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Streamflow Augmentation at Fosters Brook, Long Island, New York A Hydraulic Feasibility Study

United States Geological SurveyWater-Supply Paper 2208

Prepared in cooperation with the Nassau County Depart ment of Public Works and the Suffolk County Depart ment of Health Services

Streamflow Augmentation at Fosters Brook, Long Island, New York a Hydraulic Feasibility Study

By KEITH R. PRINCE

Prepared in cooperation with the Nassau County Department of Public Works and the Suffolk County Department of Health Services

U.S. GEOLOGICAL SURVEY WATER-SUPPLY PAPER 2208

DEPARTMENT OF THE INTERIOR

WILLIAM P. CLARK, Secretary

U.S. GEOLOGICAL SURVEY

Dallas L. Peck, Director

UNITED STATES GOVERNMENT PRINTING OFFICE: 1984

For sale by Distribution Branch Text Products Section U.S. Geological Survey 604 South Pickett Street Alexandria, Virginia 22304

Library of Congress Cataloging in Publication Data

Prince, Keith R.Streamflow augmentation at Fosters Brook, Long Island, NewYork.

(Water-supply paper ; 2208)Bibliography: p.Supt. of Docs, no.: I 19.13:22081. Rivers New York (State) Long Island Regulation.

I. Nassau County (N.Y.). Dept. of Public Works.II. Suffolk County (N.Y.). Dept. of Health Services.III. Title. IV. Series: Geological Survey water-supply paper ; 2208. V. Fosters Brook, Long Island, New York.

TC424.N7P74 627'.12 82-600115 AACR2

CONTENTSAbstract 1 Introduction 1

Purpose and scope 2 Acknowledgments 2

Location and description of area studied 2 Test design and procedures 4

Surface water 5 Flow in the unsaturated zone 6 Ground water 7

Results of streamflow augmentation 8 Surface-water response 8

Water temperature 8 Wetted channel length 10 Duration of wetting 11

Relationship of soil moisture to infiltration rate 13 Ground-water response 15

Factors affecting seepage rates 16 Streambed composition 17 Soil moisture 17 Temperature 20 Other factors 22

Algae 22Chemical reactions , 22 Impoundments 23

Analysis 23Analytical solution 23 Numerical model 24

Summary and conclusions 30 References cited 31 Appendix Water levels in wells at Fosters Brook, Nassau County, N.Y.,

August-December 1979 32 Conversion factors and abbreviations 43

FIGURES

1-2. Maps showing location of:1. Fosters Brook, Nassau County, N.Y. 22. Reach studied on Fosters Brook 3

3. Generalized geologic cross section of Long Island 54. Map showing location of observation wells, discharge-measurement sites,

neutron-logger access holes, and water-quality sampling sites 65. Relative position of the streambed, the unsaturated zone, the observation-

well screens, and the water-table altitude on November 30, 1979, just before streamflow augmentation, and on December 12, 1979, after 13 days of flow at 1.00 ft3/s 7

Contents III

6-8. Graphs showing:6. Linear regression of stream discharge at selected sites 107. Wetted stream length in relation to the augmentation rate and

lines of best fit as calculated by least-squares regression, November 30-December 26, 1979 12

8. Relationship between stream length and discharge after stabiliza tion, December 1979 13

9. Soil-moisture logs showing moisture content of unsaturated zone beneathstream channel 14

10-14. Graphs showing:10. Water-level measurements obtained in three wells with continuous

recorders during a streamflow augmentation test, November 30- December 26, 1979 16

11. Grain-size distribution of streambed sediment in Fosters Brook 20

12. Average soil moisture beneath streambed at neutron-logger access hole 1, November 30-December 31, 1979 21

13. Five-day moving average of mean daily air temperature at Mineola, N.Y., November 30-December 30, 1979 22

14. Observed water-level change in well N 9624 in comparison with change predicted by Glover's solution for a hypothetical well similarly located 25

15. Diagram showing Fosters Brook model grid (areal view) 2616. Graph comparing observed water-level change in well N 9624, 45 ft from

the center of the stream, with change simulated by a three-dimensional numerical model for a well similarly located 27

17. Map showing net increase in ground-water levels near Fosters Brook after 27 days of streamflow augmentation, as simulated by a three-dimensional numerical model 28

TABLES

1. Characteristics of major hydrogeologic units of the ground-water reservoir underlying Long Island, N.Y. 4

2. Stream discharge at four sites on Fosters Brook 83. Infiltration rates calculated from linear regression for five stream reaches at

Fosters Brook in December 1979 124. Grain-size distribution analysis of streambed samples at Fosters Brook,

Nassau County, N.Y., December 1979 185. Chemical quality of water in Fosters Brook during flow augmentation,

December 19, 1979 23

IV Contents

Streamflow Augmentation atFosters Brook, Long Island, New York-A Hydraulic Feasibility Study

By Keith R. Prince

Abstract

A 27-day streamflow augmentation test was con ducted in December 1979 at Fosters Brook, near the south shore of Long Island, to investigate the hydraulic feasibility of pumping ground water to supply flow to an ephemeral stream during dry periods.

Measurements of soil moisture in the unsaturated zone beneath the streambed indicate that infiltration rate and soil-moisture content are interrelated. Initial infiltra tion was measured with a neutron logger; the wetting front traversed the unsaturated zone at an average of 11.2 inches per hour and reached the water table in 5.5 hours. Soil moisture in the unsaturated zone ranged from 20 percent at the start of the test to nearly 41 per cent, nearly the saturation point, 20 days later.

Stream discharge was measured at four sites along the stream channel, and the augmentation rate was mon itored continuously at the starting point. Infiltration rates increased steadily in all reaches during the first 12 days of the test, but from the 12th to the 20th day, when dis charge was increased by 50 percent, infiltration rates de creased along the two upstream reaches but continued to increase along the three downstream reaches. Infiltra tion rates remained constant from days 20 through 26.

During the first 24 hours of the test, the stream reached a maximum length of 2,050 feet, but after 13 days, it had shortened to 1,300 feet as a result of seepage losses. The relationship between discharge and stream length was linear within the range of discharge investi gated (0.54-1.63 cubic feet per second).

Ground-water levels rose in response to flow au gmentation and reached a maximum rise of about 6.5 feet in a well situated 14 feet from the center of the streambed and 225 feet downstream from the start of the flow. Measured water-level response was compared to levels predicted by a one-dimensional analytical model and a three-dimensional mathematical model; results in dicate that ground-water response is determined princi pally by streambed characteristics and soil-moisture con tent in the unsaturated zone.

Variations in water temperature and in streambed composition had significant effects upon infiltration

rates. Changes in water temperature, amount of vegeta tion, soil-moisture content, and stream stage, combined with local variations in streambed permeability and aquifer conductivity, make accurate prediction of seep age rates virtually impossible at present. Data from this study suggest that site-specific investigations are neces sary wherever streamflow augmentation is planned.

INTRODUCTION

The continued rapid population growth on Long Is land since the end of World War II has caused concern among the island's planners and water managers over the continued availability of an adequate supply of potable water. Because all freshwater for domestic and industrial use in the central and eastern part of the island (Nassau and Suffolk Counties) (fig. 1) is obtained from the ground-water reservoir, the purity of this resource should be safeguarded. In an effort to minimize contamination of ground water by septic waste, sanitary-sewer systems have been constructed in parts of both counties and are planned for most of the remaining areas.

Before construction of sanitary sewers, waste water was returned to the shallow aquifer through cesspools and septic tanks and thereby caused little net draft on the ground-water system. However, the large-scale implemen tation of sewers that carry many millions of gallons of wastewater per day to treatment plants and the ocean has caused a significant loss of recharge to the aquifer system. In southwestern Nassau County, where sewers began op eration in 1952 and became fully operational by 1964, water levels and streamflow have declined markedly (Franke, 1968; Garber and Sulam, 1976; Pluhowski and Spinello, 1978). An analog model used by the U.S. Geological Survey to simulate the long-term local and re gional effects of sewerage indicates that, after 20 years of sewer operation, the water table may decline as much as 20 ft in east-central Nassau County and that streamflow on

Introduction

\ CONNECTICUT

NEW JERSEY

0 5 10 15 20 25 MILES

I I0 5 10 15 20 25 30 35 KILOMETERS

Figure 1. Location of Fosters Brook, Nassau County, N.Y.

southern Long Island will be reduced, on the average, to approximately 40 percent of its 1975 volume (Kimmel and others, 1977).

Decreased water levels and reductions in streamfiow will reduce the amount of freshwater discharged through streams to the south-shore bays, which in turn could cause an increase in bay salinity and reduce the productivity of Long Island's large shellfish industry. Furthermore, the likelihood that the upper reaches of some streams may be come permanently dry will have detrimental effects on the aesthetic and recreational value of some of the island's wetlands and parks and on its wildlife. These issues have created a need to investigate means to offset the undesira ble effects of a lowered water table. One of several methods that have been proposed is streamfiow augmenta tion with pumped ground water or highly treated wastewater.

Purpose and Scope

The effects of sanitary sewers on Long Island's hydrologic environment have been well documented. Several approaches to minimize these effects have been suggested, one of which is streamfiow augmentation, whereby water pumped from the ground-water reservoir or, if available, highly treated wastewater (reclaimed water) is discharged into a dry-stream reach to provide streamfiow.

The purpose of this report is to describe a study of the hydrologic feasibility of using pumped ground water to augment streamfiow in a Nassau County stream that has become dry as a result of lowered ground-water levels. The report investigates the relationship between induced

flow and (1) stream length, (2) infiltration rates, (3) ground-water levels, (4) soil moisture in the unsaturated zone during recharge, and (5) grain-size distribution of streambed sediment. In addition, results of analytical com putations and computer simulation are compared with field observations to reveal the major factors that control infilt ration rate and to help delineate their complex relation ship. The testing period covered 27 days from November 30 to December 26, 1979. Augmentation was conducted at three different rates to investigate the hydrologic pro cesses under a variety of stress conditions. Water was pro vided at a constant rate of 1.00 ft3/s during the first 13 days, 1.64 ft3/s during the next 8 days, and 0.54 ft3/s dur ing the last 6 days.

Acknowledgments

The author is indebted to Michael Fender and his staff at the Nassau County Department of Public Works for assistance in site selection and operations, to the Franklin Square Water District for supplying water during a part of the flow augmentation test, and to R. E. Wright Associates for support in field operations.

LOCATION AND DESCRIPTION OF AREA STUDIED

The streamfiow augmentation test was conducted at Fosters Brook, an ephemeral stream near Franklin Square, southwest Nassau County (fig. 2). The area is suburban and surrounded by moderately to densely grouped single- family houses.

Streamfiow Augmentation at Fosters Brook, New York

73°50' 40' 35' 73°30'

40°55'

40°30'

0' 1 I 3 4 5; 6 7 KILOMETERS

Figure 2. Location of reach studied on Fosters Brook.

Location and Description of Area Studied

Franklin Square and nearby communities have had sanitary sewers since the early 1960's so that the local hydrologic regime exemplifies conditions that could prevail elsewhere after sewers have been in operation for several years. Fosters Brook was a perennial stream before the in stallation of sanitary sewers in the area but has since be come dry over most of its length as a consequence of the lowered ground-water levels. Only during storms does the stream flow, and this flow consists almost entirely of di rect runoff that enters the stream channel through storm drains from paved areas such as streets and parking lots.

The hydrogeology of Long Island has been de scribed in several reports such as those by Cohen and others (1968) and McClymonds and Franke (1972); a de tailed description of southwest Nassau County is given in Perlmutter and Geraghty (1963).

The lithology and water-bearing characteristics of the major hydrologic units beneath southwestern Nassau County are listed in table 1. The hydrologic system of the area can be characterized as an unconsolidated, south ward-dipping, wedge-shaped unit containing three major aquifers and several confining units, as shown in figure 3. The deepest unit is crystalline bedrock, which yields in significant amounts of water and is therefore regarded as the bottom of the ground-water reservoir. Overlying the

bedrock is the Lloyd aquifer, a secondary source of pub lic-supply water. Above the Lloyd aquifer is the Raritan clay, a confining unit that separates the Lloyd from the primary source of water, the Magothy aquifer. The Magothy aquifer, which includes scattered clay lenses that create local semiconfining units, is the major source of public-supply water on the island. Overlying the Magothy aquifer is the upper glacial (water-table) aquifer composed of glacial outwash. As the uppermost water-bearing unit, it is the aquifer of concern in this study.

In southwest Nassau County, the upper glacial aquifer consists mainly of highly permeable outwash de posits and contains large quantities of water. Porosity of the deposits typically ranges from 30 to 40 percent, and individual wells have been reported to have a specific ca pacity as high as 109 gal/min/ft (Perlmutter and Geraghty, 1963).

TEST DESIGN AND PROCEDURES

To determine the effectiveness of supplementing streamflow with pumped ground water, a detailed data- collection system was devised to provide records on sur face-water discharge, ground-water levels, soil moisture,

Table 1. Characteristics of major hydrogeologic units of the ground-water reservoir underlying Long Island, N.Y.[Modified from Cohen and others, 1968]

Unit Geologic nameApproximate

maximum thickness (ft) Water-bearing character

Upper glacial aquifer -

Gardiners Clay

Upper Pleistocene deposits

Gardiners Clay

Jameco aquifer Jameco Gravel

Magothy aquifer Magothy (?) Formation

Raritan clay

Lloyd aquifer-

Clay member of the Raritan Formation

Lloyd Sand Member of the Raritan Formation

400

150

200

1000

300

300

Mainly sand and gravel of moderate to high per meability; also includes clayey till of low perme ability. 1

Clay, silty clay, and some fine sand of low to very low permeability.

Mainly medium to coarse sand of moderate to high permeability.

Coarse to fine sand of moderate permeability; locally contains gravel of high permeability and abundant silt and clay of low to very low perme ability.

day of very low permeability; some silt and fine sand of low permeability.

Sand and gravel of moderate permeability; some clayey material of low permeability.

'Permeability denotes how readily water can move through porous material.

4 Streamflow Augmentation at Fosters Brook, New York

NORTH03-C SOUTH

ATLANTIC OCEANr~,~»*-~i .^^T- i ' ., > -,«.T.r»---u

URperg I a c i a Tap u i f e rfyTVrr^,,

Upper glacial and undifferentiated deposits

EXPLANATION

Clay Sandy clay, clayey sand, and silt

Sand

Gravel Consolidated rock

Figure 3. Generalized geologic cross section of Long Island (from McClymonds and Franke, 1972, p. 54).

water quality, and streambed composition. Streamflow was measured periodically throughout the test at four sites, and water-level measurements were made concur rently to determine the relationship between Streamflow and ground water.

Surface Water

Most of the water for stream augmentation was pumped from a shallow well tapping the upper glacial aquifer about 2,000 ft north of the study site, far enough to avoid significant influence on ground-water movement near the stream. The supply well was screened from 55 to 73 ft below land surface. Additional water was obtained from Franklin Square Water District near the pump site. The water was transmitted through underground storm drains into Fosters Brook. Discharge was measured both at the pump site and at the storm-drain discharge; com parison of values indicated no measurable loss of water through pipe leakage.

Three rates of Streamflow augmentation were sched uled to be used during the test: 0.50, 1.00, and 1.50 ft3/s. Because of difficulty in regulating the pumping well, the actual values of augmentation were 0.54, 1.00, and 1.63 ft3/s. Furthermore, because the capacity of the supply well was approximately. 1.00 ft3/s, an additional 0.64 ft3/s was obtained from the fire hydrant near the pump site. As the water for augmentation exited the storm drain, it flowed through a 9-in wide by 15-in high Parshall flume. This, combined with an analog stage recorder, enabled continu ous monitoring of the rate of augmentation. From there the water flowed over a 50-ft concrete apron and into the Fosters Brook stream channel (fig. 4).

During the test, Streamflow and stage were mea sured at regular intervals at four additional sites spaced 300, 678, 1,159, and 1,929 ft from the start of flow (fig. 4). Stage was measured with a staff gage; discharge was measured with current meters and wading rods. At the site farthest downstream (which varied, depending on length of stream at the time of measurement), discharge was measured with a portable 3-in wide Parshall flume

Test Design and Procedures

40°42'

41 '45"

40°41'30"

40'15"

I

73°40'

9637

9638

.9639 ,9640,9641 X9642

NU-3J 9632JL9633

D,

i 9634

Concrete apron

9619

50

9617

9620

9624

200 FEET

50 METERS

EXPLANATION

9617 Observation well# 9624 Observation well with

continuous recorder O NU-1 Neutron-logger access hole A (D Gaging station

A Stream reachJ9636

0 100 200 300 400 500 1000 FEET

100 200 300 METERS

Figure 4. Location of observation wells, discharge-measurement sites, neutron-logger access holes, and water-quality sam pling sites. (The location of area is shown in fig. 2.)

whenever flow was low enough to avoid creating an artifi- cally high stage. (If stage were raised by the flume, infilt ration rates in the area would be altered by the higher hy draulic head.)

Because the length of a wetted channel of constant width is proportional to the average rate of infiltration of stream water into the aquifer, the length of wetted channel was measured at least once a day during the test and more often when the channel length was changing rapidly.

Flow in the Unsaturated Zone

When flow augmentation was begun, the water table was between 5 and 10 ft beneath the streambed throughout the area. As water seeps through a streambed and moves downward to the water table, it flows through a zone of unsaturated material that to some extent determines the rate of seepage through the streambed. (The relative posi tion of the streambed, the unsaturated zone, and the water

Streamflow Augmentation at Fosters Brook, New York

tables is depicted in fig. 5.) Analysis of flow through the unsaturated zone indicates that both moisture content and hydraulic conductivity of the material are functions of pressure head. (Soil moisture is held between the soil grains by surface tension; higher moisture content causes lower surface tension and less negative pressure head, so the reduced tension allows water to move between the soil grains more freely. Thus the greater the pressure head, the faster will be the infiltration through the unsaturated zone.)

Because soil-moisture content plays an important role in the rate of infiltration through the unsaturated zone, a soil-moisture measurement system was incorpo rated into the data-collection network. Soil moisture was measured directly beneath the streambed at sites 210, 325, and 1,465 ft downstream from the start of flow (fig. 4) with a neutron logger that provided a graph of soil mois ture with depth. (Neutron loggers measure soil moisture with a probe containing a radiation source that produces fast neutrons and detectors that are sensitive to slow neut rons. As the fast neutrons from the probe radiate out into the soil and become scattered and slowed, some are re flected back to the detectors. Because the quantity of neut rons that become slowed depends primarily upon the moisture content of the soil, the rate at which "slow neut rons" reach the detectors can be interpreted as the concen

tration of soil moisture. Examples of soil-moisture logs are given in fig. 9 and are discussed in the "Soil Mois ture" section.)

