Managing Scarce Water Resources in Agriculture in West Asia and North Africa - Restorative Redevelopment of Devastated Ecocultural Landscapes - page 443

use, particularly with the development of new technologies, possibly making use of
natural gas as a source of energy. Breakthroughs in the cost of desalination would
open real opportunities for several countries of the region. However, potential break-
through in the desalinization technology is hampered by lack of funds to support
research in this field.
Marginal-quality water development and use offers some promise. Potential
sources include natural brackish water, agricultural drainage water, and treated efflu-
ent. Research shows that substantial amounts of brackish water exist in dry areas that
can either be utilized directly in agriculture or desalinated at low cost for human and
industrial consumption (see chapter 21). The treated effluent is an important source
of water for agriculture in areas of extreme scarcity, such as Jordan and Tunisia
where it counts for about 25 percent of total water resources in the country. Egypt
is currently producing about 1.2 billion m 3 per year of recycled water from the city
of Cairo and by 2010 it is expected that 4.9 billion m 3 year will be in the country
(El-Beltagy et al. 1997). There is, however, several health and environmental issues
associated with its use in agriculture.
U tilizing m arginal -Q Uality W ater
It is projected that the water-scarce countries will have to increasingly rely on mar-
ginal-quality water resources. Contingent upon the use of appropriate approaches,
marginal-quality water resources have the potential to narrow the gap between water
availability and its demand in water-scarce regions. Whether beneficially used or
wasted, marginal-quality water needs appropriate treatment and disposal in an envi-
ronmentally feasible manner (see chapter 18).
Estimates show that at least 20 percent of global irrigated areas fall under irriga-
tion with saline and/or sodic waters or irrigation-induced saline and sodic soils. In
case of other major category of marginal-quality waters, one-tenth of the global pop-
ulation eats food produced using wastewater. As populations in different countries
and regions continue to grow and more freshwater is diverted to cities for domestic,
commercial, and industrial uses—about 70 percent of water used in domestic, com-
mercial, and industrial activities is returned as wastewater—the use of wastewater is
certain to increase, both in terms of volumes and areas irrigated (Scott et al. 2004).
The quality of wastewater used for irrigation varies greatly, both within and between
countries. There is no precise account of the global extent of wastewater irrigation.
Although overestimated, the tentative figure suggests about 20 million hectares
(about 8 percent of global irrigated area) are under irrigation with treated, partially
treated, and diluted wastewater (Scott et al. 2004).
In the future, marginal-quality waters are expected to become an integral part
of the agricultural production systems in water-scarce countries (Qadir and Oster
2004). Different types of marginal-quality waters need suitable pre-use treatment
and/or appropriate management during the course of their application. However, a
significant part of wastewater is used by the farmers for agricultural production in
untreated or partly treated form in many developing countries in an unregulated
manner. The protection of public health and the environment are the main concerns
associated with such wastewater reuse (see chapter 19). The use of saline and/or