Generalized Estimates from Streamflow 

Data of Annual and Seasonal GroundWater-Recharge Rates for Drainage 

Basins in New Hampshire

By Robert H. Flynn and Gary D. Tasker

U.S. Department of the Interior

U.S. Geological Survey

In cooperation with the

New Hampshire Department of Environmental Services

Scientific Investigations Report 2004-5019
U.S. Department of the Interior

Gale A. Norton, Secretary

U.S. Geological Survey

Charles G. Groat, Director

U.S. Geological Survey, Pembroke, New Hampshire: 2004

For sale by U.S. Geological Survey, Information Services

Box 25286, Denver Federal Center

Denver, CO 80225

For more information about the USGS and its products:

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Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply 

endorsement by the U.S. Government.

Although this report is in the public domain, permission must be secured from the individual copyright owners to

reproduce any copyrighted materials contained within this report.
 iii

Contents

Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Purpose and Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Previous Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Description of Study Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Database Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Streamflow Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Precipitation Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Basin-Characteristics Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Methods of Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Ordinary-Least-Squares Regression Equations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Generalized-Least-Squares Regression Equations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Regional Regression for Normalized Annual and Seasonal Recharge Using 

Generalized-Least-Squares Regression . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Estimates of Annual and Seasonal Ground-Water-Recharge Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Estimation of Ground-Water-Recharge Rates from Stream-Gaging Station Data . . . . . . . . . . . . . . . . . . . . . 13

Normalization of Ground-Water-Recharge Rates Using Precipitation Data . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Generalized Estimate of Drainage-Basin Ground-Water-Recharge Rates Using Climatic 

and Basin Characteristics Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Ground-Water-Recharge Regression Equations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Regression Model Adequacy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Physical Basis for the Independent Variables in the Regression Equations . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Uncertainties in Determining Ground-Water Recharge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Limitations on the Use of Regression Equations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Summary and Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Selected References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Appendix 1. Basin and Climate Characteristics Tested for Significance in the Ground-Water Recharge 

Regression Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Reference Cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Figures

1–2. Maps showing—

1. Locations of streams, drainage basins, and stream-gaging stations in the study area 

that were used to develop the equations for estimating ground-water-recharge 

statistics for New Hampshire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

2. Locations of drainage basins, associated towns, and physiographic provinces in 

the study area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

3–7. Graphs showing distribution of rates of ground-water recharge in New Hampshire for:

3. Annual (January 1–December 31) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

4. Winter (January 1–March 15). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
iv 

5. Spring (March 16–May 31). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

6. Summer (June 1–October 31). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

7. Fall (November 1–December 31) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

8–12. Maps showing drainage basins that were used to develop the equations for estimating groundwater-recharge statistics in New Hampshire showing the proportion (in percent) of normalized 

ground-water recharge to basin-centroid precipitation for:

8. Annual (January 1–December 31) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

9. Winter (January 1–March 15). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

10. Spring (March 16–May 31). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

11. Summer (June 1–October 31) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

12. Fall (November 1–December 31). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Tables

1. Descriptions of stream-gaging stations used to develop the regression equations for estimating 

ground-water recharge in New Hampshire drainage basins. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

2. Basin characteristics for stream-gaging stations used in the ground-water recharge 

regression-analysis equations for New Hampshire drainage basins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

3–7. Normalized basin recharge rates determined from basin-specific regression equations 

relating Rorabaugh-method-determined ground-water-recharge rates and basin-centroid 

precipitation for:

3. Annual (January 1–December 31) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

4. Winter (January 1–March 15) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

5. Spring (March 16–May 31) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

6. Summer (June 1–October 31) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

7. Fall (November 1–December 31) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

8. Values of seasonal and annual basin-centroid precipitation and normalized ground-water 

recharge and the proportion (in percent) of normalized seasonal and annual ground-water

recharge to seasonal and annual basin-centroid precipitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

9–13. Ground-water recharge statistics, standard error of prediction, and 90-percent prediction 

interval estimated using available data and regression-equation predicted values for:

9. Annual (January 1–December 31) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

10. Winter (January 1–March 15). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

11. Spring (March 16–May 31). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

12. Summer (June 1–October 31). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

13. Fall (November 1–December 31). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

14. Summary of regression equations and measures of model adequacy for estimating 

ground-water-recharge statistics at selected New Hampshire stream-gaging stations . . . . . . . . . . . 20

15. Ranges of basin characteristics used to develop the regression equations for estimating 

ground-water-recharge rates in New Hampshire drainage basins. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
 v

Conversion Factors, Vertical Datum, 

Abbreviations, and Acronyms

Temperature in degrees Fahrenheit (°F) may be converted to degrees Celsius (°C) as follows:

°C = (°F - 32) / 1.8

Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929 

(NGVD 1929).

ABBREVIATIONS AND ACRONYMS USED IN THIS REPORT

Organizations

CSRC Complex Systems Research Center at the University of New Hampshire

ESRI Environmental Systems Research Institute

NCDC National Climate Data Center

NHDES New Hampshire Department of Environmental Services

NRCS Natural Resources Conservation Service

UNH University of New Hampshire

USGS U.S. Geological Survey

Basin Characteristics

ABT Average mean annual basin temperature, in degrees Fahrenheit

ACP Average annual basin-centroid precipitation, in inches

AGP Average annual gage precipitation, in inches

ASC Average annual basin snowcover, in inches

C Coniferous forest in the drainage basin, in percent

CD Mixed coniferous/deciduous forest in the drainage basin, in percent

FCP Average fall basin-centroid precipitation, in inches 

Multiply By To obtain

Length

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square mile (mi2) 2.590 square kilometer (km2)

Flow rate

foot per day (ft/d) 0.3048 meter per day (m/d)

cubic foot per second (ft3/s) 0.02832 cubic meter per second (m3/s)

gallon per day (gal/d) 0.003785 cubic meter per day (m3/d)

inch per year (in/yr) 25.4 millimeter per year (mm/yr)
vi 

SGP Average summer gage precipitation, in inches

SpGP Average spring gage precipitation, in inches

WBT Average mean winter basin temperature, in degrees Fahrenheit

Miscellaneous

APE Average Prediction Error of Model

AP-RASA Appalachian and Piedmont physiographic provinces Regional Aquifer

System Analysis

ARC-INFO ESRI GIS spatial analysis software

DEM Digital elevation model of topography 

EGLS Estimated generalized-least-squares

GIS Geographic information system

GLS Generalized-least-squares regression analysis

GLSNET Generalized-least-squares network computer software

HUC Hydrologic unit code

IDW Inverse Distance Weighting

MSE Mean square error 

NLCD National Land Cover Dataset

OLS Ordinary-least-squares regression analysis 

PRESS Predicted REsidual Sum of Squares statistic

PRISM Parameter-elevation regressions on independent slopes model

R2adj Adjusted R squared

RSQUARE All-possible-regression algorithm in SAS

RORA Recession-curve-displacement computer program

RECESS Streamflow recession index computer program

SAS Statistical analysis system computer software

STATSGO State soil geographic data base

VIF Variance inflation factor

WLS Weighted-least-squares regression analysis
Generalized Estimates from Streamflow Data of 

Annual and Seasonal Ground-Water-Recharge Rates for 

Drainage Basins in New Hampshire

By Robert H. Flynn and Gary D. Tasker

Abstract

This report presents regression equations to estimate generalized annual and seasonal ground-water-recharge rates in 

drainage basins in New Hampshire. The ultimate source of 

water for a ground-water withdrawal is aquifer recharge from a 

combination of precipitation on the aquifer, ground-water flow 

from upland basin areas, and infiltration from streambeds to the 

aquifer. An assessment of ground-water availability in a basin 

requires that recharge rates be estimated under ‘normal’ conditions and under assumed drought conditions.

Recharge equations were developed by analyzing streamflow, basin characteristics, and precipitation at 55 unregulated 

continuous record stream-gaging stations in New Hampshire 

and in adjacent states. In the initial step, streamflow records 

were analyzed to estimate a series of annual and seasonal 

ground-water-recharge components of streamflow in each 

drainage basin evaluated in this study. Regression equations 

were then developed relating the series of annual and seasonal 

ground-water-recharge values to the corresponding series of 

annual and seasonal precipitation values as determined at the 

centroid of each drainage basin. This resulted in one equation 

for each of the 55 basins for each of the four seasonal periods 

and the annual period, or a total of 275 regression equations. 

Average annual and seasonal precipitation data for 1961–90 

were then used to compute a set of normalized ground-waterrecharge values that reflected the long-term average annual and 

seasonal variations (normalized) and mean recharge characteristics of each drainage basin. Ordinary-least-squares regression 

was applied in the process of selecting 10 out of 93 possible 

basin and climatic characteristics for further testing in the 

development of the equations for computing the generalized 

estimate of annual and seasonal ground-water recharge based 

on the set of normalized recharge values. Generalized-leastsquares regression was used for the final parameter estimation 

and error evaluation. The following basin and climatic characteristics were found to be statistically significant predictors for 

at least one of the dependent variables: average annual, summer, and spring precipitation as determined at U.S. Geological 

Survey stream-gaging stations; average annual basin-centroid 

precipitation; average mean annual basin temperature; average 

minimum winter basin temperature; percent coniferous forest in 

a basin; percent mixed coniferous and deciduous forest in a 

basin; average fall basin-centroid precipitation; and average 

annual snowcover. These 10 basin and climatic characteristics 

were selected because they were statistically significant based 

on several statistical parameters that evaluated which combination of characteristics contributed the most to the predictive 

accuracy of the regression-equation models. A geographic 

information system is required to measure the values of the predictor variables for the equations developed in the study. 

The average annual normalized ground-water recharge 

was 21.0 in. This value was determined by generalized-leastsquares (GLS) regression analysis for all of the basins used in 

the normalized ground-water recharge analysis for precipitation 

from 1961-90. The average winter (January 1–March 15) 

ground-water recharge was 4.3 in., average spring (March 16–

May 31) ground-water recharge was 9.0 in., average summer 

(June 1–October 31) ground-water recharge was 4.0 in., and 

average fall (November 1–December 31) ground-water 

recharge was 3.6 in. Normalized ground-water recharge ranged 

annually from 12.3 to 31.8 in., for winter from 2.30 to 7.82 in., 

for spring from 5.16 to 13.7 in., for summer from 1.45 to

10.2 in., and for fall from 2.21 to 6.06 in.

Introduction

The population of New Hampshire is growing faster than 

in any other State in the northeastern United States. The population grew by approximately 141,000 people or 11.4 percent 

from 1990 to 2000 (New Hampshire State Data Center, 2001). 

Another 215,000 people are expected to live in the State by the 

year 2025 (New Hampshire State Data Center, 2001). An 

increase in population and industry, especially along the seacoast and south-central New Hampshire, has resulted in an 

increased demand for water. 

The development of large ground-water supplies associated with rapid population growth in New Hampshire has raised 

concern regarding the sustainability of the water supply and the 

balancing of competing demands between various water users. 

New, large withdrawals may have adverse effects on existing 
2 Streamflow Data of Annual and Seasonal Ground-Water Recharge Rates for Drainage Basins in New Hampshire

wells, streamflows, and wetlands. Recent development of large 

ground-water supplies in the seacoast region of New Hampshire 

may be in competition with existing uses and has raised concern 

for environmentally sensitive areas. 

In 1998, the New Hampshire Ground Water Protection Act 

and the New Hampshire Safe Drinking Water Act were 

amended to require that potential effects from large groundwater withdrawals be identified and addressed during the permitting process. The legislation requires the New Hampshire 

Department of Environmental Services (NHDES) to develop 

procedures to insure that any new, large ground-water withdrawal (a withdrawal that exceeds 57,600 gal/d over any

24-hour period) does not adversely affect existing ground-water 

users or water resources. To accomplish this, hydrologic tools 

are needed that can be used to assess regional hydrologic conditions. Such tools would be useful to water-resources managers in administering New Hampshire regulatory programs associated with source-water and drainage-basin protection.

Determination of ground-water-recharge values will aid 

Federal, State and local officials, and private interests in making 

water-resource, regulatory, and management decisions. The 

U.S. Geological Survey (USGS), in cooperation with the 

NHDES, has developed datasets, hydrologic statistical relations, and a geographic information system (GIS) of data coverages for all of New Hampshire to better understand water 

availability. This information provides a basis for sustainable 

water management for the benefit of water users and the environment. 

Ground-water recharge is commonly defined as the volume of water reaching the saturated zone by downward infiltration of water, primarily from precipitation. For the purposes of 

this study, ground-water recharge is the long-term average 

observable recharge, which is defined as that part of recharge 

that becomes observable as streamflow in a drainage basin. 

Recharge flowing out of a drainage basin as ground water, or 

that which is lost to evapotranspiration, is considered unobservable. Sources of ground-water recharge include rainfall, seepage from streams and lakes, percolation of applied irrigation 

water, effluent from septic-tank drainage fields, leakage from 

water and sewer conduits, and wastewater discharged to the 

ground surface. The amount of precipitation, which becomes 

ground-water recharge under natural conditions, is affected by 

many factors including (1) texture and gradation of surface and 

near-surface deposits and their vertical permeability; (2) nature 

and water requirements of the vegetation; (3) frequency, intensity, and volume of rainfall; (4) topography; and (5) temperature 

(American Society of Civil Engineers, 1987). The amount of 

ground-water recharge can be increased and ground-water flow 

to surface-water bodies can be reduced as a result of withdrawal 

of ground water. In addition, the direction of ground-water flow 

to a surface-water body can be reversed by nearby pumped 

wells that can cause water to flow from surface-water bodies to 

aquifers. 

Purpose and Scope

The purpose of this report is to present a method for the 

generalized estimates of annual and seasonal ground-waterrecharge rates in New Hampshire drainage basins. This report 

describes (1) an indirect method, called the recession-curvedisplacement method, for determining a series of annual and 

seasonal ground-water-recharge rates at 55 unregulated streamgaging stations in New Hampshire and in adjacent states; (2) the 

relation of the series of annual and seasonal ground-waterrecharge values to the corresponding series of annual and seasonal basin-centroid precipitation values for each drainage 

basin through regression analyses; (3) the development of a set 

of normalized annual and seasonal ground-water-recharge values corresponding to average annual and seasonal basin precipitation from 1961 to 1990; (4) the development of regression 

equations to relate normalized ground-water recharge to basin 

and climatic characteristics that can be used to determine 

ground-water recharge in any basin in New Hampshire; and 

(5) the spatial variation and uncertainty in the regressionderived ground-water-recharge rates. Ground-water-recharge 

rates developed in this report approximate the average recharge 

rates for the period from 1961 to 1990. 

Previous Studies

Previous studies used streamflow data to make estimates 

of ground-water recharge rates. These include studies in Michigan (Holtschlag, 1997), Maine (Morrissey and others, 1988), 

Nevada (Savard, 1998), Massachusetts (Bent, 1995 and 1998), 

Tennessee (Hoos, 1990), and Valley and Ridge, Blue Ridge, 

and Piedmont Physiographic Provinces of the eastern and 

southeastern United States (Rutledge and Mesko, 1996).

Description of Study Area

New Hampshire encompasses an area of 8,973 mi2 of 

which 309 mi2 is water (New Hampshire State Data Center, 

2001) (fig. 1). The State is in the Seaboard Lowland, New 

England Upland, and White Mountain sections of the New 

England Physiographic Province (Fenneman, 1938). The southeastern part of the State primarily is coastal plain, the central 

region primarily is lowland and foothills, and the northern part 

primarily is mountainous. The elevation and amount of topographic relief gradually increase from south to north. Precipitation ranges from an annual mean of about 35 in. in the Connecticut and Merrimack River valleys to about 90 in. on the summit 

of Mt. Washington (Hammond, 1989). Typically, statewide, the 

driest month is February. The wettest months are November and 

December in the area south of the White Mountains, and June, 

July, and August in the area north of the White Mountains 

(Hammond, 1989). Average runoff ranges from 18 in/yr in parts 

of the Connecticut River Valley and seacoast area to about 

42 in/yr in the White Mountains. Streamflow varies both seasonally and geographically. High flows typically occur during
Introduction 3

27 Stream-gaging station 

 and reference number

55

5

28

1

54

53

44

44 43

39

3

4

33

32 2

35

6

7

36

38 37

13

48

50

49

46

42

16

20

18

22

10

11

Mink Brk.

Mascoma R.

West Branch

Cold R.

Stony Brk.

Beards Brk.

Mohawk R.

Dudley Brk.

Priest Brk.

Moss Brk.

6

Otter Brk.

9

24

Kirby Brk.

East Orange Branch

South Branch

Kent Brk.

Flood Brk.

Saxtons R.

Beaver Brk.

Sacketts Brk.

Wild R.

Big Brk.

Lucy Brk.

Swift R.

Ellis R.

Parker R.

Nashoba Brk.

Millers R.

Saco R.

South Branch

Manchester

Concord

Deerfield R. Ayers Brk.

Beaver Brk.

Stevens Brk.

12

14

Little Androscoggin R

19

17

29

41

40

Drainage basin 

 and boundary

30

34

31

8

15

51

45

47

52

23

21

26

25

0

2

Base from U.S. Geological Survey

Digital data, 1983, 1:24,000 or 1:25,000

Figure 1. Locations of streams, drainage basins, and stream-gaging stations in the study area that were used to 

develop the equations for estimating ground-water-recharge statistics for New Hampshire. (For detailed information 

on the stations, refer to table 1.)
4 Streamflow Data of Annual and Seasonal Ground-Water Recharge Rates for Drainage Basins in New Hampshire

March, April, and May and are caused by the melting snowpack 

and concurrent precipitation (U.S. Geological Survey, 1990). 

Snowfall ranges from about 50 in/yr along the coast to approximately 100 in/yr in the White Mountains (Hammond, 1989).

New Hampshire is in the glaciated Appalachian groundwater region (Billings, 1956). The bedrock consists of metasedimentary rock in approximately two-thirds of the State and 

intrusive rock in the other third (Billings, 1956). The two principal types of aquifers in New Hampshire are stratified-glacial 

drift and crystalline bedrock. Till is the most extensive glacial 

deposit in New Hampshire and is either buried beneath stratified-drift deposits in valleys or lowlands, or overlies bedrock in 

upland areas (Flanagan and others, 1999). Other stratified-drift 

deposits include marine clays and fine- and coarse-grained 

sands along the seacoast, outwash sands and gravels, and fineand coarse-grained glacial-lake deposits (Medalie and Moore, 

1995). Stratified-drift deposits are primarily in the valleys of 

major streams. The lowlands and foothills region of New 

Hampshire has thicker deposits of till on the slopes and more 

prevalent and larger areal distributions of stratified drift along 

streams than elsewhere in the state.

Soils in New Hampshire are predominantly grouped into 

two soil hydrologic classifications (U.S. Department of Agriculture’s State Soil Geographic (STATSGO) soils database, 

1991; U.S. Geological Survey, 1997; and Schwarz and Alexander, 1995). These classifications include (1) soils with moderate infiltration rates (deep and moderately deep soils, moderately well and well-drained soils with moderately coarse 

textures), and (2) soils with slow infiltration rates (soils with 

layers impeding downward flow of water or soils with moderately fine textures). Soils with moderate infiltration rates occur 

in areas of high slope, such as the White Mountains, and in areas 

of stratified-drift deposits. Soils with slow infiltration rates 

occur in areas where glacial till is commonly found at the surface. STATSGO soils classifications reflect properties of soils 

that affect the residence time and amount of precipitation percolating into the soil surface (Flanagan and others, 1999). 

Three general land-use categories are defined by the New 

Hampshire Division of Forests and Lands (1997). These categories are forest land, farm land, and other nonforest land. New 

Hampshire is the second most forested state in the United 

States, according to the New Hampshire Division of Forests and 

Lands (1997). Forest land is classified as either timberland or 

noncommercial. Timberland is capable of producing timber 

crops and is potentially available for harvesting. Noncommercial forest land includes productive but reserved forest lands, 

unproductive forests, and urban forests. In 1997, forest land 

constituted 84 percent of land in New Hampshire, farm land 

constituted 3 percent, and other nonforest land (including 

urbanized and industrial areas) constituted 13 percent (New 

Hampshire Division of Forests and Lands, 1997).

Database Development

Streamflow, precipitation, and basin-characteristics data 

were compiled for this study from several sources. Streamflow 

data were obtained from USGS stream-gaging stations to estimate ground-water recharge. Precipitation data were obtained 

from the National Climate Data Center (NCDC) digitalprecipitation database as compiled by EarthInfo, Inc. (2000) to 

develop a relation with the ground-water recharge. The 

2-kilometer grid Parameter-elevation Regression on Independent Slopes Model (PRISM) precipitation data for 1961–90 was 

used to normalize ground-water recharge. The NCDC database 

contains precipitation-gage data beginning with the year 1949. 

Basin-characteristics data were measured within a GIS with the 

spatial analysis software ARC-INFO (Environmental Systems 

Research Institute, Inc., 1994) using available and created data 

layers to develop a generalized estimate of ground-water 

recharge.

Streamflow Data

The USGS operates a network of stream-gaging stations 

that provide continuous information on streamflow throughout 

the United States. From active and discontinued stations in New 

Hampshire and adjacent states, 60 unregulated stations were 

initially chosen for this study and between 48 and 55 stations 

were used in determining final annual and seasonal groundwater-regression equations. The 55 stream-gaging stations that 

were selected met the following criteria: (1) a minimum of

10 years of continuous record data from 1948 through 1998 

(shorter records may not provide a sufficient sample of the temporal variations in streamflow), (2) no effects of regulation, 

diversion, or augmentation on streamflow, and (3) surface- and 

ground-water divides that are thought to be approximately coincident. For continuous-record stream-gaging stations on 

streams with regulated and unregulated records, only the unregulated records were selected for determining annual and seasonal ground-water-recharge characteristics. Daily mean flows 

at the unregulated stations were used to determine ground-water 

recharge. 

The names and descriptions of the stream-gaging stations 

are in table 1. Locations of the stations, streams, and associated 

drainage basins are shown on figure 1. The locations of the New 

Hampshire towns, associated drainage basins, and physiographic provinces are shown on figure 2.

The seasonal periods for the ground-water-recharge statistics were defined by the NHDES to manage surface-water supplies for the following seasons: winter (January 1–March 15), 

spring (March 16–May 31), summer (June 1–October 31), and 

fall (November 1–December 31).
Database Development 5

Table 1. Descriptions of stream-gaging stations used to develop the regression equations for estimating ground-water recharge in 

New Hampshire drainage basins.

[No., number; fig., figure; mi2, square miles]

Streamgaging 

station 

reference 

No.

(fig. 1)

Streamgaging 

station 

No.

Latitude

(decimal 

degrees)

Longitude

(decimal 

degrees)

River name Location

Stream-gaging 

station period 

of record, 

year

Streamgaging station 

ground-water 

recharge 

period of 

record, 

year

Drainage 

area

(mi2

)

1 1052500 44.8778 71.0569 Diamond River Wentworth Location, N.H. 1941-present 1949-present 153

2 1054200 44.3908 70.9797 Wild River Gilead, Maine 1964-present 1964-present 69.9

3 1054300 44.5936 70.7336 Ellis River South Andover, Maine 1963-82 1963-82 130

4 1055000 44.6422 70.5881 Swift River Near Roxbury, Maine 1929-present 1949-present 96.8

5 1057000 44.3033 70.5394 Little Androscoggin River Near South Paris, Maine 1913-24, 

1931-present

1949-present 74.1

6 1064300 44.2200 71.2500 Ellis River Near Jackson, N.H. 1963-present 1963-present 10.5

7 1064400 44.0694 71.1750 Lucy Brook Near North Conway, N.H. 1964-92 1964-92 4.68

8 1064500 43.9908 71.0914 Saco River Near Conway, N.H. 1903-12, 

1929-present

1949-present 385

9 1072850 43.2631 71.0972 Mohawk River Center Strafford, N.H. 1964-77, 1964-77 7.47

10 1073000 43.1486 70.9656 Oyster River Durham, N.H. 1934-present 1949-present 12.2

11 1073600 42.9936 71.0233 Dudley Brook Exeter, N.H. 1962-85 1962-1985 5.85

12 1075000 43.9761 71.6800 Pemigewasset River Woodstock, N.H. 1940-77 1949-1977 195

13 1075800 43.8367 71.8853 Stevens Brook Wentworth, N.H. 1963-98 1963-1998 3.29

14 1076000 43.7961 71.8450 Baker River Rumney, N.H. 1929-75 1949-75 143

15 1076500 43.7592 71.6861 Pemigewasset River Plymouth, N.H. 1903-present 1949-present 623

16 1078000 43.5675 71.7483 Smith River Near Bristol, N.H. 1918-present 1949-present 86.0

17 1082000 42.8625 71.9597 Contoocook River Peterborough, N.H. 1945-77 1949-77 67.0

18 1084500 43.1142 71.9267 Beards Brook Hillsboro, N.H. 1945-70 1949-70 55.3

19 1085800 43.2592 72.0264 West Branch Warner River Near Bradford, N.H. 1962-present 1962-present 5.91

20 1086000 43.2517 71.7317 Warner River Davisville, N.H. 1940-78 1949-78 146

21 1089000 43.2394 71.4622 Soucook River Near Concord, N.H. 1952-87, 

1988-present

1952-87, 

1988-present

77.8

22 1091000 43.0136 71.6419 South Branch Piscataquog 

River

Near Goffstown, N.H. 1940-78 1949-78 103

23 1093800 42.8600 71.8333 Stony Brook Tributary Near Temple, N.H. 1964-present 1964-present 3.62

24 10965852 42.7831 71.3539 Beaver Brook North Pelham, N.H. 1986-present 1986-present 47.8

25 1097300 42.5108 71.4069 Nashoba Brook Near Acton, Mass. 1963-present 1963-present 12.8

26 1101000 42.7528 70.9461 Parker River Byfield, Mass. 1945-present 1949-present 21.2

27 1127880 45.1350 71.2064 Big Brook Pittsburg, N.H. 1965-83 1965-83 6.50

28 1129440 44.8744 71.4106 Mohawk River Near Colebrook, N.H. 1986-present 1986-present 35.3

29 1130000 44.6250 71.4694 Upper Ammonoosuc River Near Groveton, N.H. 1940-80, 

1982-present

1949-80, 

1982-present

230

30 1133000 44.6339 71.8981 East Branch Passumpsic East Haven, Vt. 1939-45, 

1948-79

1949-79 51.3
6 Streamflow Data of Annual and Seasonal Ground-Water Recharge Rates for Drainage Basins in New Hampshire

31 1134500 44.5117 71.8369 Moose River Victory, Vt. 1947-present 1949-present 75.2

32 1134800 44.4419 71.8792 Kirby Brook Concord, Vt. 1963-74 1963-74 8.13

33 1135000 44.4228 72.0006 Moose River St. Johnsbury, Vt. 1928-83 1949-83 129

34 1135300 44.4344 72.0394 Sleepers River (W-5) St. Johnsbury, Vt. 1989-present 1989-present 42.5

35 1137500 44.2689 71.6311 Ammonoosuc River Bethlehem Junction, N.H. 1939-present 1949-present 88.2

36 1138000 44.1539 71.9861 Ammonoosuc River Bath, N.H. 1935-80 1949-80 396

37 1139000 44.1508 72.0653 Wells River Wells River, Vt. 1940-present 1949-present 98.7

38 1139800 44.0928 72.3361 East Orange Branch East Orange, Vt. 1958-present 1958-present 8.79

39 1141800 43.7022 72.1875 Mink Brook Etna, N.H. 1962-98 1962-98 4.75

40 1142500 43.9344 72.6583 Ayers Brook Randolph, Vt. 1939-75, 

1976-present

1949-75, 

1976-present

30.5

41 1144000 43.7142 72.4186 White River West Hartford, Vt. 1915-present 1949-present 689

42 1145000 43.6500 72.0806 Mascoma River West Canaan, N.H. 1939-78 1949-78 80.4

43 1150800 43.6733 72.8092 Kent Brook Sherburne, Vt. 1964-74 1964-74 3.26

44 1150900 43.6222 72.7594 Ottauquechee River West Bridgewater, Vt. 1984-present 1984-present 23.3

45 1153500 43.2086 72.5181 Williams River Brockways Mills, Vt. 1940-84 1949-84 102

46 1154000 43.1372 72.4881 Saxtons River Saxtons River, Vt. 1940-82 1949-82 72.1

47 1155000 43.1317 72.3897 Cold River Drewsville, N.H. 1940-78 1949-78 83.3

48 1155200 42.9992 72.5331 Sacketts Brook Putney, Vt. 1963-74 1963-74 10.15

49 1155300 43.2364 72.8564 Flood Brook Londonderry, Vt. 1963-74 1963-74 9.28

50 1155500 43.1089 72.7758 West River Jamaica, Vt. 1946-60 1949-60 177

51 1156000 42.9958 72.6389 West River Newfane, Vt. 1919-23, 

1928-60

1949-60 306

52 1158500 42.9653 72.2333 Otter Brook Keene, N.H. 1924-58 1949-58 41.9

53 1162500 42.6825 72.1156 Priest Brook Winchendon, Mass. 1963-present 1963-present 19.0

54 1165500 42.6028 72.3600 Moss Brook Wendell Depot, Mass. 1909-10, 

1916-82

1949-82 12.2

55 1167800 42.8606 72.8511 Beaver Brook Wilmington, Vt. 1963-77 1963-77 6.36

Table 1. Descriptions of stream-gaging stations used to develop the regression equations for estimating ground-water recharge in 

New Hampshire drainage basins.—Continued

[No., number; fig., figure; mi2, square miles]

Streamgaging 

station 

reference 

No.

