106
Chapter 12
Worldwide, more water is diverted to and consumed by irrigated
agriculture than any other economic sector. Agriculture accounts for some
63% of the world’s use of fresh water (70–90% in developing countries).
However, increasing water demands for industry, municipalities and natural
ecosystems mean that less water will be available to sustain food production
while one third of the world’s food crops are currently produced by irrigated
agriculture, and irrigated agriculture has been the primary source of
incremental food production over the last several decades. This alarming
situation requires a full understanding of the water cycle at the regional, river
basin, and sub-continental scale. The need for better, more scale-appropriate
approaches to the measurement of water utilization in agriculture—to
improve the positive impacts of water resources development—is
complementary to the requirements for reducing negative impacts on other
ecosystems in the context of river basins.
The aim of this paper is to discuss the progress achieved in the
establishment of international data bases of information on land and water
resources, to highlight the information gaps in irrigation management, and to
show how remote sensing technologies can potentially contribute to that
information gap. The conversion between spectral and angular satellite
measurements on one side, and irrigation conditions on the other side, lies
outside the scope of this paper.
2.
AVAILABLE LAND AND WATER RESOURCES
DATABASES
Many databases at watershed, continental and global scale have been
developed in the past five years and are being continuously updated (see
Appendix 1 for selected examples). Aspects of the global water cycle are
essential for diagnosing regional scale water availability for irrigated crops.
Soil maps have been digitized and stored in electronic databases (e.g., FAO,
UNEP). River flow records have been assembled for a number of major river
basins (e.g., Global Runoff Data Center). Precipitation records have been
collected and analyzed by Legates and Willmott (1990). Rudolf et al. (1996)
characterized precipitations, using data from rain gauges, satellite
measurements and numerical models. Mintz and Serafini (1981, 1992)
worked on continental scale water balances and assimilated global soil
moisture fields from evaporation. Eswaran et al. (1995) used model
simulations with rainfall records collected from 27,000 climatic stations
around the world to infer soil moisture. In an attempt to identify the regional
and sub-continental water resources, Baumgartner and Reichel (1975),
Budyko (1986), Henning (1989), Chahine (1992) and Hartmann (1994)
Chapter 12
Worldwide, more water is diverted to and consumed by irrigated
agriculture than any other economic sector. Agriculture accounts for some
63% of the world’s use of fresh water (70–90% in developing countries).
However, increasing water demands for industry, municipalities and natural
ecosystems mean that less water will be available to sustain food production
while one third of the world’s food crops are currently produced by irrigated
agriculture, and irrigated agriculture has been the primary source of
incremental food production over the last several decades. This alarming
situation requires a full understanding of the water cycle at the regional, river
basin, and sub-continental scale. The need for better, more scale-appropriate
approaches to the measurement of water utilization in agriculture—to
improve the positive impacts of water resources development—is
complementary to the requirements for reducing negative impacts on other
ecosystems in the context of river basins.
The aim of this paper is to discuss the progress achieved in the
establishment of international data bases of information on land and water
resources, to highlight the information gaps in irrigation management, and to
show how remote sensing technologies can potentially contribute to that
information gap. The conversion between spectral and angular satellite
measurements on one side, and irrigation conditions on the other side, lies
outside the scope of this paper.
2.
AVAILABLE LAND AND WATER RESOURCES
DATABASES
Many databases at watershed, continental and global scale have been
developed in the past five years and are being continuously updated (see
Appendix 1 for selected examples). Aspects of the global water cycle are
essential for diagnosing regional scale water availability for irrigated crops.
Soil maps have been digitized and stored in electronic databases (e.g., FAO,
UNEP). River flow records have been assembled for a number of major river
basins (e.g., Global Runoff Data Center). Precipitation records have been
collected and analyzed by Legates and Willmott (1990). Rudolf et al. (1996)
characterized precipitations, using data from rain gauges, satellite
measurements and numerical models. Mintz and Serafini (1981, 1992)
worked on continental scale water balances and assimilated global soil
moisture fields from evaporation. Eswaran et al. (1995) used model
simulations with rainfall records collected from 27,000 climatic stations
around the world to infer soil moisture. In an attempt to identify the regional
and sub-continental water resources, Baumgartner and Reichel (1975),
Budyko (1986), Henning (1989), Chahine (1992) and Hartmann (1994)