Measurement Method of Turbidity Depth Profiles using ADCP for Monitoring of Coastal Sea Area

In stormy weather, dredging and filling operation and so on, water with high concentrations of solids arises in coastal sea area. Growth of seaweed and algae is obstructed to interrupt sunlight by the water with this high turbidity. To make matters worse, sediments has the character to adsorb the nutrient and organic matter on those surfaces. Water involved high concentration of solids with nutrient and organic matter make seawater and seabed polluted. In order to improve them, it is very important to measure the spatial and temporal variability of solids dynamics and to monitor the coastal environment. In this study, the authors proposed a new measurement method of solids depth profiles by using acoustic Doppler current profilers (ADCP). Authors regarded the propagation of ultrasonic waves as inverse problems in underwater and modeled these factors, which influences the propagation of ultrasonic waves. By using ADCP and optical turbidity sensor, the depth profile of the solids concentration can be measured. Since ADCP can be obtained the three-dimensional velocity, the present method is suitable for monitoring in order to understand the solids dynamics in seawater.