  Map Fig. 26. Large map (97 kB) [41] See Report on the Project Estimates of the Upper Jhelum, Upper Chenab, and Lower Bari Doab Canals. 1. General Description.Fig. 26 shows part of the Punjab. The areas marked L.J., L.C., U.B.D., and S.C. are already irrigated by the Lower Jhelum, Lower Chenab, Upper Bari Doab[42] and Sirhind Canals. The areas which it is considered very desirable to irrigate, [42] Doab means “two waters,” or the tract between two rivers. The names of the three Doabs under consideration are formed from those of the rivers. They are called the Jech (Jhelum-Chenab), Rechna (Ravi-Chenab), and Bari (Beas-Ravi) Doabs. [43] It would be very expensive to bring water for this tract from the Beas and across the Sutlej. The winter discharges of the rivers (available for the rabi crop) after the existing irrigation has been supplied, are as follows:
In summer all the rivers have discharges (available for the kharif crop) far exceeding any requirements. It was at one time proposed to supply the Lower Bari Doab Canal from near the junction of the Beas and Sutlej, and a project for this was prepared, but before it was sanctioned a proposal was put forward to convey [44] Colonel Jacob made his suggestion when in England after retiring from India, and when he had no levels to guide him. The Triple Project as prepared by Sir John Benton, K.C.I.E., recently Inspector General of Irrigation in India, gets over all the above objections. The Upper Jhelum Canal is to irrigate the country which it traverses, and in the winter, when the supply in the rivers is restricted, it is to deliver into the river Chenab, above the weir at the head of the Lower Chenab Canal, a discharge equal to that drawn out higher up by the Upper Chenab Canal.[45] Thus the Lower Chenab Canal, which at present draws off the whole of the water of the Chenab in winter, will not be injuriously affected in any way. The Upper Chenab Canal after irrigating its own tract is to deliver a large volume of water into the Ravi. The water will be taken across that river by a level [45] The Indus is at a higher level than the Jhelum. The latter river runs in a comparatively deep valley, and it is unfortunately impossible to convey the water of the Indus across this valley. 2. Areas and Discharges.The figures on which the discharges in the Triple Project are based form a useful and interesting object lesson. In order to obtain sufficient water in the winter, it is necessary to reduce the rabi supply to the existing Lower Jhelum Canal. The figure above given for the Jhelum indicates the supply available after the reduction. More water will be supplied to the Lower Jhelum Canal for the kharif, the canal being enlarged for this purpose, and its total irrigation will be unaffected. The proportion of the culturable commanded area to be irrigated in the new tracts is 75 per cent., but from this the area irrigated by wells in the Upper Jhelum and Upper Chenab tracts is deducted. On the Lower Bari Doab Canal there is little well Irrigation, but there are some low-lying tracts near the rivers, and of these only 50 per cent. will be irrigated. The kharif and rabi areas are in all cases to be equal. The areas to be irrigated in each crop are as below—
The total, excluding the existing Lower Jhelum Canal, is 937,928 acres. With an equal area in the other crop, the new annual irrigation amounts to 1,875,856 acres. The kharif duty is taken as 100 acres at the distributary heads, this being about the figure actually obtained on the Lower Chenab and Upper Bari Doab Canals, and the required kharif discharges at the distributary heads are:
The losses of water in canal and branches have been found to be, on the Upper Bari Doab Canal 10 c. feet per second, and on the Lower Chenab Canal 8 c. feet per second, per million square feet of wetted area respectively. The conditions of the latter canal most resemble those on the new canals under consideration. The losses calculated on the wetted areas of the channels, as designed, at 8 c. feet per second per million square feet, are as follows, in c. feet per second:
But in dry years the canals will be worked in rotation during the rabi, the Upper Chenab and Lower Bari Doab Canals being worked together, and the Upper Jhelum and Lower Jhelum together. When the Lower Jhelum Canal is closed, in course of rotation, the Upper Jhelum Canal will still be flowing, and the loss in it, 664 c. feet per second, has to be added to the figure (2,126) given above, thus bringing up the loss to 2,790 c. feet per second. In order to ascertain what the state of affairs will be in the rabi, the statistics obtained on the Lower Chenab Canal were examined. These show that the rabi duty at the distributary heads on that canal is 206 acres. On the Upper Bari Doab Canal the duty at the distributary heads is 263 acres, but 11 per cent. of the area receives only “first waterings.” The duty based on the remaining area is 234 acres. But the above duties are only attained by running higher supplies in October and March than during the intervening four months of the crop. The following remarks and figures are taken from the Report on the Project Estimates:— “The statistics of working of distributaries of the Chenab and Bari Doab Canals give the average discharges shown in the following table for the three years ending with 1903-04. The losses by absorption are calculated on the wetted areas for the different rotational periods. The average discharge less absorption is the supply which reached the heads of the distributaries. CHENAB CANAL.
