Quantifying temporal changes to groundwater levels in wells is a critical component of analyzing groundwater monitoring network information. Calculating water-level change over time may seem like a simple subtraction problem, but there are often important details, trends, and context that can be missed without appropriate tools for analysis and visualization. The Wellntel Analytics Dashboard includes a feature set – presented on the Change tab- that can simplify and enhance analysis and visualization.
The Change tab includes a set of tools to view the change in water levels in network wells from a starting date through time. Filtering tools are included that allow users to choose:
- which wells to include in charts,
- the period over which to average the data (e.g. day, week, month, year), and
- which readings to include in the period averages.
Wellntel sensor systems tag readings as either Timed or influenced by pumping, for example “Pump Start”, “Pump Stop”, “Pump Influenced” readings – you can read more about the tagging of pumping readings and pump influence information here and here.
On the Change tab, there is a chart of water-level change. This chart is oriented so that time is increasing from left to right on the x-axis, and so downwards from zero on the y-axis represents a decline in water levels over time, and upwards from zero on the y-axis represents recovery in water levels over time. Each point shown in the chart represents the difference between the average water level from the selected starting date to the average water level on that date. Note that the first set of data points shown on the chart are all zero. This is the start, or zero date.
There are a number of important features on the Change tab that are worth highlighting as they are often critical for accurate and robust analyses of groundwater-level change. These features are presented in order to both support a standard operating procedure when using this feature set, as well as to follow their location and layout on the dashboard.
Set the Date Range
To create a useful change chart, start with the important dates for the analysis. On the Change tab, the start date in the Date Range selection is the “zero date” or the day to which water levels looking forward will be compared. Select the start date so that you are viewing change in water level relative to that date. The end date determines the amount of time shown on the change chart.
The default start date is the first of the month one year ago. The default end date is the current date, but any date between the start date and the current date can be selected. To change the start or end date, click on the start date field and use the calendar tool to select a new date. The minimum date available is the earliest date data are available for any well in the network.
Filter to wells matching start date
For most groundwater monitoring networks, not all sensors are installed at the same time or on the same day. This means that there may be different minimum dates for every data set in the network. The “Filter to wells matching the start date” check box allows a user to quickly update the Change analysis to only include the wells that have data on the set start date forward. There do not need to be data through the set end date, but the date for which data were first collected needs to be at least the set start date.
This simple tool may be critical to a robust analysis of change. If attention is put on a specific period of time shown on the change chart, but some of the points during this period represent the change from a different starting date, then the comparison across the network will not accurately reflect the change from the selected zero date.
Normalize change to network average
In some network focused analyses, it may be important to understand the change in groundwater level relative to the network as a whole. The “Normalize to:” option enables a user to view the change in depth-to-water normalized, or divided by, the network average change. This normalization produces a visualization of how each well is changing relative to the network change, and can help identify wells that stand out as having the least, or most change over time.
Date Scroll Bar and Bar Chart
The change chart itself includes change over time, but it can be difficult to visually compare the relative magnitude of the change across the wells in the network between the start date and another specific date. To better visualize this time specific change, a date selection slider is included below the change chart. When a date is selected with the slider, the vertical dashed line on the change chart will move to the selected date and a bar chart below the slider will be populated with the values of the change in depth-to-water between the start date and the selected date producing a date specific comparison across the network.
Groundwater monitoring networks are four dimensional in that the collected information has dimensions in both space and time. Although a spatial visualization of change can be found on the Wellntel Analytics Dashboard Maps feature set, this feature on the Change tab enables a fast visualization of the temporal change in water levels.
To be truly useful and effective, a dashboard must be continually in development. The Wellntel Analytics Dashboard includes a number of very useful data and information visualization and analysis tools, as well as data aggregation and integration tools – but there is always room for new features, filters, options, charts and visuals. Let us know what you find useful on the Wellntel Analytics Dashboard and where it can be improved to better serve your network analysis and groundwater management needs. Reach out to the Wellntel Science and Information Manager, Joe Fillingham, PhD, by email at: jhfillingham@wellntel.com.
For more information about the Wellntel Analytics Dashboard see the Wellntel Operating Manual.
For technical support email techsupport@wellntel.com (include `Analytics Dashboard` in the subject line) or call 844-935-5426 between the hours of 8-5pm Central Time, Monday through Friday. If you reach us after hours, we will promptly respond the next weekday morning.