114 Transactions. 



particularly the conditions of the Taieri drainage ground, with a view to 

 ascertain, if possible, in what respects it facilitates the rapid discharge of the 

 rain or melting snow, and it will then be seen that the chief features likely to 

 promote this are the generally mountainous character of the catchment area, 

 with the exception of the Upper Taieri plain, the steep inclination of the 

 ridges, the nature of the rocks, and the general steep declivity of the bed 

 between the upper and lower plains. On the other hand the upper of these 

 plains forms a natural basin about 280 square miles in extent, but of this 

 only about one and a half square miles are an open lake, the remainder being 

 deposits of shingle of various depths lying upon impervious clay, and capable 

 of being a store reservoir only to the extent of the interstices between the 

 stones. That portion, in fact, resembles a huge sponge, acting with the open 

 lake in retaining the water, and preventing to a certain extent its sudden 

 rush down the channel towards the lower parts. The lake lies at the flank of 

 the Lammerlaw or Rock and Pillar range ; and finds along with the Kyeburn 

 an outlet through a narrow gorge, at one place not wider than 110 feet, but 

 unfortunately its low level limits the capacity of the whole reservoir as a flood 

 moderator. The point now is, to consider the practicability of raising that 

 outlet to such an extent as to store the greatest flood waters that are likely to 

 occur, and release them only at such a rate as shall not be prejudicial to the 

 low grounds lying below Outram. 



The flood of 4th February, 1868, being the greatest on record, I shall 

 take as the standard one, seeing that it is necessary in any remedial works 

 that may be proposed to provide against the occurrence of an evil at least 

 equal to that already experienced. 



The circumstances of rainfall attending the floods of January and 

 February of that year, at least so far as we can judge the Taieri basin by 

 observations taken at Dunedin, were almost such as to lead us to expect that 

 no such floods are likely to occur for very many years. Upon examination of 

 the meteorological tables prepared by Dr. Burns and the Meteorological 

 Department, it will be found that the unprecedented nature of the January 

 and February floods was more owing to the extreme degree of saturation in 

 which the ground must have been by months of previous rain, than to even 

 the heavy rains of any one particular day. Doubtless these were very heavy, 

 but not so much so as several days both before and since, which did not 

 produce the same rise in the water. For the months of October, November, 

 December, January and February, the rainfall ranged from 5-0 to 8*078 in., 

 thus showing a continuance of wet weather unequalled, I believe, in the 

 history of the settlement. In the case of the flood of January, 1870, which 

 did not rise so high as the one we are specially considering, the rainfall 

 recorded in one day exceeded that shown upon 4th February, 1868, but that 