(fig. 1)

Streamgaging 

station 

No.

Latitude

(decimal 

degrees)

Longitude

(decimal 

degrees)

River name Location

Stream-gaging 

station period 

of record, 

year

Streamgaging station 

ground-water 

recharge 

period of 

record, 

year

Drainage 

area

(mi2

)
Database Development 7

Connecticut River

Madbury

Lee Durham

Exeter

Brentwood

0

2

Marshfield Peacham

Barnet

Warren

Carlisle

Chelmsford Westford

Littleton

Boxford

Georgetown

Groveland

West

Newbury

Newbury

Erving

Warwick Royalston

Winchendon

Northfield

Acton

Marlboro

Mount Holly

Ludlow

Stratton

Winhall

Peru

Landgrove

Weston

Chester

Springfield

Londonderry Grafton

Jamaica

Rockingham

Newfane

Brookline

Putney

Westminster

Athens

Townshend

Brighton

Ferdinand

Westmore

Newark

East Haven

Wheelock

Walden

Danville

St.

Johnsbury Concord

Kirby

Lyndon Victory

Waterford

Ryegate Plainfield

Orange

Topsham

Newbury

Groton

Hartford

Norwich

Pomfret

Bridgewater

Sherburne

Goshen

Hancock

Pittsfield

Rochester

Bethel

Stockbridge

Sharon

Royalton

Strafford

Tunbridge

Vershire

Ripton Chelsea Granville

Braintree

Roxbury Williamstown

Corinth

Somerset

Livermore

Pittsburg

Hales Location

Clarksville Atkinson & Gilmanton

Stewartstown

Second

College Dixville

Dixs

Grant

Colebrook

Columbia Wentworths

Location

Millsfield

Ervings

 Location

Odell Stratford

Dummer

Stark

Northumberland

Milan

Kilkenny

Berlin

Randolph Whitefield

Dalton

Littleton Carroll Low & Burbanks

Beans Purchase

Bethlehem Monroe

Lyman

Chandlers

Purchase Crawfords

Lisbon Purchase Pinkham's Grant

Chatham

Sargents Purchase Beans Grant

Sugar

Hill

Jackson

Cutts Grant

Harts Location

Landaff

Lincoln

Hadleys 

Purchase

Bartlett

Benton

Woodstock

Thornton

Albany Waterville

Valley

Warren

Eaton Madison Orford Ellsworth

Wentworth

Sandwich Rumney Campton Lyme

Dorchester

Groton Plymouth

Holderness

Hanover

Canaan

Orange AlexandriaBristol Enfield

Grafton

Danbury Hill Springfield

Belmont

Gilmanton Andover

Northfield

Salisbury Farmington Canterbury Sutton Loudon

Warner

Boscawen

Newbury Webster

Strafford Goshen

Charlestown

Unity Chichester

Lempster Bradford

Acworth Hopkinton Washington

Hillsborough

Langdon

Marlow

Alstead Windsor

Stoddard Deering Weare

Antrim Sullivan BenningtonFrances-

 town New

Boston

Nelson HancockGreenfield

Chester

Roxbury

Lyndeborough Londonderry

Peterborough

Derry

Mont

Dublin Vernon

Temple

Jaffrey Sharon

Fitzwilliam

Rindge New

Ipswich Pelham

Bath

Piermont

Franconia

New

London

Tamworth

Haverhill

Epping

Wilton

Keene

Moultonborough

Shelburne

Walpole

Thompson & Meserve

Lincoln

Plt

Magalloway Plt

Township

E

Township

C

Byron

Weld

Roxbury

Andover

Rumford

Sumner

West

Paris

Woodstock

Albany

Twp

Gilead

Stoneham

Township

6 North

of Weld

Township

D

Andover

West

Surplus

Andover North

Surplus

C Surplus

Mason

Twp

Batchelders

Grant

Ossipee

Concord

Physiographic province

 boundary and name

Drainage basin

Town boundary

Base from U.S. Geological Survey

Digital data, 1983, 1:24,000 or 1:25,000

Windham

Hudson

Barrington

Nottingham

Stannard

Mount Washington x

White Mountains

New England Upland

Champlain

Green

Mountain New England Upland

White Mountain

Seaboard Lowland

Taconic

Hudson

Valley

Greenwood

Twp

Auburn Fremont

Randolph

Brookfield

Barnard

Wilmington

Cavendish

Sunderland

Andover

Windham

Wardsboro

Mendon

Chittenden

Mount

Tabor

Washington

Conway

Easton

Figure 2. Locations of drainage basins, associated towns, and physiographic provinces in the study area. 

(For detailed information on the stations, refer to table 1.)
8 Streamflow Data of Annual and Seasonal Ground-Water Recharge Rates for Drainage Basins in New Hampshire

Precipitation Data

The range of the digital NCDC precipitation data for 

development of the 275 (55 unregulated stations with 4 seasons 

and 1 annual period) annual and seasonal basin-specific regression equations was from 1949 to 1998. Between 48 and 55 stations were used in the development of the final regression equations because 10 years of seasonal or annual streamflow and 

ground-water-recharge data were not available at some stations 

after 1949. 

Drainage-basin-centroid precipitation was estimated from 

a weighted average of nearby NCDC precipitation-gage data. 

When seasonal or annual data for a nearby precipitation gage 

were not complete, the next nearest precipitation gage was used 

in conjunction with other nearby precipitation gages to determine the drainage-basin-centroid precipitation for that particular year or season. 

For consistency among stations that have operated during 

different periods of time, the annual and seasonal ground-waterrecharge values were normalized by substituting the average 

annual and seasonal (respectively) basin-centroid values of precipitation, as determined from the PRISM (Daly, 2000) data 

from 1961 to 1990, into each of the annual and seasonal basinrecharge equations for the NCDC basin-centroid-determined 

precipitation dependent variables. PRISM data were derived 

from data collected at National Oceanic and Atmospheric 

Administration (NOAA), SNOwpack TELemetry (SNOTEL), 

and State collection sites. NCDC data were derived from 

National Weather Service (NWS) precipitation-gage data.

Basin-Characteristics Data

The values of 93 physical and climatic (annual and seasonal) candidate explanatory variables (independent variables) 

were determined for each drainage basin upstream of the 55 

unregulated stream-gaging stations (Appendix 1). The values of 

the measured drainage-basin characteristics used in the regression analyses for each of the stream-gaging stations are provided in table 2. All of the basin characteristics were measured 

within a GIS (Environmental Systems Research Institute, Inc., 

1994) using available and created data layers. The digital data 

layers include, but are not limited to, (1) subwatersheds at 

1:24000 scale delineated by the Natural Resources Conservation Service (NRCS) and identified by 12-digit Hydrologic Unit 

Codes (HUCS), (2) centerline hydrography for New Hampshire 

at 1:24000 and 1:25000 scale developed by Complex Systems 

Research Center (CSRC) at the University of New Hampshire 

(UNH) (Complex Systems Research Center, unpublished digitized data, 2000), and (3) USGS Digital Elevation Models 

(DEMs) at 1:24000 scale. 

Some of the basin characteristics tested for inclusion in the 

regression equations (Appendix 1) were obtained with the 

drainage-basin-characteristics determination program BasinSoft (Harvey and Eash, 1995). The basin characteristics determined with BasinSoft were basin length, basin perimeter, basin 

relief, basin azimuth, effective basin width, shape factor, compactness ratio, relative relief, main channel length, main channel slope, main channel sinuosity ratio, main channel slope proportion, stream density, ruggedness number, and slope ratio. 

Precipitation, temperature, and snowcover data were 

acquired from PRISM datasets (Daly, 2000). PRISM is an analytical tool that uses point data, DEMs, and other spatial 

datasets to generate gridded estimates of annual, monthly, and 

event-based climatic parameters such as precipitation (Daly, 

2000). The PRISM data contain polygon coverages of average 

monthly and annual climatological data for 1961–90. PRISMderived raster data are the underlying datasets from which the 

polygons and vectors for the data layers were created. The 

PRISM data incorporate topographic effects on precipitation 

and include coastal and lake effects on precipitation.

The percent of the drainage basin that is coniferous or 

mixed coniferous and deciduous forest was acquired from the 

National Land Cover Dataset (NLCD) (Vogelman and others, 

2001). The NLCD was compiled from LANDSAT satellite 

Thematic Mapper imagery (circa 1992) with a spatial resolution 

of 30 meters and supplemented by various ancillary data, where 

available. The NLCD classification contains 21 land-cover categories with a spatial resolution of 30 meters. The NLCD was 

produced as a cooperative effort between the USGS and the 

U.S. Environmental Protection Agency (USEPA) to produce a 

consistent, land cover layer for the conterminous United States 

(U.S. Geological Survey, 2000). 

Methods of Analysis

The generalized estimating equations developed for 

annual and seasonal ground-water recharge were based on multiple-linear-regression analysis using records from between 48 

and 55 continuous-record stream-gaging stations. Multiple linear regression is a method of demonstrating that a response 

(dependent) variable, Y, varies with a set of independent variables, X1–Xn. The variability, which the response variable 

exhibits, has two components—a systematic and a random part. 

The systematic variation of Y can be modeled as a function of 

the X variables. The random part accounts for the model not 

exactly describing the behavior of the response variable. A 

least-squares method is used to estimate the parameters of the 

model, based on observed values of these variables, by minimizing the sum of squared differences between the actual Y values and the values of Y predicted by the regression equation 

(Freund and Littell, 2000). 

In multiple linear-regression analysis, one or more independent variables (climatic or physical basin characteristics) are 

statistically related to the dependent variable (ground-water 

recharge) for a group of stream-gaging stations. The results for 

this study are annual and seasonal equations for estimating 

ground-water recharge for ungaged drainage basins. The 

regression equations take the following form:
Methods of Analysis 9

Table 2. Basin characteristics for stream-gaging stations used in the ground-water recharge regression-analysis equations for

New Hampshire drainage basins.

[No., number; fig., figure; in., inches; NLCD, National Land Cover Dataset; ° F, degrees Fahrenheit]

Streamgaging 

station 

reference 

No.

(fig. 1)

Streamgaging 

station 

No.

Basin characteristics

Average 

annual 

basincentroid 

precipitation 

(in.)

Percent 

coniferous 

(NLCD)

Average 

annual 

gage 

precipitation 

(in.)

Average 

minimum 

winter 

basin 

temperature 

(° F)

Average 

spring 

gage 

precipitation 

(in.)

Average 

annual 

snow 

cover 

(in.)

Average 

summer 

gage 

precipitation 

(in.)

Average 

mean annual 

basin 

temperature 

(° F)

Percent 

mixed 

coniferous 

and 

deciduous

(NLCD)

Average 

fall basincentroid 

precipitation

(in.)

Basin characteristic abbreviations

ACP C AGP WBT SpGP ASC SGP ABT CD FCP

1 1052500 48.1 20.0 38.2 2.88 7.48 158 17.9 37.0 30.2 8.46

2 1054200 49.7 31.5 45.1 8.69 9.09 120 19.9 40.7 30.5 9.49

3 1054300 39.1 22.9 43.0 6.73 8.72 121 17.7 40.0 26.9 7.76

4 1055000 43.6 36.6 42.8 5.69 8.70 145 18.1 38.9 13.5 8.23

5 1057000 43.7 17.1 44.1 9.78 9.13 79.4 18.3 42.6 22.3 8.70

6 1064300 75.9 56.2 52.3 6.48 10.6 219 22.4 36.8 20.7 15.2

7 1064400 54.6 45.2 49.9 9.18 10.3 114 20.3 41.7 36.5 10.7

8 1064500 50.2 31.1 47.0 8.69 9.86 125 19.1 40.5 34.0 9.8

9 1072850 47.1 19.1 44.8 14.9 9.63 79.5 17.9 45.4 46.1 9.72

10 1073000 43.2 17.7 42.6 16.5 9.21 60.1 16.9 46.8 33.2 8.90

11 1073600 44.1 20.6 44.3 17.1 9.39 61.1 17.4 46.9 20.3 8.94

12 1075000 50.4 40.7 47.5 9.78 9.80 147 19.6 40.3 32.9 9.13

13 1075800 41.1 30.7 41.0 11.2 8.44 89.6 17.8 42.9 41.0 7.64

14 1076000 37.4 13.8 43.1 11.2 9.02 89.8 18.2 42.5 36.3 6.57

15 1076500 48.6 25.7 41.0 10.6 8.50 117 17.4 41.7 35.9 9.65

16 1078000 44.3 23.9 44.0 10.8 9.19 92.3 18.4 43.1 30.9 8.31

17 1082000 44.2 22.6 44.1 14.6 9.25 75.1 18.1 44.4 28.2 8.11

18 1084500 46.6 21.3 43.3 15.4 9.27 85.6 17.5 45.1 26.3 9.13

19 1085800 45.3 7.18 44.3 14.2 9.51 88.2 18.3 44.6 10.7 8.31

20 1086000 44.7 22.5 40.9 13.6 8.60 85.8 17.0 44.4 29.8 8.62

21 1089000 38.6 17.4 38.0 13.2 7.83 75.3 16.5 44.5 29.7 7.13

22 1091000 43.4 26.7 41.7 14.4 8.72 76.8 17.0 44.8 26.6 8.39

23 1093800 48.4 13.2 46.9 15.3 9.92 79.8 18.9 44.6 27.2 9.25

24 10965852 43.2 10.4 43.4 16.0 9.07 64.8 17.4 46.8 12.9 8.39

25 1097300 44.2 5.19 44.6 18.6 9.37 55.0 17.6 48.3 19.2 8.62

26 1101000 45.0 3.07 45.8 19.9 9.69 54.5 17.6 48.7 14.5 9.09

27 1127880 49.0 9.30 46.9 0.8 8.82 186 23.1 36.1 33.9 8.58

28 1129440 45.4 18.7 43.2 4.31 8.23 110 21.1 37.8 34.1 7.95

29 1130000 39.9 20.6 39.7 7.14 7.68 131 19.1 40.0 31.5 7.09

30 1133000 42.4 12.1 43.2 5.29 8.13 124 20.9 39.2 27.1 7.44
10 Streamflow Data of Annual and Seasonal Ground-Water Recharge Rates for Drainage Basins in New Hampshire

31 1134500 44.8 14.3 42.2 7.59 8.07 121 20.2 40.1 25.1 7.99

32 1134800 42.1 20.9 38.9 8.03 7.38 95.8 18.8 41.3 36.2 7.4

33 1135000 41.9 15.1 38.2 7.88 7.34 108 18.2 40.8 30.6 7.36

34 1135300 40.9 15.1 38.3 7.95 7.40 111 18.3 40.0 32.5 7.36

35 1137500 56.4 37.1 41.9 8.75 8.09 175 19.8 39.3 29.1 10.8

36 1138000 39.9 24.1 36.1 9.63 6.93 118 17.4 41.4 37.9 7.05

37 1139000 38.1 13.0 35.8 7.82 6.83 92.1 17.4 41.0 29.8 6.81

38 1139800 41.8 5.76 41.5 6.4 8.31 101 19.7 40.6 26.1 7.32

39 1141800 41.3 19.1 40.8 11.0 8.33 79.3 18.4 43.3 18.0 7.09

40 1142500 40.0 9.97 38.9 9.64 8.11 92.3 17.0 41.9 25.1 7.28

41 1144000 39.6 13.9 37.7 8.39 7.81 97.73 16.7 42.0 23.1 7.28

42 1145000 40.5 24.0 39.1 11.1 8.19 83.4 17.6 42.9 26.1 7.17

43 1150800 54.9 12.9 50.3 9.0 10.5 133 22.8 41.5 9.05 9.53

44 1150900 51.2 13.7 49.3 8.2 10.8 127 21.0 41.3 6.21 8.98

45 1153500 43.7 17.3 41.1 10.2 8.70 90.6 17.5 43.0 21.2 7.76

46 1154000 45.3 20.0 42.1 10.5 8.94 95.0 17.9 42.6 23.7 8.03

47 1155000 39.9 24.0 38.8 13.8 8.29 77.0 16.8 44.5 26.9 6.85

48 1155200 43.6 11.7 40.7 11.8 8.70 81.6 17.4 43.9 16.0 7.76

49 1155300 51.0 17.6 47.2 10.5 9.98 116 20.2 42.1 13.2 8.90

50 1155500 46.6 21.1 44.5 10.0 9.43 107 19.1 41.7 16.8 8.19

51 1156000 45.5 20.8 42.5 10.23 9.13 104 17.9 41.7 18.1 7.95

52 1158500 43.7 18.6 40.5 13.2 8.76 82.3 17.6 43.9 21.3 7.60

53 1162500 42.9 22.2 42.0 12.7 8.86 70.0 17.7 44.1 30.2 7.72

54 1165500 42.7 39.9 43.1 13.3 9.17 62.1 18.2 44.8 27.7 7.52

55 1167800 53.2 20.9 53.1 12.2 11.5 103 21.8 42.6 20.1 9.84

Table 2. Basin characteristics for stream-gaging stations used in the ground-water recharge regression-analysis equations for

New Hampshire drainage basins.—Continued

[No., number; fig., figure; in., inches; NLCD, National Land Cover Dataset; ° F, degrees Fahrenheit]

Streamgaging 

station 

reference 

No.

(fig. 1)

Streamgaging 

station 

No.

Basin characteristics

Average 

annual 

basincentroid 

precipitation 

(in.)

Percent 

coniferous 

(NLCD)

Average 

annual 

gage 

precipitation 

(in.)

Average 

minimum 

winter 

basin 

temperature 

(° F)

Average 

spring 

gage 

precipitation 

(in.)

Average 

annual 

snow 

cover 

(in.)

Average 

summer 

gage 

precipitation 

(in.)

Average 

mean annual 

basin 

temperature 

(° F)

Percent 

mixed 

coniferous 

and 

deciduous

(NLCD)

Average 

fall basincentroid 

precipitation

(in.)

Basin characteristic abbreviations

ACP C AGP WBT SpGP ASC SGP ABT CD FCP
Methods of Analysis 11

, (1)

where

Assumptions for use of the regression analysis are that the

(1) regression equation describes the relation between the 

dependent and independent variables, (2) mean of the residual 

error is zero, (3) variance of the residual error is constant and 

independent of the values of Xn, (4) residual errors are normally 

distributed, and (5) residual errors are independent of one 

another (Helsel and Hirsch, 2000). 

Ordinary-Least-Squares Regression Equations

Final parameter estimates for the annual and seasonal 

ground-water recharge regression equations were developed 

using GLS regression. OLS was necessary for the efficient evaluation of the many possible alternative regression equations. 

Diagnostic checks were done to test for model adequacy and 

violations of the assumptions for regression analysis. In addition, plots were made of

a. Predicted values in relation to the residuals to determine if 

there were any trends in the data,

b. Studentized (standardized) residuals in relation to 

observation number (stream-gaging station reference 

number) to determine if there were any unusually large 

residuals, and

c. Studentized residuals in relation to normal quantile to 

determine if the residuals were normally distributed. The 

normal quantile is the expected quantile if the residuals 

are normally distributed.

Generalized-Least-Squares Regression Equations

Generalized-Least-Squares (GLS) regression analysis was 

used to develop the final equations for annual and seasonal 

ground-water-recharge rates by use of the computer program 

Generalized-Least-Squares NETwork (GLSNET) (Tasker and 

Stedinger, 1989). GLS-regression analysis accounts for the differences in the variances of the basin-specific recharge estimates, as well as for the cross-correlation of concurrent basinspecific recharge estimates with other stations. According to 

Tasker and Stedinger (1989), GLS analysis is more appropriate, 

and provides better results in hydrologic regressions, than OLSregression analysis when the streamflow records at stations are 

of varying lengths and when concurrent flows at different stations are correlated. Tasker and Stedinger (1989) demonstrated 

that GLS analysis generally provides the most accurate results 

for hydrologic regressions as streamflow data are correlated 

spatially and in time. Weighted-least-squares (WLS) can compensate for differences in record length, but, unlike GLS, it does 

not compensate for cross-correlation among the stream-gaging 

stations used in the analysis. The weight given to each station in 

a GLS analysis is adjusted to compensate for differences in 

record length among the stations and for spatial correlation. 

GLS gives less weight to stations with short periods of record 

and to those stations with concurrent flows that are correlated 

with other sites. Model precision increases for models with 

decreasing standard error of estimate and increasing crosscorrelation when GLS regression methods are used instead of 

WLS regression methods (Stedinger and Tasker, 1985). 

 Covariance matrices and standard errors were determined 

using OLS regression analysis. Concurrent record lengths for 

every pair of stations were determined from GLSNET output 

determined for a report detailing a stream-gaging network analysis for New Hampshire (Flynn, 2003) using the same streamgaging stations that were used in this study. GLSNET output 

includes a concurrent record-length matrix, which was altered 

to begin in 1949. The standard errors and covariance matrices 

as determined in OLS were used to estimate the variance of prediction for the normalized recharge at each station. These estimates of variance of prediction were used in the GLS regional 

equation to weight the observations of normalized recharge. 

The residuals and concurrent record lengths for every pair of 

stations from 1949 through the last year of record (1998) were 

determined and applied to come up with an average crosscorrelation to compute the sample covariance of the normalized 

recharges between sites for the GLS weighting matrix. 

Regional Regression for Normalized Annual and 

Seasonal Recharge Using Generalized-Least-Squares 

Regression

A regional regression model is used to estimate normalized recharge as a function of average precipitation and basin 

(land use) characteristics. A linear model is assumed having the 

form

, (2)

Yg(s) is the normalized ground-water 

recharge for basin g during season s, 

where s represents the annual, spring, 

summer, fall, or winter seasons, 

X1,g(s) to Xp,g(s) are the annual and seasonal climatic 

or physical basin characteristics, 

b0,s to bp,s are the estimated regression-model 

coefficients, 

and

eg(s) is the residual error or difference 

between the measured and the estimated value of normalized recharge 

for basin g in season s. 

Yg s( ) b0,s b1,s X1, g s( ) b2,s X2, g s( )

... bp s, Xpgs , ( ) e + g s( )

+

+

= + +

ψ = Xβ ε +
12 Streamflow Data of Annual and Seasonal Ground-Water Recharge Rates for Drainage Basins in New Hampshire

where

The scalar value γ2 is called the model-error variance, and N is 

the number of stream-gaging stations in the region.

The operational problem with this model is that the average normalized recharge, ψ , from streamflow records must be 

estimated from available streamflow records that may be relatively short at some sites. At a given site, ψ is estimated by an 

at-site regression of recharge, zij, at site i in year j against precipitation wij. Each at-site regression is fit by OLS and has the 

form

, (3)

with standard error of estimate s

2

i

. The estimate of normalized 

recharge for a long representative period at site i, yi

, is 

, (4)

where

The discharge record length at site i is denoted as ni such that

, (5)

where

 

The standard error of yi is

The resulting estimate of ψi, therefore, has a random-error component such that 

, (6)

where

Substituting equation 6 into equation 1, in matrix notation the 

regional regression model is

, (7)

with E[ε + η]=0 and E[(ε + η) (ε + η ) ’]=Λ . The covariance 

matrix of errors, Λ , is

, (8)

in which the (N x N) matrix Σ has elements of

for , (9)

where

A regression model with this error structure was considered by 

Stedinger and Tasker (1985, 1986) in developing an estimated 

generalized-least squares (EGLS) analysis for regional hydrologic regression. The analysis potentially provides for more 

accurate estimates of regression coefficients when compared to 

OLS analysis when sites have different record lengths, given an 

unbiased model-error estimator and a better description of the 

relation between hydrologic data and information for hydrologic network analysis and design (Tasker and Stedinger, 1989; 

and Moss and Tasker, 1991).

The GLS analysis for regional regression of normalized 

recharge generally proceeds as follows: The Σ matrix is estimated by entering the Si

’s from the N at site regressions and 

using the relation between cross-correlation coefficients from 

mean annual values and annual values

, (10)

ψ is a (N x 1) column vector of normalized annual or seasonal recharge 

values, 

X is a (N x p) matrix of known basin 

characteristics augmented by a 

column of 1’s, 

 β is a (p x 1) column vector of 

unknown regression coefficients to 

be estimated, 

and

 ε is a (N x 1) column vector of errors 

with E[ε]=0 and E[εε’]=Iγ 2

. 

 wi is mean annual precipitation for a 

long representative base period at 

site i. 

wij is the mean of the ni observed annual 

precipitation values, 

and

SSw is the total sum of squared deviations 

from the mean.

zij ai0 a = + ilwij

yi ai0 a = + ilwi

SSw wij wij ( ) – 2

j = 1

ni

= ∑

Si si

1

ni

--- wi wij ( ) – 2

SSw

-------------------------

⎝ ⎠ ⎜ ⎟ ⎛ ⎞ = +

 ηi is a random error with E[ηi]=0 and 

Var[ηi

]=Si

2, 

That is

 yi is an unbiased estimate of ψ with a 

sampling error that is a function of si

and ni

. 

 i and j are index rows and columns of the 

matrix, 

and

ρ(yi,yj) is the correlation between estimates 

of mean annual recharge at sites i

and j.

ψi yi ηi = –

y X = βεη + +

Λ y

2 = I + Σ

Σij

Si

2

ρ yiyj ( )SiSj

--------------------------

⎩

⎨

⎧ = i j

i j ≠

=

ρ yiyj ( )

mijρij

ninj

= -------------
Estimates of Annual and Seasonal Ground-Water-Recharge Rates 13

where

 

The value of ρij used to compute ρ(yi,yj) in equation 10 was 

estimated as 0.25 from sample estimates at every pair of sites 

with at least 20 years of concurrent record. Once the Σ matrix is 

filled out from the sample data, the EGLS regression estimators 

of the model parameters, β, are determined by solving 

, (11)

with model-error variance γ 2 determined so that

. (12)

Estimates of Annual and Seasonal GroundWater-Recharge Rates

For this study, recession-curve displacement was chosen 

as the method for determining ground-water recharge. The use 

of recession-curve displacement for determining ground-waterrecharge rates provides a spatial, as well as temporal, average 

for a particular basin for a particular period of time. When 

recession-curve-displacement methods are applied to more than 

one stream-gaging station, and if the stations have different 

lengths of record, then the resulting set of recharge rates would 

be inconsistent because of temporal variations in recharge. A 

common period of data collection for average precipitation was 

used to adjust the set of recharge rates to eliminate temporal 

variation. Annual and seasonal regression equations were 

developed to describe the spatial variation of recharge rates for 

all of the drainage basins in New Hampshire. 

