History of Floods in the Hawkesbury River. 
By J. P. Josrpuson, A.M.L.C.E. 
[Read before the Royal Society of N.S.W., 2 September, 1885.] 
THE basin of the Hawkesbury is very curiously formed and con- 
stitutes one of the geographical peculiarities of New South Wales. 
It consists of three slopes inclining inwards, a north, a west, and 
east slope. The main stream comes from the north slope. It is 
formed in the first instance, of the Wollondilly, and its south 
branch, the Mulwarree. In its progress north the Wollondilly is 
joined by the Cookbundoon from the left, and by the Wingecarribe 
rom the right, bank. It then traverses the remarkable sunk valley 
called Burragorang, still keeping its north direction. The next 
important tributary, Cox’s River, collects the hott drained from 
the south portion of the Blue Mountains, flows in a general east 
direction, and joins the Wollon as the waited stream then 
uu h arr. In the next 
t epean. 
until joined by the Grose from the Blue Mountains, when it i 
designated awkesbury. ter receiving the Colo and the 
suddenly east, and discharges its waters i into Broken Bay, which 
is about 20 miles north of Sydney Heads. 
The lower portion of the Hawkesbury is navigable, and the 
scenery on its banks is remarkable for its beauty and picturesque 
appearance. The total course of the Hawkesbury is 330 miles, 
and it drains an area of 8,700 square miles. Its principal tribu- 
taries are the Macdonald, Grose, Colo, Nepean, an a ba 
Rivers, and the Mangrove, Breakfast, Gunderman, Myrtle, Billong, 
Currency, Cattai, South, and Rickaby’s Creeks. Sandstone and 
shale country. 
Some of the more recent floods have been carefully surveyed, 
and on the plan in the appendix will be found the details of these 
surveys, showing the land actually under water in 1867, here 