Ground Water

Streamflow augmentation where the water table is below streambed altitude is "strip recharge," which in time produces a rise in ground-water level beneath the streambed. This rise, or mound, will increase in height until a new equilibrium is reached at which the rate of ground-water movement away from the mound is equal to the rate of recharge to the mound. The height and areal extent of ground-water mounding was important to this study for two main reasons: (1) If the mound were to rise high enough it could cause local flooding in adjacent low- lying areas and in basements of buildings constructed since the stream originally went dry, and (2) the data pro vided a basis for use in analytical and mathematical mod els to predict the effects of a variety of stresses on infiltra tion rates.

The ground-water data-collection network consisted of 26 wells screened between 5 and 10 ft below the re gional water table. (Locations are shown in fig. 4.) Three wells (N 9622, N 9632, and N 9636) were drilled in the

O 50

Om An <40

§30 I-

Water table on December 12, 1979, after 12 days of flow augmentation

Water table onNovember 30, 1979, before augmentation

0 10I I I I I I I I I

20 30 FEET

012345671 T8 9 METERS

Figure 5. Relative position of the streambed, the unsaturated zone, the observation-well screens, and the water-table alti tude on November 30, 1979, just before streamflow augmentation, and on December 12, 1979, after 13 days of flow at 1.00 ft3 /s. (The location of section is shown in fig. 4.)

Test Design and Procedures

center of the stream channel to monitor the water table be neath the infiltration area and to determine whether the water table would rise and intersect the stream channel during the test.

All wells were measured by the wetted tape method at regular intervals concurrently with stream-discharge measurements. In addition, three wells (N 9622, at the streambed; N 9624, 45 ft east of N 9622; and N 9642, 2,000 ft east of the start of flow) were equipped with con tinuous recorders to allow continuous monitoring of water levels. Well N 9642 was used to monitor regional trends beyond the affected areas and to provide a baseline for data analysis.

RESULTS OF STREAMFLOW AUGMENTATION

Surface-Water Response

Stream-discharge measurements were obtained to determine surface-water losses between gaging stations so that the areal and temporal variation in infiltration rates could be estimated, and linear regression analyses of the discharge measurements were done to determine trends. (Discharge values are listed in table 2.) Figure 6 depicts linear regression plots of discharge at each measurement site during augmentation rates of 1.00 and 1.63 ft3/s. Re gression analysis was not necessary for the 0.54 ft3/s rate because flow was measurable only at site 1, where the Parshall flume provided high accuracy and resulted in rel atively little scatter in the data.

During the first 13 days of the test, when augmenta tion rate was constant at 1.0 ft3/s, stream discharge at each site decreased through time, as was evidenced by the downward slope of the regression line in figure 6A. This indicates that infiltration rates were increasing with time and that discharge was decreasing by a corresponding amount in each successive reach. The initial rapid increase in infiltration rates resulted partly from the increase in soil-moisture content and the corresponding increase in hydraulic conductivity in the unsaturated zone. The chan nel at site 5, the farthest downstream, became dry during the second day of the test as a consequence of increased seepage loss.

Water Temperature

During the second part of the test, December 13- 20, in which the augmentation rate was constant at 1.63 ft3/s, a greater percentage of the flow reached sites 2 and 3 than during the first part of the test (fig. 6B). The dis charge regression lines for sites 2 and 3 have a positive slope; that is, discharge was increasing with time, which indicates a reduction of infiltration rate into the streambed. In contrast, the regression lines for sites 4 and

5 have a small negative slope, which indicates that dis charge was still decreasing and that infiltration rates were increasing.

These trends could be real or may merely reflect the large variation inherent in current-meter measurements. If the trends are real, the increase in discharge at sites 2 and 3 could have been caused by a decrease in water tempera ture, which would retard infiltration rate. Water that was used to supplement flow in the second part of the test was obtained from Franklin Square Water District and is as sumed to have been colder because it was transmitted

Table 2. Stream discharge at four sites at Fosters Brook, November 30-December 24, 1979 [All values are in cubic feet per second]

Measurement site 1

Date

Nov. 30

TVr 1

Dec. 2

Dec. 3

Der d

Time

1 A/Vtlouu 180021002300

02000500070010001300160019002100

00300400070010001300160019002100

0030040007000900140018002100

010005000900130017002100

2

0.840.871.00.94

0 04.yr

0.940.900.950.990.930.940.93

0.880.920.910.920.920.930.900.84

0.870.840.880.930.890.810.83

G O'3.OJ

0.820.800.810.80

3

0.750.790.690.70

0.720.750.710.810.840.750.790.67

0.670.680.650.730.660.680.680.67

0.650.660.530.730.760.730.76

0.670.680.680.630.620.53

4

000.390.38

0.360.400.390.490.490.360.470.38

0.400.400.390.520.410.440.28

0.340.310.310.290.270.390.32

0.300.300.260.260.300.28

5

000.020.10

0.110.100.090.050.01000

00000000

0000000

000000

Streamf low Augmentation at Fosters Brook, New York

Table 2. Stream discharge at four sites at Fosters Brook, November 30-December 24, 1979 Continued

Table 2. Stream discharge at four sites at Fosters Brook, November 30-December 24, 1979 Continued

Measurement site 1

Date

Dec. 5

Dec. 6

T"%*ar» *7L/ec. /

Dec. 8

T\f>c 0

Dec. 10 -

Dec. 11

Dec. 12 -

Time

010005000900140017002100

01000500090013001600

05000900130017002000

010006000900130016002100

010005000900130017002100

010006000900130017002100

010005000900130017002100

003005000900160019002100

2

0.830.780.790.700.800.80

O Q1.01

0.760.780.740.77

0.760.790.780.810.77

0.760.740.700.720.700.72

0.710.680.720.670.710.69

0.670.640.700.740.700.73

0.740.780.700.680.720.72

0.720.720.741.41.41.4

3

0.430.490.530.540.520.60

0 54v««/*T

0.550.570.530.59

0.550.560.570.560.56

0.560.530.570.490.470.42

0.450.390.420.400.330.32

0.370.410.500.520.520.51

0.530.510.480.490.490.51

O A*I .47

0.490.501.21.11.1

4

0.280.250.230.240.290.27

0.240.240.230.210.26

0.340.270.220.220.20

0.210.210.210.210.250.21

0 18.10

0.180.190.170.210.18

0.170.170.170.180.170.16

0.160.150.150.150.150.15

0.150.150.140.780.800.80

5

000000

00000

00000

000000

000000

000000

000000

0000.230.270.22

Measurement site'

Date

Dec. 13

TVr 14

Dec. 15 -

Dec. 16 -

Dec. 17

Dec. 18

Dec 19 - -ix Vl> IS

Dec. 20 -

DPP 91

Tv»P 'yyLsCt. ZZ

Dec. 23

Dec 24 - -.LxW* Xrf"T

Time

003009002300

020006001000140017002100

0030050009001300170021002330

f\£f]f\ uouu090013001700

IfWl 1UUU

130017002300

n/uvi uouu 090013001800

nonn uyuu 13001700

1010

0850

1025

01000800

003512301851

2

1.41.61.4

1.41.41.41.51.31.4

1.41.51.71.41.61.41.3

1.41.51.51.5

1.51.51.61.6

1.6.5.5.5

.5

.51.5

1.4

0.10

0.22

0.200.20

0.200.290.30

3

1.11.31.2

1.21.21.21.21.21.2

1.21.31.41.41.41.31,2

1.41.31.41.2

1.31.21.21.3

1 21 *<

1.41.31.3

1.31.31.3

1.3

0

0

00

000

4

0.750.940.77

0.800.740.800.780.770.72

0.800.630.890.880.810.750.80

0.730.920.810.79

0.740.780.710.68

0.700.770.760.69

1.00.750.74

0.79

0

0

00

000

5

0.260.23

000.220.21

0.21

0.210.190.180.180.180.180.18

0.18

0.190.180.180.21

0.200.180.180.18

0 18.10

0.180.18

0

0

00

000

'Site locations are shown in figure 4.

Results of Streamflow Augmentation

678 TIME, IN DAYS

10 11 12

Figure 6. Linear regression of stream discharge (A) at three sites during flow augmentation at 1.00 ft3/s, November 30- December 12, 1979 and (B) at four sites during flow augmentation at 1.63 ft3/s, December 12-20, 1979. (Site locations are shown in fig. 4.)

through pipes lying near land surface, probably within 10 ft, where it would have been cooled by the winter air tem perature. In contrast, water pumped from the well instal led for this study would have been warmer because the local water table was approximately 25 ft below land sur face and was less susceptible to winter cooling. (Effects of water temperature are covered in detail in a later sec tion, "Temperature.")

If the water mixed from two sources were indeed cooler during the second part of the test than during the first, infiltration rates would decrease as a result of the greater viscosity of the water and streamflow would de crease less rapidly. Moreover, because the water was warmer than the winter air, it would be cooled as it moved downstream and would produce still lower infiltra tion rates in the downstream reaches a pattern not fully supported by the data. Table 3 gives data on average in filtration rates for all reaches during each test period and average infiltration rates for the entire test. Infiltration rates in each reach were calcuated as follows. First, linear regression analyses of the discharge data for each reach and each augmentation rate were done to obtain a dis charge value for the middle day of each test period and each reach. Seepage losses for each reach were then cal culated for each augmentation rate by determining the dif ference in stream discharge at successive downstream sites. The seepage-loss values of each reach were then di vided by the approximate area of wetted channel to yield an average infiltration rate per unit area. Comparison of infiltration rates (table 3) reveals that they differed widely from reach to reach, with no consistent trend toward

higher infiltration rates in the upper reaches. For example, the infiltration rate on December 16 in reach A was 4.43 ft/d and in reach C it was 8.81 ft/d, 99 percent higher. In filtration rates in reach C also clearly reflected the change in augmentation rate; for example, the infiltration rate on December 6 (discharge 1.00 ft3/s) was 5.56 ft/d and on December 16 (discharge 1.64 ft3/s) it was 8.81 ft/d (table 3), an increase of 58 percent.

These examples are extreme but are cited to indicate the variability of infiltration rates during the test and also the potential for error in interpreting discharge data. Infilt ration rates may vary along the stream for a number of other reasons; for example, pools and riffles having large differences in stream stage would produce local areas of high and low infiltration rate, and local variations in streambed composition would also cause local differences in infiltration rate. Thus, water temperature alone was probably not a major cause of spatial or temporal variation in the infiltration rate at Fosters Brook; this variation probably resulted from a combination of several factors, of which temperature was only one component.

Wetted Channel Length

A further indicator of average infiltration rates over the entire stream is total length of wetted channel. Stream length (distance from augmentation site to beginning of dry channel) was measured daily during the test period and is plotted in figure 7. Thirteen hours after augmenta tion began on November 30 (1.00 ft3/s), stream length had


o00D O

1.6

1.4

1.2

1.0

0.8

C3 cc <

O 0.6

0.4

0.2

Site 2

Site 4O

00O

o Q oo o

o

o

o Q00

O o

o oSite 5

13 14 15 1916 17 18

TIME, IN DAYS

Figure 6. Linear regression of stream discharge Continued

20 21

reached 2,050 ft. Thereafter it gradually shortened and by December 12 was only 1,300 ft, a 36-percent decrease as a result of increasing infiltration rate. Similarly, when the augmentation rate was increased to 1.63 ft3/s on De cember 12, the stream extended to 2,719 ft, but by De cember 20, it had decreased to 2,154 ft. On December 20, augmentation rate was reduced to 0.54 ft3/s, and that day the stream shortened to 815 ft and remained at that length until the test ended on December 26.

Duration of Wetting

The distribution of data points for the first two periods of the test (fig. 7) indicates two distinctly different hydrologic regimes. When the channel was initially wet ted, infiltration rates, as indicated by stream length, in creased in response to increasing soil-moisture levels, less

entrapped air in the unsaturated zone, and surface wetting. As a result, stream length shortened quickly. After a few days, however, the stream length began to stabilize as the factors controlling infiltration rates approached equilib rium. The similarity of regression slope for days 1-6 with that for days 15-17 reflects this tendency, and the same is true of the curves for days 6-13 and days 17-20. The number of days from the time augmentation began (or was increased) until the break in slope was about 5 days in both tests; the break in slope reflects the stabilization of some major factor(s) controlling seepage rates from the stream, most notably soil moisture in the unsaturated zone.

As was stated previously, stream length during the first two periods of the test (1.00 and 1.63 ft3/s) decreased rapidly then more gradually, but during the last part of the test remained constant. The major controlling factor would seem to be the wetting and saturation of the streambed and

Results of Streamflow Augmentation 11

Table 3. Infiltration rates calculated from linear regression for five stream reaches at Fosters Brook in December 1979 [Location of reaches and sites is shown in fig. 4]

DateInfiltration rate (ft/d)

Average of(discharge, Reach Reach Reach Reach Reach all reaches

ft3/s) A B C D E (ft/d)

Dec. 6 (1.00)

Dec. 16 (1.63)

Dec. 23 (0.54)

5.62 5.04 5.56 5.77 Dry 5.50

4.43 4.77 8.81 6.54 4.46 5.80

5.64 5.77 Dry Dry Dry 5.70

Average 5.23 5.19 7.18 6.16 4.46 5.67

material beneath it. At the beginning of the test and at the start of the second test period, a long channel length (greater than 1,000 ft) was being wetted for the first time in several days, whereas during the last test period, the channel had been under water for 21 consecutive days. This suggests that 21 days would have been enough time for stream length at the higher augmentation rates to have stabilized also. A graph of discharge in relation to stream length as it approached stabilization is given in figure 8.

Although the three data points in figure 8 are grouped closely about the line, implying close linear re lationship between stream length and discharge, three points and zero discharge at zero flow are not enough to provide confidence in the relationship. Great caution must be exercised in the adoption of this simplified model be cause any bias in measurements of stream length or dis charge would result in a biased regression coefficient. Al though the relationship between stream length and dis charge may genuinely pass through the origin, it may not

2600-

Discharge=0.54 ftVs

po o o o o o800

2 3 45 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28TIME, IN DAYS SINCE AUGMENTATION BEGAN

Figure 7. Wetted stream length in relation to the augmentation rate and lines of best fit as calculated by least-squares regression, November 30-December 26, 1979.


500 1000 1500

STREAM LENGTH, IN FEET

2000

Figure 8. Relationship between stream length and discharge after stabilization, December 1979.

be linear over the whole range of discharge values. Ex trapolation of the regression line to higher flow values, for example, to 10 ft3/s, would be even less certain because larger discharges would increase stream stage and hydrau lic head, thus altering the relationship. The data in figure 8 indicate that infiltration rates at low discharge (less than 2 ft3/s) are not sensitive to small changes in stage; rather, the major controlling factor seems to be the numerous pools and riffles along the stream channel. The stream stage in various pools is controlled by the outlet elevations from those pools and not by the discharge rate at low levels of streamflow. At higher discharges, the pools and riffles would no longer be significant, stream stage would be the dominant factor. Furthermore, at low stages the pools provide greater wetting and the riffles less wetting, which causes the local variations in infiltration rate.

Relationship of Soil Moisture to Infiltration Rate

After precipitation or some other form of surface re charge, the amount of water held in the interstices of the

soil in the unsaturated zone gradually decreases as a result of draining and evapotranspiration. Because the rate of in filtration through the unsaturated zone is partly dependent on soil moisture, prediction of infiltration rate requires knowledge of the degree of saturation before infiltration begins. As soil moisture increases in response to recharge, the rate of infiltration through the unsaturated zone in creases until saturation occurs, at which time the rate re mains constant.

Soil moisture was measured at three sites before the start of the test. Soil-moisture content in the unsaturated zone ranged from 16 to 25 percent at access holes 1 and 2 (fig. 9A and fi); at hole 3, it ranged from 19 to 32 per cent (fig. 9C). This difference is attributed to differences in soil composition because access hole 3 seemed to be in slightly finer grained material, which would have a higher negative soil pressure head and therefore higher moisture levels.

In the logs for all three access holes, moisture levels peak at about 42 percent within the capillary fringe (just above the water table), where the sediment is fully satu rated. At this depth the water has filled all available pore space, and the moisture content is equal to the effective porosity of the aquifer material.


LLJo< Ru_ 5 DC

15

Approximate location of water table

ceD

15

B


20 30 40

SOIL MOISTURE, IN VOLUME PERCENT

20 30 40


o-

o

£10o


Increased soil moisture


20 30 40


20 30 40


Figure 9. Soil-moisture logs showing moisture content of unsaturated zone beneath stream channel. A, Access hole 1 before the start of the test; B, access hole 2 before the start of the test; C, access hole 3 before the start of the test; D, ac cess hole 1 as the wetting front moved downward at the start of the test. (The location of access holes is shown in fig. 4.)

14 Streamf low Augmentation at Fosters Brook, New York

As soon as streamflow was induced, water began to infiltrate the streambed and move toward the water table. (As water moves through the unsaturated zone, some is held in place by tension forces, and as the amount held in place increases, the tension forces decrease, allowing the water to move more quickly.) To document this process in detail, soil-moisture logs were run at access hole 1 sev eral times during the test. The initial soil-moisture level beneath the streambed before the test averaged 20 percent. After 6 hours of flow it had risen to 30 percent, but after 4 days it had risen only an additional 2 percent, to 32 per cent. After 20 days of flow, soil moisture had risen to 41 percent, almost the saturation level of 42 percent, but the area beneath the stream never became totally saturated.

Water in transit to the water table through the un saturated zone causes the water table to rise rapidly be neath the recharge area because of a greatly reduced effec tive specific yield. The effective specific yield is equal to the specific yield minus the soil-moisture level. In other words, if the saturated level is 42 percent and the soil- moisture level is 41 percent, the effective specific yield (volume of pore space yet to be filled with water) is only 1 percent. Thus, a very small increase in soil moisture re sults in saturated flow.

A soil-moisture log run on December 23, after 24 days of testing and 3 days after the flow had been reduced from 1.63 ft3/s to 0.54 ft3/s, showed that moisture levels had decreased to about 30 percent, the same level re corded in the first few days of the test. Evidently, the de creased flow produced slower infiltration rates, probably because of lower water stage in the stream. Because the high soil-moisture levels could no longer be maintained, some of the stored moisture drained to the water table, re ducing the infiltration rate.

