CHAPTER II. 



THE PREVENTION OF RIVERS, WHEN IN FLOOD, OVERFLOWING 

 LOW-LYING TRACTS OF LAND. 



Flood-Water passed by rivers bears no constant ratio either to their summer water 

 discharge or to the drainage area. Ordinary and extraordinary floods. 

 Quantity of water passed off different lands during floods. Morayshire 

 floods. Cause of flooding of rivers. Remedial measures for checking flooding. 

 Navigation works on the lower reaches of rivers have diminished flooding. 



THE second branch of the subject relates to the protection of 

 low-lying lands against the effects of river floods. 



With reference to such inundations, I may here repeat what 

 I have elsewhere stated,* that the quantity of flood water passed 

 by rivers bears no constant ratio either to their summer water 

 discharge or to their drainage area. This conclusion is the 

 natural consequence of the very different geographical and 

 agricultural characteristics of the districts through which rivers 

 flow. 



The drainage area in one situation, for example, may include 

 large tracts of hill country, having steep and scantily soiled 

 slopes, from which the rain is readily discharged. In other 

 places the surface may be flat, or gently rising deeply soiled 

 land, absorbing much of the rain that falls, and giving it off 



* The Principles and Practice of Canal and River Engineering. A. & C. Black, 

 Erlinr., 1872. 



