Identifying hydrologic signatures associated with streamflow depletion caused by groundwater pumping

Abstract

Groundwater pumping can reduce streamflow in nearby waterways ('streamflow depletion'), a process which must be accounted for in integrated management of surface and groundwater resources. However, causal identification of streamflow depletion from hydrographs alone is challenging because pumping impacts are masked by other drivers of hydrologic variability. To identify potential indicators of streamflow depletion, we used synthetic hydrographs and an analytical streamflow depletion model to assess potential pumping impacts on specific hydrograph characteristics ('hydrologic signatures') for 215 streamgages spanning the conterminous United States (CONUS). We found that streamflow depletion commonly impacts signatures associated with seasonal and annual low flows and low flow recessions. The largest impacts occurred during dry years, suggesting streamflow depletion may be evident in dry years even where impacts are unmeasurable in wet years. Random forest models indicated that streamflow depletion could significantly impact Annual, Summer, and Fall signatures in most streams. Our finding that multiple hydrologic signatures are consistently responsive to streamflow depletion across CONUS suggests that the underlying hydrological processes linking pumping to streamflow reductions are consistent across diverse settings, information that will aid in identifying indicators of streamflow depletion from streamflow hydrographs.

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

“…While a variety of approaches to estimate environmental flow needs for aquatic ecosystems have been developed and proposed, these are not well-correlated with freshwater biodiversity (Mohan et al, 2022), suggesting that more information beyond just changes in water quantity is needed to link streamflow depletion to adverse ecological outcomes (Lapides et al, 2022;Yarnell et al, 2020). While recent studies have identified low-flow signatures as most sensitive to streamflow depletion across diverse hydrologic regions (Lapides et al, 2023), links between hydrologic change and ecological outcomes have predominantly been local (Liu et al, 2020;Perkin et al, 2017). Ultimately, the link between streamflow depletion and actual impacts remains poorly characterized, and further research is needed to link depletion-induced changes in water quantity to changes in water quality and social and ecological outcomes.…”