Part 4

18, 6 a. m. to 6 p. m. 10,565,000 18-19, 6 p. m. to 6 a. m. 8,690,000

19, 6 a. m. to 6 p. m. 6,952,000 19-20, 6 p. m. to 6 a. m. 6,150,000

20, 6 a. m. to 6 p. m. 5,882,000 20-21, 6 p. m. to 6 a. m. 5,749,000

21, 6 a. m. to 6 p. m. 5,481,000 21-22, 6 p. m. to 6 a. m. 5,214,000

22, 6 a. m. to 6 p. m. 4,144,000 22-23, 6 p. m. to 6 a. m. 3,677,000

23, 6 a. m. to 6 p. m. 3,877,000 23-24, 6 p. m. to 6 a. m. 5,749,000

24, 6 a. m. to 6 p. m. 5,615,000

FLOOD AT BEATTIE'S DAM, LITTLE FALLS.

The flow over Beattie's dam at Little Falls, has been calculated according to coefficients used for the same dam in Water-Supply Paper No. 88. Recorded gage heights show that over the main dam there was a maximum depth of 11.12 feet, which continued from 2 to 8 p. m., on October 10, representing a maximum flow of 31,675 cubic feet per second. (See Pl. I, A.) In the following table is set forth the flow of the river over Beattie's dam during the flood, and for purposes of comparison, the figures for the flood period of March, 1902. It should be borne in mind in consulting this table, that in the case of the flood of 1903 exact dates and hours are given, while the figures for the 1902 flood represent flow determinations at six-hour intervals, beginning with the initial rise of that flood.

* * * * *

U. S. GEOLOGICAL SURVEY WATER-SUPPLY PAPER NO. 92 PL. I

* * * * *

Flood flow over Beattie's dam during floods of 1902 and 1903.

-----------------+------------+------------+ Date and hour. | 1903. | 1902. | -----------------+------------+------------+ | Sec.-feet. | Sec.-feet. | Oct. 8. 12 p.m | 1,645 | 490 | 9. 6 a.m. | 4,235 | 700 | 12 m. | 8,560 | 1,350 | 6 p.m. | 15,755 | 2,120 | 12 p.m. | 23,927 | 3,540 | 10. 6 a.m. | 28,370 | 4,250 | 12 m. | 31,305 | 4,600 | 6 p.m. | 31,675 | 5,000 | 12 p.m. | 30,770 | 6,500 | 11. 6 a.m. | 29,840 | 7,600 | 12 m. | 28,950 | 8,250 | 6 p.m. | 26,960 | 9,000 | 12 p.m. | 25,530 | 10,200 | 12. 6 a.m. | 24,435 | 11,450 | 12 m. | 22,625 | 14,700 | 6 p.m. | 20,810 | 18,150 | 12 p.m. | 18,655 | 20,650 | 13. 6 a.m. | 17,930 | 22,200 | 12 m. | 16,190 | 22,700 | 6 p.m. | 14,900 | 23,400 | 12 p.m. | 13,615 | 23,300 | 14. 6 a.m. | 12,340 | 22,950 | 12 m. | 11,740 | 22,650 | 6 p.m. | 10,975 | 22,350 | 12 p.m. | 9,820 | 22,100 | 15. 6 a.m. | 9,180 | 21,150 | 12 m. | 8,330 | 19,900 | 6 p.m. | 7,700 | 18,900 | 12 p.m. | 7,005 | 17,350 | 16. 6 a.m. | 6,695 | 15,750 | 12 m. | 5,920 | 13,900 | 6 p.m. | 5,620 | 13,300 | 12 p.m. | 5,360 | 11,800 | 17. 6 a.m. | 4,855 | 10,650 | Below full bank | 8,900 | Do. | 8,500 | Do. | 8,100 | Do. | 8,200 | Do. | 7,000 | Do. | 6,250 | Do. | 5,900 | Do. | 5,300 | Do. | 5,200 | Do. | 4,900 | -----------------+------------+------------+ [Footnote A: At six-hour intervals.]

FLOOD FLOW OVER DUNDEE DAM.

