Managing Scarce Water Resources in Agriculture in West Asia and North Africa - Restorative Redevelopment of Devastated Ecocultural Landscapes - page 447

e volUtion of the W ater P rodUCtivity C onCePt
Water's abundance and continuous renewal through the global hydrologic cycle has
for centuries left people to consider water a free natural resource. Expansion of irri-
gated areas, followed by increasing demands from industrial and domestic water use
sectors, stemming both from population growth and improved economic develop-
ment, has changed society's views. These changes in water availability are felt hard-
est in the water scarce areas of West Asia and North Africa. Whereas no less than
two decades ago the water issue (management and scarcity) was still considered the
lone playing ground for hydrologists and engineers, it is now at the top of the priority
list for planners and policy makers around the world.
Historically, the concept of system-wide (basin) efficiency of water use began to
surface in the early 1990s. There were, however, some early gleams about it here and
there (such as Bagely 1965 and Jensen 1967) but they did not cause notable impact.
This is because water was not so scarce at that time and water problems were usually
solved by increasing supply through the construction of more water infrastructures.
Nowadays, the approach to water problems has been shifted from construction to
management.
Water scarcity crises jumped to the forefront of global/international organizations'
serious concerns in the early 1990s (Rio Declaration, Agenda 21, 1992). Among the
main issues covered in the declaration are cooperation and participation, water eco-
nomics, sustainable development, and food production. Before the Rio Declaration,
the emphasis on water related issues was on availability of safe drinking water and
sanitation. Emphasis on sustainable development and efficient use of water resources
was explicitly and critically addressed in the First World Water Forum, 1997. Since
then, water issues have become everybody's concern and worry. There has been a
growing awareness that water will be one of the most critical natural resources in the
twenty-first century.
There is considerable potential for efficiency improvement in water use in agri-
culture. But, this improvement in water use and management should be sustainable
and environment friendly. Sustainability, in simple terms, implies continuity, long
lasting, and preserving of the natural base of the development, whereas efficiency
implies output per unit input. A shortcut to sustainable development is through inte-
gration and participation. Since sustainability is time dependent, there is no fool-
proof way to guarantee it. It may take decades to achieve (or may not achieve) it.
However, sound indicators for sustainability play a paramount role in this regard.
f rom e ffiCienCy to P rodUCtivity
Generally, the term “efficiency” reflects the ratio of output to input. However, con-
stituents of the input and output components differ from one discipline to another
and vary depending on the level and/or scale at which the word “efficiency” is being
used. In irrigated agriculture, there are many efficiency terms; each has a specific
use. Among these terms are Water Conveyance Efficiency, which reflects losses of
water in the conveyance system; Water Application Efficiency, which reflects losses
of water by runoff from the field and by deep percolation below crop root zone;