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irrigation and water resources engineering
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INTRODUCTION
2 IRRIGATION AND WATER RESOURCES ENGINEERING
to feed. Primary source of prosperity in Punjab is irrigation. Irrigation from the Nile is the
source of food, life, and prosperity in Egypt. Similarly, without drainage, large parts of the
Netherlands and the coastal regions of several countries would always be under water.
Irrigation schemes can be broadly grouped into two main categories: (i) surface water
irrigation schemes, and (ii) ground water irrigation schemes. The former use diversion and
storage methods and obtain their supplies from rivers. Ground water irrigation schemes use
open wells, and deep and shallow tube wells to lift water from the water-bearing strata below
the earth’s surface. The choice of an irrigation scheme depends on several factors, such as
surface topography, rainfall characteristics, type of source available, subsoil profile, etc. One
should, however, always plan to use surface and ground waters together to derive maximum
benefits. Such use is termed conjunctive use of surface and ground waters.
In India, the sites for diversion structures without storage potential from major river
systems are now difficult to find.
. IMPACT OF IRRIGATION ON HUMAN ENVIRONMENT
The main impact of irrigation is in terms of the increased agricultural yield which, in turn,
affects social, cultural, economic, political and other aspects of human environment (Table
1.2)
Table 1.2 Impact of irrigation on human environment (3)
Impact Positive Negative
Improvement of the water regime of
irrigated soils.
WATER RESOURCES OF INDIA
India, with a geographical area of 329 Mha (million hectares), is blessed with large river basins
which have been divided into 12 major (see Table 1.4) and 48 medium river basins comprising
252.8 Mha and 24.9 Mha of total catchment area, respectively (6). It possesses about 4 per cent
of the total average annual runoff of the rivers of the world. The per capita water availability
of natural runoff is, however, only 2200 cubic metre per year which is about one-third of the
per capita water availability in USA and Japan (6). The per capita water availability in India
would further decrease with ever-increasing population of the country.
IRRIGATION AND WATER RESOURCES ENGINEERING
Central Electricity Authority has estimated the hydro-electric potential of the entire
country as 84 million KW at 60 per cent load factor from 845 economically feasible schemes in
various river basins of the country. The developed hydro-electric potential in the country stands
at about 12 million KW at 60 per cent load factor which is about 14.5 per cent of the assessed
potential (6).