Flood Insurance Study - 1976 as TIFFLOOD
INSURANCE
STUDY
CITY OF NORTHAMPTON,
MASSACHUSETTS
HAMPSHIRE COUNTY
NOVEMBER 1976
U.S. DEPARTMENT of HOUSING URBAN DEVELOPMENT
FEDERAL INSURANCE ADMINISTRATION
2.0 AREA STUDIED
2.1 Scope of Study
2.2 Community Description
2.3 Principal Flood Problems
2.4 Flood Protection Measures
3.0 ENGINEERING METHODS
3.1 Hydrologic Analyses
3.2 Hydraulic Analyses
4.0 FLOOD PLAIN MANAGEMENT APPLICATIONS
4.1 Flood Boundaries
4.2 Floodways
TABLE OF CONTENTS
Page
1.0 INTRODUCTION
1.1 Purpose of Study 1
1.2 Coordination 1
1.3 Authority and Acknowledgments 1
2
2
4
4
8
8
12
12
12
5.0 INSURANCE APPLICATION 16
5.1 Reach Determinations 16
5.2 Flood Hazard Factors 17
5.3 Flood Insurance Zones 17
5.4 Flood Insurance Rate Map Description 18
6.0 OTHER STUDIES 18
7.0 LOCATION OF DATA
8.0 BIBLIOGRAPHY AND REFERENr1S
Figure 1 Vicinity Map
Figure 2 Flooding, April 1976, Oxbow, Northampton,
Massachusetts
Figure 3 Flooding, April 1976, Oxbow, Northampton,
Massachusetts 6
Figure 4 Northampton Dike and Pumping Station 7
Figures 5 -6 Frequency Discharge /Drainage Area Curves 9
Figure 7 Floodway Schematic 16
Table 1 Floodway Data
Table 2 Flood Insurance Zone Data
Exhibit 1 Flood Profiles
Connecticut River
Mill River
PUBLISHED SEPARATELY:
TABLE OF CONTENTS continued
FIGURES
TABLES
EXHIBITS
ii
Panels O1P 02P
Panels 03P 07P
Page
20
20
3
5
14
19
Exhibit 2 Flood Boundary and Floodway Map Index
Flood Boundary and Floodway Map Panels 250167 0001A -0002A
Flood Insurance Rate Map Index
Flood Insurance Rate Map Panels 250167 0001A -0002A
1.0 INTRODUCTION
1.1 Purpose of Study
FLOOD INSURANCE STUDY
The purpose of this Flood Insurance Study is to investigate the
existence and severity of flood hazards in the City of Northampton,
Hampshire County, Massachusetts, and to aid in the administration of
the National Flood Insurance Act of 1968 and the Flood Disaster
Protection Act of 1973. Initial use of this information will be to
convert the City of. Northampton to the regular program of flood
insurance by the Federal Insurance Administration. Further use of
the information will be made by local and regional planners in their
efforts to promote sound land use and flood plain development.
1.2 Coordination
The U.S. Geological Survey and the U.S. Soil Conservation Service
were contacted in order to minimize possible conflicts or duplica-
tion of effort.
On March 10, 1975, a meeting was held with the city officials at the
office of the U.S. Army Corps of Engineers' New England Division,
for the purpose of discussing the status of the study. A brief
discussion was held on the Flood Hazard Boundary Maps.
The final coordination meeting was held on June 16, 1976, to review
the results of this study. The meeting was attended by city officials,
representatives of the Federal Insurance Administration and the U.S.
Army Corps of Engineers, and the public. The study was accepted.
1.3 Authority and Acknowledgments
The source of authority for this Flood Insurance Study is the
National Flood Insurance Act of 1968, as amended.
The hydrologic and hydraulic analyses for this study were performed
by the U.S. Army Corps of Engineers, New England Division, for the
Federal Insurance Administration, under Inter Agency Agreement No.
IAA- H -2 -73, Project Order No. 4 and IAA- H- 16 -75, Project Order
No. 22. This work, which was completed in November 1976, covered all
significant flooding sources affecting the City of Northampton.
2.0 AREA STUDIED
2.1 Scope of Study
This Flood Insurance Study covers the incorporated area of the City
of Northampton, Hampshire County, Massachusetts. The study area is
shown on the Vicinity Map (Figure 1).
