The acoustic evidence for gas bubbles in the lake Kinneret sediments

The changes in gas content of bottom sediments are associated with rapid alterations of the ambient conditions (climate change, eutrophication, water level fluctuation, etc). In this paper we present results of acoustical measurements of sound scattering at gassy sediments in the subtropical Lake Kinneret (Sea of Galilee), where the 120 kHz single beam echosounder for bottom recognition was used. Measurements were carried out over a 10-year period along 14 standard transects. The echo parameterization method was applied to study acoustical features of bottom deposits and their variability in relation to sedimentary content of gas bubbles. Particularly, we examined the influence of water level fluctuations, affecting the presence of gas bubbles in the surface sediments on sound scattering and echo envelope parameters (spectral, wavelet, fractal, statistical and energetic). Presented results indicate the usefulness of the proposed method of backscattered signals processing for monitoring of the seafloor features.