Dynamic Multidimensional Visualization for Water Quality Data in Rivers

Visualization of water quality associated with rivers is difficult because most rivers have sparse data collection points and visualizing the spatial trends described by these sparse data is challenging. Traditional isopleths maps (contours) are not suited for display of these data because the data are associated only with the stream or river and the mathematics associated with isopleth generation (e.g., kriging, distance weighted interpolation, etc.) assume the shortest distance between two points and isopleths only present one parameter. We have found that “snake diagrams”, popularized by Edward Tufte, are an effective visualization technique for river data. Snake diagrams present two or three data dimensions, such as flow and concentration using width and color, each dimension corresponding to the associated data. A third parameter can be associated with the height of the “snake”. The ability to present two or three parameters allows analysis of correlations and trends not apparent if the parameters are viewed individually. We have developed software with several spatial interpolation and data classification techniques to create snake diagrams to visualize and assess water quality in river networks. The Snake diagrams present the spatial treads and the correlation among the study variables and the software allows the analyst to explore various presentations. The software also generates more standard charts and graphs along with the data statistics. The snake diagrams can be exported and visualized in Google EarthTM using KML files. As with the software, the KML files can be animated to show temporal trends in addition to the other data dimensions that are presented.