Contents preface (VII) introduction 1—37

Table 6.6 Comparison of suitability of irrigation methods (22)

Site factor	Surface Method	Sprinkler Method	Drip Method
Soil	Uniform with moderate	All	All
	to low infiltration
Topography	Level to moderate	Level to rolling	All
	slopes
Crops	All	Tall crops limit type	High Value
		of system
Water supply	Large streams	Small stream nearly	Small stream continuous
		continuous	and clean
Water quality	All but very salty	Salty water may	All
		harm plants
Efficiency	50-80%	70-80%	80-90%
Labour requirement	High	Low to moderate	Low to high
Capital requirement	Low to high	Moderate to high	High
Energy requirement	Low	Moderate to high	Low to moderate
Management skill	Moderate	Moderate	High
Weather	All	Poor in windy	All
		conditions

In India, sprinkler as well as drip irrigation have considerable scope because of the need to save water and extend irrigation facility to as large a cropped area as possible for producing food for the growing population. Sprinklers must find useful application in undulating sandy terrains of Rajasthan, Gujarat, Haryana, and Punjab. Drip irrigation is ideal for fruit orchards vegetable crops, and some cash crops. Water saved due to the introduction of these two methods in favourable regions may be enough to increase the irrigation potential for additional 5 million hectares (8).

238 IRRIGATION AND WATER RESOURCES ENGINEERING
6.4.12. Use of Waste Water
By AD 2000, the requirement of domestic water needs and thermal power plant needs will be around 3 Mha.m most of which will be used for non-agricultural purposes (8). It would, obviously, be very beneficial even if half of this used water is suitably treated and used for irrigation. Such measures can provide additional irrigation potential for about 1.5 to 2 Mha of cropped land (8).
6.4.13. Conservation of Water on the Field
Rice fields have to be kept flooded for a sufficiently long time, and this results in large percolation losses from 50 to 80 per cent depending upon the type of soil (22). Therefore, rice cultivation should normally be restricted to soils of relatively low permeability. The percolation losses can also be reduced by puddling the soil using improved puddlers and the saving of water can be between 16 and 26 per cent depending upon the type of soil and puddlers used (22).
6.4.14. Waterlogging
Waterlogging (Sec. 5.14) results in lowered yields, loss of lands for useful activities, and health hazards. To eliminate or control waterlogging one or more of the following, remedial measures have usually been used (1, 8):
(i) Reducing inflow to the ground through lining of canals, (ii) Removing ground water through pumping,

(iii) Removing surface and ground waters through drainage, (iv) Educating farmers in water management, and

(v) conjunctive use.
Of all these methods, the conjunctive use of surface and ground water is the most cost-effective means of fighting waterlogging in canal-irrigated lands. This has already been effectively tried in parts of western UP, Haryana, and Punjab (8). Waterlogging can also be reduced by supplying less water during nights (as was done on the head reach of the Morna system in Maharashtra), cutting off water supplies during rains, rotating supplies in distributaries and minors instead of continuous supply, shortening irrigation periods, and zoning for crop type (1).