In reference to the adoption of the monolithic form for constructing the South Reservoir, the writer is so convinced as to its economy that had he to build this reservoir again, he would adopt the same method. Mr. Binckley, in drawing attention to the method of construction, has overlooked the fact that the cost of forms for a reservoir 30 ft. deep was a very serious item, and warranted the adoption of this new method, not only on account of economy but because of rapidity of construction; while, in the case of the Obispado Reservoir, which is very much shallower, simpler forms could be and were adopted.
Mr. Saucedo's remarks regarding the repetition of the extraordinary floods of August, 1909, in September, 1910, are particularly interesting, and show how abnormal conditions are in so dry a section of Mexico as the State of Nuevo León. These two floods, the writer believes, are among the most instructive in North America, particularly when one remembers that prior to 1909 the average rainfall during a period of 15 years, was less than 22 in. per annum.
TABLE 18.—Comparison of Volume of Floods, Etc.
| River. | Drainage area, in square miles. | Maximum recorded flow, in cu. ft. per sec. | Cu. ft. /sec. per square mile. | Annual amount of rainfall. |
| Santa Catarina, Monterrey, August 27th, 1907 | 544 | 235,000 | 432 | 22 |
| Estanzuela, near Monterrey, August 28th, 1909 | 3.5 | 2,900 | 825 | 25 |
| Tansa, India | 52.5 | 35,000 | 666.7 | 101 |
| Krishna, India | 345 | 118,000 | 342.6 | 258 |
| Coquitlam River, Vancouver | 100 | 12,000 | 120 | 147-189 |
| Sweetwater, Cal. | 186 | 18,150 | 99 | ... |
| Delaware, Lambertville, N. J. | 6,820 | 250,000 | 36.5 | 45 |
| Colorado, Austin, Tex. | 37,000 | 123,000 | 3.3 | 24.5 |
| Ohio, Cairo, Ill. | 214,000 | 700,000 | 3.3 | 54.9 |
Table 18, compiled by the writer, shows how very extreme the floods of 1909 were compared with those on other rivers, while those of 1910, referred to by Mr. Saucedo, although not so great, would appear to have reached a rate of flow of about 300 cu. ft. per sec. per sq. mile of the drainage area.
The writer agrees with Mr. Saucedo that in the semi-arid regions of Mexico and the Southern States, and also in India, the possibility of these abnormal floods is an important consideration in the design of hydraulic works.
Changes To This Document
Transcriber's Note: The table of contents has been added. Blank pages
have been deleted. Illustrations may have been moved. Discovered
publisher's punctuation errors have been corrected. Some wide tables
have been re-formatted to narrower equivalents with some words replaced
with commonly known abbreviations and possibly a key. Some ditto marks
have been replaced with the words represented. In addition, the
following changes or corrections were made:
p. 501: but the tampers had had[del 2nd had] previous experience
p. 508: shown on Plates VI to IX[VI, VII, VIII, IX[to accomodate links]
p. 516: at this place there is a considererable[considerable] area
p. 538: based on the following rates and and[del 2nd and] percentages
p. 579: by crossing the river, build-the[building the] reservoir
p. 550: [For Table 14: added "Total materials cost">[
p. 566: respectively (Fig. 5)[(Fig. 4)], together with lack of
p. 584: [Table 17 renamed to Table 18 to avoid duplication.]
p. 584: Table 17[18], compiled by the writer, shows how very extreme