The flood, as indicated by gage heights at Dundee dam, lasted from about 6.30 p. m. October 8 to about midnight October 18. Although the maximum recorded gage height was 19 inches higher than during the flood of 1902, the actual time during which the river was out of its banks was forty-five hours less than at the earlier flood. Examination of fig. 1 shows that the flood of 1903 was decidedly more intense than that of 1902, the maximum height being reached in 1903 in about sixty hours, while in 1902 the maximum was not reached until the expiration of about one hundred and twenty hours.

At Dundee dam the familiar break in the progress of the flood took place about thirty-five hours after the initial rise. It occurred before the time of the maximum gage height at the mouth of Pompton River, and there is nothing to indicate that it was caused, as has been claimed, by slack water from the Pompton flood being forced back into Great Piece Meadows. There is no doubt that a part of the Pompton flood was so diverted, but there was maintained throughout at Little Falls a steady pressure, which constantly increased to maximum. This flood check, at Dundee dam was observed in 1902, but it could not be shown to arise from the frequently mentioned phenomena at the mouth of Pompton River. It is important to prove or disprove this hypothesis. If it were found to be true, it could be advantageously taken into consideration in connection with measures for the prevention of flood damages. As the Pompton had no such effect upon the flood flow at Dundee dam in two consecutive historic floods, the writer is inclined to believe that the idea is entirely erroneous.

Since the flow curves in fig. 1 were drawn it has been found by careful observation that the depressions which occur in the rise of every flood over Dundee dam are probably due to the carrying away of the flashboards which are placed upon the dam crest in times of low water. A review of the gage heights recorded by floods for several years past shows that the break occurs when the height of water over the dam crest reaches from 40 to 60 inches. The flashboards used upon this dam are usually 18 inches wide, and as they are supported by iron rods, which are of approximately the same strength and are placed upon the dam by one crew of workmen, it may be safely assumed that they are of approximately equal stability and might be expected to fail almost simultaneously along the length of the dam crest. So sudden a decrease in the effectual height of the dam must lower the water on the dam crest markedly, and as every other probable cause has been eliminated in the case of the recent flood, the explanation of the check in the progress of floods over this dam may be safety accepted as due to carrying away of flashboards. This effect should be apparent in the gage-height records only.

In the flow diagrams (figs. 1 and 2) the effect would not be the same, but the curve would rise more sharply. Similarly, the measurements at the beginning are not correct, as they are calculated according to gage heights measured from the stone crest of the dam. Therefore, a true flood curve at this point would be much flatter at the beginning and rise sharply at a period coincident with the carrying away of the flashboards.

An important difference between the two floods is that the earlier continued longer, but the later one was much higher. The flood of 1902 was caused by the turning of an equivalent of approximately 6 inches of precipitation into the main channel during a period of six days. In the deluge of 1903 there fell 11.74 inches of rain, the greater part of which was precipitated in 36 hours. Thus it is seen that there was in the flood of 1903 a larger rainfall during a much shorter period than in the flood of 1902. Computation shows that the total run-off from the drainage area above Dundee dam during the earlier flood was 13,379,000,000 cubic feet, and that on account of the frozen condition of the ground at that time this amount of water represented practically all of the precipitation. During the flood of 1903 there was a total run-off for the same area of 14,772,000,000 cubic feet, which represents about 66 per cent of the observed precipitation. According to these figures the total amount of run-off in the 1903 flood was only 10 per cent greater than that in 1902, while the actual flood height during the 1903 flood was 27 per cent higher than during the flood of 1902. The above comparison shows, in a striking manner, the effect of the condition of the surface. In the case of the later flood we had, as has been stated in previous pages, an area which had been well watered during the previous summer, and the observed ground-water levels were fairly high. There was, however, sufficient storage capacity in the basin to retain about 34 per cent of the precipitation occurring between October 7 and 11. This water must have been largely absorbed by the earth. The general relations of the floods of 1903 and 1902 can therefore be briefly stated as follows:

General relations of floods of 1903 and 1902.

