Prepared in cooperation with the Rhode Island Department of Health Areas Contributing Recharge to Production Wells and Effects of Climate Change on the Groundwater System in the Chipuxet River and Chickasheen Brook Basins, Rhode Island Scientific Investigations Report 2014–5216 U.S. Department of the Interior U.S. Geological Survey Areas Contributing Recharge to Production Wells and Effects of Climate Change on the Groundwater System in the Chipuxet River and Chickasheen Brook Basins, Rhode Island By Paul J. Friesz and Janet R. Stone Prepared in cooperation with the Rhode Island Department of Health Scientific Investigations Report 2014–5216 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior SALLY JEWELL, Secretary U.S. Geological Survey Suzette M. Kimball, Acting Director U.S. Geological Survey, Reston, Virginia: 2014 For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment, visit http://www.usgs.gov/ or call 1–888–ASK–USGS. For an overview of USGS information products, including maps, imagery, and publications, visit http://www.usgs.gov/pubprod/. To order this and other USGS information products, visit http://store.usgs.gov/. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner. Suggested citation: Friesz, P.J., and Stone, J.R., 2014, Areas contributing recharge to production wells and effects of climate change on the groundwater system in the Chipuxet River and Chickasheen Brook Basins, Rhode Island: U.S. Geological Survey Scientific Investigations Report 2014–5216, 56 p., 1 pl., http://dx.doi.org/10.3133/sir20145216. ISSN 2328-0328 (online) iii Acknowledgments The authors especially thank Clayton Commons (Rhode Island Department of Health, Office of Drinking Water Quality), and Ernie Panciera (Rhode Island Department of Environmental Man- agement, Office of Water Resources), for their support of the study and suggestions. The authors appreciate the assistance of Robert Bozikowski (Water System Manager, University of Rhode Island) and Henry Meyer (Manager, Kingston Water District) for information concerning ground- water withdrawals. The authors thank Tim McCobb (U.S. Geological Survey [USGS]) for writing computer programs to facilitate the climate change analysis in this report. Finally, the authors also thank Jeff Barbaro, Dave Bjerklie, William Burton, Anna Glover, John Masterson, Rodney Sheets, and Jennifer Stanton, all of the USGS, for their helpful reviews of the report. v Contents Acknowledgments ........................................................................................................................................iii Abstract ...........................................................................................................................................................1 Introduction.....................................................................................................................................................2 Purpose and Scope ..............................................................................................................................4 Description of Study Area and Previous Investigations ................................................................4 Geology ............................................................................................................................................................7 Hydrology ......................................................................................................................................................11 Development of Steady-State and Transient Numerical Models ........................................................12 Steady-State Model ...........................................................................................................................12 Model Extent and Spatial Discretization ................................................................................12 Hydrologic Boundaries .............................................................................................................13 Recharge ............................................................................................................................15 Stream-Aquifer Interactions ...........................................................................................17 Water Withdrawals and Return Flow ............................................................................17 Hydraulic Properties .................................................................................................................17 Observation Data .......................................................................................................................18 Calibration ...................................................................................................................................19 Estimation of Model Parameters ....................................................................................19 Simulated Water Table and Water Budget ...................................................................23 Transient Model ..................................................................................................................................24 Time Discretization and Initial Conditions .............................................................................24 Recharge Rates and Water Withdrawals ..............................................................................24 Storage Properties ....................................................................................................................25 Calibration ...................................................................................................................................25 Simulation of Areas Contributing Recharge and Prediction Uncertainty Analysis ..........................27 Deterministic Areas Contributing Recharge ..................................................................................27 Probabilistic Areas Contributing Recharge ....................................................................................30 Effects of Climate Change on the Groundwater System .......................................................................35 General Circulation Models and Emission Scenarios ..................................................................35 Projected Changes in Local Climate ................................................................................................35 Projected Changes in Recharge, Actual Evapotranspiration, and Soil Moisture ....................38 Projected Changes in Groundwater Hydrology .............................................................................40 Base Flow ....................................................................................................................................40 Groundwater Levels ..................................................................................................................45 Areas Contributing Recharge ..................................................................................................47 Limitations of Analysis ................................................................................................................................49 Summary and Conclusions .........................................................................................................................49 References Cited..........................................................................................................................................52 vi Plate 1. Surficial materials map of the Chipuxet River and Chickasheen Brook Basins, Rhode Island Figures 1. Map showing generalized hydrogeology, production wells, selected U.S. Geological Survey long-term network streamgages and observation wells, and model extent in the Chipuxet River and Chickasheen Brook Basins, Rhode Island ......................................3 2. Map showing land uses in the Chipuxet River and Chickasheen Brook Basins, Rhode Island ..................................................................................................................................6 3. Diagrams showing cross sections A, A–A’, B, B–B ’, and C, C–C ’ in the Chipuxet River and Chickasheen Brook Basins, Rhode Island ........................................................................8 4. Map showing glacial lakes and retreatal ice-margin positions in the vicinity of the Chipuxet River and Chickasheen Brook Basins, Rhode Island .............................................9 5. Map showing groundwater-level observations, streamgages with continuous and partial records, and model stream cells in the Chipuxet River and Chickasheen Brook Basins, Rhode Island ......................................................................................................14 6. Map showing mean annual recharge from 1974 through 2003 in the Chipuxet River and Chickasheen Brook Basins, Rhode Island ......................................................................16 7. Graph showing composite scaled sensitivities for model parameters, Chipuxet River and Chickasheen Brook Basins, Rhode Island