Floods caused by the overflow of the Connecticut and Mill Rivers
were studied in detail. Detailed studies were not made for Basset
Brook, Roberts Meadow Brook, Broad Brook, and other minor streams in
the area. Due to the lack of current and planned development or to
the surrounding topography, flooding on these streams was studied by
approximate methods.
The areas studied in detail were chosen with consideration given to
all forecasted development through 1981.
2.2 Community Description
The City of Northampton is primarily a residential and manufacturing
city, located in west central Massachusetts, approximately 90 miles
from Boston and 150 miles from New York City (Reference 1). Bordering
Northampton are the Towns of Easthampton, Westhampton, Williamsburg,
and Hatfield. The city has a total land area of approximately 35
square miles, and a 1970 population of 29,700, or a population density
of approximately 850 persons per square mile.
The terrain is hilly with elevations ranging from 200 feet National
Geodetic Vertical Datum of 1929 (NGVD) along the central section to
800 feet NGVD along the western part of the city. The area along
the Connecticut River on the east is fairly level.
Temperatures in the region range from occasional highs slightly
above 100 F to lows below -20 °F. The annual precipitation averaging
47 inches occurs generally from November through April.
With the completion of the local flood protection project in 1941,
the floodprone areas along the Connecticut River are, in general,
located east of Interstate 91. Along the Mill River outside of the
protected areas, the notable flood plain areas are located in the
lower reaches of the river and in the area bordering North Main and
Spring Streets. Numerous city streets, state and interstate high-
ways, and the Boston Maine Railroad cross the existing flood
plains. Continuing economic development within the study area is
expected, and pressure leading to intensified flood plain use will
undoubtedly accompany such development. Some development along the
low -lying areas of the tributaries can also be expected.
l
2.3 Principal Flood Problems
Floods on the Connecticut River have resulted from excessive rain-
fall alone or in combination with snowmelt runoff (see Figures 2 and
3). Spring rains accompanied by melting snow in March 1936, resulted
in the greatest flood known on the Connecticut River at Northampton.
Another major flood, occurring in September 1938, resulted from a
week of almost continuous rain culminating with heavy rains associated
with an intense hurricane which passed up the basin. The U.S. Army
Corps of Engineers has since constructed an upstream system of nine
flood control reservoirs which will modify future floods in the
area. Recurring March 1936 and September 1938, floods on the Connecticut
River at Northampton, modified by the reservoir system, would have
peak discharges of 187,000 and 148,000 cubic feet per second (cfs),
respectively, compared to experienced flows of 244,000 and 189,000
cfs.
Two major floods have occurrred on the Mill River in recent years.
The flood of September 1938, the maximum flood known on the Mill
River in the Northampton area, was caused by rainfall associated
with an intense hurricane. In August 1955, a peak discharge of 6300
cfs was recorded at the U.S. Geological Survey gaging station in
Northampton. This is the maximum flow on record since establishment
of the gage in October 1938.
2.4 Flood Protection Measures
The U.S. Army Corps of Engineers has completed protective works at
Northampton which include an earth dike approximately 1 mile long,
in the eastern part of the city, affording protection against high
water from the Connecticut River, and an earth dike and concrete
wall approximately 0.5 mile long in the western part of the city
which affords protection against floods on the Mill River and
backwater from the Connecticut River (See Figure 4).
U.S. Army Corps of Engineers' dikes are built to provide a minimum
of 3.0 feet of freeboard, which is the vertical distance from the
design water surface to the top of the dike. Freeboard is provided
to ensure that the degree of protection will not be reduced by
unaccounted factors. These might include the effect of erratic
hydrologic phenomena, future development in the watershed, embank-
ment settlement, trash and debris, and variation of hydraulic
resistance or other coefficients from those assumed in design. The
design or effective height of a dike is, therefore, theoretically
exceeded when the computed water level is within 3 feet of the top
of dike. As shown on Flood Profile Exhibits O1P through 04P, the
computed 500 -year frequency flood level on the Connecticut exceeds
the design or effective height of the dike, somewhat, even though it
is not actually exceeding the top of dike.
