460 TPIE MONTHLY BULLETIN. 



DRAINAGE AND ALKALI RECLAMATION. 



By Frank Adams, Irrigation Investigations, U. S. Department of Agriculture. 



During the past fifteen or twenty years the owners of western irri- 

 gated lands and the communities dependent on them for prosperity 

 have quite generally come to realize that drainage is almost as funda- 

 mental, even if not fully so, as irrigation. Many hundreds of thousands 

 of acres of once highly productive lands have, acre by acre, been ren- 

 dered wholly or partially non-productive through an excess of ground 

 water in the feeding zones of plants and the consequent concentration 

 at or near the surface of excessive quantities of alkali. 



While this condition obtains in every western state, it is usually local- 

 ized in those sections of each state where considerable quantities of 

 water have been or are now being used, where the irrigated lands are 

 relatively flat and distant from ample natural drainage channels, or 

 where lands are so situated with reference to canals as to receive lateral 

 seepage from them, as, for instance, when they lie at the base of rela- 

 tively steep slopes across which canals are run. 



If the excess of water that causes injury to a farm were merely that 

 which the farmer himself applies in irrigation to his own farm over and 

 above the immediate needs of his crops, little general injury would be 

 likely to occur, because few farmers would continue long to add water 

 to land already excessively moist. But it is usually the water that seeps 

 from canals or from higher irrigated lands, and the coming of Avhich 

 the individual can not prevent, that does the damage. 



Drainage Methods. 



It would not be worth while for this convention to listen to a detailed 

 description of the various methods that have been developed in this 

 country for draining irrigated lands, even if the writer were a specialist 

 on that subject. Those interested can obtain far more information than 

 I can give by reading the various drainage publications issued by the 

 Irrigation and Drainage Investigations of the United States Depart- 

 ment of Agriculture, all of which can be obtained free on application 

 to the Secretary of Agriculture at Washington. A few general obser- 

 vations as to methods may, however, be in place here, especially as they 

 may aid in making clear the results of specific drainage experiments 

 conducted by the Irrigation and Drainage Investigations and the State 

 Engineering Department of California, near Fresno, to be taken up 

 later in this paper. 



Since the condition that makes drainage necessary is not due to the 

 Avater applied directly in irrigation, but rather to the water that seeps 

 from canals or higher overirrigated ground, the fundamental process 

 in drainage is to intercept the excess water in its lateral percolation 

 along some hard or relatively impervious substratum, or in its rise in 

 the form of ground water. Consequently, the location and depth of 

 drains is of prime importance. If it is feasible to intercept lateral 

 seepage water before it reaches a point of injury, it is obvious that 