Annual and seasonal basin-specific estimates of groundwater recharge were determined using the recession-curvedisplacement computer program RORA (Rutledge, 1998). 

RORA estimates the mean rate of ground-water recharge in a 

basin from an analysis of the streamflow record. Although at 

many stations, streamflow records were considerably longer; 

the length of record for the basin specific estimation of groundwater recharge determined in this study ranged from 10 to

50 years. The length of station records used to determine annual 

and seasonal ground-water-recharge rates was dictated by the 

length of record of the digital NCDC precipitation-gage data. 

This was a consequence of regressing basin-centroid precipitation values as determined from the NCDC gage data against the 

ground-water-recharge values to determine basin-specific estimates of ground-water-recharge rate. The digital NCDC precipitation-gage data were available from 1949 through 1998. 

Estimation of Ground-Water-Recharge Rates from 

Stream-Gaging Station Data

The estimation of ground-water recharge from streamflow 

is a process influenced by many contributing factors such as the 

variable geology and hydraulic properties of the stream channel 

sediments, the non-steady state of the streamflow, the duration 

of the streamflow, the changing channel cross section, infiltration differences due to changing hydraulic head during streamflow, and antecedent moisture conditions of the streambed sediments (Savard, 1998).

Streamflow data were initially analyzed by use of the computer program RECESS (Rutledge, 1993) to compute a recession index of streamflow at times when all flow is assumed to 

be ground-water discharge and when the ground-water head 

distribution is nearly constant. RECESS uses a repetitive interactive procedure for selecting several periods of continuous 

recession, determines a best-fit equation for the rate of recession 

as a function of flow for the selected periods, and then uses this 

equation to derive a master recession curve that describes the 

average flow-recession characteristic with time (Rutledge, 

1993). 

Once the recession characteristics were defined, streamflow data were analyzed using recession-curve-displacement 

methods (Rutledge, 1998) to determine the average annual and 

seasonal ground-water-recharge component throughout the 

length of record. RORA (Rutledge, 1998) was used to estimate 

the ground-water recharge in a basin from an analysis of the 

streamflow record. The program is a computerized version of a 

method of measuring the displacement of the streamflow-recession curve resulting from each recharge event, also known as 

the Rorabaugh method (Rorabaugh, 1964). The Rorabaugh 

method is based on the measurement of the change in the total 

potential ground-water discharge as estimated at critical time 

after the peak by extrapolation from the pre-peak and post-peak 

recession periods. The method yields an estimate of the mean 

rate of ground-water recharge through the analysis of a long 

period of record (Rutledge, 1993). Recharge rates, as determined by the Rorabaugh method, are representative of an average of the rates for relatively large geographic areas; however, 

within these geographic areas there may be places where the 

recharge rate is greater or less than the average rate determined.

Although considerable uncertainty is inherent in the recession index, the analysis of streamflow data used in the APRASA (Appalachian and Piedmont physiographic provinces 

Regional Aquifer-System Analysis) project (Swain and others, 

1991; Rutledge and Mesko, 1996) indicated the estimate of 

recharge is not particularly sensitive to the index as derived 

from the program RECESS (A.T. Rutledge, U.S. Geological 

Survey, written commun., 2000). The median recession index 

for each station from periods of continuous recession were estimated, in this study, using RECESS. RORA was then used to 

estimate recharge by designating the median recession index as 

input to that program. Most of the values of the recession index 

in the AP-RASA study were between 50 and 120 days. The sensitivity test demonstrated that if the recession index was 

 mij is the concurrent record length 

between i and j, 

and

 ρ ij is the correlation between concurrent 

annual or seasonal recharge values at 

the pair of sites. 

X'Λ –1 { }β X X'Λ –1 = y

( ) y X– β 'Λ –1( ) y X– β = N p –
14 Streamflow Data of Annual and Seasonal Ground-Water Recharge Rates for Drainage Basins in New Hampshire

decreased by 50 percent, the recharge estimate would increase 

by 4–9 percent. When the recession index was increased by

50 percent, the recharge estimate decreased by 2–4 percent. In 

a random sampling of annual and seasonal periods for the 55 

stream-gaging stations used in this study, the estimate of 

recharge was not sensitive to the recession index derived from 

the program RECESS.

RORA-derived recharge values indicate that seasonal 

recharge can be positive or negative. Negative recharge indicates regional evapotranspiration from the water table (Barlow 

and Moench, 1998). If the water table is shallow, negative 

recharge values may be obtained locally because exfiltration is 

the dominant mode of water transfer (Simmers, 1988). The boxplots in figures 3 through 7 (back of report) show the variation 

in the RORA-determined annual and seasonal ground-water 

recharge for each of the stream-gaging stations used in the analysis. Variations in the ground-water recharge between stations 

is a result of spatial and temporal differences in climatic characteristics and spatial differences in the basin characteristics.

The RORA method is intended for the analysis of a 

ground-water-flow system that is characterized by diffuse areal 

recharge to the water table and ground-water discharge to a 

stream (Rutledge, 2000). The method is appropriate for the 

determination of ground-water recharge when most or all of the 

ground water in the basin discharges to a stream and if a streamgaging station at the downstream end of the basin measures all 

or most of this outflow (Rutledge, 2000). The Rorabaugh 

method is based on an ideal flow system in which the aquifer 

has uniform thickness, hydraulic conductivity, and storage 

coefficient and the stream fully penetrates the aquifer. In addition, the initial condition set by Rorabaugh (1964) is that the 

hydraulic head everywhere in the aquifer is the same as the 

stage of the stream. Recharge is considered to be an instantaneous increase in the hydraulic head applied uniformly throughout the aquifer while the stream stage remains unchanged

(Rutledge, 2000). In the Rorabaugh method, the ground-water 

and surface-water divides are considered to be coincident. 

Because RORA is based on the assumption that the entire 

ground-water-discharge hydrograph is described by Rorabaugh’s instantaneous-recharge model, the program does not 

explicitly allow for the effects of ground-water evapotranspiration (Rutledge, 2000). To minimize errors resulting from 

ground-water evapotranspiration, the recession index at each 

station was determined by extracting only those periods of continuous recession for the 6 months of October through March 

(Rutledge, 1997) when evapotranspiration is lowest. 

Normalization of Ground-Water-Recharge Rates 

Using Precipitation Data

A point coverage of precipitation gage locations was generated for New Hampshire, Maine, Vermont, and Massachusetts with the GIS spatial analysis software ARC-INFO (Environmental Systems Research Institute, Inc., 1994) and the 

annual and seasonal NCDC precipitation data were added to the 

point coverage. Using these data, average annual and seasonal 

precipitation values were then determined at each of the drainage-basin centroid and stream-gaging stations for each year of 

record beginning in 1949, the year in which the NCDC digital 

data begins. An area/distance weighting methodology called 

“Natural Neighbor” in ARC-INFO 8.1 (Environmental Systems 

Research Institute, Inc., 1994) was used to interpolate annual 

and seasonal precipitation for each year of record at each of the 

drainage-basin centroids and stream-gaging stations based on 

the NCDC digital precipitation database TD-3240 file. Similar 

to Inverse Distance Weighting (IDW), this interpolation 

method is a weighted-average interpolation method. Instead of 

finding a value of an interpolated point using all of the input 

points weighted by their distance, “Natural Neighbors” interpolation creates a Delauney triangulation of the input points and 

selects the closest nodes that form a convex hull around the 

interpolation point, then weights their values by proportionate 

area. Delauney triangulation is a proximal method that satisfies 

the requirement that a circle drawn through the three nodes of a 

triangle will contain no other points. In other words, all sample 

points are connected with their two nearest neighbors to form 

triangles (Environmental Systems Research Institute, Inc., 

1994). This method is a general-purpose interpolation method 

that does not require parameters such as radius, number of 

neighbors, or weights to be specified (Environmental Systems 

Research Institute, Inc., 1994), but is based on the geometry of 

the network.

Annual and seasonal ground-water recharge varies among 

drainage basins because of temporal and spatial variation in 

basin and climatic characteristics (such as annual and seasonal 

precipitation that is the source of ground-water recharge). An 

estimate of long-term average annual and seasonal groundwater recharge can be made using recession-curve-displacement methods; however, this estimate is not consistent among 

stream-gaging stations that have operated during different periods. To ensure a consistent recharge estimate among selected 

recharge basins, each annual and seasonal RORA-determined 

ground-water-recharge value was related to each area/distanceweighted NCDC annual and seasonal basin-centroid precipitation (respectively, for each basin) value by a set of basin-specific regression equations. The 275 annual and seasonal drainage-basin-specific regression equations were developed by use 

of the SAS program, version 8.1 (SAS Institute, Inc., 1994) 

using OLS regression analysis. The general form of the basinspecific regression equations is

q , (13) g s( ) Bogs , ( ) B1, g s( ) Pg s( ) e = + + g s( )
Estimates of Annual and Seasonal Ground-Water-Recharge Rates 15

where

A recharge estimate and the statistical significance of the 

annual and seasonal regression equations relating ground-water 

recharge and area/distance-weighted NCDC drainage-basincentroid precipitation for each stream-gaging station was determined. Only coefficients significant at the 5-percent level were 

maintained in the equations. In some instances, the basin 

recharge rate was based only on the RORA-determined groundwater-recharge rate as the area/distance-weighted NCDC basincentroid precipitation was not statistically significant.

To help determine the spatial distribution of recharge, temporal variations in recharge were removed by normalizing the 

estimates of ground-water recharge. For consistency among stations that have operated during different periods, annual and 

seasonal normalized ground-water recharge was determined by 

substituting the average annual and seasonal basin-centroid values of precipitation, as determined from 2-kilometer-grid 

PRISM precipitation data for 1961–90 (Daly, 2000), into each 

of the annual and seasonal (respectively) basin-recharge equations for the area/distance-weighted NCDC basin-centroiddetermined precipitation values.

The set of annual and seasonal basin-specific regression 

equations that relate the RORA-determined ground-waterrecharge rate and area/distance-weighted NCDC basin-centroid 

precipitation for each station location are listed in tables 3–7 

(back of report). The general form of these equations is shown 

in equation 13. Equations in which the independent variable of 

area/distance-weighted NCDC basin-centroid precipitation was 

not significant at the 5-percent level were listed as not applicable in tables 3–7 (back of report). Rather than being normalized 

for 1961–90, the normalized basin-recharge rate for these 

basins was based only on the RORA-determined ground-waterrecharge rate.

In many cases, the sum of the normalized seasonal groundwater-recharge values in each drainage basin does not equal the 

value of the normalized annual ground-water recharge. As a 

long period of record has a greater sampling of the recession 

index, a much greater confidence is associated with the recession-curve-displacement method for the annual period rather 

than for the seasonal period. The percent error in the annual 

drainage-basin ground-water recharge, when compared to the 

sum of the seasonal drainage-basin ground-water recharge, is 

shown in table 8. 

The estimation equations developed in this study were 

incorporated into a GIS to produce a “point-and-click” tool for 

rapidly estimating low-flow, flow-duration (Flynn, 2002), and 

ground-water-recharge statistics for any unregulated stream 

reach in the State. A GIS is required to measure the value of the 

independent variables in the regression equations. As all of the 

seasonal and the annual ground-water-recharge values will be 

displayed in the “point-and-click” application that makes use of 

the regression equations developed in this report, the user has 

the option of using the sum of the seasonal values rather than the 

annual value of ground-water recharge. This difference 

between the annual value of ground-water recharge and the sum 

of the seasonal values of ground-water recharge represents the 

error that is inherent in the use of recession-curve displacement 

methods and the error in the annual and seasonal normalized 

regression equations. During the winter season (January 1–

March 15), there were many occurrences in which the independent variable of area/distance weighted NCDC drainage-basincentroid precipitation was not significant at the 5-percent level. 

The percent error in annual and summed seasonal ground-water 

recharge is also a reflection of the method of selecting precipitation gages as used to determine the basin-centroid precipitation values. If daily precipitation values at a particular precipitation gage were missing for a season or year, then that gage 

was not included for that season or year and another nearby precipitation gage was selected in its place (for determination of 

the basin-centroid precipitation) along with two other precipitation gages using Delauney Triangulation for interpolation of the 

precipitation value. Since a different precipitation gage would 

be used for that season and year than that which would be used 

for the other three seasons, the value of normalized annual 

ground-water recharge could be slightly different than the sum 

of normalized seasonal ground-water recharge.

The proportion of normalized drainage-basin recharge to 

PRISM basin-centroid precipitation for 1961–90 for each 

annual and seasonal period is shown in figures 8–12 (back of 

report). The value of average percentage of normalized drainage-basin recharge to PRISM basin-centroid precipitation for 

each basin is listed in table 8. 

On an annual basis, the average proportion (percentage) of 

normalized drainage-basin recharge to PRISM basin-centroid 

precipitation was 47 percent with a standard deviation of 6.75 

(table 8). In the winter (fig. 9), the ratio of ground-water 

recharge to precipitation is greatest on the seacoast of New 

Hampshire and low in the northern, mountainous sections of 

New Hampshire. This low ratio is due to increased snowpack 

and colder temperatures in the mountainous sections. The average proportion of normalized drainage-basin recharge to 

PRISM basin-centroid precipitation for the winter was 55 percent with a standard deviation of 12.9 (table 8). In the spring, 

snowmelt contributes significantly to ground-water recharge 

(fig. 10) such that the ratio of ground-water recharge to precipitation is greater than 100 percent for many areas in northern 

and central New Hampshire. The average proportion of

qg(s) is the Rorabaugh-method-determined 

ground-water recharge for basin g

during season s, where s represents 

the annual, spring, summer, fall, or 

winter seasons;

Pg(s) is the precipitation at the basin centroid in basin g during season s;

Bo,g(s) and B1,g(s) are a set of OLS regression coefficients for basin g during season s; 

and

eg(s) is the residual error between the 

Rorabaugh-method-determined value 

and the estimated value of groundwater recharge for basin g during 

season s. 
Table 8. Values of seasonal and annual basin-centroid precipitation and normalized ground-water recharge and the proportion (in percent) of norm

ground-water recharge to seasonal and annual basin-centroid precipitation. [No., number; Location of stream-gaging stations are shown in figure 1 and reference numbers and descriptions of stream-gaging stations are listed in table 1; --, no data] Stream- gaging station No. River Drainage-basin centroid precipitation Normalized drainage-basin recharge Percent error of annual versus sum of seasonal basin recharge values Proportion (in p

basin recha

Annual Winter Spring Summer Fall Annual Winter Spring Summer Fall Annual Winte

1052500 Diamond River 48.1 7.46 9.19 23.0 8.46 23.1 3.07 12.1 6.69 3.84 11.3 48.0 41.1 1054200 Wild River 49.7 8.74 10.1 21.5 9.49 20.7 4.15 10 3.8 2.93 0.87 41.7 47.5 1054300 Ellis River 39.1 6.91 7.85 16.5 7.76 18.2 3.35 10 3.22 3.08 7.97 46.6 48.5 1055000 Swift River 43.6 7.34 8.76 19.2 8.23 19.6 3 10.2 4.12 3.4 5.71 45.0 40.9 1057000 Little Androscoggin River 43.7 7.56 8.94 18.5 8.70 18.3 3.71 8.65 3.03 3.69 4.26 41.9 49.1 1064300 Ellis River 75.9 15.1 15.4 30.2 15.2 30 3.92 13.3 9.37 4.24 2.77 39.5 26.0 1064400 Lucy Brook 54.6 10.4 11.3 22.2 10.7 24.9 4.54 10.5 3.85 3.99 8.11 45.6 43.8 1064500 Saco River 50.2 9.41 10.5 20.4 9.80 24 4.21 11.7 3.71 3.95 1.79 47.8 44.7 1072850 Mohawk River 47.1 8.52 9.98 18.9 9.72 23.9 5.43 7.61 1.59 4.23 21.1 50.7 63.7 1073000 Oyster River 43.2 7.83 9.29 17.2 8.90 20.7 5.9 7.61 2.78 4.02 1.88 47.9 75.3 1073600 Dudley Brook 44.1 8.31 9.33 17.5 8.94 -- 3.95 5.16 1.45 2.39 -- -- 47.5 1075000 Pemigewasset River 50.4 8.37 10.1 22.8 9.13 26.2 3.43 13.7 6.21 4 4.35 52.0 41.0 1075800 Stevens Brook 41.1 7.01 8.35 18.1 7.64 12.3 3.01 6.03 1.69 2.36 6.42 30.0 43.0 1076000 Baker River 37.4 5.79 7.52 17.5 6.57 17 3 8.74 3.26 2.81 4.76 45.4 51.8 1076500 Pemigewasset River 48.6 8.92 10.1 20.0 9.65 22.1 3.65 10.4 4.92 4.45 5.97 45.5 40.9 1078000 Smith River 44.3 7.78 9.39 18.7 8.31 21 4.08 8.86 3.87 3.58 2.90 47.4 52.5 1082000 Contoocook River 44.2 8.33 9.23 18.5 8.11 21.3 5.07 8.38 3.62 3.56 3.51 48.2 60.9 1084500 Beards Brook 46.6 8.64 9.90 19.1 9.13 22.9 4.66 9.1 3.01 4.35 7.77 49.2 53.9 1085800 West Branch Warner River 45.3 7.95 9.76 19.1 8.31 22.7 5.4 9.38 3.58 4.04 1.32 50.1 67.9 1086000 Warner River 44.6 8.31 9.61 18.1 8.62 24 4.94 10.4 3.09 4.26 5.46 53.8 59.5 1089000 Soucook River 38.6 6.71 8.01 16.9 7.13 16.4 4.32 6.55 2.62 2.96 0.30 42.5 64.4 1091000 South Branch Piscataquog River 43.4 8.23 9.13 17.7 8.39 20 5.41 7.99 2.62 3.66 1.60 46.1 65.7 1093800 Stony Brook Tributary 48.4 9.15 10.3 19.6 9.25 25.1 6.14 9.34 3.71 4.9 4.02 51.8 67.1 1097300 Nashoba Brook 44.2 8.82 9.29 17.4 8.62 20.1 6.71 6.66 2.82 3.82 0.45 45.5 76.1 1101000 Parker River 45.0 9.02 9.49 17.4 9.09 26.1 7.82 8.77 3.95 4.84 2.76 58.1 86.7 1127880 Big Brook 49.0 7.28 9.21 23.9 8.58 28.9 4.47 12.4 10.2 4.82 10.3 59.0 61.4 1129440 Mohawk River 45.4 7.03 8.68 21.8 7.95 19.2 4.1 6.99 5.45 4.07 7.34 42.3 58.3 1130000 Upper Ammonoosuc River 39.9 6.28 7.85 18.6 7.09 20.7 3.27 10.3 3.18 2.55 6.76 51.9 52.1 
1133000 East Branch Passumpsic 42.4 6.42 8.03 20.6 7.44 27.1 3.41 10.8 7.4 4.26 4.54 63.9 53.1 1134500 Moose River 44.8 7.11 8.64 21.1 7.99 18.6 3.39 8.75 4.45 3.31 6.99 41.5 47.7 1134800 Kirby Brook 42.1 6.36 8.01 20.2 7.40 -- 2.3 7.37 3.37 2.26 -- -- 36.2 1135000 Moose River 41.9 6.40 8.05 20.2 7.36 16.7 2.73 8.48 3.55 2.58 3.83 39.9 42.7 1135300 Sleepers River (W-5) 40.9 6.20 7.89 19.5 7.36 -- 3.43 6.64 4.19 3.95 -- -- 55.3 1137500 Ammonoosuc River 56.4 10.3 11.3 24.1 10.8 20.6 3.32 10.2 2.66 3.02 6.80 36.5 32.3 1138000 Ammonoosuc River 39.9 6.04 7.70 19.1 7.05 13.9 2.47 6.8 2.38 2.21 0.29 34.8 40.9 1139000 Wells River 38.1 5.79 7.40 18.2 6.81 16 3.05 7.38 3.81 2.85 6.81 41.9 52.7 1139800 East Orange Branch 41.8 6.46 8.39 19.4 7.32 24.2 3.88 11.8 4.59 3.58 1.45 57.9 60.1 1141800 Mink Brook 41.3 6.97 8.43 18.7 7.09 19.3 4.09 8.03 3.67 2.99 2.69 46.7 58.7 1142500 Ayers Brook 40.0 6.75 8.37 17.7 7.28 21.1 4.4 8.83 3.3 3.33 5.88 52.8 65.2 1144000 White River 39.6 6.85 8.31 17.2 7.28 19.5 4.01 8.3 3.26 3.37 2.87 49.2 58.5 1145000 Mascoma River 40.5 6.57 8.50 18.2 7.17 16.5 3.2 7.95 2.72 2.63 0.00 40.8 48.7 1150800 Kent Brook 54.9 9.19 11.4 24.8 9.53 -- 4.15 12.4 8.83 6.06 -- -- 45.1 1150900 Ottauquechee River 51.2 8.56 10.8 22.9 8.98 31.8 7.51 10.4 7.93 5.22 2.33 62.1 87.7 1153500 Williams River 43.7 7.72 9.37 18.7 7.76 19.6 4.45 8.63 3.26 2.82 2.24 44.9 57.7 1154000 Saxtons River 45.3 8.19 9.65 19.3 8.03 20.6 4.72 8.11 3.33 3.23 5.87 45.5 57.6 1155000 Cold River 39.9 6.91 8.48 17.6 6.85 16.2 3.59 7.39 2.54 2.44 1.48 40.6 52.0 1155200 Sacketts Brook 43.6 7.91 9.37 18.5 7.76 -- 4.37 9.2 3.55 2.81 -- -- 55.2 1155300 Flood Brook 51.0 9.09 10.9 22.0 8.90 -- 4.01 12.3 3.24 4.08 -- -- 44.1 1155500 West River 46.6 8.39 9.88 20.0 8.19 19.6 4.26 8.33 3.7 3.44 0.66 42.0 50.8 1156000 West River 45.6 8.29 9.63 19.6 7.95 17.9 3.94 7.49 3.67 2.99 1.06 39.3 47.5 1158500 Otter Brook 43.7 7.76 9.33 19.0 7.60 -- 5.56 8.16 -- -- -- -- 71.7 1162500 Priest Brook 43.0 8.05 9.07 18.1 7.72 21.7 5.74 8.43 3.89 3.73 0.41 50.5 71.3 1165500 Moss Brook 42.7 7.85 9.04 18.0 7.52 18.3 4.91 7.01 2.9 2.96 2.84 42.9 62.5 1167800 Beaver Brook 53.2 9.92 11.5 22.0 9.84 28.1 4.85 10.2 4.66 4.95 12.2 52.8 48.9 

10965852 Beaver Brook 43.2 8.13 9.00 17.8 8.39 19.9 6.71 6.14 2.92 4.59 2.31 46.0 82.5 

Average percent 46.8 54.9 Standard deviation 6.75 12.9 

Table 8. Values of seasonal and annual basin-centroid precipitation and normalized ground-water recharge and the proportion (in percent) of norm

ground-water recharge to seasonal and annual basin-centroid precipitation.—Continued

[No., number; Location of stream-gaging stations are shown in figure 1 and reference numbers and descriptions of stream-gaging stations are listed in table 1; --, no data]

Streamgaging 

station 

No.

River

Drainage-basin centroid precipitation Normalized drainage-basin recharge Percent error of annual versus sum 

of seasonal basin 

recharge values

Proportion (in p

basin recha

Annual Winter Spring Summer Fall Annual Winter Spring Summer Fall Annual Winte
18 Streamflow Data of Annual and Seasonal Ground-Water Recharge Rates for Drainage Basins in New Hampshire

normalized drainage-basin recharge to PRISM basin-centroid 

precipitation for the spring was 97 percent with a standard deviation of 18.4 percent (table 8). In the summer, ground-water 

recharge decreases (fig. 11). The ratio of ground-water recharge 

to precipitation is greater in the mountainous areas in the northern part of New Hampshire than other areas in the State during 

this season. The average proportion of normalized drainagebasin recharge to PRISM basin-centroid precipitation for the 

summer was 20 percent with a standard deviation of 6.7 percent

(table 8). In the fall, the ratios of ground-water recharge to precipitation are similar but somewhat lower and more spatially 

variable than those for the annual period. For the fall, areas in 

the northwest and southeast of the study area tend to have the 

greatest proportion of ground-water recharge to precipitation 

(fig. 12). The average proportion of normalized drainage-basin 

recharge to PRISM basin-centroid precipitation for the fall was 

43 percent with a standard deviation of 8.2 percent (table 8). 

Generalized Estimate of Drainage-Basin GroundWater-Recharge Rates Using Climatic and Basin 

Characteristics Data

Ordinary Least Squares (OLS) regression analysis was 

done using the SAS (Statistical Analysis System) computer program, version 8.1 (SAS Institute, Inc., 1994) to initially select 

climatic and basin characteristics for estimation of normalized 

annual and seasonal ground-water recharge. This analysis provided a generalized estimate of ground-water recharge in New 

Hampshire. 

No significant trends were detected in the data and all of 

the residuals were normally distributed. For the annual period, 

the station at Dudley Brook (number 1073600) had an unusually large studentized residual and was eliminated from the 

ground-water-recharge regression analysis for the annual 

period only. The studentized residual for Dudley Brook was 

large but not unusually large for the fall and spring periods and 

was not eliminated for these two seasons. 

Annual and seasonal regression equations were developed 

using GLS regression to relate normalized ground-water 

recharge at 55 stream-gaging stations to basin and climatic 

characteristics in the form of 93 potential explanatory variables 

(Appendix 1). These equations can be used to estimate groundwater recharge for the unregulated stream-gaging station drainage basins used in the regression analysis, as well as for other 

unregulated, ungaged basin locations. 

Because of the large number of basin characteristics (93) 

to be analyzed as potential independent variables in the annual 

and seasonal ground-water-recharge regression equations, an 

automated procedure was required to aid in the selection of a 

subset of independent variables for the determination of the 

dependent variable in each of the final regression models. A 

variable-selection algorithm also was required to assist in determining the combination of independent variables that provided 

the best estimates of the dependent variable in the regression 

equations. To accomplish this, a stepwise-regression procedure 

was used within the SAS program, version 8.1 (SAS Institute, 

Inc., 1994) to aid in identifying which independent variables 

were to be included in the regression equations. The stepwise 

method is a modification of the forward-selection method, in 

which variables already in the model do not necessarily remain 

in the model. Variables are added one at a time to the model 

with the F-statistic (mean square for the model divided by the 

mean square for error) used to test for significance at a predefined level. In this study, the significance level was set at 

0.05. After the addition of each new variable, the stepwise 

method assessed all of the variables already included in the 

model and deleted any variable that did not produce an F-statistic significant at the selected confidence level. Only after the 

statistical significance of each independent variable was determined, and those that were statistically insignificant at the specified significance level of 5 percent were eliminated, could 

another variable be added to the model. 

