IRRIGATION. From remote times the inhabit ants of India have sought, by means of artificial water-supply. to protect themselves against the calamities of drought. Under British control the irrigation works have been enlarged and new ones constructed on an enormous scale. In 190(1 there were 31.544,000 acres. one-seventh of the total crop under irrigation. This was over four times the area irrigated in the United States. which ranks next to India in this respect. The area actually irrigated varies with the lack of rainfall front year to year. and the com mercial value of irrigation schemes varies in different sections. In Sindh and Lower Pun jab irrigation is necessary every year. In the alley of the Indus the necessity for irrigation decreases with the distance from the Himalayas, but the system is used as a protection against years. and to supplement the rainfall of average years. This is true also of the Upper Ganges region. In the Lower Ganges valley. as indicated above. becomes less and less necessary toward the Deltaic region, in por tions of which the danger of drought gives place to that of inundation. In Madras (except the west coast) and the Deccan or Central India region. irrigation is a practical necessity as a rrotection against frequent droughts. and to sup plement the usual rainfall. On the east coast of especially where 'wet crops' principally are grown. irrigation is an absolute necessity. In Orissa and Upper Bengal, though the ordinary rainfall is quite adequate and droughts seldom occur. the Government has constructed irrigation works as a safeguard against dry periods. These works are considered indireetly profitable to the Government. however. since they obviate the loss of lam] revenue and the expense of supplying, a famine-stricken district with food during a drought year. The Orissa and some of the other canals are also valuable for navigation.
The sources and methods of irrigation vary the country. Before the British oc cupation wells were used chiefly, and have con tinued to increase in absolute, though not in relative. importance. because, where practicable, they constitute the cheapest method. They are generally employed by private enterprise. and are still the largest source of irrigation in the United Provinces of Agra. Oudh. and Gujarat. Reser voirs. generally called tanks, have been used since ancient times to furnish water for irrigation, are especially adaptable to broken, hilly regions, where the construetion of a long system of canals is impracticable. They are found chiefly in the eastern portion of where they vary in size, according to the of water and the irrigable area which they com mand. In many instances they are ilry during a part of the year. and crops are sometimes raised in them. 'I'M: tank system is also earried 4.1i by private enterprise. (tut since India has been in the hands of the British the greatest progress in irrigation has be.'m accomplished through the extension of the canal system.
This method also was in ancient buoys, hut sonic of 1. he more illIport a nt systems had fallen into disuse when the British took posses sion. Their el requires heavy outlays
of capital, and presupposes a stable form of gov ernment. The numerous legal complications which rise out of such an undertaking. and the relation of the Government to the land. together for their great length and capacity. Many of them are remarkable feats of engineering, owing to the difficulties surmounted in their constriic tion, such as the crossing of 01 her Among the most famous of these art' the Ganges ('anal (q.v.). the Bari D''ab 'waters, a large district to the northeast 1.:1110rP, and the NVestern lunina Canal. generally considered the oldest in India, which waters the region be tween the sutlej and dumna rivers, tributaries, re- pppt Vely. of the Indus and Ganges rivers.
The following table shows the area in the different provinces irrigated during the years 1s99•1900. the relative importance of the differ ent sources of irrigation, and the proportion of irrigated land to the total crop area. It will be ,PP11 that the Punjab is the most, and Assam the least, dependent upon irrigation: with the necessity of constructing certain sys tems having no remunerative financial value, have all led the British Government to take the system almost wholly in its own bands. The execution of this method requires a fairly level area. The methods used for the application vary in different localities. In the .Madras Delta., dains are constructed across the rivers at their entrance to the Delta region, and since their beds are almost on a level with surface of the land, water is easily diverted into artificial channels. They yield their main supply during the animal timid period, and the region dependent upon them is therefore limited to one crop. In the Lower Punjab and Sindli the channel of the Indus liver lies so far below the surface of the riparian country that its waters cannot easily be diverted by dams. Thromffi the high banks deep mils are made, and 'inundation canals' are constructed. which convey the of the river during the flood period. By this means the land is watered sufficiently to produce one crop a year. 'the valleys of the Upper Ganges mid Upper Indus are also too deep and broad to admit of damming, nor would the inundation system of the Lower Indus answer the purpose. Sonic of the crops commonly raised, and which require irrigation, grow in those sea sou: during which the rivers are at their lowest. For tion, canals are dug so as to strike the rivers where they emerge from the mountains. The channels conduct the water along the water-shed of the plains, finally reuniting with the main streams. Some of these canals arc notable both Claws. In ISMI-1900 the area actually cropped was ISo.150,454 acres, and the current. fallow 57,165.9Il0 acres. The estimated area of the cultivable waste for the same year was 106, acre., which there were 135, 50G,01 4 not available for culture, and 65.,143,9•4 acres under forest. The crop statistics for the year mentioned are given in the table on the next page.