17 Irrigation and Drainage
393
presented by Younes et aI. (1993) and Vincent et al. (1996). A significant amount
of work has been dedicated to develop empirical correlations of spectral
retlectances and indices with crop yield and vegetation cover (e.g. Wiegand et aI.,
1992). Besides space- and airborne multispectral scanners (e.g. Hick et aI., 1984),
also multispectral aerial photography was used for this purpose (Emelyanov et aI.,
1980). The usefulness of early MSS image data to assess changes in the salt
affected area was noted by Dwivedi (1994), although several authors including
Dwivedi and Rao (1992) concluded that the TM band 5 carries highly significant
information for the detection and mapping of salt affected areas. To develop a
reproducible procedure to measure salt affected area and its change Wiegand et aI.
(1994) applied numeric classification procedures. An optimal spectral index for
mapping and monitoring of salt affected areas in an irrigation system was proposed
by Mirabile et aI. (1995).
Soil salinity. Soil dielectric properties change significantly with solute concentration. Both passive and active microwave sensors have the potential of providing
measurements of soil salinity. Taylor et aI. (1996) retrieved soil dielectric
properties from AlRSAR data. Complex dielectric constants determined by
inversion of the polarized backscatter of radar images acquired in wet conditions
clearly delineated the distribution of saline soils in the Tragowel Plains Irrigation
Area of Victoria, Australia. There was good agreement between the areas
delineated as having anomalous dielectric constants by the radar backscatter
inversion techniques with saline areas as defmed by geophysics and as inferred
from dielectric constants determined in the field. The magnitudes ofP-band radardetermined dielectric constants were close to those expected from field determinations. The L-band-determined dielectric constants gives the best discrimination
between saline and non-saline areas as seen at the surface.
Impact on crop conditions. Assessment of salinity damage to pastures using
airborne remote sensing. Schaefer et al. (1990) attempted to correlate visible and
near IR imagery with crop conditions and yield. Independent observations of soil
salinity were necessary to assess impact on yield.
17.3.7 Irrigation management
Groundwater resources. Multi-spectral and multi-temporal satellite data from
IRS LISS-I and Landsat-TM were used by Rao et aI. (1993) to assess the
hydrogeological characteristics as well as groundwater irrigated areas in the
Anantapur district, Andhra Pradesh, India. Areas of overdeveloped groundwater
were identified.
Drainage conditions. Babaev and Babaev (1994) mapped filtration lakes in the
Turkmenistan deserts. Krapil'-skaya and Sadov (1987) mapped hydrogeological
conditions in the region of the southern Aral Sea using satellite imagery and aerial
photography. This study provided useful insights on the impact of irrigation
projects in the desert area of the basin.
393
presented by Younes et aI. (1993) and Vincent et al. (1996). A significant amount
of work has been dedicated to develop empirical correlations of spectral
retlectances and indices with crop yield and vegetation cover (e.g. Wiegand et aI.,
1992). Besides space- and airborne multispectral scanners (e.g. Hick et aI., 1984),
also multispectral aerial photography was used for this purpose (Emelyanov et aI.,
1980). The usefulness of early MSS image data to assess changes in the salt
affected area was noted by Dwivedi (1994), although several authors including
Dwivedi and Rao (1992) concluded that the TM band 5 carries highly significant
information for the detection and mapping of salt affected areas. To develop a
reproducible procedure to measure salt affected area and its change Wiegand et aI.
(1994) applied numeric classification procedures. An optimal spectral index for
mapping and monitoring of salt affected areas in an irrigation system was proposed
by Mirabile et aI. (1995).
Soil salinity. Soil dielectric properties change significantly with solute concentration. Both passive and active microwave sensors have the potential of providing
measurements of soil salinity. Taylor et aI. (1996) retrieved soil dielectric
properties from AlRSAR data. Complex dielectric constants determined by
inversion of the polarized backscatter of radar images acquired in wet conditions
clearly delineated the distribution of saline soils in the Tragowel Plains Irrigation
Area of Victoria, Australia. There was good agreement between the areas
delineated as having anomalous dielectric constants by the radar backscatter
inversion techniques with saline areas as defmed by geophysics and as inferred
from dielectric constants determined in the field. The magnitudes ofP-band radardetermined dielectric constants were close to those expected from field determinations. The L-band-determined dielectric constants gives the best discrimination
between saline and non-saline areas as seen at the surface.
Impact on crop conditions. Assessment of salinity damage to pastures using
airborne remote sensing. Schaefer et al. (1990) attempted to correlate visible and
near IR imagery with crop conditions and yield. Independent observations of soil
salinity were necessary to assess impact on yield.
17.3.7 Irrigation management
Groundwater resources. Multi-spectral and multi-temporal satellite data from
IRS LISS-I and Landsat-TM were used by Rao et aI. (1993) to assess the
hydrogeological characteristics as well as groundwater irrigated areas in the
Anantapur district, Andhra Pradesh, India. Areas of overdeveloped groundwater
were identified.
Drainage conditions. Babaev and Babaev (1994) mapped filtration lakes in the
Turkmenistan deserts. Krapil'-skaya and Sadov (1987) mapped hydrogeological
conditions in the region of the southern Aral Sea using satellite imagery and aerial
photography. This study provided useful insights on the impact of irrigation
projects in the desert area of the basin.