After the statistically significant independent variables (at 

the 95-percent confidence level) were determined for each of 

the annual and seasonal ground-water-recharge statistics, an allpossible-regression algorithm called RSQUARE was run in 

SAS. The RSQUARE method is a useful linear-regression tool 

for exploratory-model building as it assists in identifying subsets of independent variables that best predict a dependent variable in a given sample (SAS Institute, Inc., 1994). This algorithm examines all of the possible combinations of the 

independent variables and ranks them according to decreasing 

order of R2 (fraction of the variance explained by the regression) magnitude for the given sample. Using this output of 

ranked R2

, the best combination of independent variables was 

tested for inclusion in the final regression equations. The test 

included using minimization of Mallow’s Cp statistic (Cavalieri 

and others, 2000; Ries and Friesz, 2000) as one of the selection 

criteria. The subsets were further analyzed using OLS regression analyses to select a final model for each ground-waterrecharge statistic. The final regression models were selected 

based upon consideration of the following statistical parameters: 

1. Mallow’s Cp statistic: a measure of the total squared error 

for a subset model containing n independent variables 

(Freund and Littell, 2000). Mallow’s Cp is an indicator of 

model bias (Cavalieri and others, 2000), in which models 

with a large Cp are biased because they contain predictors 

that are not important in the population; 

2. Mean Square Error (MSE): the precision of the biased 

estimate determined as the square of the bias plus the 

variance (Freund and Littell, 2000), also known as the 

sample model error variance of the estimates for the 

stream-gaging stations included in the analysis (Ries and 

Friesz, 2000); 

3. Adjusted R Squared (R2

adj): an alternative to R-Square 

(R2), in which the percentage of variation in the 

dependent variable can be explained by the variation of 

the independent variables in the model. In contrast to R2, 

R2

adj is adjusted for the number of parameters in the 
Estimates of Annual and Seasonal Ground-Water-Recharge Rates 19

model (number of stream-gaging stations and number of 

independent variables in the regression analysis) (Freund 

and Littell, 2000);

4. Predicted REsidual Sum of Squares (PRESS): the sum of 

squares of residuals using models obtained by estimating 

the equation with all other observations (Freund and 

Littell, 2000) and is an estimate of the prediction error 

sum of squares. The PRESS statistic measures how well 

the regression model predicts the i

th observation as 

though it were a new observation (Cavalieri and others, 

2000). 

In addition to the above statistical criteria for selecting the 

best combination of independent variables for the final regression models, independent variables were selected based on 

whether they (1) made hydrologic sense, (2) explained a significant amount of the variability of the dependent (response) 

variable (ground-water-recharge statistic), and (3) could be easily measured using a GIS. 

Regression equations were developed, using SAS software 

(SAS Institute, Inc., 1994), to determine basin-specific annual 

and seasonal ground-water-recharge rates from the selected 

independent variables and the normalized estimates of groundwater recharge. The independent variables selected for the final 

models were statistically significant at the 95-percent confidence level. This was accomplished by determining that the

p-value of the test F-statistic was less than alpha=0.05 (Cavalieri and others, 2000). In addition to statistical criteria, the sign 

(positive or negative) of all of the regression coefficients had to 

make hydrologic sense as related to ground-water recharge. 

Diagnostic checks were performed to test for model adequacy and violations of the assumptions for regression analysis. 

Regression-equation independent variables that are highly 

intercorrelated result in a duplication of the information contained in those variables and prediction equations that are likely 

to be unreliable. To test for this condition, known as multicollinearity, variance-inflation factors (VIF) were computed for 

each variable. A VIF expresses the ratio of the actual variance 

of the coefficient of the predictor variable to its variance if it 

was independent of the other predictor variables (Cavalieri and 

others, 2000) and is a measure of how multicollinearity 

increases the instability or variance of the linear-regression 

coefficient estimates (Freund and Littell, 2000). VIF values are 

computed as the inverse of the correlation matrix of the predictor variables. A value exceeding 10 indicates that a predictor 

variable is so highly correlated to other predictor variables that 

it is an unreliable predictor and should not be included in the 

estimation equation as the equation may be unstable. None of 

the predictor variables retained in the prediction models for this 

study had VIF values greater than 10.

Other diagnostic checks for model adequacy and violations of assumptions in regression analysis included the identification of influential observations. Influential observations are 

data that substantially change the fit of the regression equation. 

Three diagnostic statistics were computed to help identify influential observations. These statistics were

1. Rstudent (studentized) residuals: the ordinary residuals 

divided by their standard errors, determined from the difference between the observed dependent variable and the 

predicted value of the independent variable excluding the 

i

th observation from the regression analysis (Freund and 

Littell, 2000); and

2. DFFITS: the standardized difference between predicted 

values for the i

th observation obtained by the equation 

estimated by all observations and the equation estimated 

from all observations excluding the ith observation 

(Freund and Littell, 2000).

Ten of the 93 basin characteristics were selected because 

of their statistical significance in predicting annual and seasonal 

ground-water recharge. They include

• Average mean annual basin temperature (ABT), in 

degrees Fahrenheit, is the annual basin average mean 

temperature from 2-kilometer-grid PRISM (Daly, 

2000) data for 1961–90.

• Average minimum winter basin temperature 

(WBT), in degrees Fahrenheit, is the winter basin average minimum temperature from 2-kilometer-grid 

PRISM (Daly, 2000) data for 1961–90.

• Coniferous Forest (C), in percent, represents the portion of the basin that is classified as coniferous from 

NLCD data (Vogelman and others, 2001) and is 

defined as those areas dominated by trees where

75 percent or more of the tree species maintain their 

leaves all year. Canopy is never without green foliage;

• Mixed Coniferous/Deciduous Forest (CD), in percent, represents the percent of the basin that is classified as mixed coniferous and deciduous from NLCD 

data (Vogelman and others, 2001) and is defined as 

those areas dominated by trees where neither deciduous 

nor coniferous trees represent more than 75 percent of 

the cover present; 

• Mean annual (AGP), spring (SpGP) and summer 

(SGP) gage precipitation, in inches, is the annual, 

spring and summer precipitation determined at the 

stream-gaging station from 2-kilometer-grid PRISM 

data for 1961–90; 

• Mean annual (ACP) and fall (FCP) basin-centroid 

precipitation, in inches, is the annual and fall season 

precipitation determined at the centroid of the basin 

from 2-kilometer-grid PRISM data for 1961–90. 

• Mean annual snowcover (ASC), in inches, is the 

mean annual basin average snowfall for each of the 

basins based on monthly data acquired from 2-kilometer-grid PRISM data for 1961–90. 

The annual and seasonal normalized ground-water 

recharge, the GLS regression equation predicted values, the 

standard error of prediction at each stream-gaging station used 

in the development of the regression equations and the 
20 Streamflow Data of Annual and Seasonal Ground-Water Recharge Rates for Drainage Basins in New Hampshire

90-percent prediction interval are included in tables 9–13 (back 

of report). The standard error of prediction is a measure of the 

scatter about the computed regression line plus the error in estimating the regression line from the data. Thus, the standard 

error of prediction takes into account that the regression coefficients are estimated from observed data and as such contribute 

to the uncertainty of the model. The 90-percent prediction interval defines the range of uncertainty associated with the predicted values, which is indicated with a 90-percent probability 

that the true value of the ground-water-recharge statistic is 

between the upper and lower values as listed in tables 9–13 

(back of report). 

A value of 21.0 in. was obtained for the average annual 

normalized rate of ground-water recharge, for the basins used in 

the analysis, based on GLS regression analysis of selected basin 

characteristics and RORA-derived ground-water-recharge 

estimates adjusted for the average precipitation during 1961– 1990. The average winter ground-water recharge was 4.3 in., 

average spring ground-water recharge was 9.0 in., average summer ground-water recharge was 4.0 in., and average fall groundwater recharge was 3.6 in. Annual normalized ground-water 

recharge ranged from 12.3 to 31.8 in., normalized ground-water 

recharge for winter ranged from 2.30 to 7.82 in., for spring 

ranged from 5.16 to 13.7 in., for summer ranged from 1.45 to 

10.2 in., and for fall ranged from 2.21 to 6.06 in. The GLSdeveloped regression equations for annual and seasonal groundwater recharge are presented in table 14 along with the number 

of stream-gaging stations used in the analysis and several measures of model adequacy. 

Ground-Water-Recharge Regression 

Equations

Ten basin characteristics were selected as independent 

variables in the annual and seasonal ground-water-recharge 

regression equations given their statistical significance based on 

several statistical parameters that evaluated which combination 

of basin characteristics contributed the most to the predictive 

power of the models. To determine the regression equation 

ground-water-recharge rates, a GIS is required to measure the 

values of the independent variables used in this study.

Regression Model Adequacy

The adequacy of the generalized ground-water-recharge 

regression equations in table 14 was measured using the following statistics:

1. The Mean Square Error (MSE): an estimate of the variance of the random error term for the full model. It is 

determined from the error sum of squares (variation in the 

dependent variable not explained by the model) divided 

by the error degrees of freedom (the number of independent variable parameters minus one) (Cavalieri and others, 2000).

2. The Average Prediction Error (APE): an overall measure 

of how accurately the regression model can predict 

ground-water recharge for ungaged sites where the

Table 14. Summary of regression equations and measures of model adequacy for estimating ground-water-recharge statistics 

at selected New Hampshire stream-gaging stations.

[All recharge values are in inches per season or year; MSE, Mean Square Error; APE, Average Prediction Error of Model (G.D. Tasker, U.S. Geological 

Survey, written commun., 2002); No., number; in., inch. The following basin characteristics were derived from 2-kilometer grid Parameter-elevation Regressions on Independent Slopes Model (PRISM) data (Daley, 2000) from 1961 to 1990: AGP, average annual precipitation at USGS stream-gaging stations (inches); WBT, average mean winter basin temperature (degrees Fahrenheit); SpGP, average spring precipitation at USGS stream-gaging stations 

(inches); ASC, average annual snowcover (inches); SGP, average summer precipitation at USGS stream-gaging stations (inches); ABT, average mean annual basin temperature (degrees Fahrenheit); FCP, average fall centroid precipitation (inches); ACP, average annual centroid precipitation (inches). The 

following basin characterstics were derived from the National Land Cover Data Set (NLCD): C, percent of basin containing coniferous forest (percent); 

and CD, percent of drainage basin containing mixed coniferous and deciduous forest (percent)]

Statistic Regression equation No. of streamgaging stations

Average model 

MSE

(in.)

 APE

(in.)

R2 adj

(percent)

Ground-water recharge–Generalized-Least-Squares Regression equations

Winter -3.485+0.160(AGP)+0.168(WBT)-0.041(C) 55 0.39 0.67 67

Spring -1.544+0.721(SpGP)+0.045(ASC)-0.032(C) 55 1.11 1.11 63

Summer 3.725+0.573(SGP)-0.223(ABT)-0.039(CD) 54 1.01 1.05 57

Fall 0.389+0.499(FCP)-0.049(C) 54 .30 .57 48

Annual -1.932+0.589(ACP)-0.176(C) 48 6.40 2.63 53
Ground-Water-Recharge Regression Equations 21

3. average is taken over prediction sites with X variables 

identical to the observed ground-water-recharge data. 

APE represents an estimate of the average squared-model 

error for the n sites plus an estimate of the average 

squared error due to estimating the true model parameters 

from a sample of data.

4. Adjusted R Squared (R2

adj): an alternative to R-Square 

(R2), in which the percentage of variation in the 

dependent variable can be explained by the variation of 

the independent variables in the model. R2

adj is adjusted 

for the number of parameters in the model (number of 

stream-gaging stations and number of independent 

variables in the regression analysis) (Freund and Littell, 

2000);

The GLS model allows the weight given to each site in the 

regression analyses to be adjusted for cross correlation among 

all of the concurrent streamflows of the sites and for differences 

in record lengths. For GLS regression, the variance of the errors 

for an observation, which in this case is the ground-waterrecharge statistic, is estimated as a function of the error in the 

regression model and the error in the estimate of the true value 

of the ground-water-recharge statistic. The error in the calculated stream-gaging station ground-water-recharge statistic is 

estimated as a function of the record length, variance of the 

annual events, and cross correlation between the statistics. As a 

result, it would be inappropriate to use the equally weighted 

residuals in a GLS model to calculate a measure of predictive 

accuracy. Instead, the APE is used as a measure of the predictive accuracy of the GLS regression equations (table 14). The 

APE of the regression model is a measure of how well the 

regression equations will estimate ground-water recharge when 

applied to ungaged drainage basins. The APE was determined 

for the GLS-determined annual and seasonal ground-waterrecharge regression equations by computing the square root of 

the sum of the average squared model error for the n sites and 

the average squared error due to estimating true model parameters from sample data. 

Physical Basis for the Independent Variables in the 

Regression Equations

Recharge to a drainage basin is primarily a function of precipitation, whereas storage and discharge from a basin are controlled primarily by the physical characteristics of the basin 

(Hayes, 1991). Evapotranspiration and runoff rates are all 

affected by land use and these affect ground-water-recharge 

conditions. The drainage-basin characteristics of percent coniferous forest and percent-mixed coniferous and deciduous forest 

were found to be statistically significant variables in the 

ground-water-recharge regression equations and reflect the 

effect of interception, evapotranspiration, infiltration, and runoff rates on ground-water recharge. These two basin characteristics are inversely related to ground-water recharge. The variable of percent mixed coniferous and deciduous forest was 

found to be significant only for the summer season (June 1–

October 31), whereas the variable percent coniferous forest was 

found to be significant in each of the other seasons. The statistical significance of these two basin characteristics supports the 

concept that evapotranspiration and interception reduce flows 

and ultimately ground-water recharge by capturing ground 

water that would have otherwise remained as ground water or 

discharged to streams. Evapotranspiration results in a major 

loss of water from drainage basins. It dominates the water balance and controls soil moisture content, ground-water recharge, 

and streamflow. More than two-thirds of the precipitation falling on the conterminous United States is returned to the atmosphere through evaporation from plants and surface water 

(Dunne and Leopold, 1978). According to Dunne and Leopold, 

coniferous trees intercept slightly more rainfall than deciduous 

trees because coniferous trees have greater masses of foliage 

and branches throughout the year than deciduous trees and 

because their needles can hold more interception storage than 

broad leaves. In the summer, the combined effect of mixed 

coniferous and deciduous forest was found to be a more significant variable in the ground-water-recharge regression equation 

than the variable of coniferous forest alone as there is more canopy for interception and greater evapotranspiration during this 

season. Over the long term, canopy interception was determined to be greater under conifers than under broad-leaf hardwoods. Dunne and Leopold (1978) presumed that this was a 

result of the high density of conifers in New Hampshire and 

possibly because of the more frequent occurrence of light rains 

and snows, which are more fully intercepted in coniferous forests.

The climatic characteristic of average basin temperature 

for 1961–90 was significant for the winter (January 1–March 

15) and summer (June 1–October 31). This variable, which is 

directly related to ground-water recharge for the winter season 

and indirectly related to ground-water recharge for the summer 

season, reflects the basin latitude and elevation, which in turn 

reflects the prevalence of coniferous and deciduous forest 

cover. Average basin temperature affects the rate of evaporation 

in a particular basin. During the winter, cold temperatures result 

in less ground-water recharge as a result of the accumulation 

and storage of precipitation within the snowpack. During the 

summer, water requirements for transpiration increase dramatically and warm temperatures increase evaporation from surface 

waters, resulting in a decrease in the rate of ground-water 

recharge.

The climatic characteristic of average annual snowcover 

for 1961–90 was significant for the spring (March 16–May 31) 

ground-water-recharge regression equation as high spring flows 

occur in New England during March, April, and May as a result 

of melting snowpack and concurrent precipitation resulting in 

more water available for ground-water recharge. In general, 

flows are greater in March and April in the streams in southern 

New Hampshire and are greater in April and May in the streams 

in central and northern New Hampshire (Hammond and Cotton, 

1986).
22 Streamflow Data of Annual and Seasonal Ground-Water Recharge Rates for Drainage Basins in New Hampshire

Uncertainties in Determining Ground-Water Recharge

The Rorabaugh method was used to determine groundwater recharge in this study. This method is based on an ideal 

flow system in which the aquifer has uniform thickness, hydraulic conductivity, and storage coefficient; the stream fully penetrates the aquifer; the hydraulic head everywhere in the aquifer 

is the same as the stage of the stream; and the ground- and surface-water divides are considered to be coincident. Because of 

these assumptions, it is recognized that there is some error 

inherent in the estimation of ground-water recharge with this 

method, as well as with other estimation methods. 

Indirect and direct methods are available to estimate 

ground-water recharge to aquifers. Indirect methods include an 

estimate of the recharge rate based on the measurement or calculation of the ground-water-discharge rate. This method is 

based on the steady-state concept that the average rate of 

ground-water recharge equals the average rate of ground-water 

discharge over an extended period of time (Knott and Olimpio, 

1986). The reduction of flow along a stream reach also can be 

used to estimate recharge from streamflow losses. The measurement of flow at various locations in the stream can indicate 

directly the loss of water from the channel or amount of 

recharge contributed by the stream. A water-balance technique 

is an indirect method to estimate ground-water recharge, where 

water loss by evapotranspiration is estimated and subtracted 

from measured precipitation to calculate ground-water recharge 

during that same time period (Thornthwaite and Mather, 1957). 

Other indirect methods include numerical simulation, chemical 

tracer studies, tritium isotopic studies, studies of ground-waterlevel fluctuations, derivation of empirical relations on the basis 

of precipitation data, and studies based on hydrograph separation of streamflow records (Holtschlag, 1997). Hydrographseparation techniques are used to analyze streamflow data to 

determine base flow, which is typically derived largely from 

ground-water discharge. If it is assumed that there is no longterm change in the amount of ground water in storage, groundwater discharge, as indicated by base flow, equals the amount 

of ground-water recharge over the basin area contributing the 

low flow (Vecchioli and others, 1990). Some forms of groundwater discharge that would need to be considered in estimating 

ground-water recharge from ground-water discharge include 

withdrawals by wells and evapotranspiration from the water 

table (Vecchioli and others, 1990). 

Direct methods of measuring ground-water-recharge rates 

are difficult. These methods include, but are not limited to, the 

use of closed-bottom lysimeters buried beneath the root zone 

and tensiometers. If it is assumed that low flow is equal to base 

flow (portion of streamflow attributable to ground-water flow), 

ground-water discharge can be measured during periods of low 

flow. Discharge also can be determined using Darcy’s law, 

assuming that the estimated hydraulic conductivity and elevation of the water table are correct (Knott, 1986). 

In a study such as this, the true value against which to evaluate a ground-water-recharge estimate, and the method used, is 

not known. This study contains upland basin-recharge rates that 

are higher than those determined for till and bedrock in a study 

conducted in Maine by Morrissey (1983). In that study, the 

water year of 1981 (October 1, 1980–September 30, 1981) was 

used to estimate ground-water recharge for the Little 

Androscoggin River near South Paris (gage 1057000). This 

drainage basin consists primarily of till. The precipitation for 

the calendar year of 1980 (42.9 in.) was less than the average 

annual precipitation (from 1949 to 1998) of 49.8 in., with the 

late fall of 1980 being particularly dry. The 1981 calendar year 

precipitation of 48.3 in. was slightly below average. However, 

this value is for the calendar year and not the water year. 

According to Morrissey (1983), the National Weather Service 

determined precipitation at West Paris, Maine was 39.4 in. for 

the 1981 water year. Precipitation for November 1, 1980, 

through May 31, 1981, was 19.5 in. The average precipitation 

for November 1st through May 31st from 1948 to 1998 was 

26.1 in. This is approximately 25 percent less precipitation than 

average for this period. Much of the precipitation for the calendar year of 1981 came in the late summer and fall of 1981. 

Before 1981, precipitation conditions were below normal. 

Morrissey assumed that lateral recharge from till to the 

aquifer is equal to the ground-water runoff from till-covered 

areas. The ground-water component of runoff was determined 

for the 1981 water year for the station on the Little Androscoggin River near South Paris using a hydrograph separation 

method described by Meinzer and Stearns (1929). The resulting 

annual ground-water-recharge estimate of 7.4 in. is approximately 19 percent of total precipitation for the 1981 water year. 

The current study estimated an annual recharge rate of approximately 20 in. for the 1981 water year. This estimate of groundwater recharge is approximately 51 percent of total precipitation for the 1981 water year. The normalized recharge rate for 

the Little Androscoggin River Basin was determined to be

18.3 in/yr. 

STATSGO (STATe Soil GeOgraphic) data (Schwarz and 

Alexander, 1995) was designed primarily for regional, multicounty, river basin, State and multistate management, and 

resource planning and monitoring. Although it is a generalized 

estimate derived from more detailed soil survey maps, according to STATSGO data upstream from station 1057000, the Little Androscoggin River Basin, has a mean permeability of 

4.189 inches per hour. The 100-year, 24-hour rainfall is approximately 7 in. and the 100-year, 1-hour rainfall is approximately 

2.25 in. for the Little Androscoggin River Basin (U.S. Department of Commerce Weather Bureau, 1961). On the basis of 

these values, large precipitation events in the Little Androscoggin River Basin are capable of infiltrating and the permeability 

of the till would not be a factor leading to overland flow and 

thus a loss of recharge to the aquifer.

Morgan and Jones (1995) conducted a study of the effects 

of ground-water withdrawals on discharge to streams and 

springs in small basins typical of the Puget Sound Lowland in 

Washington State. In their study, reference is made to a written 

communication (1993) with J.J. Vaccaro (U.S. Geological Survey) in which permeameter measurements of hydraulic conductivity were made in till and showed a range from 0.0002 to
Ground-Water-Recharge Regression Equations 23

53 ft/day. Both this range and the median, 0.12 ft/d, are similar 

to values reported for till in southern New England, where the 

range and median were 0.00023–96 ft/d and 0.3 ft/d, respectively (Melvin and others, 1992). Water budgets were determined for 26 basins and the mean annual precipitation was 

determined to range from 25–61 in/yr. The range of recharge 

estimates was from 5 to 29 in/yr. Vaccaro estimated that the 

average annual recharge in areas underlain by till and other finegrained deposits was 17.5 in. In the simulation used in Morgan 

and Jones (1995), a mean annual precipitation of 44 in/yr and a 

recharge rate of 18 in/yr were used in the areas where the less 

permeable till was exposed. This recharge rate is similar to the 

18.3 in. of average annual recharge for the primarily till basin of 

Little Androscoggin River upstream from USGS stream-gaging 

station 1057000 with the precipitation being slightly less than 

the average precipitation of 49.8 in/yr for this area.

Limitations on the Use of Regression Equations

The regression equations presented in this report are limited in application by the range of the basin-characteristic data 

used to develop the equations and by the accuracy of the estimates. These equations should be used with caution when determining ground-water-recharge statistics at ungaged sites with 

basin characteristics that are beyond the range of those used to 

develop the regression equations. The ranges of the basincharacteristic data used to develop the ground-water-recharge 

regression equations are listed in table 15. The accuracy of the 

estimates when basin characteristics are within the ranges of 

those sites used in the regression analysis are listed in table 14. 

The use of these regression equations requires that the physical 

and climatic basin characteristics be determined within a GIS 

using the same datasets (Appendix 1) that were used to develop 

the equations outlined in this report. 

A GIS computer application tool is planned that will provide ground-water-recharge statistics from a database for gaged 

and ungaged sites in New Hampshire by measuring the necessary basin characteristics for a user-selected site from digital 

map data using ArcView GIS (Environmental Systems 

Research Institute, Inc., 1994) to solve the regression equations. 

The output from the tool will include a map of the drainagebasin boundary determined for the site, the values of the GISmeasured basin characteristics, the estimated ground-waterrecharge statistics, and prediction intervals for the estimates.

Summary and Conclusions

 An increase in population and industry in New Hampshire 

has resulted in an increased demand for water. Determination of 

ground-water-recharge values will aid Federal, State, local, and 

private agencies in making water-resource planning, regulatory, 

and management decisions. To better understand water availability, the U.S. Geological Survey (USGS), in cooperation 

with the New Hampshire Department of Environmental Services (NHDES), has developed datasets, hydrologic statistical 

relations, and a geographic information system (GIS) of data 

coverages for all of New Hampshire. This information provides 

a basis for water-resources managers for sustainable water-use 

management.

Table 15. Ranges of basin characteristics used to develop the regression equations for estimating ground-water-recharge rates in 

New Hampshire drainage basins.

[in., inches; PRISM, Parameter-elevation Regressions on Independent Slopes Model (Daley, 2000); NLCD, National Land Cover Dataset]

Basin characteristic

Basin 

characteristic 

abbreviation

Minimum Mean Maximum

Average annual gage precipitation (in.; PRISM) AGP 35.83 42.93 53.11

Average summer gage precipitation (in.; PRISM) SGP 16.46 18.60 23.11

Average spring gage precipitation (in.; PRISM) SpGP 6.83 8.85 11.54

Average annual basin-centroid precipitation (in.; PRISM) ACP 37.44 45.32 75.91

Average mean annual basin temperature (degrees Fahrenheit; PRISM) ABT 36.05 42.35 48.69

Average minimum winter basin temperature (degrees Fahrenheit; PRISM) WBT 0.8 10.61 19.88

Percent coniferous forest (percent; NLCD) C 3.07 20.65 56.18

Percent mixed coniferous/deciduous forest (percent; NLCD) CD 6.21 26.05 46.13

Average fall basin centroid precipitation (in.; PRISM) FCP 6.57 8.38 15.20

Average annual snowcover (in.; PRISM) ASC 54.46 102.41 219.07
24 Streamflow Data of Annual and Seasonal Ground-Water Recharge Rates for Drainage Basins in New Hampshire

Annual and seasonal ground-water-recharge rates were 

developed through the analysis of 55 unregulated continuousrecord stream-gaging stations using the Recession-Curve Displacement Computer Program RORA. The seasons, as specified 

by the NHDES are winter (January 1–March 15), spring (March 

16–May 31), summer (June 1–October 31), and fall (November 

1–December 31). Stream-gaging stations were not chosen in 

basins where the streamflow is known to be affected by regulation, diversion, flow augmentation, or hydraulic control structures. A minimum of 10 years of continuous streamflow data 

was required for a stream-gaging station to be included in the 

analysis.

Although in many cases streamflow records were considerably longer than 10 years, the length of record for the basinspecific estimation of ground-water recharge determined in this 

study ranged from 10 to 50 years. The length of the streamgaging station record used to determine the annual and seasonal 

ground-water-recharge rates was dictated by the length of 

record of the National Climate Data Center (NCDC) digitalprecipitation database. The digital NCDC precipitation-gage 

data were available from 1949 through 1998.

A consistent recharge estimate and the statistical significance of the annual and seasonal regression equations relating 

ground-water recharge and area/distance-weighted NCDC 

basin-centroid precipitation for each stream-gaging station 

were determined. Only coefficients significant at the 5-percent 

level were maintained in the equations. In a few instances, the 

basin-recharge rate was based only on the Recession-Curve 

Displacement Computer Program (RORA) (Rutledge, 1998)-

determined ground-water-recharge rate because the area/distance-weighted NCDC basin-centroid precipitation was not statistically significant.

Temporal variations in recharge were removed by normalizing the ground-water-recharge regression equations to determine the spatial relation of the annual and seasonal groundwater-recharge rates. For consistency among stations that have 

operated during different periods, annual and seasonal normalized ground-water recharge was determined by substituting the 

average annual and seasonal basin-centroid values of precipitation for 1961–90, as determined from a 2-kilometer grid

Parameter-elevation Regressions on Independent Slopes Model 

(PRISM), into each of the annual and seasonal basin-recharge 

equations for the area/distance-weighted NCDC basin-centroid 

precipitation values.

The regression equations developed in this study relate 

normalized ground-water-recharge rates at 55 stations to basin 

and climatic characteristics determined from 93 potential 

explanatory variables for each basin. The results can be used to 

estimate ground-water recharge for the unregulated streamgaging station drainage basins used in the regression analysis, 

as well as for any other unregulated, ungaged basin locations. 

Ten of the 93 basin characteristics were determined to be the 

most statistically significant in explaining a significant amount 

of the variability of the dependent (response) variable. The following basin and climatic characteristics were found to be statistically significant predictors for at least one of the dependent 

variables: average annual, summer, and spring precipitation as 

determined at U.S. Geological Survey stream-gaging stations; 

average annual basin-centroid precipitation; average mean 

annual basin temperature; average minimum winter basin temperature; percent coniferous forest in a basin; percent mixed 

coniferous and deciduous forest in a basin; average fall basincentroid precipitation; and average annual snowcover. These 

10 basin and climatic characteristics were selected because they 

were statistically significant based on several statistical parameters that evaluated which combination of characteristics contributed the most to the predictive accuracy of the regressionequation models. A geographic information system (GIS) is 

required to measure the values of the independent variables for 

the equations developed in the study. 