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The upstream flood control system completed by the U.S. Army Corps
of Engineers, consisting of nine reservoirs located on upstream
tributaries of the Connecticut River, will have a modifying effect
on future flooding in Northampton as detailed previously in Section
2.3 of this text.
The original plan for flood control in the basin consisted of a
system of dikes in combination with upstream reservoirs. The dikes
and many of the reservoirs have been constructed. It is noted,
though, that although the dikes at Northampton provide a high level
of security, the degree of protection originally planned for is not
provided.
3.0 ENGINEERING METHODS
For flooding sources studied in detail in the community, standard hydrologic
and hydraulic methods were used to determine the flood hazard data required
for this study. Floods having recurrence intervals of 10, 50, 100, and
500 years have been selected as having special significance for flood
plain management and for flood insurance premium rates. The analyses
reported here reflect current conditions in the watersheds of the streams.
3.1 Hydrologic Analyses
Hydrologic analyses were carried out to establish the peak discharge
frequency relationships for floods of the selected recurrence intervals
for each stream studied in detail in the community.
Annual peak discharge- frequency relationships for the Mill River were
derived by statistical analysis of 35 years of discharge records from
the U.S. Geological Survey gaging station on the Mill River at
Northampton. Values of the 10 50 100 and 500 -year peak dis-
charges were obtained from a log- Pearson Type III distribution of
annual peak flow data (Reference 2).
Peak discharge- frequency values for the selected recurrence intervals
for the Connecticut River were also developed using a log- Pearson
Type III distribution of annual peak flow data and then adjusted to
reflect the modifying effect of the system of upstream reservoirs.
This modified frequency data was previously developed and published
in a U.S. Army Corps of Engineers report (Reference 3).
Frequency- discharge, drainage area curves for the Connecticut and
Mill Rivers are shown in Figures 5 and 6. The modifying effect of
the U.S. Army Corps of Engineers' upstream flood control reservoir
system is reflected in the discharges for the Connecticut River.
3.2 Hydraulic Analyses
Analyses of the hydraulic characteristics of streams in the community
were performed to provide estimates of the elevations of floods of
the selected recurrence intervals along each stream studied in detail.
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FIGURE 6
Water- surface elevations of the 100 -year frequency flood on the
Connecticut River and selected cross sections were taken from a
previously published U.S. Army Corps of Engineers' study (Reference 4).
The 100 -year flood on a river is a flood having a magnitude that
might be expected to be exceeded on an average of about once per 100
years, or would have an expected 1 percent chance of exceedance in
any one year. Water surface elevations for the 10 50 and 500
year frequencies were determined by elevation discharge relationships
at selected cross sections within the study segment. Flood profiles
were drawn between computed cross sectional water- surface elevations
to an accuracy of 0.5 foot for floods of the selected recurrence
intervals (Exhibit 1).
For the Mill River, water surface elevations of floods of the 10
50 100 and 500 -year recurrence intervals were computated through
use of the U.S. Army Corps of Engineers' step- backwater computer
program (Reference 5). Cross sections for the backwater analyses for
the Mill River were determined by field surveys and located, in
general, at close intervals above and below bridges and dams in order
to compute representative flood profiles. Locations of selected
cross sections used in the hydraulic analyses are shown on the Flood
Boundary and Floodway Map (Exhibit 2). Flood profiles were drawn
between computed cross sectional water- surface elevations to an
accuracy of 0.5 foot for floods of the selected recurrence intervals
(Exhibit 1).
All elevations are measured from National Geodetic Vertical Datum
(NGVD); elevation reference marks used in the study are shown on the
maps.
Channel roughness factors (Manning's "n for these computations were
assigned on the basis of field inspection of flood plain areas and on
previous studies by the U.S. Army Corps of Engineers. Values of 0.07
were adopted for the overbanks and 0.035 for the channels. Energy
losses due to changes in cross sectional areas of flow were computed
using coefficients of 0.3 and 0.5 for contraction and expansion,
respectively.
The step- backwater computations used to determine flood levels for
the Mill River, in accordance with Federal Insurance Administration
procedures, make no allowances for debris, excessive turbulence, or
river bends which might effect flood levels experienced during a
major flood. It is, therefore, concluded that the computed profiles
represent minimum levels that might be expected under conditions of
the various magnitudes of flow. The selection of "Manning's" coeffi-
cients for both the Mill and Connecticut Rivers was based largely on
the calibration of the backwater model against experienced flood
levels and known stage- discharge ratings.
