and the demand for increased quality and additional quantities of food.