Generalized-least-squares (GLS) regression analysis was 

used to develop the final equations that determined annual and 

seasonal ground-water-recharge rates with the computer program generalized-least-squares NETwork (GLSNET). GLS 

regression analysis accounts for the differences in the variances 

of the basin-specific recharge estimates, and for the cross-correlation of concurrent flows with other stream-gaging stations. 

The proportion of variation in the dependent variables (annual 

and seasonal normalized ground-water recharge) that is 

explained by the independent variables (R2adj) in the groundwater-recharge regression equations ranged from 48 to 67 percent. Average model mean square error (MSE) ranged from

0.3 to 6.4 in. 

Generalized estimates of normalized ground-water 

recharge were derived from GLS regression analysis of selected 

basin characteristics and RORA-derived recharge values 

adjusted (normalized) for average precipitation data from 1961 

to 1990 (PRISM). A value of 21.0 in. was obtained as the average annual normalized rate of ground-water recharge. The average normalized ground-water recharge for winter was 4.3 in., 

for spring was 9.0 in., for summer was 4.0 in., and for fall was 

3.6 in. Annual normalized ground-water recharge ranged from 

12.3 to 31.8 in. Normalized ground-water recharge for winter 

ranged from 2.30 to 7.82 in., for spring ranged from 5.16 to 

13.7 in., for summer ranged from 1.45 to 10.2 in., and for fall 

ranged from 2.21 to 6.06 in.

Acknowledgments

The authors thank Craig Johnston, U.S. Geological Survey, for preparing the numerous GIS data layers that describe 

the basin and climatic characteristics used in the development 

of the ground-water-recharge regression equations in this 

report. Appreciation is extended to Ann Marie Squillacci for the 

preparation of tables, Anita Cotton for graphics assistance, and 

Debra Foster for the editorial review of this report (all from the 

U.S. Geological Survey).
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28, 2001, at http://mac.usgs.gov/mac/isb/pubs/factsheets/

fs10800.html

Vecchioli, John, Tibbals, C.H., Duerr, A.D., Hutchinson, C.B., 

1990, Ground-water recharge in Florida–a pilot study in Okaloosa, Pasco, and Volusia Counties: U.S. Geological Survey 

Water-Resources Investigations Report 90-4195, 16 p.

Vogelmann, J.E., Howard, S.M., Yang, L., Larson, C.R.,

Wylie, B.K., Van Driel, N., 2001, Completion of the 1990s 

National land cover dataset for the conterminous United 

States: LANDSAT Thematic Mapper Data and ancillary 

data sources, Photogrammetric Engineering and Remote 

Sensing, v. 67, p. 650–652.

Wandle, S.W., Jr., and Randall, A.D., 1994, Effects of surficial 

geology, lakes and swamps, and annual water availability on 

low-flows of streams in central New England, and their use 

in low-flow estimation: U.S. Geological Survey WaterResources Investigations Report 93-4092, 57 p.
28 Streamflow Data of Annual and Seasonal Ground-Water Recharge Rates for Drainage Basins in New Hampshire

ANNUAL GROUND-WATER RECHARGE RATE, IN INCHES

0

4540352520

1510

U.S. GEOLOGICAL SURVEY STREAM-GAGING STATION NUMBER

1052500

1054200

1054300

1055000

1057000

1064300

1064400

1064500

1072850

1073000

1075000

1075800

1076000

1076500

1078000

1082000

1084500

1085800

1086000

1089000

1091000

1093800

10965852

1097300

1101000

1127880

1129440

1130000

1133000

1134500

1135000

1137500

1138000

1139000

1139800

1141800

1142500

1144000

1145000

1150900

1153500

1154000

1155000

1155500

1156000

1162500

1165500

1167800

555030

5

Upper whisker

 Upper quartile Median Lower quartile Lower whisker

9010

755025

Percentile

Data value above the  90th percentile or below  the 10th percentile

Figure 3. Distribution of annual rates of ground-water recharge in New Hampshire. (Station locations are shown on figure 8 and listed in table 1.)
Figures 29

GROUND-WATER RECHARGE RATE PER WINTER SEASON, IN INCHES

-2

864

20

1210

U.S. GEOLOGICAL SURVEY STREAM-GAGING STATION NUMBER

1052500

1054200

1054300

1055000

1057000

1064300

1064400

1064500

1072850

1073000

1073600

1075000

1075800

1076000

1076500

1078000

1082000

1084500

1085800

1086000

1089000

1091000

1093800

10965852

1097300

1101000

1127880

1129440

1130000

1133000

1134500

1134800

1135000

1135300

1137500

1138000

1139000

1139800

1141800

1142500

1144000

1145000

1150800

1150900

1153500

1154000

1155000

1155200

1155300

1155500

1156000

1162500

1165500

1167800

1614

Upper whisker

 Upper quartile Median Lower quartile Lower whisker

9010

755025

Percentile

Data value above the  90th percentile or below  the 10th percentile

1158500

Figure 4. Distribution of winter (January 1–March 15) rates of ground-water recharge in New Hampshire. (Station locations are shown on 

figure 9 and listed in table 1.)
30 Streamflow Data of Annual and Seasonal Ground-Water Recharge Rates for Drainage Basins in New Hampshire

GROUND-WATER RECHARGE RATE PER SPRING SEASON, IN INCHES

50

3025201510

U.S. GEOLOGICAL SURVEY STREAM-GAGING STATION NUMBER

1052500

1054200

1054300

1055000

1057000

1064300

1064400

1064500

1072850

1073000

1073600

1075000

1075800

1076000

1076500

1078000

1082000

1084500

1085800

1086000

1089000

1091000

1093800

10965852

1097300

1101000

1127880

1129440

1130000

1133000

1134500

1134800

1135000

1135300

1137500

1138000

1139000

1139800

1141800

1142500

1144000

1145000

1150800

1150900

1153500

1154000

1155000

1155200

1155300

1155500

1156000

1162500

1165500

1167800

 Upper whisker Upper quartile Median Lower quartile Lower whisker

9010

755025

Percentile

Data value above the  90th percentile or below  the 10th percentile

1158500

Figure 5. Distribution of spring (March 16–May 31) rates of ground-water recharge in New Hampshire. (Station locations are shown on figure 10 and listed in table 1.)
Figures 31

GROUND-WATER RECHARGE RATE PER SUMMER SEASON, IN INCHES

-2.5

0

7.55.0

20.0

15.010.0

U.S. GEOLOGICAL SURVEY STREAM-GAGING STATION NUMBER

1052500

1054200

1054300

1055000

1057000

1064300

1064400

1064500

1072850

1073000

1073600

1075000

1075800

1076000

1076500

1078000

1082000

1084500

1085800

1086000

1089000

1091000

1093800

10965852

1097300

1101000

1127880

1129440

1130000

1133000

1134500

1134800

1135000

1135300

1137500

1138000

1139000

1139800

1141800

1142500

1144000

1145000

1150800

1150900

1153500

1154000

1155000

1155200

1155300

1155500

1156000

1162500

1165500

1167800

2.5

17.512.5

 Upper whisker Upper quartile Median Lower quartile Lower whisker

9010

755025

Percentile

Data value above the  90th percentile or below  the 10th percentile

Figure 6. Distribution of summer (June 1–October 31) rates of ground-water recharge in New Hampshire. (Station locations are shown on figure 11 and listed in table 1.)
32 Streamflow Data of Annual and Seasonal Ground-Water Recharge Rates for Drainage Basins in New Hampshire

GROUND-WATER RECHARGE RATE PER FALL SEASON, IN INCHES

-2

86420

1210

U.S. GEOLOGICAL SURVEY STREAM-GAGING STATION NUMBER

1052500

1054200

1054300

1055000

1057000

1064300

1064400

1064500

1072850

1073000

1073600

1075000

1075800

1076000

1076500

1078000

1082000

1084500

1085800

1086000

1089000

1091000

1093800

10965852

1097300

1101000

1127880

1129440

1130000

1133000

1134500

1134800

1135000

1135300

1137500

1138000

1139000

1139800

1141800

1142500

1144000

1145000

1150800

1150900

1153500

1154000

1155000

1155200

1155300

1155500

1156000

1162500

1165500

1167800

 Upper whisker Upper quartile Median Lower quartile Lower whisker

9010

755025

Percentile

Data value above the 90th  percentile below the 10th  percentile

Figure 7. Distribution of fall (November 1–December 31) rates of ground-water recharge in New Hampshire. (Station locations are shown onfigure 12 and listed in table 1.)
Figures 33

Manchester

Concord

EXPLANATION

Drainage-basin boundary

Proportion of normalized annual groundwater recharge to annual basin-centroid 

precipitation (PRISM, 1961-90), in percent

0 71-80

1-10 81-90

11-20 91-100

21-30 101-110

31-40 111-120

41-50 121-130

51-60 131-140

61-70 141-150

Stream-gaging station and reference 

number

0

2

27

55

5

28

1

54

53

44

39

3

4

33

2

35

6

7

36

38 37

12

14

13

50 46

42

16

20

18

22

10

9

24

19

17

29

41

40

30

31

8

15

51

45

47

21

25

26

23

Base from U.S. Geological Survey

Digital line graphs, 1:24,000 or

1:25,000 scale, 1983

Figure 8. Drainage basins that were used to develop the equations for estimating annual (January 1–December 31) 

ground-water-recharge statistics in New Hampshire showing the proportion (in percent) of normalized annual groundwater recharge to annual basin-centroid precipitation. (Station reference numbers are listed in table 1.)
34 Streamflow Data of Annual and Seasonal Ground-Water Recharge Rates for Drainage Basins in New Hampshire

Manchester

Concord

0

2

27

55

5

28

1

54

53

44 43

39

3

4

33

32 2

35

6

7

36

38 37

12

14

13

48

50

49

46

42

16

20

18

22

10

11

9

24

19

17

29

41

40

30

34

31

8

15

51

45

47

52

21

25

26

23

Base from U.S. Geological Survey

Digital line graphs, 1:24,000 or

1:25,000 scale, 1983

EXPLANATION

 Drainage-basin boundary

Proportion of normalized annual groundwater recharge to winter basin-centroid 

precipitation (PRISM, 1961-90), in percent

0 71-80

1-10 81-90

11-20 91-100

21-30 101-110

31-40 111-120

41-50 121-130

51-60 131-140

61-70 141-150

Stream-gaging station and reference 

number

Figure 9. Drainage basins that were used to develop the equations for estimating winter (January 1–March 15) 

ground-water-recharge statistics in New Hampshire showing the proportion (in percent) of normalized winter groundwater recharge to winter basin-centroid precipitation. (Station reference numbers are listed in table 1.)
Figures 35

0

2

26

23

Manchester

Concord

Base from U.S. Geological Survey

Digital line graphs, 1:24,000 or

1:25,000 scale, 1983

EXPLANATION

 Drainage-basin boundary

Proportion of normalized annual groundwater recharge to spring basin-centroid 

precipitation (PRISM, 1961-90), in percent

0 71-80

1-10 81-90

11-20 91-100

21-30 101-110

31-40 111-120

41-50 121-130

51-60 131-140

61-70 141-150

Stream-gaging station and reference 

number

27

55

5

28

1

54

53

44 43

39

3

4

33

32 2

35

6

7

36

38 37

12

14

13

48

50

49

46

42

16

20

18

22

10

11

9

24

19

17

29

41

40

30

34

31

8

15

51

45

47

52

21

25

Figure 10. Drainage basins that were used to develop the equations for estimating spring (March 16–May 31) groundwater-recharge statistics in New Hampshire showing the proportion (in percent) of normalized spring ground-water 

recharge to spring basin-centroid precipitation. (Station reference numbers are listed in table 1.)
36 Streamflow Data of Annual and Seasonal Ground-Water Recharge Rates for Drainage Basins in New Hampshire

Manchester

Concord

0

2

26

23

27

55

5

28

1

54

53

44 43

39

3

4

33

32 2

35

6

7

36

38 37

12

14

13

48

50

49

46

42

16

20

18

22

10

11

9

24

19

17

29

41

40

30

34

31

8

15

51

45

47

21

25

Base from U.S. Geological Survey

Digital line graphs, 1:24,000 or

1:25,000 scale, 1983

EXPLANATION

 Drainage-basin boundary

Proportion of normalized annual groundwater recharge to summer basin-centroid 

precipitation (PRISM, 1961-90), in percent

0 71-80

1-10 81-90

11-20 91-100

21-30 101-110

31-40 111-120

41-50 121-130

51-60 131-140

61-70 141-150

Stream-gaging station and reference 

number

Figure 11. Drainage basins that were used to develop the equations for estimating summer (June 1–October 31) 

ground-water-recharge statistics in New Hampshire showing the proportion (in percent) of normalized summer 

ground-water recharge to summer basin-centroid precipitation. (Station reference numbers are listed in table 1.)
Figures 37

Manchester

Concord

0

2

27

55

5

28

1

54

53

44 43

39

3

4

33

32 2

35

6

7

36

38 37

12

14

13

48

50

49

46

42

16

20

18

22

10

11

9

24

19

17

29

41

40

30

34

31

8

15

51

45

47

21

25

26

23

Base from U.S. Geological Survey

Digital line graphs, 1:24,000 or

1:25,000 scale, 1983

EXPLANATION

 Drainage-basin boundary

Proportion of normalized annual groundwater recharge to fall basin-centroid 

precipitation (PRISM, 1961-90), in percent

0 71-80

1-10 81-90

11-20 91-100

21-30 101-110

31-40 111-120

41-50 121-130

51-60 131-140

61-70 141-150

Stream-gaging station and reference 

number

Figure 12. Drainage basins that were used to develop the equations for estimating fall (November 1–December 31) 

ground-water-recharge statistics in New Hampshire showing the proportion (in percent) of normalized fall ground-water recharge to fall basin-centroid precipitation. (Station reference numbers are listed in table 1.)
38 Streamflow Data of Annual and Seasonal Ground-Water Recharge Rates for Drainage Basins in New Hampshire

Table 3. Annual (January 1–December 31) normalized basin-recharge rates determined from basin-specific regression equations relating Rorabaugh-method-determined ground-water-recharge rates and basin-centroid precipitation.

[No., number; Location of stream-gaging stations are shown in figure 1 and reference numbers and descriptions of stream-gaging stations are listed in table 1; 

RORA, Recession-curve-displacement computer program; in., inch; yr, year; B0, B1, R2, regression model coefficients; MSE, Mean Square Error]

Streamgaging 

station 

No.

River Location

Average 

drainagebasin 

(RORA) 

recharge 

rate 

(in/yr)

Normalized 

drainagebasin 

recharge 

rate

(in/yr)

B0 B1

Normalized 

drainagebasincentroid 

precipitation

(in/yr)

Coefficient 

of determination 

(R2

)

Root 

MSE 

(in.)

Years 

of 

record

1052500 Diamond River Wentworth Location, N.H. 21.37 23.10 12.65 0.2172 48.11 0.1668 3.499 50

1054200 Wild River Gilead, Maine 23.06 20.71 15.27 .1095 49.69 .1616 4.18 33

1054300 Ellis River South Andover, Maine 20.35 18.24 -9.971 .7217 39.09 .5849 3.715 17

1055000 Swift River Near Roxbury, Maine 19.51 19.64 9.367 .2357 43.58 .3103 3.554 50

1057000 Little Androscoggin RiverNear South Paris, Maine 19.42 18.28 9.418 .2027 43.70 .2655 4.355 50

1064300 Ellis River Near Jackson, N.H. 33.17 29.96 16.15 .182 75.91 .2821 4.853 34

1064400 Lucy Brook Near North Conway, N.H. 24.42 24.88 22.84 .0285 54.57 .0049 6.149 26

1064500 Saco River Near Conway, N.H. 26.00 23.99 17.94 .1204 50.16 .1141 5.451 50

1072850 Mohawk River Center Strafford, N.H. 18.73 23.89 -14.66 .818 47.13 .6531 2.47 11

1073000 Oyster River Durham, N.H. 19.46 20.66 -8.654 .6789 43.19 .8078 2.243 50

1075000 Pemigewasset 

River

Woodstock, N.H. 26.90 26.23 12.86 .2652 50.43 .3257 3.821 28

1075800 Stevens Brook Wentworth, N.H. 13.27 12.34 0.7134 .2831 41.06 .2896 3.088 33

1076000 Baker River Rumney, N.H. 17.54 16.96 -2.641 .5234 37.44 .759 1.973 27

1076500 Pemigewasset 

River

Plymouth, N.H. 22.13 22.14 11.671 .2152 48.62 .1612 4.6 50

1078000 Smith River Near Bristol, N.H. 18.45 20.97 -5.941 .6076 44.29 .6914 2.592 50

1082000 Contoocook River Peterborough, N.H. 20.20 21.25 -9.683 .6997 44.21 .7086 3.16 28

1084500 Beards Brook Hillsboro, N.H. 18.08 22.93 -6.692 .6361 46.57 .8099 2.225 21

1085800 West Branch 

Warner River

Near Bradford, N.H. 20.11 22.69 -2.749 .5618 45.28 .7134 2.487 35

1086000 Warner River Davisville, N.H. 20.52 24.02 -7.083 .6967 44.65 .8934 1.726 29

1089000 Soucook River Near Concord, N.H. 17.06 16.37 -9.728 .6758 38.62 .8191 2.015 44

1091000 South Branch 

Piscataquog River

Near Goffstown, N.H. 18.88 19.98 -7.581 .6347 43.43 .7031 2.814 29

1093800 Stony Brook 

Tributary

Near Temple, N.H. 22.15 25.09 -8.24 .6882 48.43 .6017 3.932 34

1097300 Nashoba Brook Near Acton, Mass. 19.51 20.05 -8.98 .6572 44.17 .5234 4.443 34

1101000 Parker River Byfield, Mass. 23.10 26.10 -20.65 1.04 44.96 .7763 3.837 50

1127880 Big Brook Pittsburg, N.H. 25.76 28.85 15.32 .276 49.02 .2393 3.584 20

1129440 Mohawk River Near Colebrook, N.H. 18.53 19.17 6.951 .2688 45.43 .5695 1.875 11

1130000 Upper Ammonoosuc RiverNear Groveton, N.H. 22.34 20.66 15.82 .1213 39.92 .1042 4.026 48
Tables 39

1133000 East Branch 

Passumpsic

East Haven, Vt. 23.01 27.11 -6.629 0.7956 42.40 0.6723 2.615 29

1134500 Moose River Victory, Vt. 18.51 18.63 11.11 .1679 44.80 .2194 3.018 50

1135000 Moose River St. Johnsbury, Vt. 16.48 16.70 3.518 .3147 41.89 .4299 2.691 34

1137500 Ammonoosuc 

River

Bethlehem Junction, N.H. 22.95 20.61 13.99 .1175 56.38 .2272 3.367 50

1138000 Ammonoosuc 

River

Bath, N.H. 15.58 13.86 7.081 .1698 39.92 .2646 2.849 31

1139000 Wells River Wells River, Vt. 16.38 15.96 3.376 .3299 38.15 .4278 3.288 50

1139800 East Orange 

Branch

East Orange, Vt. 21.61 24.19 -8.199 .7754 41.77 .5666 4.365 39

1141800 Mink Brook Etna, N.H. 16.57 19.26 -11.52 .7454 41.30 .5609 3.618 34

1142500 Ayers Brook Randolph, Vt. 18.84 21.06 -13.66 .8679 40.00 .7876 2.447 48

1144000 White River West Hartford, Vt. 18.70 19.46 -7.003 .6682 39.61 .7301 2.316 50

1145000 Mascoma River West Canaan, N.H. 15.25 16.48 -7.063 .5816 40.47 .8279 1.56 29

1150900 Ottauquechee 

River

West Bridgewater, Vt. 27.01 31.84 4.29 .5383 51.18 .3289 4.768 13

1153500 Williams River Brockways Mills, Vt. 18.00 19.56 -3.006 .5164 43.70 .6606 2.613 35

1154000 Saxtons River Saxtons River, Vt. 17.62 20.60 -5.456 .5755 45.28 .7066 2.541 33

1155000 Cold River Drewsville, N.H. 22.81 16.21 -6.244 .5625 39.92 .8048 1.804 29

1155500 West River Jamaica, Vt. 18.21 19.63 5.677 .2993 46.61 .3182 3.243 12

1156000 West River Newfane, Vt. 17.13 17.88 5.149 .2794 45.55 .2954 3.574 12

1162500 Priest Brook Winchendon, Mass. 21.54 21.72 -13.55 .821 42.95 .8455 2.617 35

1165500 Moss Brook Wendell Depot, Mass. 17.17 18.26 -12.4 .7183 42.68 .8943 1.762 33

1167800 Beaver Brook Wilmington, Vt. 23.54 28.12 -4.808 .6191 53.19 .4168 4.553 12

10965852 Beaver Brook North Pelham, N.H. 19.36 19.85 -9.46 .6781 43.23 .8836 1.617 11

Table 3. Annual (January 1–December 31) normalized basin-recharge rates determined from basin-specific regression equations relating Rorabaugh-method-determined ground-water-recharge rates and basin-centroid precipitation.—Continued

[No., number; Location of stream-gaging stations are shown in figure 1 and reference numbers and descriptions of stream-gaging stations are listed in table 1; 

RORA, Recession-curve-displacement computer program; in., inch; yr, year; B0, B1, R2

, regression model coefficients; MSE, Mean Square Error]

Streamgaging 

station 

No.

River Location

Average 

drainagebasin 

(RORA) 

recharge 

rate 

(in/yr)

Normalized 

drainagebasin 

recharge 

rate

(in/yr)

B0 B1

Normalized 

drainagebasincentroid 

precipitation

(in/yr)

Coefficient 

of determination 

(R2

)

Root 

MSE 

(in.)

Years 

of 

record
40 Streamflow Data of Annual and Seasonal Ground-Water Recharge Rates for Drainage Basins in New Hampshire

Table 4. Winter (January 1–March 15) normalized basin-recharge rates determined from basin-specific regression equations relating 

Rorabaugh-method-determined ground-water-recharge rates and basin-centroid precipitation.

[No., number; Location of stream-gaging stations are shown in figure 1 and reference numbers and descriptions of stream-gaging stations are listed in table 1; 

RORA, Recession-curve-displacement computer program; in., inch; B0, B1, R2, regression model coefficients; MSE, Mean Square Error; NA, indicates that an 

entry is not applicable on the basis of the regression analysis]

Streamgaging 

station 

No.

River Location

Average 

drainagebasin 

(RORA) 

recharge 

rate 

(in/

winter)

Normalized 

drainagebasin 

recharge 

rate

(in/

winter)

B0 B1

Normalized 

drainagebasincentroid 

precipitation

(in/

winter)

Coefficient of 

determination 

(R2

)

Root 

MSE 

(in.)

Years 

of 

record

1052500 Diamond River Wentworth Location, N.H. 3.07 3.07 NA NA 7.46 NA NA 50

1054200 Wild River Gilead, Maine 4.15 4.15 NA NA 8.74 NA NA 34

1054300 Ellis River South Andover, Maine 3.30 3.35 1.199 0.3109 6.91 0.1865 1.442 19

1055000 Swift River Near Roxbury, Maine 2.93 3.00 0.7297 .3087 7.34 .1396 1.591 50

1057000 Little Androscoggin RiverNear South Paris, Maine 4.02 3.71 1.03 .3551 7.56 .2747 1.4986 50

1064300 Ellis River Near Jackson, N.H. 3.92 3.92 NA NA 15.08 NA NA 35

1064400 Lucy Brook Near North Conway, N.H. 4.54 4.54 NA NA 10.35 NA NA 28

1064500 Saco River Near Conway, N.H. 4.21 4.21 NA NA 9.41 NA NA 50

1072850 Mohawk River Center Strafford, N.H. 5.43 5.43 NA NA 8.52 NA NA 13

1073000 Oyster River Durham, N.H. 6.07 5.90 1.328 .5837 7.83 .5108 1.525 50

1073600 Dudley Brook Exeter, N.H. 3.94 3.95 1.493 .2957 8.31 .2637 1.376 23

1075000 Pemigewasset 

River

Woodstock, N.H. 3.43 3.43 NA NA 8.37 NA NA 29

1075800 Stevens Brook Wentworth, N.H. 3.12 3.01 .059 .4218 7.01 .2983 1.513 35

1076000 Baker River Rumney, N.H. 3.00 3.00 NA NA 5.79 NA NA 27

1076500 Pemigewasset 

River

Plymouth, N.H. 3.65 3.65 NA NA 8.92 NA NA 50

1078000 Smith River Near Bristol, N.H. 3.97 4.08 .471 .4642 7.78 .2012 1.943 50

1082000 Contoocook River Peterborough, N.H. 5.21 5.07 1.577 .4199 8.33 .1924 2.172 29

1084500 Beards Brook Hillsboro, N.H. 4.66 4.66 NA NA 8.64 NA NA 22

1085800 West Branch 

Warner River

Near Bradford, N.H. 5.00 5.40 -.1999 .704 7.95 .3729 1.899 36

1086000 Warner River Davisville, N.H. 4.94 4.94 NA NA 8.31 NA NA 30

1089000 Soucook River Near Concord, N.H. 4.63 4.32 .6584 .5451 6.71 .2844 1.9 46

1091000 South Branch 

Piscataquog River

Near Goffstown, N.H. 5.44 5.41 1.753 .444 8.23 .1928 2.043 30

1093800 Stony Brook 

Tributary

Near Temple, N.H. 5.79 6.14 .4268 .6243 9.15 .4247 1.827 35

1097300 Nashoba Brook Near Acton, Mass. 6.61 6.71 .3797 .718 8.82 .4994 2.036 35

1101000 Parker River Byfield, Mass. 7.67 7.82 .552 .8057 9.02 .5198 2.16 50

1127880 Big Brook Pittsburg, N.H. 3.00 4.47 -1.878 .8716 7.28 .3469 1.756 21

1129440 Mohawk River Near Colebrook, N.H. 3.32 4.10 -1.464 .7922 7.03 .4904 1.437 12
Tables 41

1130000 Upper Ammonoosuc RiverNear Groveton, N.H. 3.27 3.27 NA NA 6.28 NA NA 48

1133000 East Branch 

Passumpsic

East Haven, Vt. 3.41 3.41 NA NA 6.42 NA NA 31

1134500 Moose River Victory, Vt. 3.34 3.39 0.9687 0.341 7.11 0.0917 1.836 50

1134800 Kirby Brook Concord, Vt. 2.30 2.30 NA NA 6.36 NA NA 11

1135000 Moose River St. Johnsbury, Vt. 2.73 2.73 NA NA 6.40 NA NA 35

1135300 Sleepers River 

(W-5)

St. Johnsbury, Vt. 3.55 3.43 -1.287 .7614 6.20 .3943 1.019 10

1137500 Ammonoosuc 

River

Bethlehem Junction, N.H. 3.32 3.32 NA NA 10.28 NA NA 50

1138000 Ammonoosuc 

River

Bath, N.H. 2.47 2.47 NA NA 6.04 NA NA 32

1139000 Wells River Wells River, Vt. 3.20 3.05 .4955 .4415 5.79 .2043 1.433 50

1139800 East Orange 

Branch

East Orange, Vt. 3.70 3.88 .154 .5764 6.46 .2346 1.896 40

1141800 Mink Brook Etna, N.H. 3.79 4.09 .2161 .5564 6.97 .265 1.696 36

1142500 Ayers Brook Randolph, Vt. 4.34 4.40 1.095 .4899 6.75 .1759 1.848 49

1144000 White River West Hartford, Vt. 4.02 4.01 1.287 .3981 6.85 .1548 1.631 50

1145000 Mascoma River West Canaan, N.H. 3.20 3.20 NA NA 6.57 NA NA 30

1150800 Kent Brook Sherburne, Vt. 4.15 4.15 NA NA 9.19 NA NA 11

1150900 Ottauquechee 

River

West Bridgewater, Vt. 6.05 7.51 -2.197 1.133 8.56 .6471 1.688 14

1153500 Williams River Brockways Mills, Vt. 4.45 4.45 NA NA 7.72 NA NA 36

1154000 Saxtons River Saxtons River, Vt. 4.58 4.72 1.869 .348 8.19 .1178 2.052 34

1155000 Cold River Drewsville, N.H. 3.67 3.59 1.176 .3487 6.91 .1309 1.612 30

1155200 Sacketts Brook Putney, Vt. 4.37 4.37 NA NA 7.91 NA NA 11

1155300 Flood Brook Londonderry, Vt. 4.01 4.01 NA NA 9.09 NA NA 11

1155500 West River Jamaica, Vt. 4.26 4.26 NA NA 8.39 NA NA 12

1156000 West River Newfane, Vt. 3.94 3.94 NA NA 8.29 NA NA 12

1158500 Otter Brook Keene, N.H. 5.56 5.56 NA NA 7.76 NA NA 10

1162500 Priest Brook Winchendon, Mass. 5.67 5.74 -.8108 .8135 8.05 .5388 1.844 36

1165500 Moss Brook Wendell Depot, Mass. 4.95 4.91 .6238 .546 7.85 .3585 1.744 34

1167800 Beaver Brook Wilmington, Vt. 4.85 4.85 NA NA 9.92 NA NA 14

10965852 Beaver Brook North Pelham, N.H. 5.79 6.71 -1.017 .9508 8.13 .8884 .8107 12

Table 4. Winter (January 1–March 15) normalized basin-recharge rates determined from basin-specific regression equations relating 

Rorabaugh-method-determined ground-water-recharge rates and basin-centroid precipitation.—Continued

[No., number; Location of stream-gaging stations are shown in figure 1 and reference numbers and descriptions of stream-gaging stations are listed in table 1; 

RORA, Recession-curve-displacement computer program; in., inch; B0, B1, R2

, regression model coefficients; MSE, Mean Square Error; NA, indicates that an 

entry is not applicable on the basis of the regression analysis]

Streamgaging 

station 

No.