Flooding on Basset Brook, Roberts Meadow Brook, Broad Brook, and
other minor streams was approximated using information received from
local sources, field inspection, and normal depth analysis.
4.0 FLOOD PLAIN MANAGEMENT APPLICATION
4.1 Flood Boundaries
A prime purpose of the National Flood Insurance Program is to encourage
state and local governments to adopt sound flood plain management programs.
Each Flood Insurance Study, therefore, includes a flood boundary map
designed to assist communities in developing sound flood plain management
measures.
In order to provide.a national standard without regional discrimina-
tion, the 100 -year flood has been adopted by the Federal Insurance
Administration as the base flood for purposes of flood plain management
measures. The 500 -year flood is employed to indicate additional
areas of flood risk in the community.
For both the Connecticut and Mill Rivers, the boundaries of the 100
year and the 500 -year flood have been delineated using elevations
determined at each cross section; between cross sections, the bound-
aries were interpolated using topographic maps at a scale of 1:6000,
with a countour interval of 5 feet (Reference 6). In cases where the
100- and 500 -year flood boundaries are close together, only the 100
year flood boundary has been shown.
For streams studied by approximate methods, the boundary of the 100
year flood was delineated using the town topographic maps (Reference 6).
Small areas within the flood boundaries may lie above the flood
elevations and, therefore, not be subject to flooding; owing to
limitations of the map scale, such areas are not shown.
4.2 Floodways
Encroachment on flood plains, such as artificial fill, reduces the
flood carrying capacity and increases flood heights, thus increasing
flood hazards in areas beyond the encroachment itself. One aspect of
flood plain management involves balancing the economic gain from
flood plain development against the resulting increase in the flood
hazard. For purposes of the Flood Insurance Program, the concept of
a floodway is used as a tool to assist local communities in this
aspect of flood plain management. Under this concept, the area of
the 100 -year flood is divided into a floodway and floodway fringe.
The floodway is the channel of a stream, plus any adjacent flood
plain areas, that must be kept free of encroachment in order that the
100 -year flood be carried without substantial increases in flood
height. As minimum standards, the Federal Insurance Administration
limits such increases in flood heights to 1.0 foot, provided that
hazardous velocities are not produced.
12
The floodway for the Connecticut River was computed on the basis of
a fixed top width as outlined in the HEC -2 Water- Surface Profiles
users manual (Reference 7). The 100 -year flood could, in general,
be conveyed in a 3000 -foot floodway without raising levels more than
1.0 foot.
The floodway for the Mill River was computed on the basis of a fixed
top width with the left and right encroachment stations made equidis-
tant from the centerline of the channel. Below the U.S. Army Corps
of Engineers' local protection project drop structure, the width of
the floodway varies from 500 to 800 feet and follows the existing
Mill River course to the Oxbow and then continues along the southerly
course of the Oxbow to the junction with the Connecticut River.
Above the drop structure, the 100 -year flood could, in general, be
conveyed in a 150 -foot floodway while adhering to the Federal Insurance
Administration criteria.
Results of the floodway computations are tabulated at selected cross
sections for the Connecticut and Mill Rivers in Table 1. As shown
on the Flood Boundary and Floodway Map, the floodway boundaries were
determined at cross sections; between cross sections, the boundaries
were interpolated using topographic maps (Reference 6). In cases
where the floodway and 100 -year flood boundaries coincide, only the
floodway is shown.
Floodway data contained in the table include information which
treats the entire width of the Connecticut River; however, floodway
delineation on•the maps only shows the floodway on the Northampton
side of the river.
The area between the floodway and the boundary of the 100 -year flood
is termed the floodway fringe. The floodway fringe thus encompasses
the portion of the flood plain that could be completely obstructed
without increasing the water- surface elevation of the 100 -year flood
more than 1.0 foot at any point. Typical relationships between the
floodway and the floodway fringe and their significance to flood
plain development are shown in Figure 7.
