392
~.~enenti
Low altitude remote sensing. Fouche and Booysen (1994) described the
development and field-testing of a remotely piloted aircraft. In field experiments in
S. Africa, in 1989-92, soyabeans, wheat and maize received irrigation treatments
which resulted in well-watered or moderately stressed conditions. The payload
comprised a thermal infrared thermometer and a camera. The difference between
canopy and air temperature was effective in assessing moisture stress in crops of
soyabeans and maize but less so in wheat.
Satellite remote sensing. Moran (1994) presented the results of an experiment
conducted in Arizona, USA, to test the feasibility of using SPOT and Landsat
satellite and aircraft data for crop monitoring and irrigation management. Several
shortcomings of present satellite systems with respect to providing timely
information for irrigation management were identified. A simple costlbenefit
analysis suggested that remotely sensed information from both, satellites and
aircraft, when shared by several users in moderately-size irrigation districts could
be profitable. Meteorological satellites provide observations at higher temporal
resolution but at lower spatial resolution. Applications of A VHRR observations to
irrigation water management were described by Vidal (1990), Vidal and Perrier
(1990) for sugar cane and by A. Brasa Ramos et al. (1996) for barley.
Irrigation performance. The requirements on timeliness of observations become
significantly less severe when aiming at the assessment of irrigation performance.
Bastiaanssen et al. (1996) evaluated the ratio of actual to maximum evaporation of
the Eastern Nile Delta with Landsat Thematic Mapper data. This ratio is a measure
of the adequacy of irrigation water supply.
17.3.5 Catchment hydrology
Localized irrigation. Satellite remote sensing has been applied to assess the
potential of surface runoff for irrigation in semi-arid regions (Humborg and Tauer,
1994) and to identify suitable sites (Tauer and Humborg, 1992).
Irrigation and watershed processes. The integration of hydrological simulation
models with remotely sensed data is a rapidly growing area of research and
applications. D' Urso et al. (1992) mapped crop water requirements in a large
irrigation district by combining analysis of Landsat Thematic Mapper images with
a calculation of reference evapotranspiration. The results were used in combination with a regional hydrological model to describe the interaction between surface
irrigation and the groundwater system. A map showing the spatial distribution of
irrigation performance indicators was also produced.
17.3.6 Detection ofsaline areas
Mapping of saline areas. Maps of salt affected areas have been produced using
aerial photographs (Wildman, 1982) and Landsat MSS and TM imagery (Joshi and
Sahai, 1993). Examples of the link with irrigation water management were
~.~enenti
Low altitude remote sensing. Fouche and Booysen (1994) described the
development and field-testing of a remotely piloted aircraft. In field experiments in
S. Africa, in 1989-92, soyabeans, wheat and maize received irrigation treatments
which resulted in well-watered or moderately stressed conditions. The payload
comprised a thermal infrared thermometer and a camera. The difference between
canopy and air temperature was effective in assessing moisture stress in crops of
soyabeans and maize but less so in wheat.
Satellite remote sensing. Moran (1994) presented the results of an experiment
conducted in Arizona, USA, to test the feasibility of using SPOT and Landsat
satellite and aircraft data for crop monitoring and irrigation management. Several
shortcomings of present satellite systems with respect to providing timely
information for irrigation management were identified. A simple costlbenefit
analysis suggested that remotely sensed information from both, satellites and
aircraft, when shared by several users in moderately-size irrigation districts could
be profitable. Meteorological satellites provide observations at higher temporal
resolution but at lower spatial resolution. Applications of A VHRR observations to
irrigation water management were described by Vidal (1990), Vidal and Perrier
(1990) for sugar cane and by A. Brasa Ramos et al. (1996) for barley.
Irrigation performance. The requirements on timeliness of observations become
significantly less severe when aiming at the assessment of irrigation performance.
Bastiaanssen et al. (1996) evaluated the ratio of actual to maximum evaporation of
the Eastern Nile Delta with Landsat Thematic Mapper data. This ratio is a measure
of the adequacy of irrigation water supply.
17.3.5 Catchment hydrology
Localized irrigation. Satellite remote sensing has been applied to assess the
potential of surface runoff for irrigation in semi-arid regions (Humborg and Tauer,
1994) and to identify suitable sites (Tauer and Humborg, 1992).
Irrigation and watershed processes. The integration of hydrological simulation
models with remotely sensed data is a rapidly growing area of research and
applications. D' Urso et al. (1992) mapped crop water requirements in a large
irrigation district by combining analysis of Landsat Thematic Mapper images with
a calculation of reference evapotranspiration. The results were used in combination with a regional hydrological model to describe the interaction between surface
irrigation and the groundwater system. A map showing the spatial distribution of
irrigation performance indicators was also produced.
17.3.6 Detection ofsaline areas
Mapping of saline areas. Maps of salt affected areas have been produced using
aerial photographs (Wildman, 1982) and Landsat MSS and TM imagery (Joshi and
Sahai, 1993). Examples of the link with irrigation water management were