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 wastewa- ter.
Purpose and Scope
The effects of sanitary sewers on Long Island's hy- drologic 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 hy- drologic 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
10 Streamflow Augmentation at Fosters Brook, New York
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.
12 Streamflow Augmentation at Fosters Brook, New York
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.
Results of Streamflow Augmentation 13
LLJo< Ru_ 5 DC
15
Approximate location of water table
ceD
15
B
Approximate location of water table
20 30 40
SOIL MOISTURE, IN VOLUME PERCENT
20 30 40
SOIL MOISTURE, IN VOLUME PERCENT
o-
o
£10o
Approximate location of water table
Increased soil moisture
Approximate location of water table
20 30 40
SOIL MOISTURE, IN VOLUME PERCENT
20 30 40
SOIL MOISTURE, IN VOLUME PERCENT
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,
Results of Streamflow Augmentation 15
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
16 Streamflow Augmentation at Fosters Brook, New York
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
18 Streamflow Augmentation at Fosters Brook, New York
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
Factors Affecting Seepage Rates 19
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
TIME, IN DAYS SINCE AUGMENTATION BEGAN
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)/infilt- ration 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
Factors Affecting Seepage Rates 21
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
TIME, IN DAYS SINCE AUGMENTATION BEGAN
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
22 Streamflow Augmentation at Fosters Brook, New York
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.
24 Streamflow Augmentation at Fosters Brook, New York
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
TIME, IN DAYS SINCE AUGMENTATION BEGAN
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.
26 Streamflow Augmentation at Fosters Brook, New York
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-
28 Streamflow Augmentation at Fosters Brook, New York
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
30 Streamflow Augmentation at Fosters Brook, New York
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