Streamflow Depletion by Wells—Understanding and Managing the Effects of Groundwater Pumping on Streamflow
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Groundwater Resources Program Streamflow Depletion by Wells—Understanding and Managing the Effects of Groundwater Pumping on Streamflow Circular 1376 U.S. Department of the Interior U.S. Geological Survey A B C D Cover. A, U.S. Geological Survey streamgage along the Watauga River near Sugar Grove, North Carolina. Photograph by J. Curtis Weaver, U.S. Geological Survey. B, Colorado River above Nortons Landing, Arizona. Photograph by Michael Collier. C, Circular irrigation system, Parshall, Colorado. Photograph by Michael Collier. D, Great Egret, Upper San Pedro Basin, Arizona. Photograph by Bob Herrmann. Background photograph Republican River below McCook, Nebraska. Photograph by Michael Collier. Streamflow Depletion by Wells—Understanding and Managing the Effects of Groundwater Pumping on Streamflow By Paul M. Barlow and Stanley A. Leake Photograph by Robert F. Breault, U.S. Geological Survey Photograph by Robert F. Wyoming Pond on the Wood River, Pawcatuck River Basin, Rhode Island. Groundwater Resources Program Circular 1376 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior KEN SALAZAR, Secretary U.S. Geological Survey Marcia K. McNutt, Director U.S. Geological Survey, Reston, Virginia: 2012 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, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this report is in the public domain, permission must be secured from the individual copyright owners to reproduce any copyrighted materials contained within this report. Suggested citation: Barlow, P.M., and Leake, S.A., 2012, Streamflow depletion by wells—Understanding and managing the effects of groundwater pumping on streamflow: U.S. Geological Survey Circular 1376, 84 p. (Also available at http://pubs.usgs.gov/circ/1376/. ) Library of Congress Cataloging-in-Publication Data Barlow, Paul M. Streamflow depletion by wells: understanding and managing the effects of groundwater pumping on streamflow / by Paul M. Barlow and Stanley A. Leake. p. cm. -- (Circular ; 1376) Understanding and managing the effects of groundwater pumping on streamflow Includes bibliographical references. ISBN 978-1-4113-3443-4 (alk. paper) 1. Streamflow. 2. Stream measurements. 3. Groundwater--Management. 4. Wells. I. Leake, S. A. II. Geological Survey (U.S.) III. Title. IV. Title: Understanding and managing the effects of groundwater pumping on streamflow. V. Series: U.S. Geological Survey circular ; 1376. GB1207.B373 2012 628.1’12--dc23 2012038485 iii Foreword Groundwater provides drinking water for millions of Americans and is the primary source of water to irrigate cropland in many of the Nation’s most productive agricultural regions. With- drawals in many aquifers throughout the United States have led to significant groundwater-level declines, resulting in growing concerns about sustainability and higher pumping costs. The U.S. Geological Survey’s (USGS) Groundwater Resources Program has been instrumental in docu- menting groundwater declines and in developing groundwater-flow models for use in sustain- ably managing withdrawals. Groundwater withdrawals also can lead to a reduction in streamflow, affecting both human uses and ecosystems. The first clear articulation of the effects of groundwater pumping on surface water was by the well-known USGS hydrologist C.V. Theis. In a paper published in 1940 entitled "The Source of Water Derived from Wells," Theis pointed out that pumped groundwater initially comes from reductions in aquifer storage. As pumping continues, the effects of groundwater withdrawals can spread to distant connected streams, lakes, and wetlands through decreased rates of discharge from the aquifer to these surface-water systems. In some settings, increased rates of aquifer recharge also occur in response to pumping, including recharge from the con- nected surface-water features. Associated with this decrease in groundwater discharge to surface waters is an increased rate of aquifer recharge. Pumping-induced increased inflow to and decreased outflow from an aquifer is now called "streamflow depletion" or "capture." Groundwater discharge is a significant component of streamflow, with groundwater contribut- ing as much as 90 percent of annual streamflow volume in some parts of the country. In order to effectively manage the entire water resource for multiple competing uses, hydrologists and resource managers must understand the effects (magnitude, timing, and locations) of ground- water pumping on rivers, streams, springs, wetlands, and groundwater-dependent vegetation. This circular, developed as part of the USGS Groundwater Resources Program, presents con- cepts relating to streamflow depletion, methods for quantifying depletion, and common mis- conceptions regarding depletion. Approaches for monitoring, understanding, and managing streamflow depletion also are described. The report is written for a wide audience interested in the development, management, and protection of the Nation's water resources. The Groundwater Resources Program provides objective scientific information and develops the interdisciplinary understanding necessary to assess and quantify the availability of the Nation's groundwater resources. Detailed assessments of regional aquifers have been completed in seven of the Nation’s major aquifers, with several additional assessments ongoing or planned. The research and understanding developed through this program for issues such as streamflow depletion can provide the Nation’s water-resource managers with the tools and information needed to manage this important natural resource. Jerad D. Bales Associate Director for Water (Acting) U.S. Geological Survey iv v Contents Foreword ........................................................................................................................................................iii Introduction.....................................................................................................................................................1 Characteristics of Groundwater Systems and Groundwater Interactions with Streamflow ............2 Streamflow Response to Groundwater Pumping ...................................................................................11 Time Response of Streamflow Depletion During Pumping ..........................................................11 Distribution of Streamflow Depletion Along Stream Reaches ....................................................21 Variable and Cyclic Pumping Effects ...............................................................................................26 Multiple Wells and Basinwide Analyses ........................................................................................29 Pumped Wells and Recharge Wells ................................................................................................33 Streamflow Depletion and Water Quality .......................................................................................35 Common Misconceptions about Streamflow Depletion .......................................................................39 Aquifer Recharge and Development of Water Resources ..........................................................39 Depletion and the Rates and Directions of Groundwater Flow ..................................................40 Depletion after Pumping Stops .........................................................................................................42 Effects of Confining Layers on Depletion ........................................................................................46 Approaches for Monitoring, Understanding, and Managing Streamflow Depletion by Wells .......50 Field Techniques .................................................................................................................................50 Analytical and Numerical Modeling ...............................................................................................54 Analytical Models of Streamflow Depletion by Wells ........................................................54 Numerical Models of Streamflow Depletion by Wells ........................................................60 Response Functions and Capture Maps ................................................................................66 Management of Streamflow Depletion ..........................................................................................73 Conclusions...................................................................................................................................................76 Acknowledgments .......................................................................................................................................78 References Cited..........................................................................................................................................78 Boxes A—Hydraulic Diffusivity ..................................................................................................................8 B—Ways to Express Streamflow Depletion ..............................................................................16