Dynamic variations in thermal regime and surface deformation along the drainage channel for an expanding lake on the Tibetan Plateau

The outburst of Zonag Lake in 2011 triggered a series of floods in the continuous permafrost region of the hinterland of the Qinghai-Tibet Plateau. This re-distributed the surface water in the basin and caused rapid expansion of the tail lake (Salt Lake). To avoid potential overflow of the expanding Salt Lake, a channel was excavated to drain the lake water into a downstream river. In this study, to investigate the permafrost thermal regime and the surface deformation around the expanding Salt Lake and the channel, in-situ monitoring sections were settled from Salt Lake to the downstream of the channel to obtain the permafrost temperature. Additionally, using small baseline subset interferometric synthetic aperture radar (SBAS-InSAR), the surface deformation around Salt Lake and the channel was measured. The data showed that the ground temperature at the channel was 0.6°C higher than the natural field and the mean subsidence rate around the channel was 1.5 mm/yr higher than that at Salt Lake. These results show that the permafrost temperature in the study area changed considerably with variations in the distance from the lake/channel, and the deformation in the study area was dominated by subsidence.</p

Non-metric multidimensional scaling (NMDS) plots of bacterial communities based on taxonomic dissimilarity (a) and betaMNTD (b) matrix, respectively.

<p>The stress value reflects how well the ordination summarizes the observed distances among samples (lower than 20% can be ecologically interpretable and useful). Soil variables were fitted as vectors onto each ordination plot, and significant vectors at 95% confidence level (<i>P</i> ≤ 0.05) were displayed.</p

Schematic diagram of the permafrost core and the associated physiochemical characteristics of different-depth samples.

<p>Error bars represent means ± the standard error (n = 3).</p

Partial correlation between environmental heterogeneity (environmental distance) and taxonomic dissimilarity (a); and betaMNTD (b); and betaNTI (c).

<p>Residuals of the x and y variables are plotted in order to account for the effects of vertical distance and spatial autocorrelation. Solid lines represent linear regressions and the significance levels are determined by partail Mantel tests (9999 permutations).</p