Movements of Ground Water 433 



maps and by the arrows representing the lines of 

 underflow, which concentrate from the surrounding 

 higher lands to pass beneath this section so near 

 the surface that the strength of capillarity was suffi- 

 cient to over -saturate the soil above. The influence 

 of the tile drains in lowering the surface of the 

 ground water is plainly shown by the distance the 

 contours are carried back from the lake shore, as seen 

 along the line marked "tile drain." 



In the case of streams winding through valleys, 

 the water comes to them at every point along their 

 course by slow seepage, entering the channel through 

 the banks and bottom in the manner represented in 

 the diagram, Fig. 134, where the heavily shaded por- 

 tion represents the soil filled with water and the lines 

 with arrow points the direction of flow. 



In Fig. 135 is represented the surface of the 

 ground water in the valley of the Los Angeles river, 

 California. The data for the contours were procured 

 by sinking wells at the points designated by the 

 heavy dots. From the map it is clear that the water 

 stands higher and higher above the bed of the stream 

 as the distance back increases, and that there must 

 be a steady flow down the valley and toward the 

 river, thus draining the surrounding country. Indeed, 

 in a distance of about 11 miles the measured growth 

 of the Los Angeles river in 1898 was 60 cubic feet of 

 water per second, and yet no visible streams entered, 

 the supply coming by slow seepage along the banks 

 and bottom of the entire length of the section 

 measured. 





BB 