River Location

Average 

drainagebasin 

(RORA) 

recharge 

rate 

(in/

winter)

Normalized 

drainagebasin 

recharge 

rate

(in/

winter)

B0 B1

Normalized 

drainagebasincentroid 

precipitation

(in/

winter)

Coefficient of 

determination 

(R2

)

Root 

MSE 

(in.)

Years 

of 

record
42 Streamflow Data of Annual and Seasonal Ground-Water Recharge Rates for Drainage Basins in New Hampshire

Table 5. Spring (March 16–May 31) normalized basin-recharge rates determined from basin-specific regression equations relating 

Rorabaugh-method-determined ground-water-recharge rates and basin-centroid precipitation.

[No., number; Location of stream-gaging stations are shown in figure 1 and reference numbers and descriptions of stream-gaging stations are listed in table 1; 

RORA, Recession-curve-displacement computer program; in., inch; B0, B1, R2, regression model coefficients; MSE, Mean Square Error; NA, indicates that an entry is not applicable on the basis of the regression analysis]

Streamgaging 

station 

No.

River Location

Average 

drainagebasin 

(RORA) 

recharge 

rate 

(in/

spring)

Normalized 

drainagebasin 

recharge 

rate 

(in/

spring)

B0 B1

Normalized 

drainagebasincentroid 

precipitation

(in/spring)

Coefficient of 

determination 

(R2

)

Root 

MSE 

(in.)

Years 

of 

record

1052500 Diamond River Wentworth Location, N.H. 11.16 12.06 7.05 0.5445 9.19 0.1073 3.046 50

1054200 Wild River Gilead, Maine 10.95 10.02 7.119 .2877 10.08 .2626 2.96 34

1054300 Ellis River South Andover, Maine 10.04 10.04 NA NA 7.85 NA NA 20

1055000 Swift River Near Roxbury, Maine 9.99 10.24 6.836 .3886 8.76 .1632 2.45 50

1057000 Little Androscoggin RiverNear South Paris, Maine 8.78 8.65 4.877 .422 8.94 .3245 2.281 50

1064300 Ellis River Near Jackson, N.H. 14.35 13.25 7.106 .3981 15.43 .5123 2.854 35

1064400 Lucy Brook Near North Conway, N.H. 10.93 10.51 6.237 .3767 11.34 .3453 2.787 27

1064500 Saco River Near Conway, N.H. 12.39 11.75 7.304 .4228 10.51 .2841 3.189 50

1072850 Mohawk River Center Strafford, N.H. 7.61 7.61 NA NA 9.98 NA NA 13

1073000 Oyster River Durham, N.H. 7.31 7.61 2.577 .5418 9.29 .4037 2.08 50

1073600 Dudley Brook Exeter, N.H. 4.66 5.16 .211 .5308 9.33 .5714 1.585 23

1075000 Pemigewasset 

River

Woodstock, N.H. 13.57 13.68 9.289 .4333 10.14 .1906 2.897 29

1075800 Stevens Brook Wentworth, N.H. 6.06 6.03 2.995 .3634 8.35 .2112 1.962 35

1076000 Baker River Rumney, N.H. 8.80 8.74 5.5 .4314 7.52 .282 1.809 27

1076500 Pemigewasset 

River

Plymouth, N.H. 9.95 10.42 6.585 .3794 10.10 .1572 2.46 50

1078000 Smith River Near Bristol, N.H. 8.43 8.86 4.399 .4755 9.39 .2608 2.365 50

1082000 Contoocook River Peterborough, N.H. 8.18 8.38 3.877 .4874 9.23 .2014 2.552 29

1084500 Beards Brook Hillsboro, N.H. 8.20 9.10 4.505 .4642 9.90 .1789 2.557 22

1085800 West Branch 

Warner River

Near Bradford, N.H. 8.74 9.38 4.029 .5477 9.76 .3185 2.356 36

1086000 Warner River Davisville, N.H. 9.64 10.38 5.103 .5491 9.61 .271 2.45 30

1089000 Soucook River Near Concord, N.H. 6.66 6.55 3.277 .4088 8.01 .346 1.715 47

1091000 South Branch 

Piscataquog River

Near Goffstown, N.H. 7.69 7.99 3.999 .4366 9.13 .2198 2.187 30

1093800 Stony Brook 

Tributary

Near Temple, N.H. 8.79 9.34 2.006 .7156 10.26 .4068 2.774 35

1097300 Nashoba Brook Near Acton, Mass. 6.57 6.66 2.274 .4725 9.29 .2969 2.262 35

1101000 Parker River Byfield, Mass. 8.09 8.77 .1891 .9039 9.49 .5645 2.478 50

1127880 Big Brook Pittsburg, N.H. 12.42 12.42 NA NA 9.21 NA NA 21

1129440 Mohawk River Near Colebrook, N.H. 6.99 6.99 NA NA 8.68 NA NA 12
Tables 43

1130000 Upper Ammonoosuc RiverNear Groveton, N.H. 11.08 10.29 7.797 0.3177 7.85 0.1266 2.74 48

1133000 East Branch 

Passumpsic

East Haven, Vt. 10.08 10.78 4.665 .7618 8.03 .2925 2.281 31

1134500 Moose River Victory, Vt. 8.48 8.75 5.486 .3804 8.64 .0944 2.47 50

1134800 Kirby Brook Concord, Vt. 7.59 7.37 2.714 .5812 8.01 .5038 1.784 11

1135000 Moose River St. Johnsbury, Vt. 8.48 8.48 NA NA 8.05 NA NA 35

1135300 Sleepers River 

(W-5)

St. Johnsbury, Vt. 6.42 6.64 3.422 .4076 7.89 .3846 1.2078 10

1137500 Ammonoosuc 

River

Bethlehem Junction, N.H. 11.08 10.21 7.317 .2566 11.26 .1797 2.771 50

1138000 Ammonoosuc 

River

Bath, N.H. 7.39 6.80 4.374 .3158 7.70 .2218 1.804 32

1139000 Wells River Wells River, Vt. 7.25 7.38 3.678 .4997 7.40 .2272 1.943 50

1139800 East Orange 

Branch

East Orange, Vt. 11.08 11.78 5.724 .7221 8.39 .258 2.928 40

1141800 Mink Brook Etna, N.H. 7.57 8.03 2.869 .6121 8.43 .2893 2.485 36

1142500 Ayers Brook Randolph, Vt. 8.51 8.83 3.363 .6538 8.37 .3041 2.497 49

1144000 White River West Hartford, Vt. 8.18 8.30 4.031 .5142 8.31 .2709 2.129 50

1145000 Mascoma River West Canaan, N.H. 7.53 7.95 2.92 .5921 8.50 .4212 1.803 30

1150800 Kent Brook Sherburne, Vt. 12.38 12.38 NA NA 11.44 NA NA 11

1150900 Ottauquechee 

River

West Bridgewater, Vt. 9.58 10.42 4.214 .576 10.77 .5203 1.601 14

1153500 Williams River Brockways Mills, Vt. 8.54 8.63 5.283 .3567 9.37 .1809 2.479 36

1154000 Saxtons River Saxtons River, Vt. 7.76 8.11 4.675 .3558 9.65 .1575 2.322 34

1155000 Cold River Drewsville, N.H. 7.23 7.39 4.4 .3522 8.48 .1329 2.294 30

1155200 Sacketts Brook Putney, Vt. 8.97 9.20 4.216 .5314 9.37 .379 2.26 11

1155300 Flood Brook Londonderry, Vt. 12.29 12.29 NA NA 10.87 NA NA 12

1155500 West River Jamaica, Vt. 8.33 8.33 NA NA 9.88 NA NA 12

1156000 West River Newfane, Vt. 7.49 7.49 NA NA 9.63 NA NA 12

1158500 Otter Brook Keene, N.H. 8.16 8.16 NA NA 9.33 NA NA 10

1162500 Priest Brook Winchendon, Mass. 8.42 8.43 1.034 .8149 9.07 .6024 2.081 36

1165500 Moss Brook Wendell Depot, Mass. 6.82 7.01 2.57 .491 9.04 .3788 1.662 34

1167800 Beaver Brook Wilmington, Vt. 10.19 10.19 NA NA 11.54 NA NA 14

10965852 Beaver Brook North Pelham, N.H. 6.45 6.14 -.8827 .7806 9.00 .5877 1.371 12

Table 5. Spring (March 16–May 31) normalized basin-recharge rates determined from basin-specific regression equations relating 

Rorabaugh-method-determined ground-water-recharge rates and basin-centroid precipitation.—Continued

[No., number; Location of stream-gaging stations are shown in figure 1 and reference numbers and descriptions of stream-gaging stations are listed in table 1; 

RORA, Recession-curve-displacement computer program; in., inch; B0, B1, R2

, regression model coefficients; MSE, Mean Square Error; NA, indicates that an entry is not applicable on the basis of the regression analysis]

Streamgaging 

station 

No.

River Location

Average 

drainagebasin 

(RORA) 

recharge 

rate 

(in/

spring)

Normalized 

drainagebasin 

recharge 

rate 

(in/

spring)

B0 B1

Normalized 

drainagebasincentroid 

precipitation

(in/spring)

Coefficient of 

determination 

(R2

)

Root 

MSE 

(in.)

Years 

of 

record
44 Streamflow Data of Annual and Seasonal Ground-Water Recharge Rates for Drainage Basins in New Hampshire

Table 6. Summer (June 1–October 31) normalized basin-recharge rates determined from basin-specific regression equations relating 

Rorabaugh-method-determined ground-water-recharge rates and basin-centroid precipitation.

[No., number; Location of stream-gaging stations are shown in figure 1 and reference numbers and descriptions of stream-gaging stations are listed in table 1; 

RORA, Recession-curve-displacement computer program; in., inch; B0, B1, R2, regression model coefficients; MSE, Mean Square Error; NA, indicates that an entry is not applicable on the basis of the regression analysis]

Streamgaging 

station 

No.

River Location

Average 

drainagebasin 

(RORA) 

recharge 

rate 

(in/

summer)

Normalized 

drainagebasin 

recharge 

rate 

(in/

summer)

B0 B1

Normalized 

drainagebasincentroid 

precipitation

(in/

summer)

Coefficient of 

determination 

(R2

)

Root 

MSE 

(in.)

Years 

of 

record

1052500 Diamond River Wentworth Location, N.H. 4.20 6.69 -6.493 0.5742 22.95 0.618 1.621 50

1054200 Wild River Gilead, Maine 4.39 3.80 .8721 .1366 21.46 .1986 1.903 34

1054300 Ellis River South Andover, Maine 3.70 3.22 -5.233 .5112 16.54 .7273 1.21 19

1055000 Swift River Near Roxbury, Maine 3.62 4.12 -4.151 .4315 19.17 .5708 1.551 50

1057000 Little Androscoggin RiverNear South Paris, Maine 3.20 3.03 -2.049 .2746 18.50 .4074 1.706 50

1064300 Ellis River Near Jackson, N.H. 10.43 9.37 1.991 .2447 30.16 .2204 2.733 35

1064400 Lucy Brook Near North Conway, N.H. 4.78 3.85 -3.944 .3511 22.20 .417 2.593 28

1064500 Saco River Near Conway, N.H. 5.21 3.71 -2.479 .303 20.43 .5118 1.8426 50

1072850 Mohawk River Center Strafford, N.H. 1.59 1.59 NA NA 18.86 NA NA 13

1073000 Oyster River Durham, N.H. 2.41 2.78 -3.109 .3422 17.20 .5117 1.277 50

1073600 Dudley Brook Exeter, N.H. 0.96 1.45 -2.052 .2 17.52 .3183 .9713 24

1075000 Pemigewasset 

River

Woodstock, N.H. 5.57 6.21 -3.835 .4407 22.80 .7426 1.033 28

1075800 Stevens Brook Wentworth, N.H. 1.78 1.69 -3.665 .2954 18.11 .6123 .8916 35

1076000 Baker River Rumney, N.H. 2.79 3.26 -2.682 .34 17.48 .6649 .9294 27

1076500 Pemigewasset 

River

Plymouth, N.H. 4.78 4.92 -3.584 .4262 19.96 .6857 1.26 50

1078000 Smith River Near Bristol, N.H. 3.01 3.87 -4.406 .4417 18.74 .732 .9431 50

1082000 Contoocook River Peterborough, N.H. 3.16 3.62 -3.131 .3648 18.50 .7441 1.077 28

1084500 Beards Brook Hillsboro, N.H. 1.93 3.01 -2.795 .3045 19.06 .7597 .7414 21

1085800 West Branch 

Warner River

Near Bradford, N.H. 2.73 3.58 -3.488 .3695 19.13 .6207 1.248 37

1086000 Warner River Davisville, N.H. 2.25 3.09 -3.567 .367 18.15 .8079 .7444 30

1089000 Soucook River Near Concord, N.H. 2.48 2.62 -4.009 .3922 16.89 .67 .9359 46

1091000 South Branch 

Piscataquog River

Near Goffstown, N.H. 2.29 2.62 -2.691 .2996 17.72 .6975 .8388 29

1093800 Stony Brook 

Tributary

Near Temple, N.H. 3.16 3.71 -3.417 .3629 19.65 .569 1.426 35

1097300 Nashoba Brook Near Acton, Mass. 2.72 2.82 -2.961 .3316 17.44 .5809 1.255 35

1101000 Parker River Byfield, Mass. 3.15 3.95 -6.665 .6117 17.36 .5716 2.359 50

1127880 Big Brook Pittsburg, N.H. 6.72 10.17 -5.646 .6609 23.94 .7253 1.53 21

1129440 Mohawk River Near Colebrook, N.H. 4.93 5.45 -1.019 .2966 21.81 .6024 .8687 12
Tables 45

1130000 Upper Ammonoosuc RiverNear Groveton, N.H. 4.75 3.18 -4.27 0.3999 18.62 0.5453 1.704 48

1133000 East Branch 

Passumpsic

East Haven, Vt. 5.93 7.40 -2.611 .4871 20.55 .5185 1.651 30

1134500 Moose River Victory, Vt. 3.75 4.45 -3.12 .3585 21.10 .4637 1.416 50

1134800 Kirby Brook Concord, Vt. 1.80 3.37 -5.615 .445 20.20 .6717 .892 10

1135000 Moose River St. Johnsbury, Vt. 2.96 3.55 -3.122 .331 20.16 .5221 1.236 34

1135300 Sleepers River 

(W-5)

St. Johnsbury, Vt. 3.95 4.19 -4.096 .4246 19.53 .4868 1.483 10

1137500 Ammonoosuc 

River

Bethlehem Junction, N.H. 5.05 2.66 -5.726 .3485 24.06 .585 1.723 50

1138000 Ammonoosuc 

River

Bath, N.H. 2.93 2.38 -4.312 .3504 19.09 .7513 .7427 31

1139000 Wells River Wells River, Vt. 3.33 3.81 -4.67 .4662 18.19 .7367 1.036 50

1139800 East Orange 

Branch

East Orange, Vt. 3.53 4.59 -6.549 .5749 19.37 .6441 1.778 40

1141800 Mink Brook Etna, N.H. 2.38 3.67 -6.297 .5338 18.66 .6616 1.364 35

1142500 Ayers Brook Randolph, Vt. 3.04 3.30 -5.895 .5192 17.72 .7498 1.219 49

1144000 White River West Hartford, Vt. 3.26 3.26 -4.409 .4458 17.20 .7717 1.036 50

1145000 Mascoma River West Canaan, N.H. 2.08 2.72 -2.943 .3114 18.19 .7543 .6276 29

1150800 Kent Brook Sherburne, Vt. 3.76 8.83 -4.667 .5449 24.76 .5023 1.392 10

1150900 Ottauquechee 

River

West Bridgewater, Vt. 6.80 7.93 -3.968 .5202 22.87 .5827 2.148 14

1153500 Williams River Brockways Mills, Vt. 2.41 3.26 -3.832 .3786 18.74 .8291 .7728 35

1154000 Saxtons River Saxtons River, Vt. 2.28 3.33 -3.767 .3687 19.25 .8514 .6909 33

1155000 Cold River Drewsville, N.H. 2.02 2.54 -3.115 .3207 17.64 .8032 .6769 29

1155200 Sacketts Brook Putney, Vt. 2.47 3.55 -1.687 .2835 18.46 .3769 1.171 11

1155300 Flood Brook Londonderry, Vt. 3.24 3.24 NA NA 22.01 NA NA 11

1155500 West River Jamaica, Vt. 2.50 3.70 -4.259 .397 20.04 .6241 1.144 12

1156000 West River Newfane, Vt. 2.62 3.67 -4.649 .4252 19.57 .5436 1.628 12

1162500 Priest Brook Winchendon, Mass. 3.60 3.89 -5.896 .539 18.15 .7806 1.291 36

1165500 Moss Brook Wendell Depot, Mass. 2.49 2.90 -4.727 .4229 18.03 .7739 1.009 33

1167800 Beaver Brook Wilmington, Vt. 3.23 4.66 -3.957 .3921 21.97 .697 1.364 14

10965852 Beaver Brook North Pelham, N.H. 3.18 2.92 -3.824 .3797 17.76 .79 .9628 12

Table 6. Summer (June 1–October 31) normalized basin-recharge rates determined from basin-specific regression equations relating 

Rorabaugh-method-determined ground-water-recharge rates and basin-centroid precipitation.—Continued

[No., number; Location of stream-gaging stations are shown in figure 1 and reference numbers and descriptions of stream-gaging stations are listed in table 1; 

RORA, Recession-curve-displacement computer program; in., inch; B0, B1, R2

, regression model coefficients; MSE, Mean Square Error; NA, indicates that an entry is not applicable on the basis of the regression analysis]

Streamgaging 

station 

No.

River Location

Average 

drainagebasin 

(RORA) 

recharge 

rate 

(in/

summer)

Normalized 

drainagebasin 

recharge 

rate 

(in/

summer)

B0 B1

Normalized 

drainagebasincentroid 

precipitation

(in/

summer)

Coefficient of 

determination 

(R2

)

Root 

MSE 

(in.)

Years 

of 

record
46 Streamflow Data of Annual and Seasonal Ground-Water Recharge Rates for Drainage Basins in New Hampshire

Table 7. Fall (November 1–December 31) normalized basin-recharge rates determined from basin-specific regression equations relating Rorabaugh-method-determined ground-water-recharge rates and basin-centroid precipitation.

[No., number; Location of stream-gaging stations are shown in figure 1 and reference numbers and descriptions of stream-gaging stations are listed in table 1; 

RORA, Recession-curve-displacement computer program; in., inch; B0, B1, R2, regression model coefficients; MSE, Mean Square Error]

Streamgaging 

station 

No.

River Location

Average 

drainagebasin 

(RORA) 

recharge 

rate 

(in/fall)

Normalized 

drainagebasin 

recharge 

rate 

(in/fall)

B0 B1

Normalized 

drainagebasincentroid 

precipitation

(in/fall)

Coefficient of 

determination 

(R2

)

Root 

MSE 

(in.)

Years 

of 

record

1052500 Diamond River Wentworth Location, N.H. 2.95 3.84 -0.1335 0.4693 8.46 0.4945 0.9322 50

1054200 Wild River Gilead, Maine 3.52 2.93 .5119 .2549 9.49 .592 1.016 35

1054300 Ellis River South Andover, Maine 3.26 3.08 -1.401 .5776 7.76 .7967 .9909 19

1055000 Swift River Near Roxbury, Maine 3.05 3.40 .459 .3574 8.23 .5088 1.009 50

1057000 Little Androscoggin RiverNear South Paris, Maine 3.52 3.69 -.7569 .5107 8.70 .7006 1.053 50

1064300 Ellis River Near Jackson, N.H. 4.51 4.24 2.013 .1465 15.20 .2547 1.628 35

1064400 Lucy Brook Near North Conway, N.H. 4.02 3.99 -.2369 .395 10.71 .5166 1.422 28

1064500 Saco River Near Conway, N.H. 4.25 3.95 1.211 .2796 9.80 .2409 1.827 50

1072850 Mohawk River Center Strafford, N.H. 3.78 4.23 -2.092 .6506 9.72 .7543 1.325 13

1073000 Oyster River Durham, N.H. 3.76 4.02 -.9709 .5611 8.90 .6573 1.262 50

1073600 Dudley Brook Exeter, N.H. 2.32 2.39 -.4265 .3148 8.94 .5323 1.12 24

1075000 Pemigewasset 

River

Woodstock, N.H. 4.20 4.00 .8289 .3477 9.13 .4765 1.397 28

1075800 Stevens Brook Wentworth, N.H. 2.30 2.36 -.0902 .3205 7.64 .5451 .7472 35

1076000 Baker River Rumney, N.H. 3.08 2.81 -.0581 .4361 6.57 .5795 .9619 27

1076500 Pemigewasset 

River

Plymouth, N.H. 3.87 4.45 1.008 .3572 9.65 .3701 1.29 50

1078000 Smith River Near Bristol, N.H. 3.13 3.58 -.0014 .431 8.31 .5172 1.025 50

1082000 Contoocook River Peterborough, N.H. 3.79 3.56 -.9511 .5561 8.11 .4921 1.584 28

1084500 Beards Brook Hillsboro, N.H. 3.55 4.35 -.6294 .5447 9.13 .6045 1.183 21

1085800 West Branch 

Warner River

Near Bradford, N.H. 3.68 4.04 .6041 .4134 8.31 .5417 1.031 37

1086000 Warner River Davisville, N.H. 3.76 4.26 -1.027 .6134 8.62 .5742 1.49 30

1089000 Soucook River Near Concord, N.H. 3.19 2.96 -.793 .5264 7.13 .567 1.157 45

1091000 South Branch 

Piscataquog River

Near Goffstown, N.H. 3.68 3.66 -.8575 .5386 8.39 .5771 1.349 29

1093800 Stony Brook 

Tributary

Near Temple, N.H. 4.37 4.90 -.8017 .6159 9.25 .5317 1.646 36

1097300 Nashoba Brook Near Acton, Mass. 3.59 3.82 -.4937 .5008 8.62 .4494 1.709 36

1101000 Parker River Byfield, Mass. 4.26 4.84 -1.511 .698 9.09 .5341 1.899 50

1127880 Big Brook Pittsburg, N.H. 3.61 4.82 -1.556 .7428 8.58 .7023 1.001 21

1129440 Mohawk River Near Colebrook, N.H. 3.30 4.07 .6765 .4269 7.95 .3443 .7948 12

1130000 Upper Ammonoosuc RiverNear Groveton, N.H. 3.27 2.55 .4125 .301 7.09 .4478 1.137 47
Tables 47

1133000 East Branch 

Passumpsic

East Haven, Vt. 3.65 4.26 0.2195 0.5429 7.44 0.5339 0.9964 30

1134500 Moose River Victory, Vt. 3.00 3.31 3.905 .3657 7.99 .4275 .9908 50

1134800 Kirby Brook Concord, Vt. 2.47 2.26 -.0497 .3123 7.40 .4233 1.051 11

1135000 Moose River St. Johnsbury, Vt. 2.45 2.58 -.301 .3909 7.36 .5309 .8303 34

1135300 Sleepers River 

(W-5)

St. Johnsbury, Vt. 2.77 3.95 -.6378 .6234 7.36 .6665 .6636 11

1137500 Ammonoosuc 

River

Bethlehem Junction, N.H. 3.49 3.02 1.307 .1586 10.79 .252 1.419 50

1138000 Ammonoosuc 

River

Bath, N.H. 2.68 2.21 .5487 .2362 7.05 .3869 1.034 31

1139000 Wells River Wells River, Vt. 2.66 2.85 -.0705 .4294 6.81 .5261 .8523 50

1139800 East Orange 

Branch

East Orange, Vt. 3.28 3.58 .5834 .4097 7.32 .2833 1.485 41

1141800 Mink Brook Etna, N.H. 2.81 2.99 .1312 .4034 7.09 .4205 1.16 36

1142500 Ayers Brook Randolph, Vt. 3.06 3.33 -.979 .5921 7.28 .616 1.033 49

1144000 White River West Hartford, Vt. 3.22 3.37 -.104 .4775 7.28 .5852 .8836 50

1145000 Mascoma River West Canaan, N.H. 2.63 2.63 -.5159 .4389 7.17 .6086 .8666 29

1150800 Kent Brook Sherburne, Vt. 5.67 6.06 2.174 .4084 9.53 .7026 .7937 10

1150900 Ottauquechee 

River

West Bridgewater, Vt. 4.59 5.22 .4852 .5278 8.98 .3392 1.028 14

1153500 Williams River Brockways Mills, Vt. 2.79 2.82 -.5874 .4389 7.76 .6414 .9479 35

1154000 Saxtons River Saxtons River, Vt. 3.03 3.23 -.9633 .5224 8.03 .6564 1.084 33

1155000 Cold River Drewsville, N.H. 2.70 2.44 -.9445 .4936 6.85 .7058 .8244 29

1155200 Sacketts Brook Putney, Vt. 3.21 2.81 -.6236 .4432 7.76 .6091 1.263 11

1155300 Flood Brook Londonderry, Vt. 4.30 4.08 .3825 .4159 8.90 .5501 1.188 11

1155500 West River Jamaica, Vt. 3.15 3.44 -1.327 .5824 8.19 .8769 .5679 12

1156000 West River Newfane, Vt. 3.02 2.99 -2.857 .7347 7.95 .8399 .8361 12

1162500 Priest Brook Winchendon, Mass. 3.84 3.73 -1.556 .6856 7.72 .6154 1.412 36

1165500 Moss Brook Wendell Depot, Mass. 2.95 2.96 -.9453 .52 7.52 .5741 1.157 33

1167800 Beaver Brook Wilmington, Vt. 4.72 4.95 -.354 .5386 9.84 .627 1.483 14

10965852 Beaver Brook North Pelham, N.H. 3.95 4.59 -.5126 .6086 8.39 .3561 1.647 12

Table 7. Fall (November 1–December 31) normalized basin-recharge rates determined from basin-specific regression equations relating Rorabaugh-method-determined ground-water-recharge rates and basin-centroid precipitation.—Continued

[No., number; Location of stream-gaging stations are shown in figure 1 and reference numbers and descriptions of stream-gaging stations are listed in table 1; 

RORA, Recession-curve-displacement computer program; in., inch; B0, B1, R2

, regression model coefficients; MSE, Mean Square Error]

Streamgaging 

station 

No.

