| Abstract: | At the Schmaler and Breiter Luzin and at the Haus lake there were carried out monthly measurements of the depth of visibility with a white and a black Secchi disk and with Secchi disks of the colours blue, green, yellow, orange, red and reddish brown. The depths of visibility are 0.55… 5.8 m with variation widths for the colours referred to white of 0.05… 2.1 m. The diagram developed by SAUBERER , ELSTER and ?TěPÁNEK for the colour determination is extended empirically on the basis of measurements in the Feldberg lakes and then the water colour of the investigated lakes was determined in the annual variation. The thus obtained classification of the water in a ten-step scale of colours shows a good agreement with the simultaneously determined colours according to FOREL and ULE . Of particular interest is the representation of the change of colours of the three lakes in the annual variation, which shows an individual distribution of colours for each lake—proceeding from a relatively uniform colour in December. |
