| The temperature, conductivity and turbidity of lake water are very important
indices of a lake environment. Conductivity reflects the total amount of
concentration of major ions (Na+, K+, Mg2+, Ca2+, C1-, S042-, HC03-). Turbidity correlates the concentration of SS (Suspended Substance). A TCT-profiler was designed for monitoring of a lake environment. It is able to quickly measure temperature, electric conductivity and turbidity at every 0.5m interval in a water column. A high speed boat equipped with the TCT-profiler makes it possible to collect data over a wide area of a lake. Measured data are automatically memorized and stored within the sensor unit, as the profiler, suspended from an ordinary rope, moves up and down beneath the lake surface. Observations were carried out at several locations in Lake Biwa, and useful data were obtained. Turbid water due to heavy rains was transported from the Ane River into the center of lake by the lake current (cyclonic gyre). The transportation speed of turbid water was estimated over a two day period at about 5cm/sec, which corresponded to the gyre speed. |