By Herbert E. Johnston and David C. Dickerman Water-Resources
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HYDROLOGY, WATER QUALITY, AND GROUND-WATER-DEVELOPMENT ALTERNATIVES IN THE CHIPUXET GROUND-WATER RESERVOIR, RHODE ISLAND By Herbert E. Johnston and David C. Dickerman U.S. GEOLOGICAL SURVEY Water-Resources Investigations Report 84-4254 Prepared in cooperation with the Rhode Island Water Resources Board Providence, Rhode Island 1985 HYDROLOGY, WATER QUALITY, AND GROUND-WATER-DEVELOPMENT ALTERNATIVES IN THE CHIPUXET GROUND-WATER RESERVOIR, RHODE ISLAND By Herbert E. Johnston and David C. Dickerman U.S. GEOLOGICAL SURVEY Water-Resources Investigations Report 84-4254 Prepared in cooperation with the Rhode Island Water Resources Board Providence, Rhode Island 1985 UNITED STATES DEPARTMENT OF THE INTERIOR WILLIAM P. CLARK f Secretary GEOLOGICAL SURVEY Dallas L. Peck, Director For additional information Copies of this report can write to: be purchased from: Chief, Rhode Island Office Open-File Services Section U.S. Geological Survey Western Distribution Branch Room 237 U.S. Geological Survey John 0. Pastore Federal Bldg. Box 25425, Federal Center Providence, RI 02903 Denver, CO 80225 (Telephone: (401) 528-5135) (Telephone: (308) 234-5888) CONTENTS Page Abstract 1 Introduction 3 Purpose and scope 7 Previous studies 7 Acknowledgments 8 Water use 8 Hydrology 10 Streamflow 10 Duration of streamflow 12 Frequency and duration of low flow 12 Components of streamflow 16 Relation of runoff to geology and topography 17 Hydrogeology 20 Bedrock 26 Till 27 Stratified drift 28 Storage coefficient and specific yield 29 Hydraulic conductivity and transmissivity 30 Yield of wells 36 Natural recharge and discharge 44 Induced recharge 47 Potential yield of ground-water reservoir 50 Quality of water 52 Source of constituents in ground water and surface water 52 Precipitation 56 Streams 56 Ground water 60 Iron and manganese 60 Nitrate 65 Ground-water-development alternatives 71 Background and description of digital model 71 Model assumptions 73 Boundary conditions 75 Calibration procedure 75 Steady-state model 77 Transient model 80 Simulation of ground-water withdrawal schemes 82 Effect of withdrawals on water levels 82 Effect of withdrawals on streamflow 88 Summary and conclusions 93 References 96 iii ILLUSTRATIONS Plate 1. Geohydrologic maps of the Chipuxet ground-water reservoir area, Rhode Island In pocket Page Figure 1. Map showing location of Chipuxet ground-water reservoir and other major ground-water reservoirs in the Pawcatuck River basin and generalized surficial geology 4 2. Map showing location of continuous-record stream-gaging stations and miscellaneous discharge measurement sites and generalized surficial geology 11 3. Graph showing flow-duration curves for the Pawcatuck River at Wood River Junction and the Chipuxet River at West Kingston, 1942- 1978 water years 13 4. Map showing locations of five generalized geo logic sections of the Chipuxet River valley- 21 5. Geologic section (A-A1 ) of the Chipuxet River valley showing the lithologic heterogeneity of the complexly interbedded aquifer system- 22 6. Generalized geologic section (B-B 1 ) of the Chipuxet River valley at the Hundred Acre Pond site 23 7. Generalized geologic section (C-C 1 ) of the Chipuxet River valley at the Thirty Acre Pond and Fairgrounds sites 24 8. Generalized geologic section (D-D 1 ) of the Chipuxet River valley near the Liberty Lane site 25 9a. Maps showing hydraulic conductivity of stratified drift, estimated from lithologic logs, in the intervals 120 to 50 and 50 to 0 feet above sea level 34 9b. Maps showing hydraulic conductivity of stratified drift, estimated from lithologic logs, in the intervals 0 to 50 and 50 to 100 feet below sea level 35 10. Map showing location of aquifer-test sites in the Chipuxet River ground-water reservoir 37 iv ILLUSTRATIONS (Continued) Page 11. Graph showing the potential yield of a large-diameter well screened in the lower 30 percent of the saturated zone 40 12. Map showing maximum yields of large-diameter wells tested in the stratified-drift aquifer 42 13. Graph of simulated withdrawals from wells in the vicinity of Thirty Acre Pond showing how percentage of pumpage induced from a recharge source varies with pumping rate duration of pumping r and distance from a from a recharge source 49 14. Relation of discharger temperature r and specific conductance of the Chipuxet River at West Kingston 58 15. Variation in quality of water with depth in Thirty Acre Pond on August 8 r 1955 59 16. (A) Map of Thirty Acre Pond showing location of University of Rhode Island supply wells; (B) section showing depths of well screens compared to pond depth; and (C) graphs showing changes in manganese content with time in water pumped from supply wells 62 17. Map showing ground-water