Integrated Applications - Transport in the Atmosphere-Vegetation-Soil Continuum - page 289

measurements, remote sensing and simulation models. An important reason to include
the ield scale is that many choices with regard to crop and water management, which
directly affect WP, are made by the farmer. Also much of our scientiic knowledge
on crop-soil-water interactions applies to ield scale processes. The regional scale is
important as many decisions on water management and agricultural policies are made
at this level. Another reason to consider regional scale is that water management in one
region may affect other regions in the catchment. For instance, reduced groundwater
recharge upstream, will result in reduced groundwater availability downstream. To
evaluate options for improvement of WP both at ield and regional scale, we applied
a physical ield scale crop and soil model. The paragraphs that follow provide a sum-
mary; details can be found in Van Dam and Malik ( 2003 ).
8.3.2 Sirsa District
The study area, Sirsa District, is located in the western part of Haryana State, India,
and covers ca. 4270 km 2 ( Figure 8.5 ). The soil texture in Sirsa District varies from
sand to sandy loam, with a belt of silty loam to silty clay loam along the Ghagger
River, which lows from east to west through the central part of the district. The cli-
mate of the region can be deined as subtropical, semiarid and continental with mon-
soon (July-September). Average annual rainfall in Sirsa District varies from 100 to
400 mm, which represents only 10-25% of the reference evapotranspiration (Jhorar
et al., 2003 ).
The temperature conditions in Sirsa District allow growing of crops throughout
the year. However, farmers generally grow two crops per year: a rabi crop (winter,
from October to April) and a kharif crop (summer, from April to October). Crop pro-
duction is very limited without irrigation, even in the summer. Since the mid-1950s,
the Bhakra irrigation system has been distributing the surface irrigation water among
the farmers in Sirsa District. The canal water distribution among farmers follows the
Warabandi system, which means that they receive canal water amounts in propor-
tion to their land holdings. The limited canal water supply in Sirsa District forces
farmers to extract groundwater for supplementary irrigation. Groundwater quality
determines the amounts of groundwater used for irrigation. Groundwater quality in
the northern and the southern parts is generally poor compared to the central and
southwestern parts of the district. Therefore, in the period 1990-2000, the northern
and southern parts of Sirsa District experienced a rise in groundwater levels (in some
parts +10 m), whereas groundwater levels declined in the central parts (in some
parts -7 m).
Water management in Sirsa District is thus complex owing to low and erratic rain-
fall, canal water scarcity, high evaporative demands, sandy soils with low water hold-
ing capacity, marginal to poor groundwater quality and rising and declining ground-
water levels. Marketable yield in the farmer ields is considerably less than at the