“The average discharge given by the third line is 5,546, and the average area being 1,155,685 acres, the duty at the heads of distributaries was 208. “The area 1,164,595 is the perennial rabi irrigation of the new projects, the area 156,424 acres, receiving only first waterings, being omitted to admit of a fair comparison, and is only 1 per cent. under the average attained on the Chenab Canal in the three years for which the table is prepared. “The absorption added for the two first periods is on the supposition that all the canals are open throughout October and March, tatilling[46] with an average absorption loss of 2,139 cusecs[47] being in force during the other four months. The last line of the table shows the average Rabi discharge required by the new projects at the heads of canals, inclusive of all losses calculated on the Chenab Canal basis of a duty of 208 acres per cusec obtained at the heads of distributaries. [46] “TÁtÍl” is the Indian word for rotational closure. [47] “Cusec” is used in India for c. ft. per second. “The Bari Doab Canal statistics furnish the means of the adequacy of available supply being gauged. The following table furnishes particulars for the average supply of water entering the head of the canal for the five years 1898-99, 1899-1900, 1901-02, 1902-03, 1903-04. The figures for the year 1900-01 are omitted, as it was a very abnormal one of very plenteous supply and heavy rainfall:— “The average irrigation for the five years in question was 442,302 inclusive of 11 per cent. which only receives first waterings. This divided by the average supply, 1,685, entering the head of a canal gives a duty of 263 acres per cusec at the heads of distributaries. BARI DOAB CANAL.
“The rabi irrigation of the new projects is 1,321,019 acres,[48] and this divided by 442,302 gives approximately the multiplier 3 referred to at (a) in the above table. [48] Including the Lower Jhelum. “The figures given in the above table and in the foregoing remarks relate to the aggregate of the areas in the rabi which receives a perennial supply and which only receives first and last waterings. On the Upper Bari Doab Canal the rabi which receives perennial irrigation is averagely 393,649 acres; the average supply of 1,685 cusecs gives on this area a duty of 234 acres per cusec at the heads of the distributaries. “In the case of the three projects the aggregate rabi area receiving perennial irrigation as shown by the table, paragraph 21[49] supra, is 1,164,595 acres: this is 2·96 times 393,649; so that the proportional supply required on this basis would be slightly less than that given by the multiplier 3 in the above table. [49] Not printed. The area is the total rabi area less the area which is to receive only first waterings. In explanation of the difference of the duties:—
it may be stated that the Lower Chenab Canal is a comparatively new work, and that the duty has been steadily rising and, with the perfect watercourse system, may be relied on to reach the Upper Bari Doab Canal 234 acres per cusec in the course of time for water arriving at the heads of distributaries. ******* “27. Summary of conclusions as to sufficiency of supply.—The following table shows all the foregoing results in a form readily admitting of comparison:—
“The 13,063 shown in brackets represents the parts of the available supply which the canals can carry, the capacity being as follows:—
“The average supplies and duty figures are based on the 13,063 cusec maximum capacity and not on the larger available supplies written above these figures where they occur. “The above table goes to show the following: (i) In order to utilize the large supplies available in the Jhelum River in October and March every year and in some or all of the intervening months in other years, it is advisable to give the Upper Jhelum Canal the large capacity of 8,500 cusecs proposed. (ii) In favourable and ordinary years, that is, in 3 out of 4, the available supply will be ample, as shown by the low duties of 189 and 167 compared with those obtaining on the Lower Chenab and Upper Bari Doab Canals. (iii) In dry years, that is, 1 in 4, it will be necessary to attain a duty almost exactly the same as that now obtaining on the Upper Bari Doab Canal. (iv) That an exceptionally dry year might occur once in 14 years, when the supply would be 10 per cent. short of that required by the average (v) That the occasional occurrence of dry years makes it inadvisable to attempt a greater proportion of rabi than half of the annual irrigation.” 3. Remarks.The Report on the Project estimates gives, for each tract, remarks on its soil, rainfall, height of subsoil water, circumstances as to existing irrigation from wells or small canals and liability to floods. On a consideration of these matters the decision as to the particular parts of the tracts which are to be irrigated and the areas which are, in the rabi, to receive only restricted irrigation, depends.[50] [50] It is not unusual, in tracts where the level of the subsoil water is high, say within 15 feet of the surface, to have some “kharif distributaries.” These are closed in the rabi. This tends to prevent water-logging of the soil. In the rabi the people lift water from wells. There may also be kharif distributaries in dry tracts if there is no water to spare in the rabi. In calculating the sizes of the canals, N in Kutter’s co-efficient was taken at ·020. In sharp curves the bed is paved on the side next the concave bank. In high embankments where the soil is sandy the best material is used as a core wall. The torrent works on the Upper Jhelum Canal have been mentioned in River and Canal Engineering, Chapter XII. Regarding the effect of the new canals on the inundation canals which take off, lower down, from the Chenab below its confluence with the Jhelum, it has for long been the policy to gradually shift the heads of these canals upstream in order to obtain better supplies, or rather to counteract the effect of the abstraction of In order to estimate the effect on the water level of the Chenab—below its junction with the Jhelum—it was necessary to observe discharges of the river, not only in the winter when it is low, but in the summer when it is high. The depth of the water was in some places 40 feet, and the stream 2,000 feet wide. Fortunately the Subdivisional Officer was a native of India and did not much mind the sun. A discharge curve (River and Canal Engineering, Chapter III. Art. 5,) having been prepared, it was possible to construct a diagram with periods of time as the abscissas, the ordinates representing the average known gauge readings on the different dates and another set of ordinates representing the probable discharges. By deducting the discharges which it was intended that the new perennial canals should draw off, it was possible to draw fresh ordinates representing the diminished river discharges and the reduced river gauge readings corresponding to them. It was found that the water level would be lowered by about 1·3 feet in April and May, and by about 1·5 feet in September. It was, however, shown that by shifting the heads of the inundation canals upstream—the gradients of the canals being flatter than that of the river—the effect of the lowering of the water level could, as heretofore, be nullified. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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