Vízügyi Közlemények, 1932 (14. évfolyam)

2. füzet - XII. Kisebb közlemények

32 third and fourth days after the outbreak of the spring, it was observed that the water in the barrel was sometimes sinking, and then rising again, which showed that a cavity had formed somewhere in the subsoil of the levee, and that the collapsing earth from time to time stopped up the water in the cavity and then was washed away again. The measures necessary for fighting this special form of flood were duly taken. On the fifth day the spring suddenly produced an eruption like a mud volcano, and at the same time a whirlpool appeared on the surface of the flood water about 30 metres (90 ft) from the crest of the levee, and kept continually approaching the latter. (Fig. 1.) Hereupon a pontoon, about 10 metres (30 ft) long and 2 m (6 ft) wide, was placed with its length at right angles to the levee, and bags filled with earth were loaded into its stern, in order that it should be sunk into the hollow, which, it was evident, had already well developed. When the whirlpool approached the crest of the levee to within about 15-—20 metres (45—60 ft), the pontoon tilted, its prow lifted, and following approximately the line indicated by the numbers 1—10 in Figure 2, it plunged under water. In a minute or two the pontoon emerged on the other side of the levee, turned upside down. The levee stood for a few minutes longer, then its crest began to crack, and suddenly it sank down in a length of 8—10 metres (25—30 ft), and the water spread over the protected flood area. The breach soon widened to 80—100 metres (250—300 ft), and the depth of the erosion attained 24 metres (72 ft) below the flood flow line. 2. ADDITIONAL REMARKS TO THE ESSAY ENTITLED „RECENTMETHODS AND IMPROVEMENTS IN GULLY-STABILIZATION". By : ÁRPÁD TRÜMMER, In connection with M. Trummer's paper in the previous issue of the „Vízügyi Közlemények", and referring to an observation sent to him, the writer describes in detail the conceptions relating to the energy of runoff water, and gives the corresponding formulae.