Critical Local Element Part 2 – Measurable Saturated Thickness

Figure 1

A fundamental reason for monitoring water levels in a well is to understand the groundwater resource available to support a home or community, a farm, or a business. The exploitable groundwater resource is directly related to the measurable saturated thickness of the aquifer.

Presenting an example from the Hill Country of Texas, the hydrograph (Figure 1) shows that, over a roughly four-week period, the water level elevation ranges from a low of about 787 ft to a high of about 854 ft AMSL. The low elevation levels are measured during pumping events and the high levels are measured during non-pumping periods.

The Wellntel sensor uniquely tags measurements that are related to pumping activity so that they can be filtered in ways important to data analysis. To better illuminate the short- and long-term trends in aquifer saturated thickness the pumping-tagged measurements can be identified (Figure 2) and then removed from the hydrograph (Figure 3).

Figure 2
Figure 3

This is accomplished in the Wellntel Analytics Dashboard by simply unselecting pumping-tagged measurements (Figure 4). If the pump is idle or the well is a dedicated monitoring well without a pump, the saturated thickness will be obvious with no pumping-tagged measurements to filter out.

Figure 4

With pumping-tagged measurements removed from the hydrograph, the changes in aquifer saturated thickness over this time period are more clear (Figure 5). Specifically the saturated thickness increased by about 10 ft over 17 days of the record, with a 5-day period responsible for about 6.5 ft of that increase. After the water level has reached its highest elevation, it has exhibited a slow decline.

Figure 5

Being able to identify and separate out water-level elevation measurements that are influenced by pumping activity is critical to evaluating fluctuations in the saturated thickness of an aquifer. As data collection continues over years and decades, local understanding of the dynamics of the groundwater resource increases – in particular the relation of aquifer saturated thickness to normal seasonal influences, longer weather trends, local extraction, and anthropogenic climate change. Integrating data from a network of wells completed in the same aquifer can provide regional insight into the same dynamics.

The next part in this series will present how the pumping-tagged measurements, uniquely collected by the Wellntel acoustic sensor, can be used to increase understanding of local aquifer characteristics.