Additional soil-moisture logs were run after the end of the test to obtain data on the subsequent decline in moisture level. Streamflow was stopped on December 26, and by December 31, the moisture level had decreased to 22 percent, just 2 percent above the initial level.

When the flow was begun, nine soil-moisture logs were run at irregular intervals over a 6-hour period at site 1 to determine the rate of movement of the wetting front through the unsaturated zone. (In figure 9D, the wetting front is evident as a sharp increase in soil moisture at a depth between 6 and 7 ft). During this period, the wetting front traversed the unsaturated zone in about 5.5 hours at a rate of 11.2 in/h.

The rate of advance of the wetting front through the unsaturated zone at Fosters Brook was much lower than rates calculated for three recharge basins on Long Island. Seaburn and Aronson (1974) calculated rates that range from 18 to 74 in/h, and the average for all storms studied at the basins was 40 in/h. Because these storms occurred from November through March, the extreme difference between infiltration rates at the basins and at Fosters

Brook is not attributable to temperature but to geohyd- rologic differences. For example, the larger amounts of fine-grained sands or clay beneath Fosters Brook would produce significantly lower infiltration rates. (Grain-size distribution is discussed in the "Streambed Composition" section.) Also, the depositional environment in the stream is considerably different from that in a recharge basin in asmuch as stream deposition occurs in moving water, whereas deposition in the recharge basin occurs in stand ing water. This would affect the orientation of the sedi ment as it settles out. Furthermore, recharge basins are lo cated in areas favorable to infiltration of water and are scoured and cleaned routinely to maintain high infiltration rates.

Ground-Water Response

Ground-water levels near Fosters Brook began to rise as soon as the wetting front reached the water table, as evidenced by measurements at well N 9622, in reach A at the center of the streambed (fig. 4). During the first 12 days, water levels rose sharply, but thereafter they rose more slowly and at some wells eventually declined. The maximum rise was 6.47 ft in well N 9627, located 14 ft east of the stream and 225 ft downstream from the start of flow, on December 13. Although the range of water- level change at N 9627 was greater than it was in most other wells in which maximum change was generally less than 3 ft, the overall trend at all wells was similar, as was indicated by a hydrograph of wells N 9624, N 9622, and N 9642 (fig. 10).

The influence of recharge can be readily seen as a rise in water levels along the entire stream length. For ex ample, water levels in reach E (wells N 9634, N 9635, and N 9639) rose in response to the arrival of streamflow and decreased rapidly when stream length receded. (Well records are given in the appendix, at the end of the re port.)

The areal extent of ground-water mounding could not be closely defined because the wells were insufficient in number and distribution. (The density of housing pre cluded installing wells where they might have helped to define the ground-water mound; drilling operations were thus confined to the narrow right-of-way along Fosters Brook and outlying streets where a drill rig could be man euvered.) However, the data indicate that the mound was of relatively limited width and that it dissipated quickly with distance from the stream. The hydrographs in figure 10 indicate that well N 9624, 45 ft from the stream, rose a maximum of 1.75 ft and that well N 9622, directly in the streambed, rose 3.91 ft. Beyond 45 ft, net change in water levels decreased even more rapidly with distance; for example, none of the nearby houses (within a few hundred feet) were affected by the ground-water mound,


35.0

26 27 28 29 30 1 2 34 56 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

November December

TIME, IN DAYS SINCE AUGMENTATION BEGAN

Figure 10. Water-level measurements obtained in three wells with continuous recorders during a streamflow augmentation test, November 30-December 26, 1979. Well N 9622 is in reach A at the center of the stream, N 9624 is 45 ft east of the stream, and N 9642 is 2,000 ft east of the stream. (Locations are shown in fig. 4.)

and at well N 9642, 2,000 ft from the stream, no response to augmentation was discernible.

At three sites along Fosters Brook, a pair of wells was drilled equidistant from the stream center. These were wells N 9621 and N 9623 in reach A, wells N 9626 and N 9627 in reach A, and wells N 9629 and N 9630 in reach C (fig. 4). Comparison of water levels on either side of the stream (Appendix) indicates that the ground-water mound was not symmetrical in relation to the center of the stream channel nor was the amount of ground-water mounding uniform along the channel length. For example, the difference between net water-level increase at the two wells of each group from November 30 to December 12 was as follows:

reach A (N 9621 and N 9623): 0.40 ft reach A (N 9626 and N 9627): 0.90 ft reach C (N 9629 and N 9630): 1.29 ft

In addition, water levels were consistently higher on the east side of the stream than on the west. This discre pancy is attributed to variation in streambed composition

and to the bend in stream channel just north of well N 9625 (fig. 4). In addition, the wells were not drilled to exactly the same depth below the water table. (Because a ground-water mound had formed, flow was three dimen sional, that is, radial and downward away from the center of the mound, so that wells screened at different depths would indicate different pressure heads.) Thus, the ground-water mound could be expected to be symmetrical only under ideal conditions, that is, with uniform areal re charge from the stream and an isotropic, homogeneous porous medium. At Fosters Brook, recharge was not uni form along the length of the stream, as exhibited by the variation in infiltration rates (table 3) both longitudinally and transversely, and in addition, the aquifer material was neither isotropic nor homogeneous. Thus, a certain degree of asymmetry is to be expected.

FACTORS AFFECTING SEEPAGE RATES

Much of the information presented thus far demon strates the variability of rate at which water will seep from


the stream channel into the aquifer. As was explained ear lier, several factors influence these seepage rates, some of which are (1) composition of the streambed and aquifer, (2) soil-moisture conditions, (3) water temperature, (4) stream stage, and (5) clogging of streambed. An under standing of the relationship among these factors is neces sary to evaluate the feasibility of streamflow augmentation at any given site.

Streambed Composition

Composition of the streambed and surrounding aquifer determines the basic characteristics of seepage from the stream. Variations in composition will produce local differences in seepage rate from the stream; for ex ample, seepage will be much slower where sediments con sist of silt and clay than in areas of coarse sand and gravel.

Samples of streambed sediment were collected at 11 sites along Fosters Brook for grain-size distribution analyses to be related to seepage rates in this study and to, provide data for studies on other streams.

Streambed samples were taken at 250-ft intervals along the stream channel. At each site one sample was collected at the center of the stream with a small hand shovel from a depth less than 2 in., and another was col lected in the same manner from the 6- to 8-in. depth inter val. At a site 500 ft downstream from the point of flow augmentation, an additional sample was collected from the 3- to 5-in. depth interval because the sediment there seemed to differ considerably from that in the rest of the reach. Results of the grain-size analyses are listed in table 4; a graph (fig. 11) depicts results of the grain-size analyses as average percentages for all samples in the given grain-size ranges. The unshaded area above and below an individual bar represents the range from the highest to lowest percentage encountered in each grain- size group. For example, in the column representing the grain-size range from 8 to 4 mm, the highest percentage of grains of that size among all samples was 74 percent and the lowest was 1.02 percent. The average of all sam ples in the 8- to 4-mm range was 32.46 percent by weight, as indicated by the bar.

The largest range in percentage of total sample weight was in the 8- to 4-mm size group (1-75 percent) followed by the 0.5- to 0.25-mm group (7.5-46.5 per cent). In addition, the average percentage in these two groups (32.5 and 20.5, respectively) are the highest of all size fractions examined (fig. 11), which indicates that gravel and sand form the largest percentage of streambed sediment. The smallest range in percentage of total sample weight was in the 0.125- to 0.063-mm and the < 0.063- mm groups (the silts and clays), both from 0 to 4 percent. These groups also form the smallest average percentage of

total weight in the samples (1 percent and 0.8 percent, re spectively).

The small range in amount of silt and clay contained in samples (<0.125 mm) may be misleading in relation to their influence on infiltration rate. In poorly sorted aquifer material, the permeability is generally controlled by the amount of clay because the fine particles occupy the inter stices between larger particles and inhibit the flow of water. Even small amounts of silt and clay can retard this flow, therefore, small differences in silt and clay content can produce large differences in permeability. However, the permeability of the streambed depends also upon shape, size, compaction, and distribution of the silts and clays; therefore, grain-size analysis alone is not sufficient to determine permeability of the source material.

Comparison of grain-size data from Fosters Brook with data from another stream to predict results of streamflow augmentation could be of questionable value owing to differences in depositional environment and the source of material available to the streams. Fosters Brook is no longer a natural stream channel such as is found elsewhere on Long Island because flow occurs only during storms, and this flow as well as most of the sediment is derived from local surface runoff instead of the natural stream deposits. The washed-in sediment is coarser and of a different color than that typical of perennial Long Island streams; also, the streambed contains broken glass and trash to depths as great as 6 in. The washed-in material may have significant bearing upon seepage rates; how ever, this was not investigated.

Soil Moisture

As was discussed earlier, both soil-moisture content and hydraulic conductivity are functions of pressure head, and as soil moisture increases, hydraulic conductivity also increases. This is described by Darcy's Law for one-di mensional flow in an unsaturated isotropic soil:

where

Q is flow through an unsaturated medium, K is hydraulic conductivity, ¥ is pressure head, and

or. is gradient. ox

This relationship implies that, given a constant gradient, flow rate increases as soil moisture (and consequently pressure head) increases.

Factors Affecting Seepage Rates 17

Table 4. Grain-size distribution analysis of streambed sarr [Weight columns indicate absolute weight held by each sieve, in gr

Grain-size range,

Sample source

Distance from start of flow

(ft)

0

250

500

750

1000

1250

1500

1750

2000

2250

2500

Depth interval (in.)

0

6

0

6

0

3

6

0

6

0

6

0

6

0

6

0

6

0

6

0

6

0

6

- 2

- 8

9

ft

- 2

- 5

- 8

- 2

- 8

- 2

- 8

- 2

- 8

- 2

- 8

- 2

- 8

- 2

- 8

- 2

- 8

- 2

- 8

8

Weight

22.62

47.93

57.65

76.52

74.66

9.54

31.71

26.15

60.13

81.11

25.19

105.00

84.99

104.95

147.92

90.61

1.19

55.51

27.13

62.96

6.76

104.15

60.89

- 4

Percent

17.96

26.19

39.45

41.70

36.32

8.79

20.85

16.02

30.56

49.30

16.82

50.84

52.06

48.78

74.00

47.22

1.02

28.75

14.69

33.74

3.96

51.81

35.67

4

Weight

4.75

7.72

11.67

15.93

25. 18

3.11

5.01

8.42

9.96

11.90

5.02

13.92

9.50

13.97

4.41

12.42

1.32

13.44

11.12

6.54

4.31

11.78

10.80

in millimeters

- 2.8

Percent

3.77

4.22

7.99

8.68

12.25

2.87

3.29

5.16

5.06

7.23

3.35

6.74

5.82

6.49

2.21

6.47

1.13

6.96

6.02

3.50

2.52

5.86

6.33

2.8

Weight

7.11

15.01

14.10

14.75

20.34

2.91

6.20

9.47

10.47

10.42

4.25

11.03

8.06

13.66

3.06

9.64

2.02

14.16

13.17

5.95

7.61

8.43

10.51

- 2

Percent

5.65

8.20

9.65

8.04

9.89

2.68

4.08

5.80

5.32

6.33

2.84

5.34

4.94

6.35

1.53

5.02

1.73

7.33

7.13

3.19

4.45

4.19

6.16

2

Weight

18.58

42.64

26.72

26.02

30.16

12.30

15.45

18.57

22.84

19.42

6.71

18.08

13.35

24.78

6.01

18.57

6.82

31.70

26.74

11.79

23.85

15.97

18.07

- 1

Percei

14.75

23.30

18.29

14.18

14.67

11.34

10.16

11.37

11.61

11.80

4.48

8.75

8.18

11.52

3.01

9.68

5.85

16.42

14.47

6.32

13.95

7.94

10.58


Posters Brook, Nassau County, N.Y., December 1979 rnt columns indicate percentage of composite sample weight]

Grain-size range, in millimeters

1

"^iijht

A 7. 59

''2.66

;.1.88

~2.04

5.99

;:9.06

7.5. 22

'^0.99

::2.08

23.51

'6.43

28.21

'4.41

34. 00

'4.39

28.47

25.44

30. 56

49.82

31.40

47.39

33.27

25.47

-0.5

: Percent

21.91

23.32

14.97

17.46

17.51

26.78

16.58

25.11

26.47

14.29

10.97

13.66

8.83

15.80

7.19

14.84

21.83

26.18

26.97

16.83

27.73

16.55

14.92

0.5 -

Weight

32.31

24.73

9.98

16.26

16.93

33.43

47.24

52.70

37.88

14.80

52.06

25.41

21.52

21.75

19.59

29.02

54.14

26.36

50.83

59.81

61.51

26.13

31.62

0.25

Percent

25.66

13.52

6.83

8.86

8.24

30.81

31.06

32.28

19.25

8.99

34.76

12.30

13.18

10.11

9.80

15.12

46.46

13.65

27.52

32.05

35.99

12.99

18.52

0.25

Weight

11.78

1.71

2.51

1.44

1.76

11.04

15.42

5.66

2.52

2.20

34.42

3.04

9.31

1.36

3.08

2.31

16.49

0.78

5.01

6.80

13.38

0.93

8.97

- 0.125

Percent

9.35

0.93

1.72

0.78

0.86

10.17

10.14

3.47

1.28

1.34

22.98

1.47

5.70

0.63

1.54

1.20

14.15

0.40

2.71

3.64

7.83

0.46

5.25

0.125

Weight

0.94

0.38

1.11

0.33

0.36

4.21

2.78

0.65

0.49

0.59

4.55

0.90

1.38

0.32

0.86

0.42

4.46

0.25

0.54

0.66

3.12

0.15

2.25

- 0.063

Percent

0.75

0.21

0.76

0.18

0.18

3.88

1.83

0.39

0.25

0.36

3.04

0.44

0.85

0.15

0.43

0.22

3.83

0.13

0.29

0.35

1.83

0.07

1.32

<

Weight

0.25

0.19

0.50

0.19

0.16

2.91

3.08

0.65

0.36

0.56

1.13

0.95

0.72

0.34

0.56

0.41

4.65

0.35

0.34

0.71

2.98

0.21

2.14

0.063

Percent

0.20

0.10

0.34

0.10

0.08

2.68

2.02

0.39

0.18

0.34

0.75

0.46

0.44

0.16

0.28

0.21

3.99

0.18

0.18

0.38

1.74

0. 10

1.25


2.8 2 1 0.5 .25 .125 .063 <.063

GRAIN SIZE, IN MILLIMETERS

Figure 11. Grain-size distribution of streambed sediment in Fosters Brook. A bar indicates the average grain-size fraction among all samples. The unshaded area represents the range of values in a grain-size fraction among all samples.

Within a limited range of recharge (infiltration) rates, soil moisture varies in response to recharge. The change in soil-moisture content at neutron-logger access hole 1 during and shortly after the augmentation test is de picted in figure 12. On the first day of the test, soil mois ture increased abruptly from approximately 20 percent to approximately 30 percent (see also fig. 5), and from days 2 to 15 it continued to increase because seepage from the stream was faster than flow through the unsaturated zone. By the 15th day (December 14), soil moisture had reached a peak of about 41 percent, which represents saturated flow under negative pressure head or unsaturated flow very close to the effective porosity of the aquifer. After day 21, soil moisture decreased in response to the abrupt

decrease in augmentation rate. At the lower augmentation rate (0.54 ft3/s), stream stage declined, and seepage through the streambed decreased as a result of the lower pressure head. This lower seepage rate was not sufficient to maintain the nearly saturated flow conditions above the water table, and soil moisture decreased accordingly. In time, a new soil-moisture equilibrium for this new re charge rate would have been reached.

The decrease in soil moisture after the streamflow rate was reduced indicates that the soil-moisture level was controlled by the rate of seepage from the stream and that seepage rate was more dependent on pressure head at the streambed than on soil-moisture content in the unsaturated zone, although the reverse may be true at certain times, such as during the initial wetting phase at the start of au gmentation.

Temperature

Changes in water temperature alter the viscosity of water and thus affect the rate of flow through an aquifer. Hydraulic conductivity of an aquifer can be expressed as

(2)

where

K is hydraulic conductivity,k is intrinsic permeability,6 is density of water,g is gravitational constant,H is kinematic viscosity of water

and density (p) and kinematic viscosity (JJL) are temperature dependent.

Although the changes in density and viscosity of water resulting from seasonal extremes in air temperature are not great, they can have a significant effect on the rate of infiltration. During the initial phase of flow augmenta tion, when water was derived solely from the nearby well, the stream temperature was 14°C. If this were to decrease by 2°C, hydraulic conductivity would decrease by approx imately 5-6 percent (from eq. 2).

During the second phase of the test (days 13-21), when additional water was supplied by Franklin Square Water District to increase the flow, the added water was presumably colder than the well water so that when the two were mixed the temperature would have dropped about 2°C. The hydrograph of well N 9622 (fig. 10) sub stantiates this assumption because when the additional

20 Streamf low Augmentation at Fosters Brook, New York

cn O

40

O

LL O

z2 30

LUOoc 20^- u

10

Discharged.63 ft3/s Discharge=0.54 ftVs

10 15 20


25 30

Figure 12. Average soil moisture beneath streambed at neutron-logger access hole 1, November 30-December 31, 1979. (The location is shown in fig. 4.)

water was added to the stream on day 13, the water level in the well began to decline, and on day 21, when the ad ditional water was shut off, the water level rose. This water-level response reflects changes in infiltration rates that are inconsistent with a stream stage (discharge)/infiltration rate relationship until the effects of temperature are considered.

Temperature of stream water will also fluctuate daily and seasonally in response to air temperature. De spite wide variations in air temperature from day to day, an overall trend was determined from a 5-day moving av erage by the following procedure. First, the mean daily values for the first 5-day series were averaged, and that value was assigned to the last day of the 5-day period. The next 5-day series began with day 2 of the first group and ended with day 6 of the test, and the mean daily values for that group were averaged. The process was continued until the period of interest had been covered.

Mean daily temperatures were obtained from the weather station, which is maintained by the U.S. Department of Commerce, National Oceanic and Atmospheric Adminis tration, at Mineola, N.Y. (fig. 1); the record derived by this method is shown as a graph in figure 13. The trend of mean daily air temperature (fig. 13) shows a general similarity to the hydrograph of well N 9622 (fig. 10). Even though air temperature is only partly responsible for the changes in infiltration rates and water levels, a correla tion seems evident.

