211 貯水池に侵入する濁水流の可視化計測

Abstract

Turbid water intruding into a stratified reservoir was visualized by two kinds of equipment mounted on a boat; Precise Echo Sounder (PES) and Acoustic Doppler Current Profiler (ADCP). By PES, a cloud of fine solids suspended in the water was clearly visualized even if the turbidity was less than 20 ppm. On the other hand, the velocity measurements by ADCP contained a lot of error because of the trembling of the sensor caused by wind waves. The order of the velocity fluctuation at each cell was 5 cm/s while the order of the current was 10 cm/s. However, the resultant picture shows the flow pattern and the velocity distribution in a section fairly well : The turbid water flowed down on the bottom slope as an inclined plume with the maximum velocity of 15cm/s, took off the bottom at the depth of 16 meters, and intruded into the reservoir horizontally along the thermocline with the velocity of 10 cm/s. It is noteworthy that the horizontal stream along the thermocline concentrated in a narrow region in the transverse section although the reservoir water was highly stratified.