U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Map 3196

Sheet 20 of 20

Pamphlet accompanies map

Prepared in cooperation with the

New Hampshire Department of Homeland Security and Emergency Management

Publishing support provided by: West Trenton Publishing Service Center

Manuscript approved for publication December 18, 2011

For more information concerning this publication, contact:

Director, New Hampshire Water Science Center

U.S. Geological Survey

331 Commerce Way

Pembroke, NJ 03275

Or visit the New Hampshire Water Science Center web site at:

http://nh.water.usgs.gov/

This report is available at: http://pubs.usgs.gov/sim/3196/

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.

This and other USGS information products are available at: 

http://store.usgs.gov/

U.S. Geological Survey, Information Services 

Box 25286 

Denver Federal Center 

Denver, CO 80225

To learn about the USGS and its information products, 

visit: http://www.usgs.gov/, or call: 1–888–ASK–USGS

UNCERTAINTIES AND LIMITATIONS REGARDING USE OF FLOOD INUNDATION MAPS

Although the flood-inundation maps represent the boundaries of inundated areas with a distinct line, some 

uncertainty is associated with these maps. The flood boundaries shown were estimated based on water stages 

(water-surface elevations) and streamflows at USGS streamgage 01089500, Suncook River at North Chichester, N.H. 

Water-surface elevations along the stream reaches were estimated by steady-state hydraulic modeling, assuming 

unobstructed flow, and using streamflows and hydrologic conditions anticipated at the USGS streamgage. The 

hydraulic model reflects the land-cover characteristics and any bridge, dam, levee, or other hydraulic structures 

existing as of July 2011. Unique meteorological factors (timing and distribution of precipitation) may cause actual 

streamflows along the modeled reach to vary from those assumed during a flood, which may lead to deviations 

in the water-surface elevations and inundation boundaries shown. Additional areas may be flooded due to 

unanticipated conditions such as: changes in the streambed elevation or roughness, backwater into major tributaries 

along a main stem river, or backwater from localized debris or ice jams. The accuracy of the floodwater extent 

portrayed on these maps will vary with the accuracy of the digital elevation model used to simulate the land surface. 

Additional uncertainties and limitations pertinent to this study are described in the document accompanying this set 

of flood-inundation maps.

If this series of flood-inundation maps will be used in conjunction with National Weather Service (NWS) 

river forecasts, the user should be aware of additional uncertainties that may be inherent or factored into NWS 

forecast procedures. The NWS uses forecast models to estimate the quantity and timing of water flowing through 

selected stream reaches in the United States. These forecast models (1) estimate the amount of runoff generated 

by precipitation and snowmelt, (2) simulate the movement of floodwater as it proceeds downstream, and (3) predict 

the flow and stage (water-surface elevation) for the stream at a given location (AHPS forecast point) throughout 

the forecast period (every 6 hours and 3 to 5 days out in many locations). For more information on AHPS forecasts, 

please see: http://water.weather.gov/ahps/pcpn_and_river_forecasting.pdf. 

DISCLAIMER

Inundated areas shown should not be used for navigation, regulatory, permitting, or other legal purposes. 

The USGS provides these maps “as-is” for a quick reference, emergency planning tool but assumes no legal liability 

or responsibility resulting from the use of this information.

Suggested citation:

Flynn, R.H., Johnston, C.M., and Hayes, Laura, 2012, Flood-inundation maps 

for the Suncook River in Epsom, Pembroke, Allenstown, and Chichester, New 

Hampshire: U.S. Geological Survey Scientific Investigations Map 3196, 10 p. 

pamphlet, 20 sheets, scale 1:24,000. 

Flood-Inundation Map of the Suncook River in Chichester, Epsom, Pembroke, and Allenstown, 

New Hampshire, for a Flood Corresponding to a Stream Stage of 18 Feet at the U.S. Geological Survey 

Streamgage at Suncook River at North Chichester, New Hampshire (Station 01089500)—Southern Region

By

Robert H. Flynn, Craig M. Johnston, and Laura Hayes

2012

Area of detail

(Southern region)

ROCKINGHAM

STAFFORD

BELKNAP

GRAFTON

SULLIVAN

CHESHIRE

MERRIMACK

HILLSBOROUGH

10 20 KILOMETERS 

0 10 20 MILES

0

72 ̊00’ 71 ̊00’

43 ̊00’

43 ̊30’

Lake Winnipesaukee

71°

44°

43°

45°

Concord

Manchester

MAINE

MASSACHUSETTS

VERMONT

72°

NEW

HAMPSHIRE

PEMBROKE

3

28

Merrim

a

ck

River

Merrim

a

ck

River

S

u

n

c

o

o

k

R i v e r

S

u

n

c

o

o

k

R i v e r

SUNCOOK

ALLENSTOWN

Buck Street

dams

B e a r

B r o

o

k

B e a r

B r o

o

k

01089925

1 0.5 0

1 0.5 0

SCALE 1:24 000

NORTH AMERICAN VERTICAL DATUM 1988 (NAVD 88)

1 KILOMETER

1 MILE

Base from New Hampshire Department of Transportation, 2006, 2005, 

1-foot color aerial photos, southeastern New Hampshire; 

North American Datum of 1983 (NAD 83)

EXPLANATION

Depth, in feet

 0–1

>1–3

>3–6

>6–9

>9–12

>12–14

>14–15

>15–18

>18–24

>24–27

Limit of study area

U.S. Geological Survey 

streamgage and number

Road and highway identifier

U.S. route marker

State route marker

3

28

01089925

71°27'

43°12'

43°11'

43°10'

43°9'

43°8'

43°7'

43°12'

43°11'

43°10'

43°9'

43°8'

43°7'

71°26' 71°25' 71°24'

71°27' 71°26' 71°25' 71°24'