The effect of ambient temperature on stream water is also evidenced by a change in seepage rates from the stream during several periods of rainfall. Rain fell on De cember 6-7, 13, 16-17,19, and 24-25, and each storm was intense enough to generate overland runoff and to in crease flow through the stream channel. Early in each storm, ground-water levels within 50 ft of the stream rose sharply but peaked and began falling before the storm had


1 2 34 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31


Figure 13. Five-day moving average of mean daily air temperature at Mineola, N.Y., November 30-December 30, 1979. Data are from U.S. Department of Commerce, National Oceanic and Atmospheric Administration.

ended, and shortly after the end of each storm, water levels resumed the trend they had exhibited beforehand. The temporary decline in water levels during each rainstorm (fig. 10, well N 9622) is attributed to a decrease in seepage rates during the storm in spite of the elevated stream stage. These decreases were probably caused by a lowering of water temperature by the addition of winter runoff, which was substantially colder than the ground water being pumped for the test.

The above example implies a strong correlation be tween infiltration rate and water temperature. The relation ship between temperature and water density and viscosity is not linear, and as the temperature approaches freezing, the viscosity and density increase faster. During the storms mentioned above, the water falling as precipitation was just above 0°C, the range in which temperature changes would have the greatest effect.

Other Factors

Algae

A moderate growth of algae developed on the streambed during the stream-augmentation test. In warm weather the algae might eventually become thick enough to reduce seepage rates from the streambed, but because

the test was relatively short and the season not conducive to algal growth, its effect on seepage rates could not be determined. However, it may be advisable to study the ef fect of algal growth on seepage rates before major deci sions concerning streamflow augmentation are made.

Chemical Reactions

To determine chemical interactions between the water and the streambed sediments that might affect seep age rates or the quality of stream water, water samples were taken at three sites. Results of these analyses are listed in table 5.

The change in chemical character of the water as it moved downstream was relatively small. Some con stituents showed no change at all, and among those that showed a change, the differences were probably within the range of laboratory precision or where zero is the re ported value, the actual value is below detection limits. The only changes of any significance were in dissolved iron, manganese, and pH. Dissolved iron was 20 M-g/L at the upstream site and was below detection limit at the two downstream sites. Manganese was 210 fAg/L at the up stream site and had decreased to 160 fig/L at the down stream site, and pH decreased from 6.5 to 6.0 between the upstream and downstream sites. Even though these


Table 5. Chemical quality of water in Fosters Brook, Nassau County, N.Y. during flow augmen tation, December 19, 1979 [Site locations are shown in fig. 4]

Concentration or value

Constituent or characteristic Unit of measure Site 1 Site 3 Site 5

Alkalinity, total (CaCO3) mg/L 33 32 31Calcium (Ca) mg/L 16 17 17Chloride (Cl) mg/L 20 20 19Fluoride (F) mg/L 000Hardness, noncarbonate mg/L 21 24 25Hardness, total mg/L 54 56 56Iron, Dissolved (Fe) /ig/L 20 0 0Iron, Suspended (Fe) /ig/L 40 40 40Magnesium, dissolved (Mn) mg/L 3.3 3.3 3.3Maganese, total (Mg) /ig/L 210 200 160Nitrite NO2 (as N, total) mg/L 0.01 0.01 0.01Nitrate NO3 (as N, total) mg/L 4.5 5.1 5.0Nitrogen NH4 (as N, total) mg/L 000Nitrogen NO2 (as N, dissolved) mg/L 0.01 0.01 0.01Nitrogen NO3 (as N, dissolved) mg/L 4.0 5.3 4.1Nitrogen, total (as N) mg/L 4.7 5.5 5.2Nitrogen, total organic (as N) mg/L 0.21 0.39 0.18Nitrogen (as NH4, total) mg/L 0.0 0.0 0.0pH 6.5 6.3 6.0Phosphate, total (as P) mg/L 0.01 0.01 0.01Phosphorus, total (as P) mg/L 0 0 0.01Phosphorus, total (as PO4) mg/L 0 0 0.03Potassium, dissolved (K) mg/L 2.0 2.0 2.1Silica, dissolved (Si) mg/L 12 12 12Sodium adsorption ratio 1.1 1.0 0.9Sodium, dissolved (Na) mg/L 18 17 16Specific conductance /imho/cm 215 210 225

@25°C Sulfate, dissolved (SO4) mg/L 28 27 27

changes are minor, they could affect the streambed sedi ments and in turn alter seepage rates from the stream channel, possibly through clogging of the streambed by precipitate.

Impoundments

Artificial impoundments may locally increase seep age rates from the stream by raising the stream stage and therefore the hydraulic head driving the water into the aquifer. Fosters Brook contains several artificial impound ments that have been created behind cement spillways where storm drains emptied into the stream. The normal depth of the stream during augmentation was usually less than 0.5 ft, but behind the spillways it reaches 1 or 2 ft during periods of runoff. However, determination of the effect of impoundments on local seepage rates was beyond the scope of this study.

ANALYSIS

The hydrologic mechanisms involved in stream au gmentation are highly variable and interact in a complex manner that is as yet poorly understood. To assess the workings of these factors during flow augmentation and to evaluate their effects individually and collectively, field data were compared with solutions from both analytical and numerical models.

Analytical Solution

Analytical expressions to determine the growth of water-table mounds beneath recharge sites have been pre sented by Bittinger and Trelease (1965), Hantush (1967), and Marino (1974). The expression selected for this analy sis, presented by Glover (1966), is an adaptation of

Analysis 23

Darcy's Law, the basic ground-water flow equation, and is written as

h =f e~u2 ^ \ ~rduJ x U

(3)

where

h is change in head (ft), <7, is rate of recharge (ftVs), x is distance from center of stream (ft), K is aquifer hydraulic conductivity (ft/d), D is aquifer thickness (ft),

KD is aquifer transmissivity (ft2/s), a is KD/V where Fis the specific yield (ftVs),

and t is time since recharge began (s).

This solution assumes an isotropic, homogeneous aquifer and uniform seepage rate from a straight channel of infinite length. Percolation beneath the recharge site (streambed) is vertically downward to the water table, and the space which can be filled is a constant equal to the drainable porosity. The analysis of flow in this case examines only one-dimensional flow beneath the water table.

Glover's solution (1966) was applied to a hypotheti cal well 45 ft from the center of the stream channel, simi lar to well N 9624 in reach A (fig. 4). This distance was chosen to avoid the following problems in mathematical representation of the system: (1) changes that develop in pore space which can be filled beneath the recharge area during infiltration, (2) flow in more than one dimension near the recharge mound, and (3) anisotropy of streambed and unsaturated zone and aquifer.

Analysis of ground-water mounding at adequate dis tance from the recharge strip (streambed) minimizes the disparity between the fillable pore space and the drainable porosity of the aquifer. For example, when the unsatu rated zone is under conditions similar to those beneath the streambed, recharge causes soil moisture to increase and fillable porosity to decrease as a result of in-transit water, but the potentially drainable porosity remains the same. Thus, if soil moisture in the unsaturated zone were to rise to 30 percent through recharge and the total drainable porosity were 35 percent, the fillable pore space beneath the recharge area would be only 5 percent. The effect of this decrease in the pore space yet to be filled would be that the ground-water mound would rise more rapidly than was predicted by analytical solutions that do not consider this phenomenon. In addition, flow in two or three dimen sions instead of one, as assumed by Glover's solution,

would also cause a more rapid rise in the ground-water mound than was predicted, as evidenced by water levels observed in well N 9622 (fig. 10), which rose much more quickly than was predicted by Glover's solution.

A comparison of Glover's solution with measured water-level change at well N 9624 is given in figure 14. Aquifer characteristics used in this analysis were hydraulic conductivity of 200 ft/d, specific yield of 0.35, and aquifer thickness of 70 ft.

Initial calculations used an average recharge rate that had been determined from seepage rates calculated from the regression analysis of streamflow measurements (fig. 6); the resulting analytical solutions showed the ground-water mound to be rising more rapidly than the field data indicated. A different approach was then used, whereby a recharge rate was calculated for each day, again from the regression analysis; this method more ac curately simulated the water-table rise observed through the first 12 days of the test.

When the augmentation rate was increased from 1.00 to 1.63 ft3/s on day 13, ground-water levels began to decline partly as a result of slower infiltration rates (fig. 9) caused by the lowered water temperature. In the analyt ical solution for days 13-20, infiltration rate was reduced by 30 percent, considerably more than the calculated 5- percent reduction, in an attempt to represent the assumed real-world conditions; but still the predicted water-level decline was smaller than the observed decline at well N 9624. In fact, the predicted water level declined for only 1 day and then began to rise again. The analytical proce dure was not extended to the third period of testing be cause water levels and overall trends were not being simu lated, and the results would therefore have been meaning less.

The analytical solution can accurately predict changes in water level only if the values used for aquifer characteristics and seepage rates are correct. Because the change in water levels during the second phase of the test was not accurately predicted (the decrease in infiltration rate as a result of lower water temperature was not suffi cient to account for the decline in water levels), some ad ditional factor governing infiltration possibly hydraulic characteristics of the streambed combined with the be havior of flow in the unsaturated zone is indicated.

Numerical Model

Computer simulation was done with a three-dimen sional numerical model presented by Trescott (1975) which represents flow at or beneath the water table but not in the unsaturated zone. Even so, the model provides a more useful representation of the flow system than the analytical solution because it simulates flow in three di mensions and can also represent a finite stream channel.


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20


Figure 14. Observed water-level change in well N 9624, 45 ft from the center of the stream, in comparison with change pre dicted by Glover's solution for a hypothetical well similarly located.

Model water levels were set at zero elevation at the start of simulation, and all changes calculated by the model represent net change in water-table elevation. The simulation represented only one side of Fosters Brook be cause ground-water flow was assumed to move symmetri cally away from the center of the recharge strip (streambed).

The numerical model uses a variable grid spacing, as depicted in figure 15. The area modeled is surrounded by constant-head boundaries on three sides, and the center of the stream is represented by an impermeable boundary. The aquifer system is represented as six layers: layer 1 (bottom layer) represents the Magothy aquifer, 700 ft thick; layer 2 represents a Pleistocene clay, 10 ft thick, of limited areal extent but continuous throughout the mod eled area; and layers 3-6 represent the saturated thickness of the upper glacial aquifer with thicknesses of 20, 20, 15, and 10 ft, respectively. (The Raritan clay is considered a no-flow boundary because flow through it is minimial.)

The water-transmitting properties of the aquifers in the modeled area were assumed to be areally uniform. Hy draulic conductivity and storage coefficients for the Magothy aquifer were obtained from Franke and Cohen (1972); hydraulic conductivity and storage coefficients for the clay layer were assumed to be similar to those of the Gardiners clay, an extensive Pleistocene unit described also in Franke and Cohen (1972). Values of hydraulic

conductivity and specific yield for the upper glacial aquifer were those used in the analytical solution previ ously discussed.

As was discussed earlier, water in transit through the unsaturated zone reduced effective specific yield be cause it occupies part of the drainable pore space. The model accounts for this phenomenon by reducing the spe cific yield in the streambed nodes to 0.2 times the value used elsewhere in that layer.

Seepage from the stream channel into the aquifer could not be simulated directly by the numerical model and was therefore represented as wells injecting water into the uppermost layer of the model. The stream was simu lated by two nodes in each row acting as injection wells; these nodes are identified in figure 15 as stream channel. Injection rates were based on stream-length data (fig. 7) and stream-discharge measurements (table 2). Simulation of the augmentation test was divided into three pumping periods that correspond to the three different rates of stream augmentation. Average seepage rate for each of the five reaches was calculated as follows: (1) linear regres sion analysis was done on discharge data obtained by streamflow measurements given in table 2, (2) discharge values for the middle day of each of the three pumping periods was calculated by the linear regression equations, (3) seepage loss per stream reach was calculated as the difference between discharge values measured at the upper

Analysis 25

BLOCK SIZE, IN FEET

Stream channel

Impermeable boundary

Constant head

Figure 15. Fosters Brook model grid (areal view). Blocks that simulate injection (seepage) are de picted as stream channel. Impermeable (no-flow) boundary is at center of streambed. Hachures indicate constant-head boundary. Block dimensions are in feet.


and lower end of each reach, (4) seepage rate per unit area of stream channel was calculated by dividing seepage loss for each reach by the area of the reach, and (5) the appro priate injection rate for each node was calculated from the area represented by each individual block. The total stabilized stream length for each pumping period was ap proximated as closely as the model grid would allow.

As was stated previously, the principal goal of the model simulation was not to obtain a precise prediction of water levels but to compare simulated trends and re sponses with observed data to observe and assess the dy namics of factors governing the ground-water response to flow augmentation.

Simulated water levels were within an order of mag nitude of observed values, and ground-water trends ob served in two of the three test periods were successfully duplicated by the three-dimensional model. Figure 16 compares water levels at well N 9624 (fig. 4) with simu lated water levels in a hypothetical well similarly located. The simulated water levels rise more sharply than the ob served levels over the first 4 days of the test, but from days 4 through 12, the observed levels rise more sharply than the simulated levels. This discrepancy is attributed to use of an average infiltration rate for the entire 12-day period when in fact that rate of infiltration was increasing, as is indicated by trends depicted in figure 6.

Simulated water levels from days 20 to 26 also fol low the general observed water-level trends, rising at the beginning of the new pumping period and falling after the first few days; total simulated change in water levels dur ing this 6-day period is also fairly close to the observed change. Simulated water levels from days 12 to 20 do not follow the observed trend; the simulated levels drop slightly on day 13 but slowly rise over the next 7 days,

whereas observed water levels fell steadily from beginning to end. This discrepancy is similar to that produced by the analytical equation (fig. 14); in both cases the error is at tributed to exclusion of factors affecting infiltration at the streambed and in the unsaturated zone.

Alternatively, the infiltration (recharge) rates used in the numerical model, which were obtained from the linear regression of discharge measurements (fig. 6), may be in error because of the inherent variability of streamflow measurements. However, when the recharge rate in the analytical solution discussed previously was changed to account for the decrease in water temperature, the result was similar to that produced by the three-dimen sional model.

When the entire 27-day test period was simulated, water level at the hypothetical well on the last day was close to the observed level at well N 9624, with a differ ence of less than 0.3 ft. However, simulated and observed water levels near the start of flow differ significantly, as indicated by the water-level net change contours in figure 17. The observed water-level changes are asymmetrical about the center of the stream channel, especially at wells N 9626 and N 9627, near the lower end of reach A (fig. 4), where the water-level increases were 1.7 and 6.2 ft. This asymmetry reflects the heterogeneity of streambed sediments and the corresponding variation in hydraulic conductivity; under ideal conditions the ground-water mound beneath the stream would develop symmetrically around the center of the streambed. Thus, it is probable that the source of error in the model representations is local variation in hydraulic conductivity of streambed and aquifer.

In an idealized flow system, the area of greatest water-level rise would be beneath the stream channel

Measured change

Calculated change

Discharge=1.63 ftVs Discharge=0.54 ft3/sDischarged.00 ftVs

1 2 34 567 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

TIME, IN DAYS

Figure 16. Comparison of the observed water-level change in well N 9624, 45 ft from the center of the stream, with change simu lated by a three-dimensional numerical model for a well similarly located.

Analysis 27

73°40'30" 40'15" 73°40'

40°42'

40°41'45"

73°40'45"

9641 (-07)

EXPLANATIONWell location and number;

number in parentheses indicates observed net rise in water level

Line of predicted equal net rise. Contour interval 0.5 ft

100 200 300 METERS

Figure 17. Net increase in ground-water levels near Fosters Brook after 27 days of streamflow augmentation, as simulated by a three-dimensional numerical model. A, general view. B, detail of upper reaches.

about 400 ft downstream of the point of flow augmenta tion. However, model response does not conform to ob served data, as evidenced by wells in the center of the stream channel (N 9622 and N 9632 in reaches A and D, respectively) which had a net change of less an 2.5 ft, whereas wells in the streambank at other locations indi cated more than twice this increase. Furthermore, the point of maximum ground-water buildup along the stream

channel was much further downstream (about 700 ft at well N 9627) than was indicated by model analysis.

From wells N 9629 and N 9630 in reach C (fig. 17/4) to N 9635 in reach E (fig. 17J3), net change would be expected to diminish gradually, as shown by the water- level contours. However, the field data indicate areas of small net increase (N 9632) surrounded by areas of greater net increase (N 9631 and N 9634), which implies a sub-


73°40'15" 40°42'

40°42'

73°40'30"

T

B

9639 .63)

/9620 /(1.3)

- *9619

(1.6)

9624 (1.4)

9625X9623 (2.2)

9618(2.0)

9621 (2.0)/. 9622 (2.5)

0 50 100 150 200 250 300 FEET I

9639 Well location and number; ( 63) number in parentheses

indicates observed net rise in water level

Line of predicted equal net rise. Contour interval 0.5 ft

_ Location of model stream center, where different from Fosters Brook

Figure 17. Net increase in ground-water levels near Fosters Brook after 27 days of streamflow augmentation Continued.

stantial variability of infiltration rates along the stream channel.

Results of the three-dimensional simulation indicate specific aspects in which the errors may have occurred. Of all factors in the stream-augmentation process, flow in the unsaturated zone is the least understood, and the mathematical model does not account for it. Infiltration rates vary not only along the length of stream channel but

also across it, but studies to obtain sufficient data on the minute variations in composition and hydrologic charac teristics of the aquifer and streambed would not be economically feasible.

As was stated previously, the simulated infiltration rates did not duplicate field conditions exactly; the dispar ity is attributed mainly to inherent error in the discharge measurements from which infiltration rates were calcu-

Analysis 29

lated. Division of the stream into small reaches to provide more precise delineations of infiltration rates did not yield substantial improvement because, again, measurements are too imprecise for this purpose. Changes in water-level trends after the augmentation rate was increased on day 12 of the test are assumed to have been related to this in crease; however, simulation with analytical and mathemat ical models indicated that neither temperature change nor local variations in aquifer hydraulic conductivity alone could produce changes as great as those observed.

Thus, infiltration rate varies locally within the stream channel and is affected by external forces such as temperature, evapotranspiration, and clogging. The major factor seems to be hydraulic conductivity of the streambed, but transient changes within the unsaturated zone during infiltration may offset the general trends, making precise calculation difficult or impossible.

