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AND PROTECTION OF AGRICULTURAL LAND. 17 



t of their periodic occurrence to a greater or less extent in 

 many rivers gives the subject a general interest. 



Perhaps it may seem almost unnecessary to say that flooding 

 takes place when the combined sectional area of a river channel 



d the fall on its bed do not afford sufficient discharge for 

 the passage of the drainage water. The obstruction due to 

 deficient sectional area may be lessened, or perhaps altogether 

 removed by enlarging the channel of the river, while that due 

 to insufficient fall may often be removed by making a short 

 cut instead of a long detour, as already noticed at page 6, and 

 thus increasing the slope of the surface and the velocity of the 

 current, and when such operations cannot be carried out, or 

 do not either singly or combined afford sufficient relief, recourse 

 must be had to artificial embankments. 



In forming straight cuts to shorten a river's course and 

 increase the fall on its surface, and, consequently, its velocity, 

 care must be taken that the inclination be not so much 

 increased as to produce a current so rapid as to injure the banks 

 of the new cut; and as their liability to injury (as explained in 

 treating of the abrasion of banks) depends on the materials 

 of which they are composed, it is not possible to lay down 

 any rule of universal application in deciding what rate of 

 inclination may safely be adopted. The formation of a new cut 



channel is, however, a work that should not be undertaken 

 without careful consideration of all the circumstances, as such a 

 work may in some cases prove injurious to the bed and banks 

 below the point where it joins the original course of the river, 

 and thus prove detrimental to the interests of adjoining pro- 

 prietors. 