-----+--------------+--------------+-------------+-------------> |Average | Duration of | Maximum | Total |precipitation.|precipitation.| flood flow. | run-off. | | | | -----+--------------+--------------+-------------+-------------> | Inches. | Days. |Sec.-feet. | Cubic feet. 1902 | 6 | 6 | 24,800 |13,379,000,000 1903 | 11.74 | 3 | 35,700 |14,772,000,000 -----+--------------+--------------+-------------+------------->

<-----------+------------- Run-off. | Duration of | flood at | Dundee dam. <-----------+------------- Per cent.| Hours. 100 | 270 66 | 225 <-----------+------------- [Footnote B: Approximately]

In the following table and fig. 2 are recorded gage heights taken at hourly intervals during the crucial part of the flood and the amount of water expressed in cubic feet per second flowing over the crest of the dam at each gage height.

Flow of Passaic River at Dundee dam, 1903.

------------------------------------------- Date and hour. | Gage. | Flow. ---------------------+-------+------------- |Feet.| Sec.-feet. Oct. 8. 6.30 a. m. | 0.66 | 780 1 p. m. | 1.50 | 3,175 6.30 p. m. | 2.17 | 5,500 8 p. m. | 2.59 | 7,300 10 p. m. | 3.00 | 9,125 11 p. m. | 3.33 | 10,700 12 p. m. | 3.50 | 11,525 9. 1 a. m. | 3.50 | 11,550 2.30 a. m. | 3.59 | 11,950 4 a. m. | 3.50 | 11,525 6 a. m. | 3.66 | 12,300 8.30 a. m. | 3.75 | 12,775 9.40 a. m. | 4.00 | 14,075 10.55 a. m. | 4.66 | 17,650 12 m. | 4.75 | 18,200 1 p. m. | 5.25 | 21,050 2 p. m. | 5.37 | 21,750 3 p. m. | 5.45 | 22,250 3.45 p. m. | 5.37 | 21,750 4.25 p. m. | 5.29 | 21,300 5 p. m. | 5.23 | 20,950 5.45 p. m. | 5.19 | 20,700 6.30 p. m. | 5.17 | 20,600 7 p. m. | 5.11 | 20,250 8 p. m. | 5.13 | 20,350 9 p. m. | 5.17 | 20,600 10 p. m. | 5.21 | 20,750 11 p. m. | 5.27 | 21,150 12 p. m. | 5.4 | 21,950 10. 1 a. m. | 5.5 | 22,500 2 a. m. | 5.66 | 23,500 3 a. m. | 5.73 | 23,900 4 a. m. | 5.91 | 25,050 5 a. m. | 6.00 | 25,650 6 a. m. | 6.2 | 26,900 7 a. m. | 6.33 | 27,700 8 a. m. | 6.4 | 28,150 9 a. m. | 6.6 | 29,400 10 a. m. | 6.83 | 30,750 11 a. m. | 6.89 | 31,250 11.35 a. m. | 6.97 | 31,750 12 m. | 6.93 | 31,450 1 p. m. | 6.95 | 31,650 2 p. m. | 7.13 | 32,800 3 p. m. | 7.19 | 33,150 4 p. m. | 7.25 | 33,500 5 p. m. | 7.39 | 34,450 6 p. m. | 7.39 | 34,450 7 p. m. | 7.40 | 34,500 8 p. m. | 7.54 | 35,350 9 p. m. | 7.62 | 35,800 10 p. m. | 7.60 | 35,700 11 p. m. | 7.57 | 35,500 12 p. m. | 7.43 | 34,650 11. 