GIS in Irrigation andWater Management - Practices of Irrigation and On-farm Water Management - page 430

a series of equations, which expresses the relationship among the parameters and
finally providing an output. The second type of model also called lumped parameter
model. If under GIS environment all the basic functions (data input, management,
analysis, and output generations) are integrated with the rule-based or other nec-
essary tools for the modeling under one graphical users interface (GUI), then it is
called the GIS-based modeling or decision-support system.
GIS have been used in many areas such as agricultural watershed management
(Sarker, 2002 ) , hydrology (Chandrapala and Wimalasuriya, 2003 ) , water produc-
tivity estimation (Ines et al., 2002 ) , monitoring of irrigation delivery (Rowshown
et al., 2003 ) , groundwater assessment (Chowdary et al., 2003 ) , estimating water
demand (Satti and Jacobs, 2004 ) , hydrologic impacts of land-use change (Bhaduri
et al., 2000), and water resources management (McKinney and Cai, 2002; Knox and
Weatherfield, 1999).

11.12 Remote Sensing Techniques

Remote sensing is the collection of data through imaging sensor technologies,
usually on an aircraft or satellite. The remote sensing techniques involve close
examination of enlarged landsat imageries and aerial photographs followed by iden-
tification, interpretation, and mapping of various water and agricultural resource
data connected with water bodies, forests, soil and land types, crop areas, roads,
villages, etc. In addition to collection and mapping of various resources data, cor-
relation studies between two or three types of data can easily be made from the
imageries and air-photos. Remote sensing technique can be used in water resources
management (Chandrapala and Wimalasuriya, 2003 ) .
Crop yield estimation can be improved by using agrometeorological and remote
sensing data which involve the development of crop-specific and area-specific crop
growth and yield models. Soil moisture also plays an important role under both
irrigated and rain-fed conditions. Thus monitoring of soil moisture status in a region
using remote sensing data would be useful for assessing the crop condition as well
as for advising the farming community for providing life saving irrigation, thinning
operation, post-ponding fertilizer, and pesticide application.
Remote sensing techniques are useful for irrigation water management in the
following areas:

• Identifying, inventory and assessment of irrigated crops

• Determination of irrigation water demand over space and time

• Assessment of water availability in reservoir for optimal management of water to

meet the irrigation demand

• Distinguishing lands irrigated by surface water bodies

• Estimating crop yield

• Water logging and salinity problems in irrigated land

• Irrigation system performance evaluation