flow pattern and area of river and pond infiltration estimated for average pumping and drawdown conditions in the University of Rhode Island well field r October 1974-December 1975 64 18. Graph showing variation in the concentration of nitrate in ground water at the University of Rhode Island well field at Thirty Acre Pond from 1954-57 67 19. Map showing location of wells in and adjacent to a potato field at Liberty Lane that yielded water contaminated by nitrate in 1970-73 69 20. Map showing finite-difference grid and boundary conditions for Chipuxet aquifer model 72 ILLUSTRATIONS (Continued) Page 21. Map showing comparison of water table observed August 1959 and simulated steady-state water table 76 22-26. Graphs showing: 22. Predicted and measured increases in low stream flow caused by ground-water runoff to the Chipuxet River from the area modeled 78 23. Water-table altitudes predicted by the calibrated Chipuxet digital model are more sensitive to decreases (ratios < 1.0) than to increases (ratios > 1.0) in aquifer transmissi- vity. 7 9 24. Water-table altitudes predicted by the calibrated Chipuxet digital model are sensitive to both increases and decreases (ratios > 1.0 or < 1.0) in streambed hydraulic conductivity 79 25. Comparison of observed and simulated steady-state water levels in observa tion well SNW 6 81 26. Simulated and observed water levels at observation well SNW 6 during the 1959 water year 81 27. Map showing location of public supply wells and proposed public supply wells within the model area 84 28. Graph showing comparison of steady-state and transient simulations for increase in ground-water runoff under pumping scheme I 85 29. Map showing simulated water-table drawdown caused by pumping well scheme I for 180 days 86 30. Map showing simulated water-table drawdown caused by pumping well scheme V for 180 days 87 VI ILLUSTRATIONS (Continued) Page 31-33. Graphs showing: 31. Simulated effect of pumping schemes I and V on increase in ground-water runoff in the Chipuxet River for a low-flow condition similar to that of September 1959 89 32. Simulated effect of pumping schemes I and V on increase in ground-water runoff in the Chipuxet River for a high-flow condition similar to that of March 1959 90 33. Simulated effect of ground-water with drawal on increase in ground-water runoff in the Chipuxet River at West Kingston for streamflow conditions similar to those in water year 1959 92 TABLES Page Table 1. Estimated average daily water use in the Chipuxet River and Chickasheen Brook drainage basins in 1979 9 2. Average duration of lowest mean flows of streams in the Pawcatuck River basin and average percentage of time in which stream- flow equaled or exceeded the lowest mean flow for indicated recurrence interval 14 3. Estimated low-flow discharge at selected recur rence intervals for the stream-gaging sta tion on the Chipuxet River at West Kingston under natural (nonpumping) streamflow conditions 15 4. Estimated long-term (1941-78) average annual ground-water runoff from areas underlain by till and stratified-drift in the Pawcatuck River basin upstream of Wood River Junction 19 5. Specific yield of sediments from the upper Pawcatuck River basin 31 VI1 TABLES (Continued) Page 6. Values of hydraulic conductivity used to estimate transmissivity from lithologic logs in the Chipuxet River basin ground-water reservoir 32 7. Example showing how transmissivity and average hydraulic conductivity are estimated from the lithologic log of a hypothetical well 33 8. Well construction and pump-test data for pumping well tested in the Chipuxet River stratif ied-drift aquifer 38 9. Summary of hydraulic properties determined from aquifer tests for the stratified-drift aquifer in the Chipuxet River basin 39 10. Potential yield of large-diameter wells at selected sites in the Chipuxet ground-water reservoir 43 11. Monthly ground-water budget for the Chipuxet River basin, 1959 water year 46 12. Summary of chemical and physical properties of surface water and ground water in the Chipuxet ground-water reservoir area 53 13. Source and significance of common constituents of water 54 14. Nitrate in well water at the Liberty Lane aquifer-test site 70 15. Alternative schemes for developing 3 million gallons per day from the Chipuxet ground-water reservoir 83 16. Simulated drawdowns in wells after being pumped continuously for 180 days at rates listed in table 15 88 Vlll CONVERSION FACTORS For use of those readers who may prefer to use metric (SI) units rather than inch-pound units, the conversion factors for terms used in this report are listed below. Multiply inch-pound unit By To obtain metric (SI) unit Length inch (in) 25.40 millimeter (mm) foot (ft) 0.3048 meter (m) mile (mi) 1.609 kilometer (km) Area acre 0.4047 hectare (ha) square mile (mi2 ) 2.590 square kilometer (km2