BASE FLOOD
WATER SURFACE ELEVATION
O co CO O l O l
O O O O O
H o o o o d' M o d' O CO d' Ln O O d' O u)
O O O O H O O O O r-1 O O O H O O O O
WITHOUT
FLOODWAY
(FEET NGVD)
co M w O O
N M d' In Ln
N N N N N
H H H r-I 1--I
CO O O O Ln O Ol i Ol In co Ol m O C` H H Ol
N M M M l0 o O M M CO d' 0 0 In IO dl r-1 N
N N N N N M M M M d' N Ol Ol r-I N M d' d'
r-I H 1-1 H H r-1 r-1 r-1 r-I r 1 rl r-I r-1 N N N N N
C O 0 d' O l N
N CO Ill I) 0
N N N N N
H r-I H ri H
O1 O O 0 11) d' N r-I M II) lO M d' O N IC1 r-1 d'
N CO CO CO N. O r-I M d' Ol Ln H H LO If) Ol r-I M
N N N N N CO M M CO d' N. Ol Ol r-I N M d' d'
H H H H H H H H H H H H H N N N N N
FLOODWAY
MEAN
VELOCITY
(FEET R
SE PER
Ol dr LO 1 l0
N M M M N
IO d' M N CO Ol 0 O l0 N O In M dl Ol N
0 O H r-1 lO N N 0 0 d' M CO 0 r-1 d' 1. CO 01
H r-1 H H
(ZSH
axvnZs
vaaV
NOLLOHS
0 0 0 0 0
0 0 0 0 0
d' d' d' Ol O
N Ol N CO 00
0 In Ln d 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 O r-1 CO 0 LC) M N CO O N In d' O In O
co Ln t.n M CO Il) Ill l0 N dr. N M r 01 N ("n N r
CO LC) r-I CO H H H H r-1 CO H r-I 1-1 r-1 r-I
N N r-1
WIDTH
(FEET)
N N N N N N
0 0 0 0 0
00000
000C d'
M CO Cr) H N
N N
O O O O O In Ill I.n 0 0 0 0 0 0 Ill O LO O
0 0 0 0 In d' In M Ill If) d' M M N N If) N O
CO CC Ill In r-I r-1 r-1 r-1 r-1 M r-1 ri r-I r-1 r-1 r-I rl r1
FLOODING SOURCE
DISTANCE
0 0 0
rH Ln r 1� H
M d N I 01
ma) Ol Ol Ol
CO M
0 0 0 O N N 0 N N In N 0 CO N 0 CO O d'
H M I� d' U) r-1 r-♦ N d' N d' 0 0 1� Ol Ol O N
H O O H H N N N N M d' d' d' In CO In w l0
1 1
CROSS SECTION
Urt+WUQw
0
IA
z
0
U
g4 ploQwwc.9xHhazoaota4
1-4 1---A
H
m
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0
N
P�
m
rd
N
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rj
m
r4
E
N
TABLE 1
CONNECTICUT RIVER-MILL RIVER
FLOODWAY DATA
0
a1
0
m
a)
W
W
UJ
0 G
M
o wet
a c
z
C O
o
1
o O
z
1-
c
Q
W
TABLE 1
FLOODWAY DATA
l0 0 o to
0 0
BASE FLOOD
WATER SURFACE ELE
WITHOUT
FLOODWAY
;FEET NGVD)
o co l0 61
In r
0 i n
d 01 N m
N N O1 M
■0 CO l0 szr
tr1 O M l0
cr 01 N CO
N N M M
FLOODWAY
MEAN
VELOCITY
(FEET
l0 N N N
V u1 l0 CO
-4
SECTION
AREA
(SQUARE
FEET)
O O O O
N N M r-I
CO l0 CO N
N rl H
WIDTH
(FEET)
O O O O
1.11 O to CO
r r1 H H
FLOODING SOURCE
DISTANCE
LO rl CO cr
N N CO N
l0 CO CO OD
CROSS SECTION
124 r0
W a)
a•i
a
H o
U1
0
a1
0
m
a)
W
W
UJ
0 G
M
o wet
a c
z
C O
o
1
o O
z
1-
c
Q
W
TABLE 1
FLOODWAY DATA
t FLOODWAY
FRINGE
5.0 INSURANCE APPLICATION
5.1 Reach Determinations
FLOOD ELEVATION WHEN
CONFINED WITHIN FLOODWAY
100 -YEAR FLOOD PLAIN
FLOODWAY
STREAM
-4- CHANNEL' -111.
