Rethinking Groundwater Pumping

Groundwater pumping in many places in the U.S. is done with no regard to its impacts on the surrounding environment. In most cases, groundwater is extracted in a binary manner, where the pump is turned on at a fixed rate while a tank or a reservoir is filled to its designed capacity. Therefore, the impacts of groundwater pumping on aspects like aquifer health and land subsidence are not considered at all. This past summer, I had the opportunity to look at an alternative data-driven approach to groundwater extraction. This method alone cannot resolve all issues associated with groundwater over-pumping, but it holds the potential to help the health of individual wells and the surrounding environment. Moreover, utilizing this approach at a larger scale might reduce the impacts of groundwater pumping at regional scales.

2D slice view of numerical simulation of groundwater pumping using ParFlow model. The boundary conditions, pumping rate and soil properties are all assigned artificially for the purpose of illustrating the formation of cone of depression in a fast simulation. The soil profiles under long over-extraction periods, depending on the situation, might be imposed to higher risks of land subsidence.

I have been researching and studying groundwater-land surface-atmosphere interactions over the past several years. I have utilized numerical models and machine learning algorithms to address research questions regarding urban hydrology and microclimatic conditions in Baltimore city where groundwater is shallow. When I was asked to investigate water systems in California, where groundwater is a big driver of agriculture and has been on a steady decline over the past century, I had to make some adjustments in my research approach. The golden state has been one of the largest agricultural producers in the whole nation and according to USDA’s Economic Research Service was the top producer in 2021¹. California’s agriculture relies heavily on groundwater during dry seasons. Due to recent droughts, scientists have sounded the alarm that groundwater depletion in Central Valley has accelerated dramatically. The main reason: agricultural over-pumping.

I first learned about the new alternative data-driven system of groundwater pumping through a family member working for Lamarr company. Lamarr is a new California startup developing technologies to modernize rural living. Knowing my focus on atmospheric-hydrologic science, my cousin shared with me some information about the meter.me project Lamarr has been working on for the past few years. She asked my opinion about the founders’ vision of a solution that could help alleviate drought impacts in California imposed by climate change and anthropogenic activities. Considering slow and large-scale characteristics of groundwater flow and changes, my first answer was a definite “No.” I was very hesitant that a well monitoring system installed for an individual well owner can help mitigate regional hydrologic impacts of groundwater pumping.

The conversation with my cousin about the project and the vision behind their project continued over several weeks. Moreover, she shared that the number of local farmers and ranchers who have signed up for meter.me monitoring system increased steadily over several months. The fact that their monitoring system had been implemented by several dozen well owners steadily was intriguing, so I finally connected with one of the co-founders, Ofer Tenenbaum. In our first meeting, Ofer shared the roadmap, the status of their project, and the five-year plan. He had a heuristic view, which he has proved to himself, through further studies of the impacts of long groundwater over-extraction on the health of an aquifer. The idea behind their patented technology is quite simple:

• Measure the water table.
• Measure the extraction rate.
• Calculate the groundwater recharge rate.
• Adjust the pumping schedule so as not to overdraw the well.

Figure 1. Lamarr team installing well monitoring instruments at a local farm in Napa Valley.

Knowing that the product could be useful and convenient for an individual well owner on a small farm, Ofer asked me if utilizing data-driven pumping has any potential benefits to reduce impacts on the local aquifers being pumped. My answer was again “no! unless it is employed and managed for the entire region.” I emphasized that the impact on the aquifer correlates directly to all these individual wells. Nevertheless, Ofer raised a good question: “if not for the entire aquifer, are there any immediate benefits at a local scale?” As a groundwater enthusiast with an interest in its conservation, I realized this was not a binary answer and that there were more nuances to it. The conversation steered an interesting quest for me to find out what are more localized effects of excessive pumping sessions. It took a quick literature review to find the four fundamental damages excessive pumping sessions can cause at a local scale:

1. Land subsidence²
2. Drying out a well³
3. Wasting higher energy rates to extract water²
4. Extracting harmful materials settled deeper in the aquifer (e.g., arsenic materials)⁴

During the summer, I helped the Lamarr team to run some tests on a 200 ft. deep Northern California well that was struggling to recover after each extraction (Figure 2). With a modified pumping strategy, we were able to see some positive impact, primarily in shortening the recovery time. We have many more tests to run on more wells over an extended period. However, reflecting upon our initial findings, I think there might be an intelligent pumping scenario that could alleviate some of these harmful impacts for an individual well owner. Of course, meter.me’s full potential requires deployment at a larger scale. Considering project’s benefits and convenience for an individual well, I am optimistic that homeowners, farmers, and ranchers will adopt the product that Ofer and his team are providing them. Lamarr’s project holds the potential to mitigate the widespread damage of groundwater over-pumping; deployed statewide, it could positively change the fate of California’s aquifers.

Figure 2. Illustration of numerous pumping test scenarios conducted by Lamarr team for evaluation of different pumping adjustment strategies. Visualization created by Andrew Emerick.

[1] USDA Economic Research Service. FAQ https://www.ers.usda.gov/faqs/

[2] USGS Water Science School. (June 5, 2018). Land Subsidence https://www.usgs.gov/special-topics/water-science-school/science/land-subsidence

[3] USGS Water Science School. (June 6, 2018). Groundwater Decline and Depletion https://www.usgs.gov/special-topics/water-science-school/science/groundwater-decline-and-depletion

[4] Smith, R., Knight, R. & Fendorf, S. Overpumping leads to California groundwater arsenic threat. Nat Commun 9, 2089 (2018). https://doi.org/10.1038/s41467-018-04475-3