Plate 13

DAM TROUBLES AND STUDIES, continued

 

   Upper: A "fuse" or low spot in a wall under construction which protected this dam when sudden heavy flood rains occurred before it was completed to full height and broke the wall where it was only six feet high above natural ground surface. Ten million gallons of water flowed out through the "fuse" in half an hour. The earth lost could be replaced in an hour or two. (Chapters XVIII, XIX, XX.)

   Middle: Damage caused by heavy flood to a large uncompleted dam wall when the water broke over the middle of the wall. The section of wall left standing was only a few feet thick and there was insufficient suitable earth left to reconstruct this dam (Chapter XVIII).

   Lower left: Slip scars on the back of a dam wall 40 feet high where heavy flow through the wall was stopped by the use of explosives as described in Chapter XX. Lower right: Merino wethers near Homestead Ridge Dam on "Yobarnie".