SUMMARY AND CONCLUSIONS

Large-scale construction of sanitary sewers in Nas sau and Suffolk Counties has caused ground-water levels" to decline and streamflow to decrease in many areas, and expansion of sewerage in the future is expected to cause similar effects in other areas. A 27-day streamflow au gmentation test was made at Fosters Brook in December 1979 to determine the hydraulic feasibility of pumping ground water into the stream channel to restore streamflow in the dry upper reaches.

Stream discharge, flow in the unsaturated zone, ground-water levels, and water quality were monitored at several points to determine the hydrologic effects of flow augmentation. During the first 12 days, water was pro vided at 1.00 ft3/s, from day 13 to day 21 at 1.63 ft3/s, and from day 22 to day 27 at 0.54 ft3/s. Stream length was monitored regularly.

Soil-moisture measurements were made beneath the stream channel at seven locations throughout the test. Background soil-moisture levels were about 20 percent, but after 20 days of streamflow they had increased to 41 percent, almost saturation level. Soil-moisture logs indi cate that the initial wetting front moved through the un saturated zone at an average rate of 11.2 in/h.

Stream discharge was measured periodically at four sites along the reach and continuously at the point where augmentation was begun. During the first 12 days of the test, discharge decreased with distance from the source, but during the next 6 days it increased within the first 1,500 ft but decreased downstream. Infiltration rates var ied greatly from reach to reach.

Stream length, an indicator of average infiltration rates, was monitored throughout the test and indicated that infiltration rates were constantly changing. The stream at tained a maximum length of 2,719 ft at a discharge of

1.63 ft3/s but shortened to 2,154 ft over the next 8 days even though discharge remained the same. Minimum stream length was 815 ft after day 21 at a discharge of 0.54 ft3/s. The data suggest two distinct infiltration re gimes at any given discharge. When the channel is in itially wetted, the stream attains maximum length and then shortens quickly because infiltration rates increase rapidly. After a few days, however, when the soil-moisture con tent approaches saturation, stream length decreases at a distinctly slower rate. Analysis of stream length and au gmentation rate indicate a linear relationship within the discharge range studied. However, this relationship was not projected to significantly greater discharge and may become invalid as stream discharge and stage increase beyond values investigated in this study.

Infiltration rates from the stream were affected by several factors including streambed composition (grain size and clay content), water temperature, stream stage, presence of algae, and soil-moisture content. These factors are interdependent, but their relationships are so complex as to make quantified assessments of each nearly impossi ble.

Ground-water response to flow augmentation was measured at 26 shallow wells along the stream; three were equipped with continuous stage recorders. Response var ied areally; the maximum net increase of 6.47 ft occurred about 700 ft below the start of flow during a discharge of 1.63 ft3/s, while water levels at outlying wells merely re flected the regional decline that occurred during the period studied.

The observed response was compared with results from an analytical and a numerical model to determine and evaluate the hydrologic mechanisms involved. Both analyses indicated that changes in infiltration rate and the resultant water levels in wells could not have been caused solely by temperature changes in the water.

The three-dimensional numerical model simulated the recharge mound as being symmetric about the center of the stream channel with maximum head changes near the point of flow augmentation. The comparison of model results with field data shows that recharge rate varied con siderably along the stream and that net change as mea sured in wells was not symmetrical with respect to the center of the stream. This discrepancy is attributed to vari ations in infiltration through the streambed as a result of streambed composition and stream-channel alinement. The three-dimensional model successfully duplicated the gen eral trend in water levels during the first and last parts of the test but not the decline in the second test period. Again, this difference is attributed to imprecise measure ment of stream discharge and the resulting error in calcu lated seepage rates.

The test at Fosters Brook demonstrated that flow au gmentation in a dry stream channel is hydrologically feasi ble on Long Island. Small quantities of water (less than 2


ft3/s) introduced into the dry stream channel flowed over a channel length ranging from 1,000 to 2,000 ft.

If augmentation of a stream similar to Fosters Brook were desired and the initial augmentation rate were less than 2 ft3/s, water would need to be added downstream to offset seepage losses. If a minimum flow of 0.5 ft3/s were desired, additional augmentation would be required every 1,000 or 2,000 ft.

The feasibility of augmenting streams at rates ex ceeding 5 ft3/s was not tested; this would produce greater velocities and higher stream stages than were considered in this study. Because higher stage would increase infiltra tion rates, the linear relationship between stream length and augmentation rate would probably not apply.

Before streamflow augmentation is considered as a valid method of replenishing dried-up stream reaches, site- specific studies should be done to evaluate potential haz ards. For example, the Fosters Brook study was done where the water table was at sufficient depth that recharge would not raise it to streambed level; in areas where the water table is at lesser depth, flooding could result. Also, even though this investigation was conducted during De cember, when air temperature was frequently below freez ing, algal growth on the streambed was sufficient to de crease infiltration through the stream channel. It is likely that algal growth and other aquatic vegetation during warm seasons would be far greater.

The Fosters Brook test demonstrated that the interre lated factors involved in flow augmentation are complex and difficult to assess. The variability of hydrologic char acteristics along any stream may be so great as to make prediction of response almost impossible and to make it likely that the responses observed at Fosters Brook differ from those at other Long Island streams.

REFERENCES CITED

Bittinger, M. W., andTrelease, F. J., 1965, The development and dissipation of a groundwater mound beneath a spreading basin: Transactions, American Society of Agricultural Engineers, v. 15, p. 103-106.

Cohen, Philip, Franke, O. L., and Fox worthy, B. L., 1968, An atlas of Long Island's water resources: New York Water Resources Commission Bulletin 62,117 p.

Franke, O. L., 1968, Double-mass curve analysis of the effects of sewering on ground-water levels on Long Island, New York, in Geological Survey Research, 1968: U.S. Geological Survey Professional Paper 600-B, p. B205-B209.

Franke, O. L., and Cohen, Philip, 1972, Regional rates of ground- water movement on Long Island, New York, in Geological Survey Research, 1972: U.S. Geological Survey Professional Paper 800-C, p. C271-C277.

Garber, M.S., and Sulam, D. J., 1976, Factors affecting declining water levels in a sewered area of Nassau County, New York: U.S. Geological Survey Journal of Research, v. 4, no. 3, p. 225-265.

Glover, R. E., 1966, Ground-water movement: U.S. Bureau of Reclamation, Engineering Monograph 31,76 p.

Hantush, M. S., 1967, Growth and decay of groundwater mounds in response to uniform percolation: Water Resources Research, v. 3, p. 227-234.

Kimmel, G. E., Ku, H. F. H., Harbaugh, A. W., Sulam, D. J., and Getzen, R. T., 1977, Analog model prediction of the hydrologic effects of sanitary sewerage in southeast Nassau and southwest Suffolk Counties, New York: Nassau County Department of Public Works, Long Island Water Re sources Bulletin 6, 25 p.

Marino, M. A., 1974, Growth and decay of groundwater mounds induced by percolation: Journal of Hydrology, v. 22, p. 295- 301.

McClymonds, N. E., and Franke, O. L., 1972, Water-transmitting properties of Long Island's aquifers: U.S. Geological Survey Professional Paper 627-E, 24 p.

Perlmutter, N. M., and Geraghty, J. J., 1963, Geology and ground- water conditions in southern Nassau and southeastern Queens Counties, Long Island, N.Y.: U.S. Geological Survey Water- Supply Paper 1613-A., p. A1-A205.

Pluhowski, E. J., and Spinello, A. G., 1978, Impact of sewerage systems on stream baseflow and ground-water recharge on Long Island, New York: U.S. Geological Survey Journal of Research, v. 6, no. 2, p. 263-271.

Seaburn, G. E., and Aronson, D. A., 1974, Influence of recharge basins on the hydrology of Nassau and Suffolk Counties, Long Island, New York: U.S. Geological Survey Water-Supply Paper2031,66 p.

Trescott, P. C., 1975, Documentation of finite-difference model for simulation of three-dimensional ground-water flow: U.S. Geological Survey Open-File Rept. 75-438,32 p.

References Cited 31

Ap

pen

dix

. W

ater

lev

els

in w

ells

at

Fost

ers

Bro

ok,

Nas

sau

Cou

nty,

N.Y

., A

ug

ust

-Dece

mber

1979

N-9617

Latitude:

Date

Aug.

6No

v. 16 23 26 27 30

Dec.

1 2

N-9618

Latitude:

Date

Aug.

6No

v. 16 23 26 27 30

Dec.

1 2

40°42'

Time

1030

1015

1045

1035

1226 840

1520

1710

1910

2100

2300 200

500

700

920

1119

1318

1522

1750

1906

2100

140

0700

40°4

2'

Time 945

1030

1040

1040

1234 840

1531

1712

1912

2105

2301 202

503

701

925

1121

1320

1523

1721

1909

21022

402

702

Long

itud

e:

73 "40

Water

Leve

l Date

31.5

1 Dec.

230.89

30.90

30.6

930

.77

30.6

6 3

30.66

30.6

430

.62

30.6

330

.64

30.6

530.70

430.70

30.7

230

.74

30.7

730

.80

30.7

8 5

30.7

830

.75

30.8

830.90

30.92

Long

itud

e:

73°4

0

Water

Level

Date

31.58

Dec.

231

.00

31.4

630

.62

30.8

230.68

330.59

30.5

630

.58

30.63

30.72

30.85

30.9

7 4

31.03

31,0

731

.15

31.1

731

.19

31.21

531

.23

31.28

31.36

31.3

931.42

'19" Time

1007

1313

1610

1905

2100

140

070

01025

1425

1729

2000 100

500

920

1325

1705

2125 100

503

902

1304

1705

2110

'19" Time

1010

1315

1612

1907

2102

1410

701

1025

1425

1733

2010 103

503

922

1327

1707

2128 103

506

1020

1305

1708

2118

Water

Level

Date

30.9

0 De

c. 6

30.9

330.94

30.94

30.98

30.98

31.02

731

.02

31.05

31.07

31.0

831.16

831.18

31.22

31.24

31.23

31.31

31.35

931.34

31.38

31.39

31.43

31.4

631

.50

10

Sequence No

. :

2

Water

Leve

l Date

31.39

Dec.

631.44

31.47

31.51

31.57

31.61

31.6

4 7

31.6

731.71

31.7

031.77

31.84

831

.88

31.93

31.94

31.94

32.06

32.0

7 9

32. 12

32.16

32.19

32.2

232

.25

32.2

8 10

Time 130

500

914

1309

1632

2300 515

904

1301

1707

2100 138

510

910

1300

1720

2148 45 612

905

1335

1730

2212 56

Time 125

506

916

1311

1636

2303 519

906

1303

1708

2102 140

512

912

1301

1730

2142 40609

907

1335

1730

2205 48

Water

Level

Date

31.51

Dec.

10

31.54

31.57

31.58

31.60

31.6

7 11

31.6

931.67

31.69

31.70

31.7

131.71

1231.71

31.80

31.8

131.80

32.00

31.83

1331.80

31.8

331

.87

31.88

1431.87

31.87

Water

Level

Date

32.32

Dec.

10

32.39

32.3

832.41

32.44

32.57

1132.47

32.43

32.46

32.49

32.88

32.8

9 12

32.57

32.62

32.6

432.66

32.6

432.64

1332

.64

32.69

32.7

232.73

1432.77

32.77

Time 549

902

1311

1650

2260 59559

900

1301

1702

2156 115

610

900

1305

1804

2220 129

910

1644

2203 111

609

900

Time 547

904

1313

1652

2159 56

615

902

1303

1705

2154 112

608

903

1307

1808

2219 128

902

1647

2159 109

606

902

Wate

r Level

31.88

31.9

231.95

31.99

32.02

32.02

32.0

232.04

32.0

632.06

32.07

32.07

32.0

732

.08

32.10

32.14

32.15

32.1

532.13

32.1

332

.10

32. 10

32.09

32.06

Water

Leve

l

32.7

932.78

32.78

32.78

32.8

432.86

32.90

32.8

932.91

32.91

32.9

432.94

32.9

532.96

32.9

832

.97

33.00

32.98

32.99

32.9

332.97

32.9

232.83

32.7

8

Date

Dec.

14 15 16 17 18 19

Date

Dec.

14 15 16 17 18 19

Time

1305

1702

2147 45 607

946

1406

1720

2001

2330 613

980

1400

1653 900

1300

1713 26 627

908

1421

1759 950

1300

Time

1306

1704

2145 43 603

945

1406

1718

2002

2339 615

930

1400

1655 903

1303

1716 22

623

911

1420

1758 903

1303

Water

Leve

l

32.06

32.05

32.05

32.05

32.03

32.0

132.05

32.0

432.03

32.05

32.05

32.07

32.1

032.11

32.11

32.07

32.0

032

.00

32.02

32.01

32.0

132.01

32.02

32.0

2

Water

Level

32.8

032.80

32.78

32.78

32.77

32.78

32.8

032.80

32.79

32.80

32.79

32.83

32.87

32.8

832.89

32.78

32.74

32.74

32.75

32.73

32.74

32.73

32.73

32.74

Date

Dec. 19 20 21 22 23 24 25 26 27 28 31

Date

Dec.

19 20 21 22 23 24 25 26 27 28 31Jan.

2 4

Time

1630 900

1612 35

823

1606 31

823

1638 10

854

15533

1234

1853

1119

1936

956

1635

1020

1132 945

Time

1633 901

1614 53830

1610 27 827

1640 20

855

15556

1232

1852

1116

1934 958

1640

1021

1134 947

1022

1200

Water

Leve

l

32.00

31.97

31.99

32.00

31.98

32.01

32.04

31.98

32.03

32.08

32.08

32.10

32.1

232.16

32.12

32.03

31.95

31.8

031.78

31.5

131.22

30.87

Wate

rLevel

32.77

32.71

32.6

832.72

32.76

32.77

32.82

32.82

32.81

32.85

32.86

32.88

32.90

32.90

32.81

32.5

932

.43

32.21

32.17

31.42

31.3

130.67

30.56

30.41

Ap

pen

dix

. W

ater

lev

els

in w

ells

at

Fost

ers

Bro

ok,

Nas

sau

Cou

nty,

N.Y

., A

ug

ust

-De

cem

be

r 1

97

9 C

on

tinu

ed

N-9619

Latitude:

Date

Aug.

6Nov.

16 23 26 27 30

Dec.

1 2

N-9620

Latitude:

Date

Aug.

6

Nov.

16 23 26 27 30

Dec.

1

Dec.

2

40°42'

Time

1000

1035

1050

1041

1238 845

1530

1715

1915

2107

2303 109

505

705

930

1122

1323

1525

1723

1912

21034

403

703

40°4

2'

Time 915

1040

1100

1043

1244 850

1525

1720

1918

2110

2310 112

508

706

940

1125

1325

1527

1722

1912

21054

405

707

Longitude:

73°4

0'

Water

Leve

l Da

te

31.4

5 Dec.

230.94

30.7

630

.58

30.7

730

.61

330

.57

30.5

630

.57

30.57

30.5

830

.67

30.7

3 4

30.7

430.77

30.82

30.84

30.87

30.9

0 5

30.9

030.97

31.0

031.04

31.05

Longitude:

73°40'

Water

Level

Date

31.59

Dec.

2

30.8

130

.49

30.64

30.7

430

.64

330

.61

30.6

030

.59

30.5

830.58

30.63

30.65

430

.65

30.65

30.7

130

.75

30.7

630.75

530

.79

30.8

130.85

30.87

30.8

8

19" Time

1012

1317

1612

1911

2100 10412

705

1028

1427

1736

2005 110

507

925

1330

1709

2130 106

509

911

1307

1709

2120

19"

Time

1015

1319

1615

1913

2110 15

411

707

1030

1427

1738

2010 117

515

927

1332

1711

2133 109

511

914

1309

1711

2122

Sequence No.

: 3

Water

Level

Date

31.05

Dec. 6

31.0

731

.08

31.1

131

.16

31.16

31.2

1 7

31.2

331

.26

31.2

731

.33

31.3

9 8

31.4

431

.48

31.4

631

.49

31.5

831.60

931

.63

31.67

31.6

931

.73

31.7

631

.78

10

Sequence No

. :

4

Water

Level

Date

30.84

Dec.

6

30.87

30.8

930

.89

30.9

530

.96

30.9

8 7

31.00

31.0

431

.02

31.0

931

.15

831

.18

31.2

131

.18

31.1

931.27

31.3

6 9

31.3

231

.34

31.3

631

.40

31.4

331

.47

10

Time 128

545

917

1312

1637

2305 523

907

1304

1711

2107 43 523

915

1302

1730

2145 38 605

908

1330

1725

2209 52

Time 110

539

918

1314

1639

2307 525

909

1306

1713

2110 45 520

918

1303

1736

2149 36 601

901

1330

1728

2210 49

Water

Level

Date

31.82

Dec.

10

31.8

731

.88

31.9

131

.93

31.9

7 11

32.0

031

.97

32.0

132.02

32.48

32.0

6 12

32.0

732.12

32.14

32.1

232.14

32.1

4 13

32.1

432

.18

32.20

32.2

4 14

32.25

32.27

Water

Leve

l Date

31.5

0 Dec.

1031.54

31.53

31.56

1131

.56

31.6

331.64

31.62

31.6

631.66

1231

.70

31.71

31.72

31.75

31.7

731.79

1331.89

32.09

32.2

931.81

1431

.84

31.8

531

.92

31.93

Time 545

906

1315

1654

2158 54 612

903

1304

1706

2152 109

607

905

1308

1808

2217 126

903

1648

2154 105

604

903

Time

1422

1656

2154 51 608

905

1306

1707

2150 108

606

910

1310

1810

2216 124

904

1650

2150 103

601

904

1308

1708

Water

Level

32.3

132

.27

32.27

32.2

832.34

32.3

632.38

32.38

32.3

932.41

32.4

432.46

32.4

632.46

32.48

32.4

832.49

32.42

32.44

32.42

32.42

32.3

832

.35

32.3

2

Water

Leve

l

31.82

31.9

031.96

32.03

32.0

832

.00

32.0

131

.99

32.0

532.05

32.0

532

.05

32.0

732.09

32.11

32.09

32.1

132

.10

32.0

832.04

32.0

331.98

31.9

431

.97

Date

Dec.

