WATER CIRCUL vTION AND ITS CONTROL 



By BAILEY WILL). E.M.C.E., United States Geological Survey 



(Continued} 



Outlin of Methods of Control 



ENGINEERI NG CONTROL OF SURF CE FLOW is persistently aggravated by these 



widespread activities ; he is required to 



THE engineer aims to reinate sur- take care of sediment whose volume is 



face flow through ir:liods of constantly increased by vicious meth- 



storage, diversion, or colinement ocls of agriculture, grazing, and defor- 



in an established channel. Hi selection estation, and the Nation collectively 



of method is determined b} ic topo- spends millions on engineering while 



graphic conditions of the parcular lo- the people individually render the ex- 



cality primarily, and also by te balanc- penditure useless. 



ing conditions of need and cos The re- The engineer urgently needs the sup- 

 suit is a reservoir, canal, or oier struc- port of an educated, enlightened public 

 ture designed to be permaner, to meet opinion which will control individuals, 

 the greatest emergency which lay arise, In proportion as every landowner man- 

 and to supply such water or a : ord such ages his property intelligently with re- 

 relief from water as condition require, gard to its perpetual value and the 

 When practicable the investir at should welfare of the commonwealth, the engi- 

 return to the people at least fair in- neer's problem will shrink within those 

 terest on the cost. These liming con- limits of reasonable magnitude and cost 

 ditions are so well understoa and en- which it now threatens to exceed, 

 gineering practise is based pon such Let us consider some of the examples 

 a thorough knowledge of fudamental of the engineer's methods of regulating 

 mechanical principles that ir. ny given surface flow by storage, drainage, di- 

 case the engineer's calculate may be version, and .canalization, 

 implicitly trusted, provide* that the The construction of reservoirs for 

 factors of run-off, fluctuatio. and sedi- the storage of waters is, in compari- 

 ment, which are fundament; elements son with its possibilities, very slightly 

 of the problem, do not at ay future developed in the United States. A few 

 time exceed the maximum inits which examples will illustrate the magnitude 

 past experience leads him ) assume. and purposes of existing works. 

 This provision implies that tr progress The Croton reservoir system cost 

 of settlement and the expntation of Greater New York $86,359,562 up to 

 our natural resources shoul not unfa- 1898; and estimates on extensions and 

 vorably modify the relatior <i run-off improvements are $161,000,000. The 

 to ground storage and caporation. city can afford it, for the system sup- 

 Through ignorance, carelemess, and plies pure water to 4,000,000 persons, 

 greed, the farmer, herdsma. and lum- among whom, considering one benefit 

 berman are constantly vio.ting this only, the death rate from typhoid fever 

 provision, as we shall se when we was, in 1905, sixteen per 100,000, as 

 come to the consideration othe specific against more than 100 per 100,000 in 

 relation of their activities t the parti- certain cities supplied with polluted 

 tion and distribution of fecipitation. river water. 



The engineer is now called uon to reg- On the upper Mississippi a reservoir 



ulate run-off, the irregular/- of which system has been gradually installed 



325 



