Maximizing information from a water quality monitoring network through visualization techniques

This paper describes a variety of visualization techniques that have been v ery useful for demonstrating important aspects of a water quality monitorin g programme in South Florida. The first level of visualization was at the s ingle station or grouped stations using the box-and-whisker plot as a graph ical/statistical tool. This plot was used to compare intra-annual variabili ty and correlation between total phosphorus (TP) and chlorophyll a (chl a) at a site in Florida Bay. Secondly, time was added as a dimension to produc e a 9-year, monthly time series plot of declining salinity at a site in NE Florida Bay. It was shown how a centred moving average could be used to smo oth out the noise and disclose inter-annual oscillations. Time series of an omalies from long term means were discussed as a means of displaying corres pondence and coupling among variables. Thirdly, the utility of 2-D contour maps of variables was demonstrated in showing sources and mixing of fresh w ater across the hydroscape as well as nutrient loading to the South Florida ecosystem. From this expanded spatial view, it was observed that the water quality of different bays and coastal areas are differentially affected bo th by external and internal processes and how management of pump operations and canal conductance can overwhelm the natural hydrological cycle and hav e far reaching impacts in Florida Bay and the SW Florida Shelf. We also sho wed that contouring was useful for elucidating causal relationships among v ariables over the spatial domain. Time step animations of monthly salinity contours in Florida Bay showed the importance of mixing with western bounda ry waters to alleviation of hypersaline conditions. These animations also s howed that it is the shifting lags between TP concentration and chi a which make it so difficult to derive a simple regression model. Finally, a 3-D v olumetric rendering of the area between Key West and the Tortugas was used to describe a strong density stratification event during July 1998 and to v isualize the source of water masses and general circulation patterns in thi s region. It is concluded that visualization techniques are useful not only to show patterns in the data but in developing new hypotheses for future r esearch and monitoring activities. (C) 2000 Academic Press.