ENGINEERING CONSTRUCTION AND RA.INFALL. 



LVIL 



former (A.) the discharge would be found to be of sufficient 

 volume to have created a fairly well denned channel, and where 

 semi-tropical rains are experienced, as in New South Wales, the 

 flooding would have left distinct marks behind. The safest 

 course in all such cases would be to depend upon flood marks 

 and other reliable data obtained locally. The information thus 

 obtained should be checked by taking in conjunction the drainage 



STORMWATER DRAINAGE. 



Details of Rainfall provided for. 



Name of Channel. 



0) 



c P o 



P -s 



Rainfall allowed for 

 in inches per hour. 



Length of Channel 

 Constructed 



Length of Fetch 

 above Channel. 



Wallsend and Plattsburg 





3040 



^ inch 



53 chains 



3 m. 10 chns. 



Orange Stormwater Channel 



4600 



J inch 



25 chains 



— 



Newcastle Pasturage Reserve 











Stormwater Channel 





7787 



^ inch 



2 m. 64 chns. 



2 m. 40 chns. 



Homebush Creek — 







i 1 inch Albyn St. 

 J branch 

 \ 1^ in. Railway St. 

 ( branch 







Upper portion . . 





620 







Iron Cove Creek — 







— 



— 



Upper portion . . 



1 



1700 



J 1J inch . . 

 \ 1 inch . . 



— 



— 



Lower portion . 





J 



— 



. — - 



Long Cove Creek — 















Upper portion . 





1 



1000 



J 1^ inch . . 

 \ 1 inch . . 



— 



— 



Lower portion . 





J 



— 



. — 



Johnstone's Creek — 















Upper portion . 





} 



1147 



[ \\ inch . . 



— 



— 



Lower portion . 





\ 1 inch . . 



— 



— 



Rushcutter's Bay — 













* 



Upper portion . 





1 



330 



f 2 inches 

 \ 1^ inch . . 



— 



— 



Lower portion . 





/ 



— 



— 



White's Creek — 















Upper portion . 





} 



830 



/ \\ inch . . 



— 



— 



Lower portion . . 



[ 1 inch 





~ 



areas, the maximum rainfall, and the grade which the water 

 course would be likely to give when in flood. To compute the 

 discharge for the latter (B), when the slopes are great, and the 

 surface rocky or impervious, the only absolutely reliable course 

 was to assume that the maximum rainfall would flow off" at once, 

 and ma e provision in the culverts accordingly. Referring to the 

 typical case quoted on Page xli., presumably the Author would 

 make provision for 6" of rainfall over the whole of the catch- 



