They need to be able to irrigate without relying solely on rain.
The latter is also used to irrigate a small, cultivated valley.
It was designed to command an area of about 22 million acres, and to irrigate annually rather less than half that area.
The river brings down from the mountains enough water to supply the town and irrigate a considerable area in its vicinity.
But to irrigate this upper 18 m., water must either be raised artificially, or supplied from another canal taking its source 18 m.
Or more below the surface one wind-mill often supplies sufficient water to irrigate ten acres.
The river has a course of about 200 m., and its waters irrigate the best and most populous part of the province.
South-east Transbaikalia suffers from want of water, and the Buriats have to irrigate their fields.
A much greater scheme than any of the above is that of the Sind Sagar canal, projected from the left bank of the Indus opposite Kalabagh, to irrigate 1,750,000 acres at a cost of Bx.6,000,000.
The Periyar irrigation project conducts water through the ghats in a tunnel to irrigate the Madras district of Madura, for which compensation of Rs.
Some farmers on tile uplands between the valleys in western Nebraska irrigate by means of wind-mills, and although the underground water is 175 ft.
The fifth project, the Bowman, was to irrigate 10,000 acres in North Dakota and the northwestern part of South Dakota by storing the waters of the North Fork of Grand river.
Ajmere is almost totally devoid of rivers, the Banas being the only stream which can be dignified with that name, and it only touches the south-eastern boundary of the district so as to irrigate the pargana of Samur.
In 1900 the Colorado river (q.v.) was tapped south of the Mexican boundary for water wherewith to irrigate land in the Imperial Valley along the Southern Pacific railway, adjoining Salton Sea.
The total length of the main canal is 213 m., navigable throughout, and designed to irrigate 1,500,000 acres.
It reclaims 360 acres, and was estimated to irrigate 4320.
Above Echo, with a reservoir of 1500 acres, was authorized in 1905 and was 851% finished in 1909; the Klamath project, to irrigate 181,000 acres in Klamath county, Oregon (about 145,000 acres) and Siskiyou and Modoc counties, California, by two canals from Upper Klamath Lake and by a storage dam (33 ft.
We irrigate chiefly in the colder and wetter half of the year, and we " saturate " with water the soil in which are growing such plants as are perfectly content with earth not containing more than one-fifth of its weight of moisture.
Another great canal scheme for the Punjab proposed to take off from the right bank of the Sutlej, and to irrigate about 600,000 acres in the Montgomery and Multan districts, at a cost of Rx.
Among them are: the Huntley project in Yellowstone county, begun in 1904 and practically completed in 1908, covering land formerly in the Crow Indian reservation, the irrigable area being 28,921 acres; the Lower Milk river project (and the subsidiary St Mary project), in Chouteau, Valley and Teton counties, by which the water of St Mary river 1 is stored and diverted to the headquarters of the Milk river to irrigate an area of 300,000 acres; the Sun river project (Teton, Lewis and Clark, Chouteau and Cascade counties), by which, as the ordinary flow of that river is already utilized for irrigation, the flood waters are stored and carried to the higher bench lands of the district; in Montana (Dawson county) and North Dakota (McKenzie county), the Lower Yellowstone project; and the Blackfeet project, to irrigate the Blackfeet reservation in Teton county.
The points which require constant attention are - the perfect freedom of all carriers, feeders and drains from every kind of obstruction, however minute; the state and amount of water in the river or stream, whether it be sufficient to irrigate the whole area properly or only a part of it; the length of time the water should be allowed to remain on the meadow at different periods of the season; the regulation of the depth of the water, its quantity and its rate of flow, in accordance with the temperature and the condition of the herbage; the proper times for the commencing and ending of pasturing and of shutting up for hay; the mechanical condition of the surface of the ground; the cutting out of any very large and coarse plants, as docks; and the improvement of the physical and chemical conditions of the soil by additions to it of sand, silt, loam, `` chalk, &c.
The central agricultural provinces are traversed by several important rivers, all of them rising on the western slopes of the snow-clad Andes and breaking through the lower coast range to the Pacific after being extensively used to irrigate the great central valley of Chile.
Two of these projects had been begun by 1909: the Umatilla project in Umatilla county, to irrigate 20,440 acres with water diverted from the Umatilla river by a dam (98 ft.
The Washburn project was to irrigate 5000 acres in McLean county with water pumped from the Missouri river.
Thus, water, moisture, weep, tears, inundate, irrigate," &c. The word a can also mean " shining, glistening," an idea evidently developed from the shining rippling of water.
Up to 1906 dependence was mainly upon the streams, which it is estimated might furnish 3 or 4 million acre-feet - enough to irrigate between 10 and 15% of the arid section - were all the water available, and the land I Data of the State Bureau of Labor and Industrial Statistics, which are lower than those of the state Board of Agriculture, and (in census years) the Federal Census.
With a shaduf it is only possible to keep about 4 acres watered, so that a great number of hands are required to irrigate a large surface.
In Upper Burma three productive irrigation works were planned at the opening of the century - the Mandalay, the Shwebo, and the Mon canals, of which the first was estimated to cost -Rx.323,280, and to irrigate 72,000 acres.
Whatever may be the command of water, it is unwise to attempt to irrigate too large a surface at once.
The rivers of the province of Coquimbo - the Elqui or Coquimbo, Limari and Choapa - exist under less arid conditions, and like those of the province of Aconcagua - the Ligua and Aconcagua - are used to irrigate a much larger area of cultivated territory.
Deep valleys winding through the barren foothills lead gradually up to the higher mountains, and as the track ascends the scenery and vegetation change their character; the trees which line the banks of the wadi are overgrown with creepers, and the running stream is dammed at frequent intervals, and led off in artificial channels to irrigate the fields on either side; the steeper parts of the road are paved with large stones, substantially built villages, with their masonry towers or da y s, crowning every height, replace the collection of *mud walls and brushwood huts of the low country; while tier above tier, terraced fields cover the hill slopes and attest the industry of the inhabitants and the fertility of their mountains.