River Location

Average 

drainagebasin 

(RORA) 

recharge 

rate 

(in/fall)

Normalized 

drainagebasin 

recharge 

rate 

(in/fall)

B0 B1

Normalized 

drainagebasincentroid 

precipitation

(in/fall)

Coefficient of 

determination 

(R2

)

Root 

MSE 

(in.)

Years 

of 

record
48 Streamflow Data of Annual and Seasonal Ground-Water Recharge Rates for Drainage Basins in New Hampshire

Table 9. Ground-water-recharge statistics, standard error of prediction, and 90-percent prediction interval estimated using available 

data and regression-equation predicted values for the annual period (January 1–December 31).

[No., number; fig., figure; in., inch; --, no data]

Streamgaging 

station

reference 

No. 

(fig. 1)

Streamgaging 

station 

No.

Latitude

(decimal 

degrees)

Longitude

(decimal 

degrees)

River name Location

Annual

(January 1–December 31)

 90-percent 

prediction 

intervals

Normalized 

basinrecharge 

estimate 

(in.)

Equationpredicted 

value 

(in.)

 Standard 

error of 

prediction

 Upper

(in.)

 Lower

(in.)

1 1052500 44.8778 71.0569 Diamond River Wentworth Location, N.H. 23.1 22.9 2.59 27.2 18.5

2 1054200 44.3908 70.9797 Wild River Gilead, Maine 20.7 21.8 2.61 26.1 17.4

3 1054300 44.5936 70.7336 Ellis River South Andover, Maine 18.2 17.0 2.62 21.4 12.7

4 1055000 44.6422 70.5881 Swift River Near Roxbury, Maine 19.6 17.3 2.68 21.8 12.8

5 1057000 44.3033 70.5394 Little Androscoggin RiverNear South Paris, Maine 18.3 20.8 2.58 25.1 16.5

6 1064300 44.2200 71.2500 Ellis River Near Jackson, N.H. 30.0 32.8 3.30 38.4 27.3

7 1064400 44.0694 71.1750 Lucy Brook Near North Conway, N.H. 24.9 22.2 2.73 26.8 17.7

8 1064500 43.9908 71.0914 Saco River Near Conway, N.H. 24.0 22.1 2.61 26.5 17.7

9 1072850 43.2631 71.0972 Mohawk River Center Strafford, N.H. 23.9 22.4 2.59 26.8 18.1

10 1073000 43.1486 70.9656 Oyster River Durham, N.H. 20.7 20.4 2.57 24.7 16.1

11 1073600 42.9936 71.0233 Dudley Brook Exeter, N.H. -- -- -- -- --

12 1075000 43.9761 71.6800 Pemigewasset 

River

Woodstock, N.H. 26.2 20.6 2.67 25.1 16.1

13 1075800 43.8367 71.8853 Stevens Brook Wentworth, N.H. 12.3 16.8 2.65 21.3 12.4

14 1076000 43.7961 71.8450 Baker River Rumney, N.H. 17.0 17.7 2.61 22.0 13.3

15 1076500 43.7592 71.6861 Pemigewasset 

River

Plymouth, N.H. 22.1 22.1 2.59 26.5 17.8

16 1078000 43.5675 71.7483 Smith River Near Bristol, N.H. 21.0 19.9 2.58 24.3 15.6

17 1082000 42.8625 71.9597 Contoocook River Peterborough, N.H. 21.3 20.1 2.57 24.4 15.8

18 1084500 43.1142 71.9267 Beards Brook Hillsboro, N.H. 22.9 21.7 2.58 26.1 17.4

19 1085800 43.2592 72.0264 West Branch 

Warner River

Near Bradford, N.H. 22.7 23.5 2.65 27.9 19.0

20 1086000 43.2517 71.7317 Warner River Davisville, N.H. 24.0 20.4 2.57 24.7 16.1

21 1089000 43.2394 71.4622 Soucook River Near Concord, N.H. 16.4 17.7 2.60 22.1 13.4

22 1091000 43.0136 71.6419 South Branch 

Piscataquog River

Near Goffstown, N.H. 20.0 18.9 2.59 23.3 14.6

23 1093800 42.8600 71.8333 Stony Brook 

Tributary

Near Temple, N.H. 25.1 24.2 2.64 28.7 19.8

24 10965852 42.7831 71.3539 Beaver Brook North Pelham, N.H. 19.9 21.7 2.60 26.0 17.3

25 1097300 42.5108 71.4069 Nashoba Brook Near Acton, Mass. 20.1 23.2 2.66 27.7 18.7

26 1101000 42.7528 70.9461 Parker River Byfield, Mass. 26.1 24.0 2.70 28.5 19.5

27 1127880 45.1350 71.2064 Big Brook Pittsburg, N.H. 28.9 25.3 2.69 29.8 20.8

28 1129440 44.8744 71.4106 Mohawk River Near Colebrook, N.H. 19.2 21.5 2.58 25.8 17.2
Tables 49

29 1130000 44.6250 71.4694 Upper Ammonoosuc RiverNear Groveton, N.H. 20.7 17.9 2.59 22.3 13.6

30 1133000 44.6339 71.8981 East Branch 

Passumpsic

East Haven, Vt. 27.1 20.9 2.59 25.3 16.5

31 1134500 44.5117 71.8369 Moose River Victory, Vt. 18.6 21.9 2.59 26.3 17.6

32 1134800 44.4419 71.8792 Kirby Brook Concord, Vt. -- -- -- -- --

33 1135000 44.4228 72.0006 Moose River St. Johnsbury, Vt. 16.7 20.1 2.58 24.4 15.7

34 1135300 44.4344 72.0394 Sleepers River 

(W-5)

St. Johnsbury, Vt. -- -- -- -- --

35 1137500 44.2689 71.6311 Ammonoosuc 

River

Bethlehem Junction, N.H. 20.6 24.7 2.7 29.3 20.2

36 1138000 44.1539 71.9861 Ammonoosuc 

River

Bath, N.H. 13.9 17.3 2.61 21.7 12.9

37 1139000 44.1508 72.0653 Wells River Wells River, Vt. 16.0 18.2 2.60 22.6 13.8

38 1139800 44.0928 72.3361 East Orange 

Branch

East Orange, Vt. 24.2 21.7 2.63 26.1 17.2

39 1141800 43.7022 72.1875 Mink Brook Etna, N.H. 19.3 19.0 2.58 23.4 14.7

40 1142500 43.9344 72.6583 Ayers Brook Randolph, Vt. 21.1 19.9 2.60 24.2 15.5

41 1144000 43.7142 72.4186 White River West Hartford, Vt. 19.5 18.9 2.59 23.3 14.6

42 1145000 43.6500 72.0806 Mascoma River West Canaan, N.H. 16.5 17.7 2.60 22.1 13.3

43 1150800 43.6733 72.8092 Kent Brook Sherburne, Vt. -- -- -- -- --

44 1150900 43.6222 72.7594 Ottauquechee 

River

West Bridgewater, Vt. 31.8 25.8 2.68 30.3 21.3

45 1153500 43.2086 72.5181 Williams River Brockways Mills, Vt. 19.6 20.7 2.57 25.1 16.4

46 1154000 43.1372 72.4881 Saxtons River Saxtons River, Vt. 20.6 21.2 2.57 25.5 16.9

47 1155000 43.1317 72.3897 Cold River Drewsville, N.H. 16.2 17.3 2.61 21.7 12.9

48 1155200 42.9992 72.5331 Sacketts Brook Putney, Vt. -- -- -- -- --

49 1155300 43.2364 72.8564 Flood Brook Londonderry, Vt. -- -- -- -- --

50 1155500 43.1089 72.7758 West River Jamaica, Vt. 19.6 21.8 2.58 26.1 17.5

51 1156000 42.9958 72.6389 West River Newfane, Vt. 17.9 21.2 2.57 25.5 16.9

52 1158500 42.9653 72.2333 Otter Brook Keene, N.H. -- -- -- -- --

53 1162500 42.6825 72.1156 Priest Brook Winchendon, Mass. 21.7 19.4 2.58 23.7 15.1

54 1165500 42.6028 72.3600 Moss Brook Wendell Depot, Mass. 18.3 16.2 2.74 20.8 11.6

55 1167800 42.8606 72.8511 Beaver Brook Wilmington, Vt. 28.1 25.7 2.67 30.2 21.2

Table 9. Ground-water-recharge statistics, standard error of prediction, and 90-percent prediction interval estimated using available 

data and regression-equation predicted values for the annual period (January 1–December 31).—Continued

[No., number; fig., figure; in., inch; --, no data]

Streamgaging 

station

reference 

No. 

(fig. 1)

Streamgaging 

station 

No.

Latitude

(decimal 

degrees)

Longitude

(decimal 

degrees)

River name Location

Annual

(January 1–December 31)

 90-percent 

prediction 

intervals

Normalized 

basinrecharge 

estimate 

(in.)

Equationpredicted 

value 

(in.)

 Standard 

error of 

prediction

 Upper

(in.)

 Lower

(in.)
50 Streamflow Data of Annual and Seasonal Ground-Water Recharge Rates for Drainage Basins in New Hampshire

Table 10. Ground-water-recharge statistics, standard error of prediction, and 90-percent prediction interval estimated using available 

data and regression-equation predicted values for the winter (January 1–March 15).

[No., number; fig., figure; in., inch]

Streamgaging 

station

reference 

No. 

(fig. 1)

Streamgaging 

station 

No.

Latitude 

(decimal 

degrees)

Longitude

(decimal 

degrees)

River name Location

Winter

(January 1–March 15)

 90-percent 

prediction 

intervals

Normalized 

basinrecharge 

estimate 

(in.)

Equationpredicted 

value 

(in.)

 Standard 

error of 

prediction

 Upper

(in.)

 Lower

(in.)

1 1052500 44.8778 71.0569 Diamond River Wentworth Location, N.H. 3.07 2.31 0.68 3.45 1.16

2 1054200 44.3908 70.9797 Wild River Gilead, Maine 4.15 3.92 .66 5.03 2.81

3 1054300 44.5936 70.7336 Ellis River South Andover, Maine 3.35 3.60 .65 4.70 2.50

4 1055000 44.6422 70.5881 Swift River Near Roxbury, Maine 3.00 2.84 .67 3.97 1.71

5 1057000 44.3033 70.5394 Little Androscoggin RiverNear South Paris, Maine 3.71 4.53 .65 5.62 3.43

6 1064300 44.2200 71.2500 Ellis River Near Jackson, N.H. 3.92 3.70 .76 4.97 2.43

7 1064400 44.0694 71.1750 Lucy Brook Near North Conway, N.H. 4.54 4.22 .70 5.40 3.03

8 1064500 43.9908 71.0914 Saco River Near Conway, N.H. 4.21 4.24 .67 5.36 3.12

9 1072850 43.2631 71.0972 Mohawk River Center Strafford, N.H. 5.43 5.42 .66 6.53 4.31

10 1073000 43.1486 70.9656 Oyster River Durham, N.H. 5.90 5.39 .66 6.51 4.28

11 1073600 42.9936 71.0233 Dudley Brook Exeter, N.H. 3.95 5.65 .67 6.77 4.53

12 1075000 43.9761 71.6800 Pemigewasset 

River

Woodstock, N.H. 3.43 4.11 .68 5.26 2.97

13 1075800 43.8367 71.8853 Stevens Brook Wentworth, N.H. 3.01 3.72 .66 4.82 2.61

14 1076000 43.7961 71.8450 Baker River Rumney, N.H. 3.00 4.74 .65 5.84 3.65

15 1076500 43.7592 71.6861 Pemigewasset 

River

Plymouth, N.H. 3.65 3.82 .65 4.91 2.73

16 1078000 43.5675 71.7483 Smith River Near Bristol, N.H. 4.08 4.41 .65 5.50 3.32

17 1082000 42.8625 71.9597 Contoocook River Peterborough, N.H. 5.07 5.12 .66 6.22 4.01

18 1084500 43.1142 71.9267 Beards Brook Hillsboro, N.H. 4.66 5.18 .66 6.28 4.07

19 1085800 43.2592 72.0264 West Branch 

Warner River

Near Bradford, N.H. 5.40 5.71 .67 6.83 4.58

20 1086000 43.2517 71.7317 Warner River Davisville, N.H. 4.94 4.44 .65 5.54 3.34

21 1089000 43.2394 71.4622 Soucook River Near Concord, N.H. 4.32 4.11 .66 5.22 3.00

22 1091000 43.0136 71.6419 South Branch 

Piscataquog River

Near Goffstown, N.H. 5.41 4.53 .66 5.64 3.42

23 1093800 42.8600 71.8333 Stony Brook 

Tributary

Near Temple, N.H. 6.14 6.06 .67 7.20 4.93

24 10965852 42.7831 71.3539 Beaver Brook North Pelham, N.H. 6.71 5.73 .67 6.85 4.62

25 1097300 42.5108 71.4069 Nashoba Brook Near Acton, Mass. 6.71 6.58 .69 7.74 5.42

26 1101000 42.7528 70.9461 Parker River Byfield, Mass. 7.82 7.07 .71 8.26 5.88

27 1127880 45.1350 71.2064 Big Brook Pittsburg, N.H. 4.47 3.78 .75 5.04 2.53

28 1129440 44.8744 71.4106 Mohawk River Near Colebrook, N.H. 4.10 3.40 .67 4.53 2.27
Tables 51

29 1130000 44.6250 71.4694 Upper Ammonoosuc RiverNear Groveton, N.H. 3.27 3.24 0.65 4.34 2.14

30 1133000 44.6339 71.8981 East Branch 

Passumpsic

East Haven, Vt. 3.41 3.83 .67 4.97 2.70

31 1134500 44.5117 71.8369 Moose River Victory, Vt. 3.39 3.97 .66 5.07 2.87

32 1134800 44.4419 71.8792 Kirby Brook Concord, Vt. 2.30 3.25 .65 4.35 2.15

33 1135000 44.4228 72.0006 Moose River St. Johnsbury, Vt. 2.73 3.35 .66 4.45 2.24

34 1135300 44.4344 72.0394 Sleepers River 

(W-5)

St. Johnsbury, Vt. 3.43 3.37 .66 4.48 2.27

35 1137500 44.2689 71.6311 Ammonoosuc 

River

Bethlehem Junction, N.H. 3.32 3.19 .67 4.31 2.07

36 1138000 44.1539 71.9861 Ammonoosuc 

River

Bath, N.H. 2.47 2.94 .67 4.07 1.81

37 1139000 44.1508 72.0653 Wells River Wells River, Vt. 3.05 3.04 .67 4.16 1.91

38 1139800 44.0928 72.3361 East Orange 

Branch

East Orange, Vt. 3.88 4.00 .68 5.14 2.87

39 1141800 43.7022 72.1875 Mink Brook Etna, N.H. 4.09 4.12 .65 5.21 3.04

40 1142500 43.9344 72.6583 Ayers Brook Randolph, Vt. 4.40 3.96 .66 5.07 2.86

41 1144000 43.7142 72.4186 White River West Hartford, Vt. 4.01 3.40 .66 4.51 2.29

42 1145000 43.6500 72.0806 Mascoma River West Canaan, N.H. 3.20 3.67 .66 4.77 2.57

43 1150800 43.6733 72.8092 Kent Brook Sherburne, Vt. 4.15 5.56 .71 6.75 4.37

44 1150900 43.6222 72.7594 Ottauquechee 

River

West Bridgewater, Vt. 7.51 5.23 .70 6.41 4.06

45 1153500 43.2086 72.5181 Williams River Brockways Mills, Vt. 4.45 4.11 .65 5.20 3.02

46 1154000 43.1372 72.4881 Saxtons River Saxtons River, Vt. 4.72 4.21 .65 5.30 3.13

47 1155000 43.1317 72.3897 Cold River Drewsville, N.H. 3.59 4.08 .66 5.19 2.96

48 1155200 42.9992 72.5331 Sacketts Brook Putney, Vt. 4.37 4.54 .65 5.64 3.45

49 1155300 43.2364 72.8564 Flood Brook Londonderry, Vt. 4.01 5.13 .67 6.25 4.01

50 1155500 43.1089 72.7758 West River Jamaica, Vt. 4.26 4.47 .65 5.56 3.37

51 1156000 42.9958 72.6389 West River Newfane, Vt. 3.94 4.20 .65 5.28 3.11

52 1158500 42.9653 72.2333 Otter Brook Keene, N.H. 5.56 4.47 .65 5.56 3.37

53 1162500 42.6825 72.1156 Priest Brook Winchendon, Mass. 5.74 4.48 .65 5.57 3.38

54 1165500 42.6028 72.3600 Moss Brook Wendell Depot, Mass. 4.91 4.03 .68 5.18 2.89

55 1167800 42.8606 72.8511 Beaver Brook Wilmington, Vt. 4.85 6.22 .72 7.43 5.01

Table 10. Ground-water-recharge statistics, standard error of prediction, and 90-percent prediction interval estimated using available 

data and regression-equation predicted values for the winter (January 1–March 15).—Continued

[No., number; fig., figure; in., inch]

Streamgaging 

station

reference 

No. 

(fig. 1)

Streamgaging 

station 

No.

Latitude 

(decimal 

degrees)

Longitude

(decimal 

degrees)

River name Location

Winter

(January 1–March 15)

 90-percent 

prediction 

intervals

Normalized 

basinrecharge 

estimate 

(in.)

Equationpredicted 

value 

(in.)

 Standard 

error of 

prediction

 Upper

(in.)

 Lower

(in.)
52 Streamflow Data of Annual and Seasonal Ground-Water Recharge Rates for Drainage Basins in New Hampshire

Table 11. Ground-water-recharge statistics, standard error of prediction, and 90-percent prediction interval estimated using available 

data and regression-equation predicted values for the spring (March 16–May 31).

[No., number; fig., figure; in., inch]

Streamgaging 

station

reference 

No. 

(fig. 1)

Streamgaging 

station 

No.

Latitude

(decimal 

degrees)

Longitude

(decimal 

degrees)

River name Location

Spring

(March 16–May 31)

 90-percent 

prediction 

intervals

Normalized 

basinrecharge 

estimate 

(in.)

Equationpredicted 

value 

(in.)

 Standard 

error of 

prediction

 Upper

(in.)

 Lower

(in.)

1 1052500 44.8778 71.0569 Diamond River Wentworth Location, N.H. 12.1 10.4 1.15 12.3 8.43

2 1054200 44.3908 70.9797 Wild River Gilead, Maine 10.0 9.43 1.10 11.3 7.59

3 1054300 44.5936 70.7336 Ellis River South Andover, Maine 10.0 9.49 1.09 11.3 7.66

4 1055000 44.6422 70.5881 Swift River Near Roxbury, Maine 10.2 10.1 1.12 12.0 8.24

5 1057000 44.3033 70.5394 Little Androscoggin RiverNear South Paris, Maine 8.65 8.08 1.09 9.91 6.26

6 1064300 44.2200 71.2500 Ellis River Near Jackson, N.H. 13.3 14.2 1.30 16.4 12.0

7 1064400 44.0694 71.1750 Lucy Brook Near North Conway, N.H. 10.5 9.60 1.16 11.5 7.64

8 1064500 43.9908 71.0914 Saco River Near Conway, N.H. 11.7 10.2 1.11 12.1 8.37

9 1072850 43.2631 71.0972 Mohawk River Center Strafford, N.H. 7.61 8.39 1.09 10.2 6.55

10 1073000 43.1486 70.9656 Oyster River Durham, N.H. 7.61 7.25 1.10 9.09 5.41

11 1073600 42.9936 71.0233 Dudley Brook Exeter, N.H. 5.16 7.33 1.10 9.18 5.48

12 1075000 43.9761 71.6800 Pemigewasset 

River

Woodstock, N.H. 13.7 10.9 1.14 12.8 8.96

13 1075800 43.8367 71.8853 Stevens Brook Wentworth, N.H. 6.03 7.61 1.10 9.47 5.76

14 1076000 43.7961 71.8450 Baker River Rumney, N.H. 8.74 8.58 1.09 10.4 6.76

15 1076500 43.7592 71.6861 Pemigewasset 

River

Plymouth, N.H. 10.4 9.06 1.09 10.9 7.23

16 1078000 43.5675 71.7483 Smith River Near Bristol, N.H. 8.86 8.49 1.08 10.3 6.67

17 1082000 42.8625 71.9597 Contoocook River Peterborough, N.H. 8.38 7.80 1.09 9.63 5.97

18 1084500 43.1142 71.9267 Beards Brook Hillsboro, N.H. 9.10 8.33 1.09 10.1 6.51

19 1085800 43.2592 72.0264 West Branch 

Warner River

Near Bradford, N.H. 9.38 9.07 1.11 10.9 7.20

20 1086000 43.2517 71.7317 Warner River Davisville, N.H. 10.4 7.82 1.08 9.64 6.00

21 1089000 43.2394 71.4622 Soucook River Near Concord, N.H. 6.55 6.95 1.10 8.79 5.11

22 1091000 43.0136 71.6419 South Branch 

Piscataquog River

Near Goffstown, N.H. 7.99 7.36 1.10 9.21 5.52

23 1093800 42.8600 71.8333 Stony Brook 

Tributary

Near Temple, N.H. 9.34 8.80 1.11 10.7 6.94

24 10965852 42.7831 71.3539 Beaver Brook North Pelham, N.H. 6.14 7.59 1.10 9.44 5.75

25 1097300 42.5108 71.4069 Nashoba Brook Near Acton, Mass. 6.66 7.53 1.12 9.41 5.65

26 1101000 42.7528 70.9461 Parker River Byfield, Mass. 8.77 7.81 1.13 9.71 5.90

27 1127880 45.1350 71.2064 Big Brook Pittsburg, N.H. 12.4 12.9 1.24 15.0 10.9

28 1129440 44.8744 71.4106 Mohawk River Near Colebrook, N.H. 6.99 8.77 1.09 10.6 6.94
Tables 53

29 1130000 44.6250 71.4694 Upper Ammonoosuc RiverNear Groveton, N.H. 10.3 9.26 1.11 11.1 7.40

30 1133000 44.6339 71.8981 East Branch 

Passumpsic

East Haven, Vt. 10.8 9.54 1.11 11.4 7.68

31 1134500 44.5117 71.8369 Moose River Victory, Vt. 8.75 9.29 1.10 11.1 7.44

32 1134800 44.4419 71.8792 Kirby Brook Concord, Vt. 7.37 7.44 1.11 9.30 5.58

33 1135000 44.4228 72.0006 Moose River St. Johnsbury, Vt. 8.48 8.15 1.11 10.0 6.29

34 1135300 44.4344 72.0394 Sleepers River 

(W-5)

St. Johnsbury, Vt. 6.64 8.33 1.11 10.2 6.47

35 1137500 44.2689 71.6311 Ammonoosuc 

River

Bethlehem Junction, N.H. 10.2 11.0 1.16 13.0 9.1

36 1138000 44.1539 71.9861 Ammonoosuc 

River

Bath, N.H. 6.80 8.02 1.13 9.92 6.12

37 1139000 44.1508 72.0653 Wells River Wells River, Vt. 7.38 7.13 1.13 9.03 5.24

38 1139800 44.0928 72.3361 East Orange 

Branch

East Orange, Vt. 11.8 8.83 1.11 10.7 6.97

39 1141800 43.7022 72.1875 Mink Brook Etna, N.H. 8.03 7.44 1.09 9.26 5.61

40 1142500 43.9344 72.6583 Ayers Brook Randolph, Vt. 8.83 8.16 1.09 10.0 6.32

41 1144000 43.7142 72.4186 White River West Hartford, Vt. 8.30 8.06 1.09 9.90 6.23

42 1145000 43.6500 72.0806 Mascoma River West Canaan, N.H. 7.95 7.37 1.09 9.20 5.53

43 1150800 43.6733 72.8092 Kent Brook Sherburne, Vt. 12.4 11.6 1.17 13.6 9.67

44 1150900 43.6222 72.7594 Ottauquechee 

River

West Bridgewater, Vt. 10.4 11.5 1.17 13.5 9.58

45 1153500 43.2086 72.5181 Williams River Brockways Mills, Vt. 8.63 8.27 1.08 10.1 6.46

46 1154000 43.1372 72.4881 Saxtons River Saxtons River, Vt. 8.11 8.56 1.08 10.4 6.74

47 1155000 43.1317 72.3897 Cold River Drewsville, N.H. 7.39 7.15 1.10 8.99 5.31

48 1155200 42.9992 72.5331 Sacketts Brook Putney, Vt. 9.20 8.05 1.09 9.87 6.22

49 1155300 43.2364 72.8564 Flood Brook Londonderry, Vt. 12.3 10.3 1.11 12.2 8.47

50 1155500 43.1089 72.7758 West River Jamaica, Vt. 8.33 9.42 1.09 11.3 7.59

51 1156000 42.9958 72.6389 West River Newfane, Vt. 7.49 9.08 1.08 10.9 7.26

52 1158500 42.9653 72.2333 Otter Brook Keene, N.H. 8.16 7.90 1.08 9.72 6.08

53 1162500 42.6825 72.1156 Priest Brook Winchendon, Mass. 8.43 7.30 1.09 9.14 5.47

54 1165500 42.6028 72.3600 Moss Brook Wendell Depot, Mass. 7.01 6.60 1.17 8.57 4.63

55 1167800 42.8606 72.8511 Beaver Brook Wilmington, Vt. 10.2 10.7 1.18 12.7 8.76

Table 11. Ground-water-recharge statistics, standard error of prediction, and 90-percent prediction interval estimated using available 

data and regression-equation predicted values for the spring (March 16–May 31).—Continued

[No., number; fig., figure; in., inch]

Streamgaging 

station

reference 

No. 

(fig. 1)

Streamgaging 

station 

No.

Latitude

(decimal 

degrees)

Longitude

(decimal 

degrees)

River name Location

Spring

(March 16–May 31)

 90-percent 

prediction 

intervals

Normalized 

basinrecharge 

estimate 

(in.)

Equationpredicted 

value 

(in.)

 Standard 

error of 

prediction

 Upper

(in.)

 Lower

(in.)
54 Streamflow Data of Annual and Seasonal Ground-Water Recharge Rates for Drainage Basins in New Hampshire

Table 12. Ground-water-recharge statistics, standard error of prediction, and 90-percent prediction interval estimated using available 

data and regression-equation predicted values for the summer (June 1–October 31).

[No., number; fig., figure; in., inch; --, no data]

Streamgaging 

station

reference 

No. 

(fig. 1)

Streamgaging 

station 

No.

Latitude

(decimal 

degrees)

Longitude

(decimal 

degrees)

River name Location

Summer

(June 1–October 31)

 90-percent 

prediction 

intervals

Normalized 

basinrecharge 

estimate 

(in.)

Equationpredicted 

value 

(in.)

Standard 

error of 

prediction

 Upper

(in.)

 Lower

(in.)

