Doab Canal | | | | 3·3) }| | | | | }| Distributaries |Sandy | | | 5 to 12 }| Sirhind Canal |Soil | | | (average }| | | | | 8·0) }|Somewhat rough | | | | }|estimates. Watercourses |Loam | |·015[4]| 3·3 to 20}| Upper Bari | | | to | (average }| Doab Canal | | |·045[5]| 9·4) }| | | | | }| Watercourses |Sandy | | | 7 to 60 }| Sirhind Canal |Soil | | | (average }| | | | | 22) }| ---------------+-------+----------+-------+----------+---------------- [4] When the channel was in continuous flow. [5] Maximum value when flow was intermittent. Some information as to losses of water is also given in CHAPTER IV. Art. 2. The relative losses of water in the channels of the Upper Bari Doab Canal were as follows:-- Relative Loss. In main line and branches 20 In distributaries 6 In watercourses 21 Used in the fields 53 --- Total 100 The reasons for the great variation in the value of _c_ are not properly known. The depth of water is not likely to have much influence on it. It is well known that the fine silt carried by the water tends to render the channels watertight when it deposits. The canals and branches receive either no deposits or deposits consisting chiefly of sand. The distributaries, especially in their lower reaches, receive deposits of fine silt which is only occasionally cleared away. The watercourses receive similar deposits but they are very frequently cleared out by the cultivators. This is perhaps the reason why the rate of loss of water in the watercourses is nearly three times as great as the rate of loss in the distributaries of the same canal. On the Sirhind canal the distributaries have more branches than on the Bari Doab canal and the watercourses are smaller. This accounts for the different relative losses in the two cases. The sandy nature of the soil on the Sirhind canal accounts for the general higher value of _c_ on that canal. The following formula has been deduced as giving the loss by absorption on a Punjab Canal. WL P = 3·5 √d --------- 1,000,000