394
M. Menenti
Inventories of irrigation systems. Landsat imagery has been used routinely since
1972 to identify and map central pivot systems in Nebraska (Rundquist et aI.,
1989). Data concerning the location of pivots have been collected since 1972 and
summarized annually as a map publication. Inventory procedures consist of
identifying and mapping occurrences of the characteristically circular pivot
systems as interpreted from photographic enlargements of Landsat imagery.
Irrigation uniformity. Lahlou and Vidal (1991) demonstrated that diverse
informations can be extracted from satellite data and used in irrigation water
management. Mapping of irrigated crops and detection of intra-plot heterogeneity
(a measure of irrigation uniformity) were of particular relevance.
Irrigation performance. Menenti et al. (1989) described the determination,
mapping and interpretation of three performance indicators. All indicators are
calculated with Landsat TM data and ancillary geo-referenced data. The three
indicators provide respectively a measure of equity, adequacy and effectiveness (or
marginal benefit) of water allocation. The implications for irrigation water
management in Mendoza, Argentina, were elaborated further by Menenti et al.
(1990). Broadly similar conclusions, but based on a study of four irrigation
schemes in India were drawn by Thiruvengadachari et al. (1995). Satellite remote
sensing is currently being employed as a operational tool to monitor and evaluate
system performance and to diagnose pockets of sub-optimal performance. These
techniques can provide useful data during project preparation, implementation and
post-completion phases of scheme construction. The case studies demonstrate that
primary data on irrigated area, cropping pattern, crop conditions and yield can be
generated.
17.4 Current and future observations
The techniques and applications reviewed in the previous chapter span a period of
time during which there has been a significant evolution in sensor technology.
Changes in the type of measurements obtained with earth observation satellites
have been limited, the only fundamentally new observations being radar backscatter with a suite of SAR instruments. A major technological evolution of
airborne sensors has taken place however. The driving force of such evolution has
been the development of the new International Earth Observing System (lEaS), a
very diverse suite of instruments developed by space agencies: NASA, ESA,
NASDA and CNES. In many cases a series offorerunners of the sensors scheduled
for flight in the time frame 1999 - 2005 has been developed to test new
technological solutions. Some of these developments are of direct relevance for the
determination of soil moisture, e.g. the synthetic aperture microwave radiometer
(EST AR), while solid state arrays of detectors have made imaging spectrometry
accessible to a larger community. The extent and direction of technological
evolution can be documented by looking at three categories: current satellite
sensors, current airborne sensors and future satellite sensors. For accurate and
M. Menenti
Inventories of irrigation systems. Landsat imagery has been used routinely since
1972 to identify and map central pivot systems in Nebraska (Rundquist et aI.,
1989). Data concerning the location of pivots have been collected since 1972 and
summarized annually as a map publication. Inventory procedures consist of
identifying and mapping occurrences of the characteristically circular pivot
systems as interpreted from photographic enlargements of Landsat imagery.
Irrigation uniformity. Lahlou and Vidal (1991) demonstrated that diverse
informations can be extracted from satellite data and used in irrigation water
management. Mapping of irrigated crops and detection of intra-plot heterogeneity
(a measure of irrigation uniformity) were of particular relevance.
Irrigation performance. Menenti et al. (1989) described the determination,
mapping and interpretation of three performance indicators. All indicators are
calculated with Landsat TM data and ancillary geo-referenced data. The three
indicators provide respectively a measure of equity, adequacy and effectiveness (or
marginal benefit) of water allocation. The implications for irrigation water
management in Mendoza, Argentina, were elaborated further by Menenti et al.
(1990). Broadly similar conclusions, but based on a study of four irrigation
schemes in India were drawn by Thiruvengadachari et al. (1995). Satellite remote
sensing is currently being employed as a operational tool to monitor and evaluate
system performance and to diagnose pockets of sub-optimal performance. These
techniques can provide useful data during project preparation, implementation and
post-completion phases of scheme construction. The case studies demonstrate that
primary data on irrigated area, cropping pattern, crop conditions and yield can be
generated.
17.4 Current and future observations
The techniques and applications reviewed in the previous chapter span a period of
time during which there has been a significant evolution in sensor technology.
Changes in the type of measurements obtained with earth observation satellites
have been limited, the only fundamentally new observations being radar backscatter with a suite of SAR instruments. A major technological evolution of
airborne sensors has taken place however. The driving force of such evolution has
been the development of the new International Earth Observing System (lEaS), a
very diverse suite of instruments developed by space agencies: NASA, ESA,
NASDA and CNES. In many cases a series offorerunners of the sensors scheduled
for flight in the time frame 1999 - 2005 has been developed to test new
technological solutions. Some of these developments are of direct relevance for the
determination of soil moisture, e.g. the synthetic aperture microwave radiometer
(EST AR), while solid state arrays of detectors have made imaging spectrometry
accessible to a larger community. The extent and direction of technological
evolution can be documented by looking at three categories: current satellite
sensors, current airborne sensors and future satellite sensors. For accurate and