The Department of Water and Environmental Regulation supports the management of other water bodies in addition to those supported by Healthy Estuaries WA. This includes Cockburn Sound, where the department monitors water quality at eight sites using automated instruments.
The department monitors water quality in Cockburn Sound using four fixed buoys. Each of the buoys is equipped with an instrument (EXO2, YSI) which can measure temperature, salinity, dissolved oxygen (DO), and light intensity at different wavelengths to determine photosynthetic active radiation (PAR, a measure of light penetration). A winch on the buoy lowers the instrument every hour to collect data between the surface and bottom. Each vertical profile takes about 20 minutes to complete.
At an additional four sites in shallow water, an EXO instrument is mounted on a frame so that measurements are collected above the seagrass. Data from all eight sites is telemetered to the department’s servers for storage and sharing with users. The data are shown here as they become available.
Statistical analysis and data visualisation:
For data visualisation and to remove outliers, a Loess model was applied to each vertical profile. Loess model is a nonparametric technique (a statistical technique for data that is not normally distributed) that fits a smooth curve through each data point in the vertical profile. The data for each parameter is presented as colour coded curtain plots with time on the horizontal axis and depth on the vertical axis.