Access this interactive dashboard online to browse through maps and graphs based on multi-year satellite data and observe the water-quality trends and the current status of large lakes around the world.
Key messages
- Satellite data provide a comprehensive indication of recent trends and the current status of water quality in large lakes in time and space.
- Satellite data complement in-situ data where the latter are sparse or even absent in water bodies.
What is this Dashboard used for?
The Inland Water Remote Sensing Dashboard was developed as a demo in response to the needs of the World Water Quality Alliance. The dashboard aims to assist with the visualization of remote-sensing and in-situ water-quality data in large lakes around the world. In its initial version and to showcase its capabilities, the dashboard displays data for a selection of eight lakes extracted from the lake water-quality products provided by the Copernicus Global Land Monitoring Service, which offers products for more than 4000 lakes globally. Those on the dashboard are lakes Garda (Italy), Markermeer and Ijsselmeer (the Netherlands), Nicaragua (Nicaragua), Titicaca (Peru and Bolivia), Turkana (Kenya and Ethiopia), Vänern (Sweden) and Volta (Ghana).
Selecting parameters to display (lake, time period, and water-quality variable)
Using the top menu, the user can select the water body (fig 1), the period for which to display the datasets (fig 2) and the parameter to be shown on the lake map and boxplots. Currently, the dashboard contains data for turbidity (an indicator of how clear or turbid the water is), and the trophic state index (TSI), an indicator of the eutrophication status of the water body).
Visualizing the data on various plots
The main body of the dashboard displays on the top left a map with remote-sensing-based water-quality estimates that are averaged for the selected parameter for the selected time period. The user can hover over the lake map and display the parameter value for each available position in the lake. On the top right, the time series of the TSI is shown on an interactive graph (all available dates in the selected time period) and a heatmap (per month, per year) (fig 1). Users can hover their computer mouse over the time series graph to show the date and lake average TSI value at that particular date (fig 3). The heatmaps are interactive in a similar manner.
On the bottom left, seasonal boxplots are displayed (per month) over the time period for the selected parameter (fig 1, fig 2). These are interactive – boxplots statistics are displayed when users hover a mouse over a boxplot. Finally, on the bottom right, an interactive time series graph and associated interactive heatmap for the turbidity data in the selected lake are displayed (fig 1, fig 2).
All dashboard graphics are zoomable (the lake map as well as the time series and heatmaps).
Comparing in-situ measurements with remote-sensing data
For those lakes for which in-situ turbidity and chlorophyll measurements are available, these are shown on the time series on top of the remote-sensing long-term data (fig 4). This is helpful to local users and stakeholders because they can compare the two data sources to get an idea of their agreement. Showing both data sources can also help users complete any gaps left in either dataset due to cloud cover (which may affect the remote-sensing data) or infrequent in-situ sampling (which is often the case in many lakes).
Where do the data come from?
The dashboard acknowledges all data sources. It uses remote-sensing information derived from lake water-quality products from the Copernicus Global Land Monitoring Service. The products are showing 10-day averages of TSI and turbidity. The in-situ data sources are as follows: the Swedish Environmental Protection Agency (Vänern), United Nations Environment Programme Global Environment Monitoring System for freshwater (GEMS/Water) (Volta), WaterInfo portal of the Monitoring Water Management State of the Land programme of the Dutch Ministry of Infrastructure and Water Management (Marker).