610 PROTECTION AGAINST SWAMPS. 



The loss of area taken up in open drains is not of any 

 practical importance in forestry, and provided care be taken 

 about the number and dimensions of the ditches, the other 

 disadvantages of the method may to some extent be avoided. 

 In mountain forests, where the snow is long in melting, and 

 which are subject to unusually heavy rainfall, a system of 

 open drains along the line of steepest gradient removes such 

 a large volume of water from the forest, that this method, 

 which is usually employed, especially on peaty ground, where 

 the flowing water in the drains cuts into the land below, is of 

 doubtful expediency. Under such circumstances the following 

 method is preferable : 



b. Kaiser's Method of Drainage. 



The principle of Kaiser's* method of drainage consists in 

 avoidance of the direct removal of the water from the forest 

 and yet in a complete drainage of the wet land. 



This is effected by the lowering of the water-level by means 

 of a number of interrupted drains (collecting trenches) dis- 

 tributed uniformly over the area to be drained, combined with 

 a system of small ditches widening out laterally. 



The collecting trenches are 1 to 2 meters long, about 

 1 meter deep, and 1 meter wide, and are dug horizontally 

 along contour lines. The lateral trenches, that unite these 

 collecting trenches, and the dimensions of which correspond 

 to the depth to which the water-level is to be reduced, are at 

 right angles to the collecting trenches. 



The following reasons are given in support of Kaiser's 

 method of drainage : 



i. In every case too rapid and complete drainage, with its 

 injurious consequences, is prevented. 



ii. The degree of drainage required by the proposed plan- 

 tation is completely under control, as the lateral drains are 

 dug only deep enough to reduce the water-level sufficiently. 

 The water removed from the soil and from the spoil-heaps 

 that remain alongside the collecting trenches fills the latter 



* Kaiser. " Beitrage sur Pflege der Bodenwirthschaft mit besonderc 

 Riicksicht auf die Wasserstandsfrage." With 24 plates. Berlin, 1883. 



