Q28 PROCEEDINGS OF SECTION H. 



Q= -9 Ri At Q=l-26 r At 



a = -9 Rl At a =l-26 r At 



V V 



D= l-07 Ri Ai D ^l-27 ri Ai 



The following Table No. 2 will serve to indicate the application 

 of the formula in actual practice ; but for this purpose, as the slope 

 of waterway and hydraulic radius are not known in the majority 

 of cases, a velocity of 6 feet per second (which is generally attained 

 in all waterways) has been adopted for them. The particulars for 

 all cases cited except those for Adelaide are taken from the late 

 Prof. Kernot's paper on Waterways of Bridges and Culverts ; those 

 for Adelaide are from the author's practice. 



In the case of the Torrens River catchment the flood flow was 

 accurately measured. At top flood the water flowed over the crest 

 of the weir 8 ft. deep, the crest being 132 feet long and 9 feet wide ; 

 at the same time six slu'ces each 3 ft. diameter and 26 ft. long were 

 also carrying off water under a head of 18 ft. 



In presenting the above formula it is not pretended that it 

 represents the last word on the subject. It is, however, believed 

 to embody the primary essentials governing flood discharge, and 

 is in such a form that it can be applied intelligently to any locality. 

 It also is of such simple form that it can be modified without diffi- 

 culty as further data and experience may prove desirable, either by 

 assigning special values to c or otherwise. For instance, the co- 

 efficient c may have unit value in the temperate zone, and higher 

 in sub-tropical and tropical countries subject to monsoonal rains 

 both heavy, prolonged, and extensive ; but this refinement has not 

 been attempted for lack of data. 



Indeed, while it is believed that the formula is at least as reliable 

 as any other and lends itself to more rational and general use with 

 equal facility, and probably gives better results for very large 

 catchments, the chief object of the author has not been the per- 

 petration of another formula on the already long list, but to direct 

 the attention of the Government, civic and shire authorities to the 

 necessity of keeping and publishing frequent and comprehensive 

 records of rainfall and flood discharge in connection with catch- 

 ments for water supply, etc., throughout the States. And to this 

 end it was necessary to demonstrate the inadequacy of existing 

 formulae and the grave risk in their indiscriminate use. 



Every day culverts and waterways are being built too small 

 or of very excessive size through the want of proper data, thereby 

 entailing serious loss on the community, damaging property, inter- 

 fering with business, and causing great waste of public money and 

 inconvenience. To prevent this great annual loss and hardship 

 should warrant considerable expenditure in time and money to 

 collect reliable data so as to establish this branch of knowledge on 



