DRAINAGE 177 



the tract of land shown in Figures 78 and 79, the flood 

 water, coming through the northeast portion of the farm 

 from farms beyond, necessitates the construction of a 

 large open drain. Since water does not flow upon the 

 tract from any other watershed of considerable extent, 

 it seemed wise to make all other drains by the use of 

 the tiles. Thus, while the slough entering the drain from 

 the northwest, received some water from the farm be- 

 yond, it could best be drained by means of three lines of 

 tile entering the open drain. The method of placing the 

 drains in flat areas at either side of the open drains in 

 the center of the farm illustrates how low areas may be 

 reached with economy of labor and tiles. 



Surface drains may sometimes be used to supplement 

 tile drains, in countries where the ground freezes deeply. 

 Thus, a broad, flat ditch thrown out with the reversible 

 road machine, or even a dead furrow, will take the sur- 

 face water from a low area before the ground is suf- 

 ficiently thawed out to allow it to percolate downward 

 to the under drain, and thus permit this low area to 

 become dry as early in the spring as the surrounding 

 areas. 



A section of land with surface drains. In Figure 80 

 is shown a section of land drained wholly by surface 

 drains. This land is located in the Valley of the Red 

 River of the North, some distance from a stream. Since 

 there is a fall of only two to four feet per mile from this 

 land to the river, it seemed impracticable to use tile 

 drains until surface drainage was first thoroughly tried. 

 Besides, this land is not often too wet except while frost 

 is leaving the ground in the spring. This region being 

 far north and the growing season short, it is necessary 

 for the best results to get the crops into the ground as 

 early in the spring as possible. 



Figure 80 shows the general level character of this 

 section of land. The drainage of this section for a prac- 