14 15 16 17 18 19

Date

Dec. 14 15 16 17 18 19

Time

1307

1706

2143 40 601

941

1405

1717

2003

2340 616

925

1358

1700 906

1308

1718 19

619

912

1428

1757 906

1306

Time

2141 38 559

945

1405

1715

2004

2341 617

925

1338

1700 909

1315

1718 13

613

914

1417

1755 910

1310

1639

Water

Level

32.3

132

.31

32.3

232

.38

32.4

532

.29

32.3

132

.31

32.3

032

.31

32.3

132.34

32.3

732.38

32.3

432

.33

32.2

632

.27

32.27

32.2

732

.26

32.24

32.2

532

.26

Water

Level

31.9

931

.99

31.9

931

.98

31.9

931

.99

31.99

31.9

932.00

32.0

332

.05

32.0

532

.01

32.0

031.95

31.9

932

.01

31.94

31.9

731

.95

31.9

631.96

31.9

7

Date

Dec.

19 20 21 22 23 24 25 26 27 28 31

Jan.

2 4

Date

Dec.

20 21 22 23 24 25 26 27 28 31

Jan.

2 4

Time

1636 904

1615 51 831

1612 2683

016

43 23856

1536 10

1230

1851

1114

1933

1000

1643

1023

1136 949

1024

1203

Time 906

1616 49 834

1614 24

832

1644 24

857

1557 12

1228

1848

1112

1931

1002

1645

1024

1138 951

1026

1158

Water

Level

32.24

32.2

232

.22

32.2

232

.26

32.27

32.34

32.32

32.34

32.3

732

.37

32.3

832

.40

32.42

32.3

232.16

32.0

731.87

31.7

731

.36

31.0

230

.69

30.5

630

.41

Water

Level

31.92

31.92

31.9

131

.95

31.96

31.99

31.97

32.0

332

.08

32.0

332.04

32.0

732.09

32. 15

31.92

31.8

631.69

31.6

231.36

31.0

830

.76

30.6

430

.50

Ap

pen

dix

. W

ate

r le

vels

in

wel

ls a

t Fo

ster

s B

rook

, N

assa

u C

ounty

, N

.Y.,

Au

gu

st-D

ece

mb

er

1979 C

ontin

ued

N-9621

Lati

tude

:

Date

Sept.

19No

v.

16 23 26 27 30

Dec.

1 2

N-96

23

Lati

tude

:

Date

Aug.

6No

v. 16 23 26 27 30

Dec.

1 2

40°42'

Time

1300

1045

1120

1045

1248 905

1550

1737

1932

2129

2324 225

525

715

945

1145

1342

1544

1736

1935

2125 40 430

730

40°42'

Time

1046

1050

1115

1050

1255 852

1535

1722

1914

2310 213

510

708

940

1127

1325

1528

1723

1917

2106 15407

711

1017

Longitude:

73°4

0'

Water

Leve

1

Date

31.3

1 Dec.

230

.93

30.8

130.60

30.81

30.6

2 3

30.4

830

.46

30.5

230

.58

30.5

930

.78

30.8

6 4

30.9

130

.95

31.0

131

.03

31.0

631

.06

531

.10

31.1

531

.20

31.2

231

.25

Long

itud

e:

73°4

0'

Water

Leve

l Da

te

31.4

3 Dec.

230

.72

30.5

930

.49

30.7

2 3

30.7

130.47

30.4

730.47

30.50

30.6

130

.74

430.81

30.87

30.93

30.98

31.05

31.0

7 5

31.0

931.13

31.2

131

.25

31.2

931

.28

6

21" Time

1032

1336

1641

1936

2132 40 435

730

1050

1521

1832

2015 120

520

945

1343

1716

2137 111

517

924

1314

1717

2136

19" Time

1321

1621

1916

2112 18414

710

1034

1429

1742

2020 123

525

929

1335

1712

2136 115

515

917

1311

1713

2127 120

Sequ

ence

No.

: 1

Wate

r Level

Date

31.2

4 De

c.

631

.28

31.31

31.33

31.3

831.40

31.46

731.47

31.54

31.5

331

.56

31.66

831.70

31.7

531.73

31.7

731

.89

31.88

931

.92

31.96

32.0

032.06

32.0

932.15

10

Sequ

ence

No.

: 5

Wate

rLe

vel

Date

31.34

Dec.

631

.38

31.39

31.2

631.51

31.5

4 7

31.57

31.6

431.66

31.6

931

.80

831.84

31.9

031

.91

31.94

32.06

32.0

9 9

32.14

32.2

032

.23

32.2

832

.36

32.4

2 10

32.4

6

Time 113

543

924

1319

1643

2310 537

915

1312

1719

2132 40 518

935

1315

1747

2146 33 559

920

1315

1720

2155 41

Time 520

920

1315

1641

2313 520

911

1307

1715

2135 49 530

922

1305

1735

2137 30 555

911

1320

1715

2152 39 537

Water

Leve

l Da

te

32.1

7 Dec

1032

.30

32.2

632

.29

32.27

32.4

6 11

32.3

932

.37

32.4

032

.42

32.4

732

.46

1232

.46

32.59

32.6

332

.64

32.65

32.6

8 13

32.70

32.72

32.7

632.80

1432.89

32.8

9

Wate

rLevel

Date

32.51

Dec.

10

32.5

332

.58

32.5

932

.80

1132

.68

32.68

32.7

332.75

32.81

32.81

1232.86

32.91

32.9

632.97

32.9

833

.00

1333

.04

33.09

33.13

33.2

1 14

33.2

233

.24

33.2

4

Time 539

912

1320

1704

2139 49 602

909

1309

1714

2140 104

555

912

1312

1820

2206 112

907

1640

2149 100

559

912

Time 908

1316

1658

2149 45 559

906

1307

1710

2146 100

601

915

1315

1812

2212 118

905

1638

2126 58 555

906

1410

Wate

r Le

vel

32.88

32.84

32.85

32.87

32.9

232

.96

33.02

33.0

133

.04

33.0

333

.07

33.07

33.0

933

.08

33.1

033

.10

33.12

33.0

733

.07

32.9

632.97

32.90

32.8

632

.85

Wate

rLe

vel

33.2

433

.25

33.2

833

.51

33.5

133.41

33.4

133

.44

33.4

433

.47

33.47

33.4

733.49

33.5

133

.58

33.51

33.4

833

.46

33.4

233

.26

33.2

533

.27

33.1

833.16

Date

Dec.

14 15 16 17 18 19

Date

Dec.

14 15 16 17 18 19

Time

1315

1716

2135 36 552

938

1400

1700

2005

2343 619

915

1349

1700 912

1315

1725

2355 609

922

1408

1751 913

1313

Time

1710

2138 35 557

930

1400

1715

2006

2344 619

920

1350

1702 915

1320

1722 11

608

916

1413

1754 915

1315

1642

Wate

r Le

vel

32.85

32.83

32.8

532.85

32.83

32.80

32.8

132

.81

32.7

932.80

32.81

32.8

232

.88

32.9

032

.80

32.7

532

.72

32.71

32.7

232

.70

32.7

032

.67

32.6

732.68

Wate

rLevel

33.1

633

.21

33.1

733

.08

33.1

333

.16

33.1

333

.12

33.11

33.1

233

.13

33.19

33.2

133

.11

33.08

33.0

033

.00

33.08

32.98

32.96

32.94

32.93

32.9

432

.94

Date

Dec. 19 20 21 22 23 24 25 26 27 28 31

Jan.

2

Date

Dec. 20 21 22 23 24 25 26 27 28 31

Jan.

2 4

Time

1650 918

1626 43 836

1628 20 834

1647 30 907

1602 16

1223

1846

1106

1929

1008

1147

1025

1140

1001

1028

1155

Time 910

1618 46 840

1616 21 835

1649 33 900

1558 14

1226

1844

1109

1927

1004

1645

1028

1142

1003

1030

1152

Water

Level

32.6

832

.64

32.66

32.6

832.71

32.76

32.85

32.7

832

.84

32.8

532

.87

32.9

032.90

32.95

32.7

532

.46

32.21

31.9

731

.88

31.35

30.9

930

.60

20.4

830

.29

Wate

rLe

vel

32.9

632.89

33.0

133

.06

33.0

033

.14

33.2

033

.07

33.1

333.15

33.2

133

.18

33.16

32.9

632

.65

32.3

631

.99

31.91

31.37

30.97

30.6

530

.51

30.3

5

Ap

pen

dix

. W

ater

lev

els

in w

ells

at

Fost

ers

Bro

ok,

Nas

sau

Cou

nty,

N.Y

., A

ug

ust

-De

cem

be

r 1

97

9 C

on

tinu

ed

N-96

25

Lati

tude

:

Date

Aug.

6No

v. 16 23 26 27 30

Dec.

1 2

N-9626

Latitude:

Date

Sept.

19No

v.

16 23 26 27 30

Dec.

1 2

40°41'59"

Time

1128

1105

1140

1055

1300 915

1540

1730

1928

2121

2315 215

515

710

952

1130

1330

1531

1727

1921

2110 20

415

715

40°4

1 '58"

Time

1400

1110

1145

1100

1305 910

1545

1735

1935

2127

2320 220

520

712

948

1142

1340

1542

1735

1931

2120 25426

725

Long

itud

e:

73°4

0'

Water

Level

Date

31.7

3 Dec. 2

30.99

30.9

032.63

31.00

30.78

330.50

30.48

30.65

30.8

731

.11

31.36

31.5

5 4

31.62

31.70

31.76

31.84

31.8

831

.96

531

.94

32.01

32.0

732.14

32.1

8

Long

itud

e:

73°4

0'

Water

Level

Date

32.1

7 Dec.

230.49

30.3

130.26

30.42

30.2

9 3

30.2

430

.25

30.2

530.22

30.2

530.30

30. 33

430

.38

30.3

930.42

30.46

30.4

730

.48

530.50

30.55

30.59

30.6

130.62

20" Time

1019

1322

1623

1928

2117 25 420

716

1040

1430

1745

2035 127

528

938

1338

1714

2145 119

523

921

1319

1719

2123

21" Time

1030

1333

1634

1934

2129 25430

735

1047

1520

1828

2045 130

534

940

1340

1718

2154 122

528

931

1323

1724

2130

Sequence No

.:

1

Wate

r Level

Date

32.18

Dec. 6

32.24

32.30

32.3

432

.41

32.4

432.52

732.57

32.6

432.67

32.64

32.85

832.94

33.04

33.1

133.19

33.32

33.4

2 9

33.51

33.61

33.69

33.78

33.87

33.99

10

Sequence No.

: 1

Wate

rLe

vel

Date

30.6

0 Dec.

630

.63

30.65

30.67

30.82

30.75

30.8

0 7

30.8

030.88

30.89

30.9

231

.02

831.06

31.11

31.09

31.1

031.22

31.22

931.25

31.3

031.31

31.3

431.39

31.44

10

Time 110

523

925

1319

1645

2321 545

916

1314

1721

2119 200

559

925

1310

1740

2134 38 609

912

1318

1715

2156 46

Time 118

538

928

1323

1649

2326 550

920

1317

1725

2129 203

601

932

1314

1745

2132 3660

791

915

1017

1221

50 41

Wate

r Level

Date

34.07

Dec.

10

34.1

634

.25

34.33

34.36

34.70

1134.54

34.56

34.65

34.63

34.7

434

.73

1234

.73

34.98

35.04

35.0

735

.08

35.08

1335.09

35.28

35.35

35.3

8 14

35.4

435

.48

Wate

rLevel

Date

31.46

Dec.

10

31.49

31.53

31.54

31.56

31.69

1131

.67

31.7

131.69

31.6

631.70

31.6

6 12

31.6

731.80

31.91

31.82

31.82

31.8

2 13

31.82

31.87

31.90

31.91

1431.91

31.92

Time 533

914

1345

1708

2141 32610

910

1310

1717

2143 58558

920

1318

1817

2210 115

908

1635

2143 52

552

913

Time 530

917

1348

1712

2139 30558

913

1315

1720

2139 56

553

922

1320

1818

2204 109

911

1632

2142 53 549

916

Wate

r Level

35.52

35.5

235

.54

35.5

735.63

35.6

735

.73

35.75

35.79

35.81

35.82

35.8

235

.82

35.84

35.87

35.9

135.92

35.85

35.84

35.7

135.57

35.57

35.53

35.4

6

Water

Level

31.9

531.92

31.9

231.93

31.9

632.00

32.0

432

.02

32.01

32.01

32.06

32.0

632.05

32.0

432

.07

32.09

32.13

32.09

32.1

232.12

32.1

432.21

32.2

532

.09

Date

Time

Dec. 14

13

1617

1721

3315

33 555

930

1402

1700

2009

2348

16

622

920

1350

1701

17

915

1321

1723

2359

18

602

918

1411

1753

19

918

1318

Date

Time

Dec. 14

13

1817

2021

3115

32 550

935

1400

1700

2011

2352

16

627

915

1347

1715

17

918

1325

1726

2351

18

559

919

1410

1749

19

920

1320

Wate

r Le

vel

35.39

35.30

35.19

35.12

35.08

35.09

35.02

34.99

34.9

934.98

34.95

34.98

35.16

35.22

34.80

34.74

34.67

34.68

34.69

34.64

34.58

34.63

34.54

34.54

Wate

rLevel

32.04

32.0

332.02

32.0

232.04

32.02

32.03

32.04

32.03

32.03

32.02

32.07

32.09

32.1

132

.07

32.04

32.02

32.04

32.04

32.0

232.02

32.02

32.02

32.02

Date

Dec.

120 21 22 23 24 25 26 27 28 31

Jan.

2 4

Date

Dec. 19 20 21 22 23 24 25 26 27 28 31

Jan.

2 4

Time

1645 912

1622 37

845

1618 13

844

1655 35 903

1600 18

1220

1813

1101

1925

1006

1647

1032

1147

1020

1040

1143

Time

1648 916

1622 36 847

1624 16

847

1657 47 905

1601 24

1220

1830

1103

1923

1010

1650

1033

1150

1022

1044

1141

Wate

r Level

35.40

34.50

34.70

34.85

34.94

35.06

35.08

35.12

35.23

35.3

135.35

35.38

35.40

35.38

34.79

34.07

35.5

132.89

32.63

31.95

31.46

30.90

30.69

30.48

Wate

rLevel

32.03

32.00

31.99

31.94

32.03

32.02

32.1

132.03

32.04

32.06

32.07

32.08

32.08

32.12

32.07

31.97

31.89

31.6

131.54

31.1

930.92

30.54

30.39

30.19

Ap

pen

dix

. W

ater

lev

els

in w

ells

at

Fost

ers

Bro

ok,

Nas

sau

Cou

nty,

N.Y

., A

ugust

-Dece

mber

1979 C

ontin

ued

Si i

N-9627

Latitude:

Date

Aug.

6Nov. 16 23 26 27 30

Dec.

1 2

N-9628

Latitude:

Date

Aug.

7

Sept

. 10

Nov.

16 23 26 27 30

Dec.

1 2

40°4

1 'S

B-

Time

1145

1115

1155

1105

1310 910

1500

1751

1901

2100

2300 200

500

700

1001

1134

1333

1534

1724

1923

2115 25418

720

40°41'56"

Time

1124

1130

1120

1200

1110

1315 920

1505

1712

1905

2105

2305 205

500

705

1008

1137

1336

1538

1732

1926

2118 30

422

Long

itud

e:

73°40'21"

Water

Leve

l

32.6

131.11

31.2

230.66

31.1

331.10

30.6

130.63

30.6

130

.60

30.6

430

.84

31.14

31.3

531

.58

31.7

131.83

31.90

32.00

32.09

32.2

132.35

32.5

132

.61

Long

iti

Water

Leve

l

33.6

732.98

32.55

32.7

132

.75

32.99

32.9

931

.87

31.86

32.3

432.79

33.09

33.3

833

.56

33.66

33.7

433

.79

33.8

533

.88

33.9

233

.94

34.00

34.10

34.1

5

Date

Ti

me

Dec.

2 1023

1325

1627

1929

2120

3 28

422

713

1042

1433

1750

2050

4 13

553

894

813

5017

1821

485

125

525

927

1321

1721

2132

ide:

73°40'21"

Date

Ti

me

Dec.

2 10

2613

2716

3019

3021

243

30 425

718

1044

1435

1752

2055

4 137

541

951

1352

1721

2153

5 128

531

934

1326

1727

2130

Sequence No.

: 2

Wate

r Level

Date

32.69

Dec.

6

32.8

132

.93

33.0

733

.19

33.29

733.49

33.60

33.77

33.8

834

.03

834

.24

34.40

34.5

934

.75

34.93

35.07

935. 13

35.3

235

.44

35.53

35.6

235

.73

1035.81

Sequence No.

: 1

Wate

rLe

vel

Date

34.2

3 Dec.

634

.27

34.31

34.37

34.4

134

.44

34.4

9 7

34.52

34.56

34.5

434.60

34.67

834.70

34.74

34.74

34.7

434

.79

34.8

4 9

34.87

34.91

34.9

334.94

34.97

35.02

10

Time 100

534

926

1321

1647 553

918

1316

1723

2138 206

608

930

1312

1741

2130 34

603

916

1310

1710

2148 39 527

Time 5253

8930

1325

1652

2333 556

922

1319

1727

2124 208

603

939

1317

1715

2129 30 600

925

1306

1707

2145 35

Wate

r Le

vel

Date

35.87

Dec. 10

35.95

36.05

36.12

36.1

4 11

36.3

536.33

36.39

36.41

36.4

336.48

1236.45

36.56

36.5

936.60

36.63

36.6

3 13

36.70

36.6

836

.73

36.7

3 14

36.76

36.77

36.79

Water

Level

Date

35.08

Dec. 10

35.1

135.13

35.16

35.1

935

.34

1135.35

35.31

35.36

35.37

35.3

835.38

1235

.43

35.5

035

.51

35.52

35.5

635.57

1335.57

35.62

35.64

35.6

6 14

35.74

35.54

Time 915

1346

1710

2136 28552

913

1312

1718

2136 52

550

925

1320

1822

2202 100

910

1630

2139 50546

915

1317

Time 524

921

1350

1705

2135 26549

917

1316

1722

2134 48

547

906

1320

1824

2159 106

914

1627

2135 47

542

918

Water

Level

36.7

736.78

36.80

36.84

36.87

36.8

936.89

36.91

36.92

36.96

36.9

636.96

36.95

36.98

37.00

37.01

37.05

37.0

337

.07

37.01

36.97

36.92

36.89

36.91

Water

Leve

l

35.52

35.7

235

.74

35.75

35.80

35.83

35.8

735.89

35.89

35.89

35.89

35.9

035

.92

35.96

36.0

036.03

36.2

936.07

36.11

36.13

36.16

36.14

36.14

36.1

4

Date

Ti

me

Dec.