1 1052500 44.8778 71.0569 Diamond River Wentworth Location, N.H. 6.69 4.57 1.10 6.41 2.72

2 1054200 44.3908 70.9797 Wild River Gilead, Maine 3.80 4.88 1.04 6.62 3.14

3 1054300 44.5936 70.7336 Ellis River South Andover, Maine 3.22 3.91 1.05 5.67 2.15

4 1055000 44.6422 70.5881 Swift River Near Roxbury, Maine 4.12 4.92 1.11 6.78 3.06

5 1057000 44.3033 70.5394 Little Androscoggin RiverNear South Paris, Maine 3.03 3.86 1.02 5.58 2.14

6 1064300 44.2200 71.2500 Ellis River Near Jackson, N.H. 9.37 7.57 1.11 9.44 5.70

7 1064400 44.0694 71.1750 Lucy Brook Near North Conway, N.H. 3.85 4.65 1.07 6.44 2.85

8 1064500 43.9908 71.0914 Saco River Near Conway, N.H. 3.71 4.32 1.03 6.06 2.59

9 1072850 43.2631 71.0972 Mohawk River Center Strafford, N.H. 1.59 2.07 1.11 3.93 .20

10 1073000 43.1486 70.9656 Oyster River Durham, N.H. 2.78 1.69 1.06 3.47 .00

11 1073600 42.9936 71.0233 Dudley Brook Exeter, N.H. 1.45 2.47 1.05 4.23 .71

12 1075000 43.9761 71.6800 Pemigewasset 

River

Woodstock, N.H. 6.21 4.70 1.04 6.44 2.96

13 1075800 43.8367 71.8853 Stevens Brook Wentworth, N.H. 1.69 2.77 1.05 4.54 1.00

14 1076000 43.7961 71.8450 Baker River Rumney, N.H. 3.26 3.27 1.03 5.01 1.53

15 1076500 43.7592 71.6861 Pemigewasset 

River

Plymouth, N.H. 4.92 3.01 1.04 4.75 1.26

16 1078000 43.5675 71.7483 Smith River Near Bristol, N.H. 3.87 3.47 1.03 5.19 1.74

17 1082000 42.8625 71.9597 Contoocook River Peterborough, N.H. 3.62 3.11 1.03 4.84 1.39

18 1084500 43.1142 71.9267 Beards Brook Hillsboro, N.H. 3.01 2.69 1.03 4.42 .96

19 1085800 43.2592 72.0264 West Branch 

Warner River

Near Bradford, N.H. 3.58 3.87 1.06 5.66 2.09

20 1086000 43.2517 71.7317 Warner River Davisville, N.H. 3.09 2.42 1.03 4.15 .69

21 1089000 43.2394 71.4622 Soucook River Near Concord, N.H. 2.62 2.11 1.04 3.85 .37

22 1091000 43.0136 71.6419 South Branch 

Piscataquog River

Near Goffstown, N.H. 2.62 2.46 1.03 4.19 .73

23 1093800 42.8600 71.8333 Stony Brook 

Tributary

Near Temple, N.H. 3.71 3.57 1.04 5.31 1.82

24 10965852 42.7831 71.3539 Beaver Brook North Pelham, N.H. 2.92 2.78 1.07 4.57 .99

25 1097300 42.5108 71.4069 Nashoba Brook Near Acton, Mass. 2.82 2.31 1.07 4.12 .51

26 1101000 42.7528 70.9461 Parker River Byfield, Mass. 3.95 2.41 1.09 4.24 .58

27 1127880 45.1350 71.2064 Big Brook Pittsburg, N.H. 10.2 7.60 1.14 9.52 5.68

28 1129440 44.8744 71.4106 Mohawk River Near Colebrook, N.H. 5.45 6.07 1.07 7.87 4.27
Tables 55

29 1130000 44.6250 71.4694 Upper Ammonoosuc RiverNear Groveton, N.H. 3.18 4.53 1.03 6.27 2.80

30 1133000 44.6339 71.8981 East Branch 

Passumpsic

East Haven, Vt. 7.40 5.92 1.06 7.69 4.15

31 1134500 44.5117 71.8369 Moose River Victory, Vt. 4.45 5.40 1.04 7.14 3.65

32 1134800 44.4419 71.8792 Kirby Brook Concord, Vt. 3.37 3.89 1.04 5.63 2.15

33 1135000 44.4228 72.0006 Moose River St. Johnsbury, Vt. 3.55 3.88 1.03 5.60 2.15

34 1135300 44.4344 72.0394 Sleepers River 

(W-5)

St. Johnsbury, Vt. 4.19 4.04 1.04 5.78 2.30

35 1137500 44.2689 71.6311 Ammonoosuc 

River

Bethlehem Junction, N.H. 2.66 5.19 1.04 6.93 3.44

36 1138000 44.1539 71.9861 Ammonoosuc 

River

Bath, N.H. 2.38 3.00 1.05 4.75 1.24

37 1139000 44.1508 72.0653 Wells River Wells River, Vt. 3.81 3.40 1.04 5.15 1.66

38 1139800 44.0928 72.3361 East Orange 

Branch

East Orange, Vt. 4.59 4.96 1.03 6.69 3.23

39 1141800 43.7022 72.1875 Mink Brook Etna, N.H. 3.67 3.93 1.03 5.67 2.20

40 1142500 43.9344 72.6583 Ayers Brook Randolph, Vt. 3.30 3.16 1.04 4.91 1.41

41 1144000 43.7142 72.4186 White River West Hartford, Vt. 3.26 3.05 1.05 4.81 1.28

42 1145000 43.6500 72.0806 Mascoma River West Canaan, N.H. 2.72 3.24 1.02 4.96 1.52

43 1150800 43.6733 72.8092 Kent Brook Sherburne, Vt. 8.83 7.21 1.17 9.18 5.24

44 1150900 43.6222 72.7594 Ottauquechee 

River

West Bridgewater, Vt. 7.93 6.33 1.12 8.21 4.46

45 1153500 43.2086 72.5181 Williams River Brockways Mills, Vt. 3.26 3.36 1.03 5.09 1.62

46 1154000 43.1372 72.4881 Saxtons River Saxtons River, Vt. 3.33 3.58 1.02 5.30 1.86

47 1155000 43.1317 72.3897 Cold River Drewsville, N.H. 2.54 2.40 1.03 4.13 0.66

48 1155200 42.9992 72.5331 Sacketts Brook Putney, Vt. 3.55 3.30 1.04 5.06 1.55

49 1155300 43.2364 72.8564 Flood Brook Londonderry, Vt. 3.24 5.42 1.07 7.22 3.63

50 1155500 43.1089 72.7758 West River Jamaica, Vt. 3.70 4.74 1.04 6.49 2.99

51 1156000 42.9958 72.6389 West River Newfane, Vt. 3.67 4.00 1.04 5.75 2.24

52 1158500 42.9653 72.2333 Otter Brook Keene, N.H. -- -- -- -- --

53 1162500 42.6825 72.1156 Priest Brook Winchendon, Mass. 3.89 2.87 1.03 4.60 1.15

54 1165500 42.6028 72.3600 Moss Brook Wendell Depot, Mass. 2.90 3.10 1.03 4.83 1.37

55 1167800 42.8606 72.8511 Beaver Brook Wilmington, Vt. 4.66 5.96 1.11 7.83 4.09

Table 12. Ground-water-recharge statistics, standard error of prediction, and 90-percent prediction interval estimated using available 

data and regression-equation predicted values for the summer (June 1–October 31).—Continued

[No., number; fig., figure; in., inch; --, no data]

Streamgaging 

station

reference 

No. 

(fig. 1)

Streamgaging 

station 

No.

Latitude

(decimal 

degrees)

Longitude

(decimal 

degrees)

River name Location

Summer

(June 1–October 31)

 90-percent 

prediction 

intervals

Normalized 

basinrecharge 

estimate 

(in.)

Equationpredicted 

value 

(in.)

Standard 

error of 

prediction

 Upper

(in.)

 Lower

(in.)
56 Streamflow Data of Annual and Seasonal Ground-Water Recharge Rates for Drainage Basins in New Hampshire

Table 13. Ground-water-recharge statistics, standard error of prediction, and 90-percent prediction interval estimated using available 

data and regression-equation predicted values for the fall (November 1–December 31).

[No., number, fig., figure; in., inch; --, no data]

Streamgaging 

station

reference 

No. 

(fig. 1)

Streamgaging 

station 

No.

Latitude

(decimal 

degrees)

Longitude

(decimal 

degrees)

River name Location

Fall

(November 1–December 31)

 90-percent 

prediction 

intervals

Normalized 

basinrecharge 

estimate 

(in.)

Equationpredicted 

value 

(in.)

 Standard 

error of 

prediction

 Upper

(in.)

 Lower

(in.)

1 1052500 44.8778 71.0569 Diamond River Wentworth Location, N.H. 3.84 3.64 0.56 4.58 2.70

2 1054200 44.3908 70.9797 Wild River Gilead, Maine 2.93 3.60 .57 4.55 2.64

3 1054300 44.5936 70.7336 Ellis River South Andover, Maine 3.08 3.15 .56 4.09 2.21

4 1055000 44.6422 70.5881 Swift River Near Roxbury, Maine 3.40 2.72 .58 3.69 1.75

5 1057000 44.3033 70.5394 Little Androscoggin RiverNear South Paris, Maine 3.69 3.90 .56 4.85 2.96

6 1064300 44.2200 71.2500 Ellis River Near Jackson, N.H. 4.24 5.24 .71 6.43 4.06

7 1064400 44.0694 71.1750 Lucy Brook Near North Conway, N.H. 3.99 3.53 .59 4.53 2.53

8 1064500 43.9908 71.0914 Saco River Near Conway, N.H. 3.95 3.77 .57 4.72 2.81

9 1072850 43.2631 71.0972 Mohawk River Center Strafford, N.H. 4.23 4.31 .57 5.27 3.35

10 1073000 43.1486 70.9656 Oyster River Durham, N.H. 4.02 3.97 .56 4.92 3.03

11 1073600 42.9936 71.0233 Dudley Brook Exeter, N.H. 2.39 3.85 .56 4.79 2.91

12 1075000 43.9761 71.6800 Pemigewasset 

River

Woodstock, N.H. 4.00 2.97 .58 3.95 1.99

13 1075800 43.8367 71.8853 Stevens Brook Wentworth, N.H. 2.36 2.71 .57 3.67 1.75

14 1076000 43.7961 71.8450 Baker River Rumney, N.H. 2.81 3.00 .57 3.95 2.05

15 1076500 43.7592 71.6861 Pemigewasset 

River

Plymouth, N.H. 4.45 3.96 .57 4.91 3.01

16 1078000 43.5675 71.7483 Smith River Near Bristol, N.H. 3.58 3.38 .56 4.32 2.44

17 1082000 42.8625 71.9597 Contoocook River Peterborough, N.H. 3.56 3.34 .56 4.28 2.40

18 1084500 43.1142 71.9267 Beards Brook Hillsboro, N.H. 4.35 3.91 .56 4.86 2.97

19 1085800 43.2592 72.0264 West Branch 

Warner River

Near Bradford, N.H. 4.04 4.19 .57 5.15 3.22

20 1086000 43.2517 71.7317 Warner River Davisville, N.H. 4.26 3.60 .56 4.54 2.66

21 1089000 43.2394 71.4622 Soucook River Near Concord, N.H. 2.96 3.10 .56 4.05 2.16

22 1091000 43.0136 71.6419 South Branch 

Piscataquog River

Near Goffstown, N.H. 3.66 3.28 .56 4.22 2.34

23 1093800 42.8600 71.8333 Stony Brook 

Tributary

Near Temple, N.H. 4.90 4.37 .57 5.33 3.40

24 10965852 42.7831 71.3539 Beaver Brook North Pelham, N.H. 4.59 4.07 .57 5.03 3.12

25 1097300 42.5108 71.4069 Nashoba Brook Near Acton, Mass. 3.82 4.44 .58 5.42 3.46

26 1101000 42.7528 70.9461 Parker River Byfield, Mass. 4.84 4.78 .60 5.78 3.78

27 1127880 45.1350 71.2064 Big Brook Pittsburg, N.H. 4.82 4.22 .57 5.18 3.26

28 1129440 44.8744 71.4106 Mohawk River Near Colebrook, N.H. 4.07 3.45 .56 4.39 2.51
Tables 57

29 1130000 44.6250 71.4694 Upper Ammonoosuc RiverNear Groveton, N.H. 2.55 2.93 0.56 3.87 1.98

30 1133000 44.6339 71.8981 East Branch 

Passumpsic

East Haven, Vt. 4.26 3.52 .56 4.46 2.57

31 1134500 44.5117 71.8369 Moose River Victory, Vt. 3.31 3.68 .56 4.63 2.74

32 1134800 44.4419 71.8792 Kirby Brook Concord, Vt. 2.26 3.07 .56 4.01 2.12 

33 1135000 44.4228 72.0006 Moose River St. Johnsbury, Vt. 2.58 3.33 .56 4.27 2.39

34 1135300 44.4344 72.0394 Sleepers River 

(W-5)

St. Johnsbury, Vt. 3.95 3.33 .56 4.27 2.39

35 1137500 44.2689 71.6311 Ammonoosuc 

River

Bethlehem Junction, N.H. 3.02 3.98 .58 4.96 3.00

36 1138000 44.1539 71.9861 Ammonoosuc 

River

Bath, N.H. 2.21 2.74 .57 3.69 1.78

37 1139000 44.1508 72.0653 Wells River Wells River, Vt. 2.85 3.16 .56 4.11 2.21

38 1139800 44.0928 72.3361 East Orange 

Branch

East Orange, Vt. 3.58 3.76 .57 4.72 2.80

39 1141800 43.7022 72.1875 Mink Brook Etna, N.H. 2.99 3.00 .56 3.95 2.05

40 1142500 43.9344 72.6583 Ayers Brook Randolph, Vt. 3.33 3.54 .56 4.49 2.59

41 1144000 43.7142 72.4186 White River West Hartford, Vt. 3.37 3.35 .56 4.29 2.40

42 1145000 43.6500 72.0806 Mascoma River West Canaan, N.H. 2.63 2.80 .57 3.75 1.85

43 1150800 43.6733 72.8092 Kent Brook Sherburne, Vt. 6.06 4.52 .58 5.49 3.55

44 1150900 43.6222 72.7594 Ottauquechee 

River

West Bridgewater, Vt. 5.22 4.21 .57 5.16 3.25

45 1153500 43.2086 72.5181 Williams River Brockways Mills, Vt. 2.82 3.42 .56 4.36 2.48

46 1154000 43.1372 72.4881 Saxtons River Saxtons River, Vt. 3.23 3.43 .56 4.36 2.49

47 1155000 43.1317 72.3897 Cold River Drewsville, N.H. 2.44 2.64 .57 3.60 1.68

48 1155200 42.9992 72.5331 Sacketts Brook Putney, Vt. 2.81 3.69 .56 4.64 2.75

49 1155300 43.2364 72.8564 Flood Brook Londonderry, Vt. 4.08 3.98 .56 4.92 3.03

50 1155500 43.1089 72.7758 West River Jamaica, Vt. 3.44 3.45 .56 4.39 2.51

51 1156000 42.9958 72.6389 West River Newfane, Vt. 2.99 3.35 .56 4.29 2.41

52 1158500 42.9653 72.2333 Otter Brook Keene, N.H. -- -- -- -- --

53 1162500 42.6825 72.1156 Priest Brook Winchendon, Mass. 3.73 3.16 .56 4.10 2.22

54 1165500 42.6028 72.3600 Moss Brook Wendell Depot, Mass. 2.96 2.20 .60 3.21 1.20

55 1167800 42.8606 72.8511 Beaver Brook Wilmington, Vt. 4.95 4.29 .57 5.25 3.33

Table 13. Ground-water-recharge statistics, standard error of prediction, and 90-percent prediction interval estimated using available 

data and regression-equation predicted values for the fall (November 1–December 31).—Continued

[No., number, fig., figure; in., inch; --, no data]

Streamgaging 

station

reference 

No. 

(fig. 1)

Streamgaging 

station 

No.

Latitude

(decimal 

degrees)

Longitude

(decimal 

degrees)

River name Location

Fall

(November 1–December 31)

 90-percent 

prediction 

intervals

Normalized 

basinrecharge 

estimate 

(in.)

Equationpredicted 

value 

(in.)

 Standard 

error of 

prediction

 Upper

(in.)

 Lower

(in.)

Appendix 1 59

• Total drainage area, in square miles, is the area measured in a horizontal plane that is enclosed by a drainage divide. 

• Basin length, in miles, is the length of the basin measured along a line areally centered through the drainage 

divide data layer from the basin outlet to where the 

main channel extended meets the basin divide.

• Basin perimeter, in miles, is the length as measured 

along the entire drainage-basin boundary.

• Average basin slope, in percent, is the average slope of 

the drainage basin measured using a Digital Elevation 

Model (DEM) in the computer software ARC-INFO.

• Basin relief, in feet, is the measured difference 

between the elevation of the highest grid cell and the 

elevation of the grid cell at the basin outlet. A lattice 

data layer, created using ARC-INFO, is used to determine the minimum and maximum land-surface elevation.

• Basin azimuth, in degrees, is the direction of a line 

projected from where the main channel meets the basin 

divide downslope to the basin outlet (clockwise from 

north = 0 degrees). 

• Basin azimuth, in radians.

• Basin azimuth region, Four quadrants where 0–90 

degrees = 1, 90–180 degrees = 2, 180–270 degrees = 3, 

and 270–360 degrees = 4. 

• Effective basin width, in miles, is the ratio of the total 

drainage area to the basin length.

• Shape factor, dimensionless, is the ratio of basin 

length to the effective basin width.

• Compactness ratio, dimensionless, is the ratio of the 

perimeter of the basin to the circumference of a circle 

of equal area.

• Relative relief, in foot/mile, is the ratio of the basin 

relief to the basin perimeter.

• Main channel length, in miles, is measured along the 

main channel from the basin outlet to where the main 

channel meets the basin divide using centerlined 

hydrography.

• Main channel slope, in foot/mile, is the slope of the 

main channel based on the difference in streambed elevation at points 10 and 85 percent of the distance along 

the main channel from the basin outlet to the basin 

divide.

• Main channel sinuosity ratio, dimensionless, is the 

ratio of the main channel length to the basin length.

• Stream density, in miles per square mile, is the ratio of 

the main channel length to the drainage area.

• Main channel slope proportion, dimensionless, is the 

ratio of the main channel length to the square root of the 

main channel slope.

• Ruggedness number, in foot/mile, is the product of 

the stream density multiplied by the Basin Relief.

• Slope ratio, dimensionless, is the ratio of the main 

channel slope to the basin slope.

• Minimum basin elevation, in feet, is the minimum 

elevation in the drainage basin based on the intersection 

of the basin polygon coverages and the DEMs.

• Maximum basin elevation, in feet, is the maximum 

elevation in the drainage basin based on the intersection 

of the basin polygon coverages and the DEMs.

• Mean basin elevation, in feet, is mean basin elevation 

in the drainage basin based on the intersection of the 

basin polygon coverages and the DEMs.

• Median basin elevation, in feet, is the median basin 

elevation in the drainage basin based on the intersection 

of the basin polygon coverages and the DEMs.

• Ground-water head, in feet, is a surrogate for the 

effective head in the sand and gravel deposits determined by subtracting the minimum basin elevation 

from the mean basin elevation.

• Basin elevation group, either a “1” or a “2”, is based 

on the median value of the mean basin elevations for all 

60 basins used to develop the regression equations, 

which is 1,498 feet above mean sea level. A “1” indicates that the mean basin elevation is above this value 

and a “2” indicates that the mean basin elevation is 

below this value.

• Standardized centroid latitude and longitude is the 

latitude and longitude of the basin centroid, which was 

standardized by replacing the centroid latitude (and 

similarly centroid longitude) of each basin with [Latitude–mean (Latitude)] divided by the Standard Deviation (Latitude). The standardized latitude and longitude 

are symmetrically distributed with a mean of zero and 

a standard deviation of one.

• Centroid latitude and longitude, in decimal degrees, 

is the latitude and longitude at the centroid of the drainage basin.

• Significant sand and gravel deposits, in square miles 

plus 0.01, is the total area of sand and gravel deposits in 

the basin plus 0.01.

Appendix 1. Basin and Climate Characteristics Tested for Significance in the 

Ground-water Recharge Regression Analysis
60 Streamflow Data of Annual and Seasonal Ground-Water Recharge Rates for Drainage Basins in New Hampshire

• Percent sand and gravel in basin, in percent plus 

0.01, is the percentage of the total drainage basin area, 

which has sand and gravel deposits, to the total drainage basin area plus 0.01.

• Ratio of sand and gravel in basin in contact with 

stream network to total drainage basin area, in percent plus 0.01, is the percent of drainage basin underlain by sand and gravel, which is in contact with the 

stream network (based on the intersection of stream 

centerline data and polygon coverages of sand and 

gravel deposits) as a percentage of the total drainagebasin area.

• Minimum elevation of sand and gravel deposits, in 

feet, is the minimum elevation of the sand and gravel 

deposits based upon DEMs and sand and gravel data.

• Maximum elevation of sand and gravel deposits, in 

feet, is the maximum elevation of the sand and gravel 

deposits based upon DEMs and sand and gravel data.

• Mean elevation of sand and gravel deposits, in feet, 

is the mean elevation of the sand and gravel deposits 

based upon DEMs and sand and gravel data.

• Maximum sand and gravel deposit elevation above 

minimum basin elevation, in feet plus 0.01, is the difference in elevation between the maximum and minimum sand and gravel deposit elevations as determined 

from DEMs and sand and gravel data (plus 0.01).

• Mean sand and gravel deposit elevation above minimum basin elevation, in feet plus 0.01, is the difference in elevation between the mean sand and gravel 

deposit elevation and the minimum basin elevation 

based upon DEMs and sand and gravel data (plus 0.01). 

• Mean sand and gravel deposit elevation above minimum basin elevation divided by drainage area, in 

feet plus 0.01, is the difference in elevation between the 

mean sand and gravel deposit elevation and the minimum basin elevation divided by drainage area and 

based upon DEMs and sand and gravel data (plus 0.01). 

• Relief of sand and gravel deposits, in feet plus 0.01, 

is the difference between the maximum sand and gravel 

elevation and minimum sand and gravel elevation 

based upon DEMs and sand and gravel data (plus 0.01). 

• Mean annual and seasonal precipitation, in inches, 

at a stream-gaging station, is from PRISM average 

monthly and annual precipitation data for 1961–90. It is 

based on 2-kilometer grid data. Five parameters were 

determined based on these data: 

• annual gage

• winter gage (January 1–March 15)

• spring gage (March 16–May 31)

• summer gage (June 1–October 31)

• fall gage (November 1–December 31)

• Mean annual and seasonal precipitation, in inches, 

at the centroid of the basin, is from PRISM average 

monthly and annual precipitation data for 1961–90. It is 

based on 2-kilometer grid data. Five parameters were 

determined based on these data:

• annual centroid

• winter centroid (January 1–March 15)

• spring centroid (March 16–May 31)

• summer centroid (June 1–October 31)

• fall centroid (November 1–December 31)

• Mean annual and seasonal precipitation, in inches, 

as a basin average for the drainage basin, is from 

PRISM average monthly and annual precipitation data 

for 1961–90. It is based on 2-kilometer grid data. Five 

parameters were determined based on these data:

• annual basin

• winter basin (January 1–March 15)

• spring basin (March 16–May 31) 

• summer basin (June 1–October 31)

• fall basin (November 1–December 31)

• Average mean, minimum and maximum annual 

and seasonal basin temperature, in degrees Fahrenheit, is based on monthly data acquired from PRISM 

for 1961–90. It is based on 2-kilometer grid data. The 

temperature values for the entire month of March were 

used for each of the seasonal “half March” periods:

• annual basin mean, minimum, maximum

• winter basin mean, minimum, maximum

(January 1–March 31)

• spring basin mean, minimum, maximum

(March 1–May 31)

• summer basin mean, minimum, maximum

(June 1–October 31)

• fall basin mean, minimum, maximum

(November 1–December 31)

• Soil drainage, in percent, is the percentage of drainage 

basin that is well drained as determined from 

STATSGO (State Soil Geographic) (Schwarz and 

Alexander, 1995, and U.S. Department of Agriculture, 

1991) data.

• Mean permeability, in inches per hour, is the mean 

permeability in each basin as determined from 

STATSGO (Schwarz and Alexander, 1995, and U.S. 

Department of Agriculture, 1991) data.

• 32fday, in days, is the seasonally and annually determined basinwide average number of days in which the 

temperature was a minimum of 32 degrees or less. The 

seasonal value for the month of March was determined 
Appendix 1 61

by dividing the March value in half (assumes uniform 

distribution). 

• annual basinwide

• winter basinwide (January 1–March 15)

• spring basinwide (March 16–May 31)

• summer basinwide (June 1–October 31)

• fall basinwide (November 1–December 31)

• Curve_25thquartile, dimensionless, is the curvature 

of the basin based on a DEM for all of New Hampshire 

and Vermont and part of Maine and Massachusetts. The 

area encompasses all of the 60 basins used in this study. 

The curvature command was used in a grid of the DEM. 

A slope and a curvature grid were generated. The 

lowest 25 percent of slope and curvature grid cells were 

given a value of one while everything else was given a 

value of zero. These two grids were then cross-multiplied and a grid was produced that identifies those cells 

representing the lowest 25 percent of both slope and 

curvature. The curvature grid calculates the curvature 

of a surface at each cell center and the slope grid show 

the rate of maximum change in Z value from each cell. 

Slope is the first derivative of surface; curvature is the 

second derivative of surface. A negative value indicates 

that the surface (relative to a best fit plane) is concave 

at that cell. The basin characteristic is the lowest 25-

percent quartile of curvature and slope relative to a best 

fit plane and indicates the smallest change in Z value 

from each cell (slope grid) and most curved cell surface 

(curvature grid). This grid was intersected with the 

basin grids to obtain percent flat and curved in each 

basin.

• Curve cell_relief, dimensionless, is the relief (maximum–minimum) of curvature of the basin grid surface 

at each cell center for each basin.

• Profile curve (mean, minimum, maximum), dimensionless, is the average curvature of the grid surface at 

each cell center in the direction of slope for each basin.

• Total stream length, in miles, is the total length of all 

streams in the basin. 

• Area of water bodies, in square miles plus 0.01, is the 

total area of water bodies in the basin.

• Percent water bodies, in percent plus 0.01, is the percent of each drainage basin that contains a body of 

water.

• Area of sand and gravel in contact with the stream 

network, in square feet plus 0.01, is the total area of 

sand and gravel in each drainage basin in contact with 

the stream network.

• Ratio of sand and gravel deposits to streams which 

are in contact with the sand and gravel deposits in 

the basin, in miles plus 0.01, is the ratio of the square 

miles of sand and gravel deposits to the miles of stream 

length in contact with the sand and gravel deposits plus 

0.01. 

• Ratio of sand and gravel deposits to the total stream 

length in the basin, in miles plus 0.01, is the ratio of 

the square miles of sand and gravel deposits to the 

miles of total stream length plus 0.01. The stream centerline data was intersected with the polygon coverages 

of sand and gravel deposits.

• Annual snowcover, in inches, is the mean annual basin 

average snowfall for each of the basins based on 

monthly data acquired from 2-kilometer PRISM grid 

data for 1961–90. 

• Forest coverage, in percent, is National Land Cover 

Data Set (NLCD) data used to determine the percent of 

the basin that is forested.

• Deciduous forest, in percent, is the percent of the basin 

that is deciduous. Defined in NLCD metadata as areas 

dominated by trees where 75 percent or more of the tree 

species shed foliage simultaneously in response to seasonal change.

• Coniferous forest, in percent, is the percent of the 

basin that is coniferous. Defined in NLCD metadata as 

areas dominated by trees where 75 percent or more of 

the tree species maintain their leaves all year. Canopy 

is never without green foliage.

• Mixed coniferous/deciduous forest, in percent, is the 

percent of the basin that is mixed coniferous and deciduous. Defined in NLCD metadata as areas dominated 

by trees where neither deciduous nor evergreen species 

represent more than 75 percent of the cover present.

• Hypsometric curve area, dimensionless, is the area 

under the curve for a hypsometric curve of the basin 

elevation. Elevation data was grouped in equal-area 

classifications to create a hypsometric curve and the 

area under the curve was determined by summing the 

products of elevation and basin area above a given 

maximum elevation for each of the particular equal 

area groupings.

Reference Cited

U.S. Department of Agriculture, Natural Resources Conservation Service, National Soil Survey Center, 1991, State Soil 

Geographic (STATSGO) Data Base: Data use information: 

Miscellaneous Publication No. 1492, 110 p. (revised July 

1994).