Contents preface (VII) introduction 1—37

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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. Therefore, further use of surface water has to be through storage methods only. India is not blessed with really good storage sites, particularly in the Himalayas, as can be noted from Table 1.1 which gives the storage for some major dams in the Himalayas as well as in other parts of the world.