Engineering Wonders of the World
Volume III

236 ENGINEERING WONDERS OF THE WORLD. The laying out was a very arduous task. The survey parties had to work across vast stretches of totally uninhabited country, where the only source of water might be a brackish well 100 feet deep, and where no supplies of any kind could be obtained. It was often necessary to remain in the field throughout the hot season, when the tempera- Laying out the Chenab Canal System. people has founded homesteads cultivated with the assistance of the canal waters. The Chenab River usually remains fairly full until the middle or end of October, and suffices to irrigate the sowings of the winter crop. But later in the season the available dis- charge sometimes falls as low as 4,000 cubic feet per second, rising suddenly, when a freshet comes down, to 10,000 cubic feet. Arrange- MAP OF THE CHENAB RIVER AND CANAL SYSTEM. Escape reservoirs marked in solid black. The water is turned into these reservoirs when the volume is greater than the canals can carry. turo rises to over 110 degrees Fahrenheit in the shade. It will be readily understood that under these circumstances high organization and much energy and determination were re- quired from all concerned in the work. The survey completed, there followed the task of dividing the tract into villages of con- venient size, averaging the gross area of 1,500 to 2,000 acres. The main principle was that the lands in each village should be irrigable from its own separate water-course. Each of these water-courses is supplied direct from a Government channel; so that all disputes that may arise are confined to the village it- self, or lie between the villagers and the Gov- ernment. Since the Chenab Canal was opened more than one and a half million acres of Crown land have been allotted to settlers, and a new population of more than 1,000,000, ments therefore have to be made for distribut- ing 4,000 feet one day and 10,000 the next. It has been found necessary to have canal telegraph, lines run Escape „ , Reservoirs. in all directions to control the distribution. This telegraph system is doubly useful when, after an unexpected fall of rain, there is a sudden reduction in the demand for water in the fields. One can easily appreciate the anxiety of an engineer who learns that the canal is bringing down 300 tons of water a second, and that he must dispose of it. If there be no escapes for the water, and the cultivators decline to run it on to their fields, he knows that the canal must burst its banks. On most Indian canals there are facilities for letting off surplus water, but in the case of the Chenab Canal the main courses are so far from thø rivers that tho provision of escapes