Integrated Applications - Transport in the Atmosphere-Vegetation-Soil Continuum - page 293

Table 8.3 Mean crop yields and standard deviations (fresh matter, tons ha -1 ) of
wheat, rice and cotton as obtained by distributed SWAP-WOFOST modelling,
remote sensing (SEBAL) and ield measurements at farmer ields in Sirsa District
during the agricultural year 2001-2002

Method Wheat Rice Cotton

Mean SD Mean SD Mean SD

SWAP-WOFOST 4.8 1.0 3.5 2.5 2.0 0.5

SEBAL 4.4 0.3 3.7 1.1 2.2 0.3

Field measurements 4.5 1.5 — — 2.1 1.1

After Singh et al. ( 2005 a).

Table 8.4 Water productivity WP ET (kg m -3 ) as estimated with SWAP-WOFOST
(distributed modelling) and with SEBAL (remote sensing) in Sirsa District during
the agricultural year 2001-2002

Wheat Rice Cotton

Mean SD Mean SD Mean SD

SWAP-WOFOST 1.37 0.20 0.47 0.30 0.36 0.05

SEBAL 1.22 0.07 0.43 0.19 0.31 0.04

The evapotranspiration is calculated during the entire growing season.

unit water consumed. At the same time, the irrigated agriculture should be sustain-
able. This means a higher water productivity, less groundwater rise and lower salinity
levels in the northern commands and less groundwater level decline in the central
commands. Therefore we evaluated three scenarios ( Table 8.5 ) and compared them to
'business as usual' for a 10-year period.
Scenario 1 mimics the reference situation with the crop and water management as
measured during the agricultural year 2001-2002. Scenario 2 quantiies the impact
of improved crop cultivars, cultivation and nutrient, weed, pest and disease manage-
ment. These developments are expected to increase crop yields by about 15%. Sce-
nario 3 targets the rising groundwater levels in the northern parts of Sirsa District.
The seepage losses from the conveyance system amounted about 40% of the net canal
inlow. By canal lining and proper canal maintenance it should be able to reduce the
seepage amount by 25-30%. Scenario 4 was formulated to divert canal water from
the northern regions with rising groundwater levels to the central and southern com-
mands with declining groundwater levels.
The simulation results showed that improved crop management (Scenario 2)
increases water productivity with about 12%. Lower seepage losses in the irrigation
canals (Scenario 3) reduced the current salinization in the area with 35%. Canal water