ENCROACHMENT
AREA OF FLOOD PLAIN THAT COULD
BE USED FOR DEVELOPMENT BY
RAISING GROUND
16
SURCHARGE'
Figure 7. Floodway Schematic
FLOODWAY
FRINGE
ENCROACHMENT
FLOOD ELEVATION
BEFORE ENCROACHMENT
ON FLOOD PLAIN
LINE AB IS THE FLOOD ELEVATION BEFORE ENCROACHMENT.
LINE CD IS THE FLOOD ELEVATION AFTER ENCROACHMENT.
'SURCHARGE IS NOT TO EXCEED 1.0 FOOT (FIA REQUIREMENT) OR LESSER AMOUNT IF SPECIFIED BY STATE.
In order to establish actuarial insurance rates, the Federal Insurance
Administration has developed a process to transform the data from the
engineering study into flood insurance criteria. This process includes
the determination of reaches, Flood Hazard Factors, and flood insurance
zone designations for each flooding source studied in detail affecting the
City of Northampton.
Reaches are defined as lengths of watercourses having relatively the
same flood hazard, based on the average weighted difference in water
surface elevations between the 10- and 100 -year floods. This dif-
ference does not have a variation greater than that indicated in the
following table for more than 20 percent of the reach.
rTh
Average Difference Between
10- and 100 -year Floods Variation
2 to 7 feet 1.0 foot
The Connecticut River was considered to be one reach.
Two reaches meeting the above criterion were required for the Mill
River. Locations of the reaches for both the Connecticut and Mill
Rivers are shown on the Flood Profiles (Exhibit 1).
5.2 Flood Hazard Factors
The Flood Hazard Factor (FHF) is the Federal Insurance Administration
device used to correlate flood information with insurance rate
tables. Correlations between property damage from floods and their
FHF are used to set actuarial insurance premium rate tables based on
FHFs from 005 to 200.
The FHF for a reach is the average weighted difference between the
10- and 100 -year flood water surface elevations expressed to the
nearest one -half foot, and shown as a three -digit code. For example,
if the difference between water surface elevations of the 10- and
100 -year floods is 0.7 foot, the FHF is 005; if the difference is
1.4 feet, the FHF is 015; if the difference is 5.0 feet, the FHF is
050. When the difference between the 10- and 100 -year water surface
elevations is greater than 10.0 feet, accuracy for the FHF is to the
nearest foot.
5.3 Flood Insurance Zones
After the determination of reaches and their respective Flood Hazard
Factors, the entire incorpoated area of the City. of Northampton was
divided into zones, each having a specific flood potential or hazard.
Each zone was assigned one of the following flood insurance zone
designations:
Zone A:
Zones A7, Al2, and A13:
17
Special Flood Hazard Areas inundated by
the 100 -year flood, determined by
approximate methods, no base flood
elevations shown or Flood Hazard Factors
determined.
Special Flood Hazard Areas inundated by
the 100 -year flood, determined by
detailed methods; base flood elevations
shown, and zones subdivided according
to Flood Hazard Factors.
Zone B:
Zone C:
Table 2, "Flood Insurance
differences, Flood Hazard
flood elevations for each
community.
5.4 Flood Insurance Rate Map Description
6.0 OTHER STUDIES
Areas between the Special Flood Hazard
Area and the limits of the 500 -year
flood, including areas of the 500 -year
flood plain that are protected from the
100 -year flood by dike, levee, or other
water control structure; or, areas
subject to certain types of 100 -year
shallow flooding where depths are less
than 1.0 foot. Zone B is not subdivided.
Areas of minimal flooding.
Zone Data," summarizes the flood elevation
Factors, flood insurance zones, and base
flooding source studied in detail in the
The Flood Insurance Rate Map for the City of Northampton is, for
insurance purposes, the principal result of the Flood Insurance
Study. This map (published separately) contains the official
delineation of flood insurance zones and base flood elevation
lines. Base flood elevation lines show the locations of the expected
whole -foot water- surface elevations of the base (100 -year) flood.