14

1719

2129

15

30548

925

1356

1658

2010

2350

16

626

910

1345

1705

17

918

1330

1730

2349

18

554

923

1405

1748

19

922

1322

1654

Date

Time

Dec.

14

1320

1723

2127

15

2854

0925

1356

1655

2012

2356

16

629

910

1340

1710

17

920

1332

1732

2344

18

549

925

1403

1746

19

925

1325

Wate

r Level

36.8

936.89

36.88

36.88

36.89

36.9

136.92

36.92

36.93

36.93

36.94

36.97

36.9

836

.91

36.89

36.86

36.9

136.90

36.88

36.88

36.86

36.86

36.86

36.87

Water

Level

36.16

36.18

36.19

36.19

36.22

36.20

36.22

36.25

36.2

636.26

36.27

36.27

36.3

136.44

36.37

36.37

36.32

36.35

36.37

36.37

36.38

36.38

35.4

036.40

Date

Dec. 20 21 22 23 24 25 26 27 28 31

Jan.

2 4

Date

Dec. 19 20 21 22 23 24 25 26 27 28 31

Jan.

2 4

Time 922

1628 34

850

1620 11

849

1700 45 908

1604 21

1218

1833

1058

1921

1012

1652

1035

1018

1024

1040

1138

Time

1657 926

1618 31 856

16009

855

1704 50

912

1607 30

1212

1832

1056

1917

1014

1654

1037

1155

1030

1046

1135

Water

Level

36.86

36.94

36.85

36.89

36.91

36.93

36.9

336

.96

37.02

36.9

336.96

37.00

37.0

436

.90

36.7

836

.72

35.63

35.4

234

.09

33.1

531.93

31.37

31.09

Wate

rLevel

36.43

36.44

36.35

36.34

36.34

36.37

36.40

36.4

036.45

36.4

636.44

36.4

636.18

36.53

36.47

36.46

36.5

136.19

36.16

35.12

34.46

33.44

32.84

32.29

Ap

pen

dix

. W

ater

lev

els

in w

ells

at

Fost

ers

Bro

ok,

Nas

sau

Cou

nty,

N.Y

., A

ugust

-Dece

mber

1979 C

ontin

ued

I

N-96

29

Latitude:

Date

Sept.

10Oct.

18Nov.

16 23 27 30

Dec.

1 2

N-9630

Latitude:

Date

Aug.

7

Sept

. 10

Nov.

16 23 26 27 30

Dec.

1 2

40°41'54"

Time

1200

947

1125

1300

1321 925

1510

1716

1912

2115

2310 210

505

710

940

1115

1320

1520

1805

1906

21005

412

715

40°41'54"

Time

1110

1120

1130

1255

1115

1325 927

1515

1719

1908

2110

2310 210

510

710

945

1117

1322

1525

1802

1907

2105 10415

708

Longitude:

73°4

0'

Water

Level

Date

32.1

4 Dec. 2

29.54

30.84

30.72

30.71

30.7

230.11

330

.05

30.06

30.2

930.49

30.76

31.0

3 4

31.1

731.32

31.48

31.61

31.76

31.9

5 5

31.9

532

.02

32.1

532

.33

32.38

Longitude:

73°40'

Water

Leve

l Date

32.13

Dec. 2

3"l.81

30.7

830.13

30.2

230.82

30.3

2 3

29.96

29.9

530.23

30.76

31.1

931.63

431

.97

32.1

432.36

32.51

32.69

32.83

532.99

33.03

33.1

833.35

33.5

533

.67

:i" Time

1008

1316

1620

1915

2100

2350 412

710

1030

1439

1754

2105 140

538

1000

1358

1724

2216 106

510

943

1336

1732

2110

21" Time

1014

1320

1622

1915

2105

2355 415

715

1025

1438

1753

2115 145

540

958

1359

1725

2117 105

515

940

1334

1730

2105

Sequ

ence

No

.:

1

Water

Leve

l Da

te

32.46

Dec.

b

32.6

232

.72

32.79

32.8

432.92

33.0

5 7

33.1

033

.14

33.2

533

.30

33.4

4 8

33.5

033

.56

33.5

333

.58

33.6

433.71

933

.74

33.7

533

.73

33.80

33.8

333.80

10

Sequence No.

: 1

Wate

rLe

vel

Date

33.79

Dec.

6

33.9

434.03

34.13

34.1

734

.25

34.35

734.43

34.4

734

.55

34.6

134

.72

834.78

34.8

334

.83

34.9

034

.95

34.98

934.99

35.0

335

.06

35.1

035.12

35.19

10

Time 10510

934

1329

1657

2300 503

927

1323

1732

2122 248

600

945

1318

1705

2123 27

557

938

1305

1705

2140 31

Time

5505

932

1328

1654

2303 507

925

1322

1729

2218 231

558

947

1322

1701

2121 24 552

935

1302

1705

2136 31

Water

Level

Date

33.94

Dec. 10

33.9

533

.95

33.9

533

.97

33.99

1134

.05

33.9

734.01

34.01

34.0

134.01

34.02

34.08

34.0

934.04

34.09

34.0

7 13

34.0

634.14

34.2

334

.24

1434

.22

34.24

Water

Level

Date

35.21

Dec. 10

35.2

435.24

35.2

535

.25

35.26

1135.32

35.37

35.3

435

.33

35.3

335.13

1234

.41

35.39

35.4

235.42

35.4

235

.42

1335

.42

35.4

635.48

35.4

9 14

35.51

35.48

Time 539

925

1354

1720

2131 24547

922

1320

1727

2131 4554

390

913

251827

2155 104

919

1625

2132 44 539

923

Time 531

923

1352

1717

2129 23545

920

1319

1725

2128 4053

9911

1327

1837

2153 101

916

1624

2129 4153

6921

Water

Level

34.24

34.18

34.2

234.20

34.2

534

.26

34.28

34.29

34.33

34.36

34.32

34.3

234

.33

34.3

434.37

34.3

534.38

34.3

434.40

34.4

334

.37

34.3

434

.33

34.32

Water

Leve

l

35.49

35.4

935

.50

35.5

035

.63

35.62

35.6

035

.57

35.61

35.59

35.59

35.6

135.63

35.6

135

.67

35.68

35.69

35.7

035.73

35.68

35.6

935

.67

35.6

335

.66

Date

Dec.

14 15 16 17 18 19

Date

Dec.

14 15 16 17 18 19

Time

1324

1728

2124 27544

921

1348

1650

2020

2359 633

905

1335

1650 923

1330

1736

2340 548

927

1402

1744 927

1327

Time

1322

1725

2122 26542

920

1348

1650

2017

2357 631

905

1335

1650 926

1335

1737

2336 545

928

1400

1742 929

1330

Water

Leve

l

34.3

634

.34

34.3

734

.35

34.35

34.3

634

.44

34.4

534

.43

34.4

434.42

34.4

834.52

34.52

34.41

34.4

234

.37

34.4

834.47

34.4

534

.49

34.4

434

.48

34.4

7

Water

Leve

l

35.6

735

.65

35.67

35.68

35.7

035

.67

35.7

035

.70

35.6

935

.69

35.7

135

.73

35.73

35.7

535

.76

35.7

535

.71

35.7

635

.79

35.7

435

.75

35.7

335

.77

35.7

8

Date

Dec. 19 20 21 22 23 24 25 26 27 28 31

Jan.

2 4

Date

Dec. 19 20 21 22 23 24 25 26 27 28 31

Jan.

2 4

Time

1700 928

1626 28 900

16047

858

1707 56 914

1608 27

1208

1828

1054

1915

1016

1656

1038

1159

1032

1048

1132

Time

1702 930

1630 27 903

16055

859

1709 59 917

1610 35

1207

1825

1052

1912

1018

1659

1039

1201

1034

1050

1129

Water

Leve

l

34.4

834.46

34.5

434

.42

34.4

034

.29

34.2

934

.22

34.1

634

.14

34.08

34.0

834.05

34.0

634

.10

34.2

234

.09

33.6

033

.41

32.2

631

.79

30.8

530

.42

30.2

2

Water

Leve

l

35.7

735.77

35.77

35.7

835

.56

35.5

635

.57

35.5

535

.56

35.54

35.5

035.52

35.5

035

.56

35.5

335

.56

35.47

34.62

34.4

933

.13

32.1

430

.88

30.4

830.15

Ap

pen

dix

. W

ate

r le

vels

in

wel

ls a

t Fo

ster

s B

rook

, N

assa

u C

ount

y, N

.Y.,

Au

gu

st-D

ece

mb

er

1979 C

ontin

ued

8 i i

N-9631

Latitude:

Date

Aug.

7

Sept

. 10

Nov

. 1 6 23 26 27 30

Dec.

1 2

N-9632

Latitude:

Date

Oct. 18

Nov. 16 23 30

Dec.

1 2

40°4

1'51

1-

Time

1105

1230

1135

1305

1120

1331 930

1525

1722

1915

2120

2320 215

515

715

950

1120

1325

1527

1800

1911

2110 15

420

40°4

1'46

"

Time

1000

1200

1350

1535

1727

2220

2330 220

520

720

958

1130

1330

1536

1754

1917

2118 2243

0735

1025

1330

1631

1930

Longitude:

73°40'

Wate

r Le

vel

Date

29.92

Dec.

230

.86

29.58

29.1

129

.30

29.7

629

.54

329

.03

29.03

29.2

729.64

29.84

30.0

030.09

430.14

30.19

30.2

730

.31

30.3

530.39

530

.43

30.46

30.51

30.57

Longitude:

73°40'

Water

Leve

l Da

te

28.0

1 Dec.

228.22

328.16

28.0

027

.97

28.04

28.08

28.3

328

.63

428

.75

28.81

29.0

129

.11

29.18

29.2

3 5

29.2

729.35

29.3

329

.43

29.44

29.5

5 6

29.5

829.64

29.6

9

23" Time 720

1017

1322

1625

1920

2110

1420

720

1034

1443

1755

2125 130

545

1003

1402

1727

2119 108

520

945

1339

1735

25" Time

21205

428

725

1038

1448

1800

2155 200

555

1012

1410

1733

2206 113

530

953

1345

1741

2120 25 530

941

1336

Sequ

ence

No

. :

1

Wate

r Level

Date

30.59

Dec.

5

30.64

630.69

30.70

30.7

430

.72

30.79

30.8

5 7

30.8

530.87

30.78

30.95

31.0

1 8

31.0

531.08

31.0

731

.09

31.15

31.1

8 9

31.21

31.2

331

.22

31.26

31.27

Sequ

ence

No

. :

1

Wate

rLe

vel

Date

29.6

6 Dec. 6

29.6

529

.70

729.72

29.7

129

.61

29.63

29.6

6 8

29.69

29.7

229

.67

29.6

929

.60

29.48

929.44

29.36

29.27

29.2

129.17

29.14

1029

.12

29.07

28.9

728.94

Time

2145 15515

936

1331

1659

2310 511

924

1336

1734

2115 220

552

952

1325

1705

2119 20 549

930

1300

1700

2132

Time

1706

2321 524

934

1331

1741

2215 218

545

1000

1330

1645

2112 1454

0941

1255

1650

2118 21 518

934

1401

Wate

r Le

vel

Date

31.3

3 De

c. 10

31.3

531.37

31.3

731.38

31.3

931.41

1131.45

31.48

31.5

031

.53

31.54

31.5

1 12

31.53

31.6

031

.61

31.5

731

.59

31.59

1331.61

31.65

31.6

831

.70

1431.74

Wate

rLe

vel

Date

28.94

Dec. 10

29.0

029

.44

1129

.51

29.45

29.4

129

.24

29.1

729.11

1229.13

29.0

729

.04

29.00

28.99

28.9

9 13

28.89

28.9

028

.87

28.88

1428.84

28.83

28.77

28.75

Time 28 527

928

1356

1723

2126 21 540

927

1323

1729

2126 36

535

913

1330

1838

2151 59921

1719

2124 38533

Time

1729

2121 18525

934

1328

1729

2123 30 532

922

1334

1847

2145 56

926

1616

2119 30529

930

1330

1711

Wate

r Level

31.69

31.6

931

.70

31.72

31.7

531

.78

31.8

832.18

31.8

831

.83

31.82

31.8

331

.83

31.8

631

.86

31.88

31.92

31.9

531

.98

32.0

032

.06

32.1

532

.11

32.0

8

Water

Leve

l

28.7

628

.79

28.8

929

.19

28.8

428

.77

28.7

328

.79

28.7

928

.77

28.75

28.7

828

.79

28.9

529

.33

29.6

529

.69

29.9

329

.99

30.0

430

.03

30.0

830

.14

Date

Dec. 14 15 16 17 18 19

Date

Dec. 14 15 16 17 18 19

Time 926

1326

1730

2120 24 540

916

1340

1645

2025

1603

902

1332

1640 930

1338

1740

2334 542

930

1358 930

1332

Time

2117 21 531

915

1342

1640

20287

555

900

1330

1635 940

1340

1745

2330 540

935

1354

1735 930

1335

1720

Water

Leve

l

32.07

32.1

032

.10

32.1

132.12

32.1

432

.14

32.1

732

.18

32.1

932

.20

32.2

332

.25

32.2

832

.30

32.3

032.31

32.3

032

.36

32.3

532

.37

32.3

632

.40

32.4

0

Water

Leve

l

30.2

030

.25

30.3

030

.29

30.37

30.4

030

.42

30.4

230

.38

30.5

230

.60

30.6

230

.68

30.72

30.7

130

.78

30.7

730

.80

30.8

230

.83

30.9

030

.92

30.9

2

Date

Dec.

19 20 21 22 23 24 25 26 27 28 31

Jan.

2 4

Date

Dec.

20 21 22 23 24 25 26 27 28 31

Jan.

2 4

Time

1704 934

1635 22

907

16083

905

1712 105

919

1612 40

1204

1823

1050

1409

1020

1700

1040

1205

1036

1054

1126

Time 940

1645 13 924

1613

190

917

18 112

923

1619 51

1200

1819

1044

1906

1024

1705

1043

1211

1040

1058

1120

Wate

r Le

vel

32.4

132.42

32.32

31.85

31.4

531.22

31.05

30.82

30.7

130.44

30.4

530.38

30.32

30.24

30.7

531

.35

31.32

31.0

030

.81

30.42

30.04

29.44

29.2

529

.05

Wate

rLe

vel

30.97

30.7

630

.36

29.78

29.56

29.47

29.2

429

.12

29.0

528

.95

28.9

128

.86

28.8

128.77

29.49

29.4

629

.03

28.9

028

.72

28.57

28.2

728

.14

27.94

Ap

pen

dix

. W

ate

r le

vels

in

wel

ls a

t Fo

ster

s B

rook

, N

assa

u C

ount

y, N

.Y.,

August

-Dece

mber

1979 C

ontin

ued

N-96

33

Lati

tude

:

Date

Aug.

Sept

.Nov.

Dec.

N-96

34

7 10 16 23 26 27 30

1 2

Lati

tude

:

Date

Aug.

Sept.

Nov.

Dec.

7 10 16 23 26 27 30

1 2

40°4

1'46

"

Time

1045

1345

1140

1315

1125

1337 935

1530

1726

1919

2125

2325 220

520

720

955

1126

1329

1535

1750

1915

2115 2042

5

40°41'4r

Time 953

1400

1210

1325

1130

1345 940

1540

1732

1925

2130

2342 225

525

725

1002

1205

1337

1543

1737

1922

2125 27435

740

Long

! ti

Wate

r Le

vel

28.8

528

.69

28.1

828.07

28.0

428

.30

28.04

27.97

27.97

27.9

627

.98

28.0

628

.20

28.3

228.41

28.5

328.60

28.67

28.7

628

.80

28.83

28.87

28.9

528

.98

Long

! ti

Wate

rLe

vel

30.7

629

.94

28.3

228.21

27.8

328.41

28.3

928

.02

27.9

627.89

27.8

227

.82

27.8

528

.44

28.7

628.97

28.9

928.93

28.8

528

.80

28.7

528

.73

28.6

428

.54

28.4

4

ide:

73°4

1'25

"

Date

Time

Dec.

2

723

1022

1326

1630

1925

2115

3 3

425

723

1038

1447

1758

2140

4 15

5550

1008

1408

1731

2121

5 11

0525

945

1342

1739

ide:

73°4

0'27

"

Date

Ti

me

Dec.

2

1032

1340

1633

1745

2125

3 15

432

627

1042

1453

1805

2205

4 205

600

1018

1415

1736

2153

5 11

7535

957

1349

1745

2125

Sequ

ence

No.

: 2

Water

Leve

l Da

te

28.9

9 Dec.

529.08

629.14

29.16

29.17

29.20

29.22

29.23

729

.24

29.23

29.22

29.20

29.24

829

.26

29.27

29.27

29.2

329.25

29.47

929.27

29.19

29.01

28.9

828.96

Sequ

ence

No

. :

1

Water

Leve

l Da

te

28.41

Dec.

6

28.36

28.29

28.22

28.22

28.17

28.11

728

.09

28.01

28.0

327

.94

27.9

9 8

27.9

827

.95

27.8

927.85

27.90

28.0

6 9

27.8

927

.74

27.79

27.82

27.8

027

.80

10

Time

2115 20 520

940

1334

1703

2315 518

932

1329

1738

2210 215

549

956

1327

1645

2110 17543

940

1256

1650

2129

Time 32535

944

1338

1709

2330 535

938

935

1744

2200 212

539

1003

1335

1640

2107 11535

945

1252

1650

2115 18

Water

Leve

l Date

28.9

5 De

c. 10

28.95

28.96

28.91

28.91

28.9

029

.16

1129.21

29.2

029

.20

29.1

529

.08

29.02

1228

.95

28.9

828

.95

28.9

228.82

28.82

1328

.82

28.81

28.8

528.82

1428.85

Wate

rLe

vel

Date

27.80

Dec.