1 a. m. | 7.47 | 34,950 2 a. m. | 7.5 | 35,100 3 a. m. | 7.42 | 34,700 4 a. m. | 7.3 | 34,450 5 a. m. | 7.3 | 34,150 6 a. m. | 7.3 | 34,150 7 a. m. | 7.37 | 34,300 8 a. m. | 7.33 | 34,100 9 a. m. | 7.31 | 33,900 10 a. m. | 7.23 | 33,450 11 a. m. | 7.25 | 32,525 12 m. | 7.18 | 33,100 1 p. m. | 7.18 | 33,100 2 p. m. | 7.17 | 33,300 3 p. m. | 7.08 | 32,450 4 p. m. | 7.00 | 31,950 5 p. m. | 6.96 | 31,700 6 p. m. | 6.89 | 31,250 7 p. m. | 6.86 | 31,050 8 p. m. | 6.83 | 30,850 9 p. m. | 6.79 | 30,600 10 p. m. | 6.81 | 30,700 11 p. m. | 6.73 | 30,200 12 p. m. | 6.71 | 30,100 12. 1 a. m. | 6.63 | 29,600 2 a. m. | 6.59 | 29,350 3 a. m. | 6.55 | 29,100 4 a. m. | 6.51 | 28,800 5 a. m. | 6.42 | 28,250 6 a. m. | 6.42 | 28,250 7 a. m. | 6.39 | 28,100 8 a. m. | 6.39 | 28,100 9 a. m. | 6.25 | 27,200 10 a. m. | 6.21 | 26,950 11 a. m. | 6.17 | 26,700 12 m. | 6.05 | 26,100 1 p. m. | 6.06 | 26,050 2 p. m | 5.93 | 25,200 3 p. m. | 5.89 | 24,950 4 p. m. | 5.87 | 24,800 5 p. m. | 5.79 | 24,300 6 p. m | 5.77 | 24,150 7 p. m. | 5.75 | 24,250 8 p. m. | 5.73 | 23,950 9 p. m | 5.63 | 23,300 10 p. m. | 5.59 | 23,100 11 p. m. | 5.54 | 22,750 12 p. m. | 5.49 | 22,450 13. 1 a. m. | 5.44 | 22,200 2 a. m. | 5.39 | 21,000 3 a. m. | 5.35 | 21,650 4 a. m. | 5.30 | 21,350 5 a. m. | 5.24 | 21,000 6 a. m. | 5.21 | 20,850 7 a. m. | 5.16 | 20,525 8 a. m. | 5.13 | 20,350 9 a. m. | 5.08 | 20,100 10 a. m. | 5.04 | 19,800 11 a. m. | 5.00 | 19,560 12 m. | 4.94 | 19,200 1 p. m. | 4.89 | 18,900 2 p. m. | 4.85 | 18,700 3 p. m. | 4.84 | 18,650 4 p. m. | 4.75 | 18,200 5 p. m. | 4.71 | 17,900 6 p. m. | 4.66 | 17,650 7 p. m. | 4.64 | 17,550 8 p. m. | 4.59 | 17,250 9 p. m. | 4.54 | 17,000 10 p. m. | 4.51 | 16,750 11 p. m. | 4.49 | 16,700 12 p. m. | 4.37 | 16,000 14. 1 a. m. | 4.37 | 16,000 2 a. m. | 4.35 | 15,925 3 a. m. | 4.35 | 15,925 4 a. m. | 4.33 | 15,800 5 a. m. | 4.34 | 15,850 6 a. m. | 4.31 | 15,700 7 a. m. | 4.27 | 15,500 8 a. m. | 4.25 | 15,300 9 a. m. | 4.17 | 14,900 10 a. m. | 4.08 | 14,500 11 a. m. | 4.05 | 14,325 12 m. | 4.02 | 14,150 1 p. m. | 4.02 | 14,150 2 p. m. | 4.01 | 14,100 3 p. m. | 3.97 | 13,900 4 p. m. | 3.94 | 13,750 5 p. m. | 3.85 | 13,300 6 p. m. | 3.75 | 12,775 7 p. m. | 3.75 | 12,775 9 p. m. | 3.71 | 12,550 12 p. m. | 3.66 | 12,300 15. 6.30 a. m. | 3.50 | 11,525 1 p. m. | 3.41 | 11,050 6.30 p. m. | 3.41 | 11,050 16. 6.30 a. m. | 3.00 | 9,125 1 p. m. | 3.00 | 9,125 6.30 p. m. | 2.91 | 8,700 17. 6.30 a. m. | 2.5 | 6,900 1 p. m. | 2.5 | 6,900 6.30 p. m. | 2.5 | 6,900 18. 6.30 a. m. | 2.5 | 6,900 1 p.m. | 2.41 | 6,500 6.30 p. m. | 2.33 | 6,200 19. 6.30 a. m. | 2 | 4,900 1 p. m. | 2 | 4,900 6.30 p. m. | 2 | 4,900

DAMAGES.

GENERAL STATEMENTS.