REPORT OF BOARD OF CONSULTING ENGINEERS, PANAMA CANAL.


 In order to foresee even the improbable, we shall reserve for the storage of floods a space equal to twice that; that is to say, a variation of level of 20 feet.
 This will store the maximum flood known during ninety-six hours; or during forty-eight hours a flood of 3,200 cubic meters (106,000 c. f.) a second-twice as great as the largest known.

 THE BOHIO LAKE AN EMERGENCY FLOOD CONTROLLER, WHICH MAY GRADUALLY DISAPPEAR.

 We are thus protected by the largest margins of safety ever contemplated. If, however, nature sends a still harder trial, it will be only necessary to let the water drop into the canal as it comes. This will cause no danger, as the Bohio Lake is there created to act as an emergency controller for a 5,000 cubic meter (140,000 c. f.) flood of indefinite duration.
 In the first.period of the life of the canal Lake Bohio will exist, and it will be very easy and cheap to enlarge the narrow parts of the canal in the upper section of Lake Bohio in order to admit even 1,600 cubic meters or more into the canal without creating a current damaging to navigation.
 In the second period of the canal life, the sea-level period, its dimensions will be necessarily enlarged and the cross section brought to about 1,000 square meters or more. With such a section a flow of 1,600 cubic meters a second will generate a current of only about 3 knots.
 Such an accident as the one we suppose would certainly not happen once in a century, as the flood on which we have based our calculations happened but once in fifty years, and as we are normally prepared to dispose of a still larger flood of double duration and equal violence, or of equal duration and double violence, without dropping any water from the Gamboa Lake.
 The fact of not making the Bohio Lake a vital organ of the Chagres regulation, as the Comit6 Technique was forced to do, owing to the adoption of the Alhajuela location, entirely liberates the transformation of the canal from the Chagres flood question. During the transformation the Bohio Lake will disappear without impairing the regulation of the Chagres, which could not have been done with the system adopted by the Comit6 Technique.
 STORAGE FOR DRY SEASON-IT WILL BE AMPLE FOR 50,000,000 TONS OF TRAFFIC.

 The part which the Gamboa Lake has to play is double. First, it must form a water reserve for the dry season, and, second, it must control the floods at the same time. The months of November and December are precisely the months when, if you expect a flood, you must have your reservoir low, and if you expect an early dry season you must have its surface high. Therefore there are two distinct volumes affected, each one to its individual service.
 The volume of the lake between level 160 and 180 will be devoted to storage for the dry season, and the volume of the lake between 180 and 200 will be devoted to the storage of the floods, as we have seen. There will thus be no conflict between two inverse necessities, nor any discretion left to weather prophecy.
 The volume stored for the dry season will amount to about 550,000,000 cubic meters or 18,500,000,000 cubic feet. This will mean for every one of the one hundred days of dry season 5,500,000 cubic meters, or about 67 cubic meters a second, which, increased by the minimum inflow of 14 cubic meters, would give about 80 cubic meters a second for the canal, or 2,700 cubic feet.
 The Isthmian Canal Commission, in its report of November 16, 1901, declared that for 10,000,000 tons the canal will absorb for the lockages 406 cubic feet per second (13.5 c. m.), and for various needs not varying with traffic another quantity of 664 cubic feet per second, making 1,070 cubic feet per second (35.6 c. m.) in all.
 It results from these figures that the amount of water stored behind the Gamboa dam will satisfy a traffic of 40,000,000 tons with the height of the locks of the Canal Commission, and therefore a traffic of 50,000,000 tons with the locks of less height, which I propose to use.
 One sees that the Gamboa Lake affords an equally perfect solution of the storage question as it does of the flood question. The traffic it guarantees during the dry season is precisely the traffic which is considered the highest traffic attainable with a lock canal.


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