10

27.8

027.77

27.75

27.7

227.81

1130

.68

30.1

829

.80

29.49

29.2

829

.09

1229

.06

28.8

528

.74

28.6

528.54

28.46

1328.37

28.3

428.32

28.2

8 14

28.2

428

.19

Time 2552

1932

1359

1727

2123 20 536

931

1326

1733

2122 33531

919

1333

1842

2146 5492

41614

2121 35

Time 520

938

1403

1733

2117 1653

0937

1331

1737

2119 25527

925

1340

1852

2140 50

929

1609

2116 27 526

933

Wate

r Level

28.83

28.83

28.7

828

.77

28.7

528.77

28.7

728.79

28.7

828

.77

28.74

28.7

728

.77

28.7

728

.73

28.7

428.76

28.9

029

.03

29.3

429.49

29.5

729.57

Wate

rLe

vel

28.1

528.07

28.0

528

.05

28.0

328

.02

28.00

27.97

27.9

427

.86

27.8

627

.84

27.9

227

.83

27.8

327.87

30.15

30.09

30.13

31.54

31.7

131

.92

30.0

232

.19

Date

Time

Dec. 14

53

1928

1328

1708

2118

15

23538

915

1345

1640

2027

16

555

7900

1330

1615

17

933

1339

1743

2330

18

544

933

1336

Date

Time

Dec. 14

1333

1715

2121

15

19528

910

1340

1636

2034

16

10540

855

1325

1630

17

945

1342

1748

2323

18

538

928

1351

1730

19

935

1340

Wate

r Le

vel

29.5

729

.66

29.7

029

.72

29.7

929.81

29.8

429

.88

29.9

629.98

30.0

230

.05

30.1

330.14

30.15

30.19

30.3

330

.35

30.3

630

.37

30.3

730

.43

30.4

7

Water

Leve

l

32.2

932.35

32.48

32.5

032

.58

32.61

32.6

032

.73

32.76

32.73

32.7

232

.79

32.8

632

.88

33.01

33.0

233

.02

33.05

33.07

33.0

933.11

33.1

333.18

33.2

0

Date

Dec. 19 20 21 22 23 24 25 26 27 28 31

Jan.

2 4

Date

Dec. 19 20 21 22 23 24 25 26 27 28 31

Jan.

2 4

Time

1722 938

1640 19

913

1611 6

907

1717 112

1618 43

1201

1820

1048

1904

1022

1704

1044

1208

1038

1056

1123

Time

1725 950

1646 12919

1619

2351 912

1724 125

928

1620 46

1158

1817

1044

1901

1026

1706

1047

1215

1042

1100

1117

Water

Leve

l

30.5

630

.62

30.5

330

.00

29.6

029

.43

29.3

228

.80

29.27

29.7

528

.83

28.81

28.7

328

.75

29.1

029

.14

28.8

228

.75

28.6

228

.50

28.22

28.1

329

.76

Water

Leve

l

35.1

833

.19

33.0

531

.86

30.9

033

.43

30.0

429

.66

29.4

829.37

29.02

28.9

828

.98

28.7

429

.36

31.1

931

.25

29.7

729

.52

29.0

028.62

28.0

527

.85

27.6

2

Ap

pen

dix

. W

ate

r le

vels

in

wel

ls a

t Fo

ster

s B

rook

, N

assa

u C

ount

y, N

.Y.,

August

-Dece

mber

1979 C

ontin

ued

N-96

35

Latitude:

Date

Aug.

7Nov. 16 23 27 30

Dec.

1

N-9636

Lati

tude

:

Date

Oct. 18

Nov. 23 30

1 2

40°4

1'36

"

Time 930

1220

1330

1350 945

1545

1736

1930

2140

2345 230

530

730

1005

1137

1342

1545

1732

1925

2135 40 440

745

1036

40°4

1'29

"

Time

1010

1405

1045

1550

1740

1935

2150

2350 235

535

735

1010

1142

1345

1540

1720

1930

2140 50

450

750

1043

1350

1640

Longitude:

73°4

0'28

"

Water

Level

Date

27.5

2 De

c.

226.80

26.6

926.89

26.5

8 3

26.56

26.5

526.55

26.55

26.54

26.54

26.56

426.54

26.5

526.58

26.5

826

.58

26.55

526

.57

26.5

926.56

26.57

26.5

226.56

6

Long

itud

e:

73°40'

Water

Leve

l Date

26.86

Dec.

226

.82

26.5

1 3

26.12

26.0

726

.07

26.11

26.12

26.0

926.08

426

.12

26.0

226.03

26.0

125

.99

26.00

526.04

26.0

326

.00

25.98

25.91

25.9

2 6

25.9

725

.96

Time

1345

1635

1947

2135 20 435

730

1045

1455

1808

2220 210

605

1022

1420

1740

2141 120

540

1000

1353

1748

2130 39

30" Time

1950

2145 25445

735

1047

1501

1812

2230 215

610

1028

1427

1744

2149 128

545

1005

1357

1752

2135 47 550

952

Sequ

ence

No

.:

1

Water

Level

Date

26.53

Dec.

6

26.5

426

.56

26.55

26.52

26.5

3 7

26.5

426

.49

26.5

426

.49

26.5

6 8

26.5

726

.57

26.5

226

.51

26.5

426

.55

926.56

26.56

26.52

26.5

426

.54

26.56

1026

.56

Sequ

ence

No.

: 1

Wate

rLevel

Date

25.94

Dec.

6

25.8

825.90

25.8

8 7

25.8

925

.84

25.8

025

.79

25.88

825.88

25.8

825

.83

25.7

725

.80

25.8

4 9

25.8

425.84

25.78

25.7

625

.78

25.8

2 10

25.80

25.9

725

.72

Time 540

947

1341

1713

2339 542

943

1340

1749

2152 206

541

1008

1340

1635

21007

510

945

1250

1645

2110 15

517

Time

1345

1718

2342 546

947

1344

1754

2146 200

541

1020

1345

1630

20552

505

1000

1245

1640

2100 10 503

946

Water

Leve

l Da

te

26.5

5 Dec. 10

26.5

226

.52

26.5

226

.58

1127

.01

27.02

26.9

426.77

26.8

126

.76

1226

.76

26.7

226

.69

26.6

626.62

26.5

8 13

26.5

626

.57

26.6

026

.59

1426

.60

26.6

026.60

Wate

rLevel

Date

25.7

2 De

c. 10

25.7

225

.78

28.1

0 11

27.67

27.4

227

.21

27.0

626

.98

26.77

1226

.76

26.6

826

.62

26.4

826

.46

26.4

6 13

26.3

426.31

26.2

8 14

26.1

926

.19

26.17

26.06

Time 942

1405

1737

2113 15

521

940

1335

1740

2114 19523

928

1345

1854

2134 47 933

1557

2113 23 523

936

1335

Time

1410

1743

2106 12518

944

1338

1746

2110 16

518

935

1350

1858

2129 42

1603

2110 19

519

940

1339

1725

Water

Leve

l

26.5

326.53

26.5

226.56

26.5

626

.56

26.5

226.53

26.5

526

.55

26.5

526

.55

26.5

126

.51

26.5

026

.50

26.5

226

.62

26.9

227.11

27. 16

27.2

127

.19

27.2

0

Water

Level

26.03

26.04

26.06

26.03

26.01

25.9

325

.91

25.8

725

.89

25.89

25.89

25.8

825

.88

25.8

625

.85

25.8

428.37

28.74

27.9

028

.11

27.7

627.57

27.3

8

Date

Ti

me

Dec. 14

1720

2110

15

17526

906

1335

1635

2039

16

13536

850

1320

1630

17

945

1342

1750

2319

18

534

941

1347

1727

19

936

1345

1730

Date

Time

Dec.

14

21

0615

13

521

900

1330

1630

2041

16

18533

845

1318

1630

17

950

1340

1755

2313

18

530

945

1336

1723

19

940

1350

1733

Water

Leve

l

27.1

727

.16

27.19

27.16

27.1

527

.09

27.04

27.0

126

.98

26.96

26.96

26.9

626.96

27.09

27.1

327

.08

27.0

827

.09

26.9

826

.99

26.96

26.9

626

.96

26.9

2

Wate

rLevel

27.4

127.24

27.02

26.9

126

.83

26.7

626

.71

26.65

26.5

326.50

26.4

626.43

27.35

27.20

26.9

026

.94

26.9

526.62

26.66

26.49

26.27

26.18

26.36

Date

Dec. 20 21 22 23 24 25 26 27 28 31

Jan.

2 4

Date

Dec. 20 21 22 23 24 25 26 27 28 31

Jan.

2 4

Time 955

16515

927

1623

2318 917

1730 140

933

1623 55

1156

1814

1041

1858

1028

1715

1049

1218

1044

1102

1114

Time 952

1656

2358 933

1630

2344 920

1733 135

937

1628 100

1152

1810

1100

1852

1032

1720

1053

1225

1050

1104

1111

Wate

r Le

vel

26.89

26.9

026

.91

26.8

526

.81

26.79

26.78

26.74

26.73

23.63

26.69

26.6

726

.67

26.6

727.17

27.32

26.99

26.9

027

.76

26.6

626

.50

26.46

26.3

4

Water

Leve

l

26.0

726

.06

26.0

425.96

25.95

25.9

625

.85

25.7

925

.86

25.74

25.8

625

.79

25.7

925

.79

28.39

28.3

127.29

26.9

726

.70

26.35

25.8

925

.97

25.66

Ap

pen

dix

. W

ater

lev

els

in w

ells

at

Fost

ers

Bro

ok,

Nas

sau

Cou

nty,

N.Y

., A

ugust

-Dece

mber

1979 C

ontin

ued

N-9637

Lati

tude

:

Date

Sept.

11 19 16 23 26 27 30

Dec.

1

N-96

38

Lati

tude

:

Date

Sept.

19Nov.

16 23 26 27 30

Dec.

1

N-9639

Latitude:

Date

Sept.

11Oc

t.

18Nov.

16 23 26 29 30De

c.

1

40°42' Lo

ngit

ude:

Time

-c

1345

1100 940

1405

1005

1435

1202

1805 29

1452

40°41'59"

Time

1130 950

1455

1000

1430

1157

1800 15

1450

2210

40°41'59"

Time

1400 850

955

1425

1010

1152

1808 45

1445

2214

Water

Level

30.13

30.00

29.77

29.73

29.77

29.68

29.66

29.61

29.63

29.61

Longitude

Water

Leve

l

30.48

30.17

30.19

29.86

30.16

30.19

30.06

30.07

30.11

30.15

Longitude:

Water

Level

31.21

31.11

30.85

30.75

30.70

30.67

30.62

30.65

30.69

30.72

73°4

0'30

"

Date

Dec.

1 2 3 4 5 6

: 73

"40'

Date

Dec.

2 3 4 5 6

; 73

°40'

Date

Dec.

2 3 4 5 6 7

Sequence No.:

J

Time

2205

1445

2320

1555 255

1325 210

1345 42

1312

23" Ti

me

1435

2320

1549 250

1328 140

1348 40

1317

2348

15" Ti

me

1432

2325

1545 230

1333 145

1452 28

1320

1

Water

Leve

l

29.64

29.59

29.63

29.64

29.69

29.69

29.69

29.70

29.74

29.73

Sequence No

. :

Water

Level

29.77

30.18

30.24

30.33

30.31

30.36

30.40

30.48

30.49

30.57

Sequ

ence

No

. :

Wate

r Leve

l

30.7

030.74

30.76

30.84

30.87

30.89

30.93

30.97

30.99

31.04

.

Date

Dec.

6 7 8 9 10 11

1

Date

Dec.

7 8 9 10 11

1

Date

Dec.

7 8 9 10 11 12

Time

2353

1305 120

1226 214

1230 28

1320 18

1355

Time

1309 115

1225 212

1225 25

1322 16

1350

Time

1325 109

210

1221 18

1328 15

1348 2

Water

Level

29.80

29.85

29.77

29.81

29.87

29.80

29.83

29.83

29.86

29.83

Water

Level

30.56

30.60

30.65

30.66

30.69

30.73

30.75

30.78

30.79

Water

Level

31.02

31.10

31.07

31.07

31.11

31.14

31.15

31.15

31.18

Date

Dec.

11 12 13 14 15 16

Date

Dec.

11 12 13 14 15

Date

Dec.

12 13 14 15 16

Time

2355

1330 28

1328 12

1409 8

1305

2305

1305

Time

2359

1333 25

13239

1413 4

1300

2309

Time

1335 21

1320 8

1418

11256

2312

1300

Wate

r Level

29.87

29.84

29.87

29.87

29.89

29.86

29.84

29.85

29.85

29.91

Water

Level

30.82

30.85

30.84

30.89

30.91

30.88

30.91

30.90

30.90

Wate

r Level

31.17

31.22

31.21

31.18

31.17

31.15

31.17

31.18

31.21

Date

Dec.

17 18 19 20 21 22 23

Date

Dec.

16 17 18 19 20 21 22 23

Date

Dec.

17 18 19 20 21 22 23

Time

1340

2257

1310

1350

1010 945

935

205

1002

Time

1305

1345

2254

1314

1315

1016 947

940

200

Time

1350

2248

1318

1400

1020 955

943

210

955

Water

Level

29.90

29.85

29.88

29.89

29.87

29.88

29.94

29.89

29.74

Water

Level

30.93

30.92

31.01

30.93

30.95

30.89

30.94

30.96

30.95

Water

Level

31.19

31.20

31.20

31.22

31.14

31.20

31.25

31.19

31.15

Date

Dec.

24 25 26 27 28 31

Jan.

2 4

Date

Dec.

23 24 25 26 27 28 31

Jan.

2 4

Date

Dec.

24 25 26 27 28 31

Jan.

2 4

Time 107

1143

1031

1610

1107

1230

1100

1116

1107

Time 957

111

1027

1620

1109

1234

1104

1118

1103

Time 115

1136

1024

1623

1112

1239

1105

1120

1058

Water

Level

29.89

29.92

29.93

29.84

29.67

29.73

29.65

29.59

29.50

Water

Level

30.90

30.97

30.97

30.81

30.69

30.59

30.34

30.22

30.03

Water

Level

31.20

31.24

31.25

31.08

30.95

30.87

30.73

30.66

30.54

App

endi

x. W

ater

lev

els

in w

ells

at

Fost

ers

Bro

ok,

Nas

sau

Cou

nty,

N.Y

., A

ugus

t-D

ecem

ber

19

79

Co

ntin

ue

d

N-96

AO

Latitude:

Date

Sept.

Oct.

Nov.

Dec.

N-96A1

11 18 16 23 26 30

1

Latitude:

Date

Sept.

Oct.

Nov.

Dec.

11 18 16 23 26 30

1

AO°A1'59"

Time

1AA5 830

1000

1A30

1015

1148

1814 52

1510

2218

AO°A1'58"

Time

1AA5 820

1005

1AAO

1020

11A2

1817 58

1A35

2221

Longitude

Water

Level

31. A7

31.57

31.1

731.06

31. OA

30.98

30.95

31.09

30.99

30.97

Long

itud

e:

Water

Level

31.65

31.56

31.31

31. 2A

31.22

31.22

31.13

31. 1A

31.13

31.16

: 73°AO'

Date

Dec.

2 3 A 5 6 7

: 73°39'

Date

Dec.

2 3 A 5 6 7

9"

Sequ

ence

No

. :

1

Time

1428

2330

15AO 2AO

1326 150

1355 20

132A 6

58" Ti

me

1A23

2335

1537 310

1328 155

1AOO 12

1328 12

Water

Level

Date

30.93

Dec.

7

30.95

830. 9A

30.99

930.99

30.98

1030.99

31. OA

1131.02

31.08

12

Sequ

ence

No

. :

1

Water

Level

Date

31.11

Dec.

731.10

831.08

31. 1A

931.13

31.09

1031.11

31.13

1131.10

31.13

12

Time

1328 101

1215 28

1215 12

1330 8

13A5 6

Time

1331 57

1206 25

1210 10

133A A

13A2 9

Water

Level

Date

31.01

Dec. 12

31.01

1331

. OA

31.05

1A31.01

31.06

31. OA

1531.06

31.03

1631.09

Water

Level

Date

31.08

Dec. 12

30.92

1331.13

31.05

1A31.08

31.08

31.09

1531.06

31.05

1631.06

N-96

40

Latitude:

40°A1'

Time

13AO 17

13175

1A23

2358

1253

2317

1258

Time

1342 11

13151

1A27

2355

12A5

2321

1252

Water

Level

31. OA

31.07

31.07

31.12

31.0

331.02

31.02

31.03

31.09

Water

Level

31.06

31.05

31.06

31.05

30.91

30.98

30.86

30.83

30. 8A

'59" Longitude:

73'

Date

Dec.

17 18 19 20 21 22 23

Date

Dec. 17 18 19 20 21 22 23

Time

1350

22AA

1322

1A05

1025 957

9A6

215

953

Time

1355

22A1

1325

1A10

1028 104

951

220

950

'40 '9

" Se

quen

ce No.

Water

Level

31.05

31.06

31.03

31.03

30.98

31.02

31.00

31.02

30.96

Water

Level

30.93

30.99

31.00

31.01

30.97

30.95

30.97

30.96

30.90

Date

Dec. 2A 25 26 27 28 31

Jan.

2 A

Date

Dec. 2A 25 26 27 28 31

Jan.

2 A

: 1

Time 121

1132

1021

1630

111A

12A3

1107

1122

1053

Time 125

1130

1018

1635

1117

12A5

1109

112A

10A9

Water

Level

31. OA

31.05

31.10

31.0

230.95

30.93

30.87

30.8

330

. 7A

Water

Level

30.96

30.99

31.06

31.05

30.97

30.96

30.92

30.89

30.85

CONVERSION FACTORS AND ABBREVIATIONS

The following factors may be used to convert the units of measurement In

this report to the International System of Units (metric system).

Multiply

inch (in)

feet (ft)

miles (mi)

square miles (mi2\

cubic feet per second (ft3/s )

gallons per minute per foot Ugal/min)/ft]

feet per day (ft/d)

Inch-Pound Units

by.

2.54

.3048

1.609

2.59

28*32

.02832

.01923

.3048

To obtain

centimeters (cm)

meters (m)

kilometers (km)

square kilometers (km?)

liters per second (L/s)

cubic meters per second (m3/s)

liters per second per meter {(L/s)/m]

meters per day (m/d)

millimeter (mm)

centimeter (cm)

gram (g)

degrees Celsius (°C)

SI Units

.03937

.3937

.03527

(1.8 + 32)

inch (in)

inch (in)

ounce (02)

degrees Fahrenheit (°F)

Other Abbreviations

National Geodetic Vertical Datum of 1929 (NGVD) (formerly mean sea level)

Milligrams per liter (mg/L)

Micrograms per liter (mg/L)

Conversion Factors and Abbreviations 43

streamflow augmentation at fosters brook, long island, new ... · streamflow augmentation at...

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