U.S. Department of the Interior U.S. Geological Survey Numerical-Simulation and Conjunctive- Management Models of the Hunt– Annaquatucket–Pettaquamscutt Stream-Aquifer System, Rhode Island By PAUL M. BARLOW and DAVID C. DICKERMAN U.S. Geological Survey Professional Paper 1636 Prepared in cooperation with the TOWN OF NORTH KINGSTOWN, RHODE ISLAND DEPARTMENT OF ENVIRONMENTAL MANAGEMENT, RHODE ISLAND WATER RESOURCES BOARD, and the RHODE ISLAND ECONOMIC DEVELOPMENT CORPORATION 2001 U.S. DEPARTMENT OF THE INTERIOR GALE A. NORTON, Secretary U.S. GEOLOGICAL SURVEY Charles G. Groat, Director For additional information write to: Copies of this report can be purchased from: Subdistrict Chief U.S. Geological Survey Massachusetts-Rhode Island District Branch of Information Services U.S. Geological Survey Box 25286 Water Resources Division Denver, CO 80225-0286 275 Promenade, Suite 150 Providence, RI 02908 or visit our web site at http://ma.water.usgs.gov Library of Congress Cataloging-in-Publication Data Barlow, Paul M. Numerical-simulation and conjunctive-management models of the Hunt–Annaquatucket–Pettaquamscutt stream-aquifer system, Rhode Island / by Paul M. Barlow and David C. Dickerman. p. cm. -- (U.S. Geological survey professional paper ; 1636) “Prepared in cooperation with the Town of North Kingstown; Rhode Island Department of Environmental Management; Rhode Island Water Resources Board; and the Rhode Island Economic Development Corporation.” Includes bibliographical references (p. ). ISBN 0-607-96440-5 1. Streamflow--Rhode Island--Hunt River--Mathematical models. 2. Streamflow--Rhode Island--Annaquatucket River--Mathematical models. 3. Streamflow--Rhode Island--Pettaquamscutt River--Mathematical models. I. Dickerman, David C. II. Rhode Island. Dept. of Environmental Management. III. Rhode Island. Water Resources Board. IV. Rhode Island Port Authority and Economic Development Corporation. V. Title. VI. Series. GB1207 .B37 2001 551.48’09745--dc21 2001023208 CONTENTS Abstract ................................................................................................................................................................................. 1 Introduction ........................................................................................................................................................................... 2 Purpose and Scope ...................................................................................................................................................... 3 Study Area................................................................................................................................................................... 5 Previous and Related Studies ...................................................................................................................................... 5 Acknowledgments....................................................................................................................................................... 7 Hunt–Annaquatucket–Pettaquamscutt Stream-Aquifer System ........................................................................................... 7 Hydrogeologic Units ................................................................................................................................................... 7 Water-Supply Wells..................................................................................................................................................... 8 Ground-Water Levels and Ground-Water Flow........................................................................................................... 9 Stream-Aquifer Interactions........................................................................................................................................ 10 Hydrologic Components and Budget .......................................................................................................................... 15 Inflow Components ........................................................................................................................................... 17 Outflow Components......................................................................................................................................... 20 Hydrologic Budget ............................................................................................................................................ 21 Steady-State Numerical Model ............................................................................................................................................. 22 Development................................................................................................................................................................ 22 Spatial Discretization ........................................................................................................................................ 22 Boundary Conditions and Stresses.................................................................................................................... 26 Hydraulic Conductivity ..................................................................................................................................... 29 Calibration and Sensitivity Analysis ................................................................................................................. 29 Hydrologic Budget ............................................................................................................................................ 31 Stream-Aquifer Interactions........................................................................................................................................ 32 Contributing Areas and Sources of Water to Supply Wells......................................................................................... 33 Transient Numerical Model................................................................................................................................................... 37 Development................................................................................................................................................................ 37 Temporal Discretization and Initial Conditions ................................................................................................ 37 Boundary Conditions and Stresses.................................................................................................................... 38 Storage Properties of Aquifer............................................................................................................................ 39 Calibration and Hydrologic Budget .................................................................................................................. 39 Stream-Aquifer Interactions........................................................................................................................................ 41 Conjunctive-Management Model.......................................................................................................................................... 43 Formulation of the Conjunctive-Management Model................................................................................................. 44 Response-Matrix Technique for Solution of the Conjunctive-Management Model ................................................... 47 Applications of the Model........................................................................................................................................... 49 Maintain Current Rates of Streamflow Depletion During July, August, and September.................................. 50 Decrease Current Rates of Streamflow Depletion in the Hunt River During July, August, and September, With Current Rates of Streamflow Depletion in the Annaquatucket and Pettaquamscutt Rivers ......................................................................................................................... 54 Maintain Current Rates of Streamflow Depletion in the Hunt River During July, August, and September, With Increased Rates of Streamflow Depletion Allowed in the Annaquatucket and Pettaquamscutt Rivers ......................................................................................................................... 55 Decrease Current Rates of Streamflow Depletion in the Hunt River During July, August, and September, With Increased Rates of Streamflow Depletion Allowed in the Annaquatucket and Pettaquamscutt Rivers ......................................................................................................................... 59 Summary and Conclusions.................................................................................................................................................... 61 References Cited ................................................................................................................................................................... 64 Contents III Appendix A: Water Levels at Observation Wells, 1995–96 .................................................................................................. 67 Appendix B: Streamflow at Partial-Record Sites, 1995–96 .................................................................................................. 73 Appendix C: Withdrawals from Public-Supply Wells, 1943–98..........................................................................................