In the heart of the U.S. Middle Atlantic region, a critical water source is facing significant challenges. The Potomac River, which serves as the primary drinking water supply for the Washington Metropolitan Area, is experiencing declining groundwater storage and streamflow, a trend that could have profound implications for regional water management and the energy sector. A recent study published in the journal *Environmental Research Communications* (translated from English as “Environmental Research Communications”) sheds light on these issues, offering insights that could shape future water management strategies.
Led by AJ Villaruel from Cornell University’s Department of Biological and Environmental Engineering and the Yale Conservation Scholars – Early Leadership Initiative, the research evaluates the utility of a newly available GRACE-based groundwater drought index (GDI) in supporting regional water supply management. GRACE, or the Gravity Recovery and Climate Experiment, is a satellite mission that provides critical data on Earth’s gravity field, which can be used to monitor changes in groundwater storage.
The study integrates 22 years of data, including GRACE-based groundwater storage (GWS) index estimates, river discharge (Q) measurements, and meteorological records, to investigate trends and predictive relationships between past GWS and streamflow. The findings are both alarming and enlightening. Seasonal Mann-Kendall trend analyses consistently identified severe declining trends in groundwater storage, as well as moderate declines in minimum streamflow and well water levels over the past 22 years.
“These declines are not just statistical anomalies; they represent a real and pressing challenge for water managers and the energy sector,” Villaruel explained. The energy sector, which relies heavily on consistent water supplies for cooling and other processes, could face significant disruptions if these trends continue.
The study also revealed significant time lags of 49 weeks to 22 months at weekly and monthly scales, depending on a region’s hydrogeomorphic characteristics. This means that changes in groundwater storage can have delayed but substantial impacts on river discharge, a relationship that is crucial for predictive modeling.
Vector Autoregressive (VAR) Models and Forecast Error Variance Decomposition (FEVD) highlighted the variable contributions of precipitation and temperature to the GWS-Q relationship, revealing a strong autoregressive component of Q. However, the research also showed that groundwater storage plays an important role, and this role increases with time.
“This interconnectedness of groundwater and surface water systems underscores the need for integrated predictive models to enhance water management strategies,” Villaruel noted. Incorporating GRACE-based seasonal groundwater forecasts into drought preparedness tools could bolster efforts to mitigate regional climate change impacts and improve the resilience of water resources in the Potomac River Basin.
While practical use of native GRACE data has been challenging for local, small-scale applications, this study demonstrates the utility of the GRACE-based GDI in forecasting low flows and informing regional water resource management decisions during droughts. The findings could have significant commercial impacts for the energy sector, which must plan for potential water shortages and develop strategies to mitigate risks.
As climate change continues to exacerbate extreme weather events, the need for robust water management strategies becomes ever more critical. This research not only highlights the challenges ahead but also offers a pathway forward, emphasizing the importance of integrated, data-driven approaches to water resource management. For the energy sector, this means staying informed about water availability trends and incorporating these insights into long-term planning and risk management strategies.