118 Transactions. 



could be kept back for even twelve hours, their most destructive effects would 

 be moderated. It would also be necessary to have reservoirs upon the Sutton, 

 Deep, and Lee streams, perhaps more so than in the Taieri, in proportion to 

 their areas, as the features of their catchment basins are such as to show many 

 indications of rapid flood-producing streams. 



The mode of flood prevention I have examined in this paper is one which 

 has been much adopted upon the continent of Europe, and notably upon the 

 river Loire, which I have already referred to as standing remarkably high as 

 a flood-producer. Above the particular part where the discharge I have 

 referred to was gauged, we have seen that it ranks nearly three times as 

 intense as the Taieri ; yet to moderate these waters a weir sixty-five feet high 

 was erected in 1711, which did immense service in the floods of 1846. They 

 topped it, however, by a height of about five feet, but were still sufficiently 

 restrained to lessen considerably the damage which otherwise would have been 

 sustained. 



The advantages which the prevention of the flow of the waters upon the 

 lower plain possesses over any scheme of embankment, either along the 

 present channel or any new one, are so evident as scarcely to require remark. 

 Besides being much cheaper, it possesses an advantage in this, that even if 

 carried out to a partial extent it produces general benefit to all the land which 

 has hitherto been liable to inundation ; but by the method of embankment 

 upon the plain, intended to shut the water ofl" particular parts, these portions 

 are protected only by aggravating the evil upon other spots, both by the 

 increased depth of the water and the heightened current. 



One objection to this method has been so often urged that, paradoxical 

 though it may appear, I believe that had it been founded upon facts, they 

 would, ere this, have been recognized as an argument for its immediate 

 adoption. I refer to the belief that, supposing such a work were erected, the 

 lake would quickly be silted up by tailings derived from the diggings, so that 

 the bottom being raised the weir would sj^eedily become useless. Now the 

 area proposed to be occupied by the reservoir is presently about as much 

 exposed to those deposits as it would be then, and though some parts are so 

 acted upon to a considerable extent, yet had the evil been of such proportions 

 as to be practically felt, a necessity would have existed ere this for the imme- 

 diate erection of a weir at the outlet, to counteract the shoaling process, and 

 thus prevent a more rapid discharge of the water than would be consistent 

 with its natural condition. An examination of the locality, however, would 

 convince anyone that there is bat little to fear from this evil assuming dan- 

 gerous proportions ; for, taking the Naseby diggings alone, it will be seen that 

 even after about nine years of extensive sluicing operations, during which 

 the heaviest flood on record has been experienced, the greatest distance to 



