One can notice on the figure below that the
dissolved ion content is the most important parameter in determining density variation.
At first sight this ion content is linked by a rule of proportionality to electrical
Measuring conductivity is relatively easy, either in situ
using a CTD (Conductivity, Temperature, Depth) gauge, or in the laboratory on
samples taken from different depths.
vertical contour offering excellent spatial definition was realised using a Seabird
CTD SBE39. On this conductivity curve the different homogenous layers of the lake
are quite clearly visible, separated by layers of a high gradient of density.
the figure, for example, the two homogenous layers between 280 and 300 m and 330
and 355 m are apparent. We have also taken a large number of water samples from
different depths (either by pumping or by using the auto-siphon technique). The
conductivity of these samples has been measured and appears on the figure as blue
stars as well as the CTD contour already shown. Note that the two curves are very