IRRIGATION INVESTIGATIONS. 419 



bringing together of observations from the whole country. It pro- 

 motes uniformity of methods in these investigations and thus gives to 

 the results a wider value than is possible with each station working 

 independently and alone. It brings together the experience of the 

 whole irrigated West for the use of each locality, and shows the farm- 

 ers of one section where their practices can be improved by adopting 

 those of other and oftentimes far distant sections. 



AGRICULTURAL AND ENGINEERING PROBLEMS. 



The studies of the practical questions involved in diverting water 

 from streams, transporting it through canals and ditches, distributing 

 it over the land, and determining the requirements of different crops 

 have been carried on in all of the arid and semiarid States with one 

 exception. In general, the results of this work show that the losses 

 in distribution are much greater than has usually been supposed, and 

 that the quantity of water required, where these losses are included, 

 is somewhat greater than has been estimated by many writers on the 

 subject or stipulated in many water-right contracts. The stations for 

 the measurement of the duty of water are scattered over nearly one- 

 third of the United States. The averages of the different measure- 

 ments for the past two years show a surprisingly close agreement when 

 this wide range of conditions is considered, as appears from the fol- 

 lowing summary: 



Feet. 



The average depth of water applied to crops in 1899 was 4. 35 



The average depth of water applied to crops in 1900 was 4. 13 



One of the results of this work has been to show the importance of 

 keeping canals in good condition, and to emphasize the benefits result- 

 ing from diminishing as far as possible the losses by percolation. 

 Measurements show that the loss from seepage and evaporation in 

 ditches and canals varies from 15 to 70 per cent of all the water taken 

 in at their heads, and that by far the greater part of this loss is due 

 to seepage. Formerly many believed that most of the loss was due 

 to evaporation, and was therefore be} r ond the power of man to remedy. 

 Now that it has been demonstrated that the water disappears through 

 the sides and bottoms of ditches and canals, steps can be taken to 

 improve these channels and the loss stopped to a great extent. 

 Improvements of this character will increase the area which can be 

 irrigated, and save much land for productive agriculture which would 

 otherwise become swamps and marshes. 



The difference between the high and low duties obtained under 

 practically the same conditions shows that where water can be had in 

 abundance the natural tendency is to use too much, resulting in a 

 reduction in the yield of crops, a temporary injury to the land, and a 



