PREVENTION OF FLOODS. 115 



large areas of country are carried out under a 

 general system, the cost being levied on the 

 landowners in proportion to the advantage they 

 receive. In the execution of this duty it has 

 been found that the applicants in many cases 

 have erred in not including the whole of the 

 area which should naturally fall under one 

 control, and so failing to secure uniformity over 

 the whole of the catchment basin affected. 



Floods in river valleys in autumn, and Floods 



beneficial, 



winter, and spring, provide rich irrigation for except 



where per- 



the land, the mud in which subsides when the mitted to 



remain too 



waters are for a time partially stagnant. They lon g stag- 

 nant. 



are very beneficial if not permitted to remain 

 too long. Land subject to such floods should 

 never be broken up from grass, as in no other 

 way can it in this country be more profitably 

 used. Before under-drainage became so general, 

 the floods came down much more loaded with 

 sediment, and therefore in that respect much 

 more enriching than now, when the rains of 

 the uplands pass through and are filtered by 

 the soil. But that is largely compensated by 

 the soluble salts of the manure which the rain 



12 



