Streamflow Depletion Caused by Groundwater Pumping: Fundamental Research Priorities for Management‐Relevant Science

Reductions in streamflow caused by groundwater pumping, known as “streamflow depletion,” link the hydrologic process of stream‐aquifer interactions to human modifications of the water cycle. Isolating the impacts of groundwater pumping on streamflow is challenging because other climate and human activities concurrently impact streamflow, making it difficult to separate individual drivers of hydrologic change. In addition, there can be lags between when pumping occurs and when streamflow is affected. However, accurate quantification of streamflow depletion is critical to integrated groundwater and surface water management decision making. Here, we highlight research priorities to help advance fundamental hydrologic science and better serve the decision‐making process. Key priorities include (a) linking streamflow depletion to decision‐relevant outcomes such as ecosystem function and water users to align with partner needs; (b) enhancing partner trust and applicability of streamflow depletion methods through benchmarking and coupled model development; and (c) improving links between streamflow depletion quantification and decision‐making processes. Catalyzing research efforts around the common goal of enhancing our streamflow depletion decision‐support capabilities will require disciplinary advances within the water science community and a commitment to transdisciplinary collaboration with diverse water‐connected disciplines, professions, governments, organizations, and communities. Plain Language Summary Pumping water from a well can reduce flow in surrounding streams, a phenomenon called “streamflow depletion.” It is important for water managers to know when, where, and how much streamflow depletion is occurring because it can affect the amount of water available for ecosystems and other water users. However, estimating streamflow depletion is challenging because weather and other factors affect streamflow, in addition to pumping. Here, we discuss important topics related to streamflow depletion that need further research. Most importantly, scientists need to move beyond estimating changes in flow caused by pumping, and also develop improved approaches to estimate the impacts of these streamflow changes on ecosystems and water users. Additionally, it will be important to develop improved tools for estimating streamflow depletion and linking those estimates to water management decisions. Making these advances will require basic scientific research and colla