This map is developed in accordance with the latest flood insurance
map preparation guidelines published by the Federal Insurance
Administration.
An alternative flood management plan developed by the U.S. Soil Conserva -tion
Service is contained in a report entitled, An Analysis of Alternative
Flood Management Plans in Upstream Watersheds (Reference 8). The report
outlines nonstructural plans such as flood plain delineation, flood
proofing, land use regulations, flood insurance, flood warning and
evacuation plans as methods of providing substantial reduction in flood
damages to existing properties in the Mill River watershed.
Incorporated into this study were data published previously by the U.S.
Army Corps of Engineers in the reports entitled Connecticut River Basin
Program, Supplemental Flood Management Study (Reference 3) and
Connecticut River Basin Comprehensive Water and Related Land Resources
Investigation (Reference 4).
18
1 Flood Insurance Rate Map Panel 2 Weighted Average 3 Rounded to Nearest Foot
FLOOD INSURANCE ZONE DATA
CONNECTICUT RIVER -MILL RIVER
BASE FLOOD
ELEVATION 3
(FEET NGVD)
al al a
ni oz) rd
a) a) a)
a) a)
0) co 0
1 I
in m m
a) a) a)
ro I'd It
aNOZ
f`'1 N
H H N
FLOOD
HAZARD
FACTOR
Lfl O Ln
LID lfl Cr)
O O O
ELEVATION DIFFERENCE
BETWEEN 1% (100 -YEAR) FLOOD AND
H Cr) l0
N H H
in da N
2%
(50 -YEAR)
O 00 O
O L tf)
4 II
N H H
I I I
L— O M
Ln 00 l9
Lo LO m
I I I
DEPARTMENT OF HOUSING AND URBAN DEVELOPMENT
Federal Insurance Administration
CITY OF NORTHAMPTON MA
(HAMPSHIRE CO.)
v
I 'IENVd
N
0
O
N N O
O 0
O O H
O O O
0
0
FLOODING SOURCE
1:4
H
a a
H W H N
U U 0.S 0 0
H [0 rd Ed
�a aaa
W H
Z
0
U
TABLE 2 I
This study is authoritative for purposes of the Flood Insurance Program;
data presented here supersede all previous determinations.
7.0 LOCATION OF DATA
Survey, hydrologic, hydraulic, and other pertinent data used in this
study are on file through 1981 at the Office of the U.S. Army Corps of
Engineers, New England Division, 424 Trapelo Road, Waltham, Massachusetts
02154.
8.0 BIBLIOGRAPHY AND REFERENCES
1. Department of Commerce and Development, Monograph, City of Northampton,
Massachusetts, March 1972
2. Water Resources Council, "A Uniform Technique for Determining Flood
Flow Frequencies," Bulletin 15, December 1967
3. U.S. Army Corps of Engineers, Connecticut River Basin Program,
Supplemental Flood Management Study, July 1974
4. Connecticut River Basin Comprehensive Water and
Related Land Resources Investigation, June 1970
5. Hydrologic Engineering Center, HEC -2 Water Surface
Profiles, Generalized Computer Program, Davis, California, October
1973
6. City of Northampton, Topographic Maps, Scale 1:6000, Contour Interval
5 feet: Northampton, Massachusetts (1965)
7. U.S. Army Corps of Engineers, HEC -2 Water Surface Profiles, User's
Manual, October 1973
8. U.S. Department of Agriculture, Soil Conservation Service, An Analysis
of Alternative Flood Management Plans in Upstream Watersheds, June
1975
U.S. Geological Survey, Map of Flood Prone Areas, Scale 1:24,000,
Mt. Holyoke, Massachusetts, and Easthampton, Massachusetts, 1969
U.S. Army Corps of Engineers, Survey Sections Of Mill River, July
1974
U.S. Department of Housing and Urban Development, Federal Insurance
Administration, Special Flood Hazard Areas, Northampton, Massachusetts,
Hampshire County, May 1974
20
U.S. Geological Survey, 7.5- Minute Series Topographic Maps, Scale
1:24,000, Contour Interval 5 feet: Easthampton, Massachusetts,
(1964); Mt. Holyoke, Massachusetts (1964)
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CROSS SECTION
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