Fgm l. 29?: ZSQHI INSURANCE‘ S" 5 T U D Y 1 TOWN OF BUCKLAND, MASSACHUSETTS FRANKLIN coumv NOVEMBER 1979 FEDERAL EMERGENCY MANAGEMENT AGENCY FEDERAL INSURANCE ADMINISTRATION COMMUNITY NUMBER — 250111 1.0 2.0 3.0 4.0 5.0 TABLE OF CONTENTS INTRODUCTION 1.1 Purpose of Study 1.2 Authority and Acknowledgements 1.3 Coordination AREA STUDIED 2.1 Scope of Study 2.2 Community Description 2.3 Principal Flood Problems 2.4 Flood Protection Measures ENGINEERING METHODS 3.1 Hydrologic Analyses 3. 2 Hydraulic Analyses FLOOD PLAIN MANAGEMENT APPLICATIONS 4. 1 Flood Boundaries 4. 2 Floodways INSURANCE APPLICATION 5.1 Reach Determinations 5.2 Flood Hazard Factors 5.3 Flood Insurance Zones 5.4 Flood Insurance Rate Map Description 10 10 11 15 15 15 15 16 TABLE OF CONTENTS — continued Page 6.0 OTHER STUDIES 16 7.0 LOCATION OF DATA 18 8.0 REFERENCES AND BIBLIOGRAPHY 18 FIGURES Figure 1 — Vicinity Map 3 Figure 2 - Future flood height, State Route 2 crossing of Deerfield River 6 Figure 3 — Future flood height, Ashfield Road crossing of Clesson Brook. 6 Figure 4 ~ Floodway Schematic 14 TABLES Table 1 - Summary of Discharges 9 Tabl.e 2 — Floodway Data 12 Table 3 - Flood Insurance Zone Data 17 EXHIBITS Exhibit 1 — Flood Profiles Deerfield River Clesson Brook Exhibit 2 - Flood Boundary and Floodway Map Index Flood Boundary and Floodway Map PUBLISHED SEPARATELY: Flood Insurance Rate Map Index Flood Insurance Rate Map Panels DIP - 03P Panels 04P - 0GP 1.0 FLOOD INSURANCE STUDY TOWN OF BUCKLAND, FRANKLIN COUNTY, MASSACHUSETTS INTRODUCTION 1.1 1.2 1.3 Purpose of Study This Flood Insurance Study investigates the existence and severity of flood hazards in the Town of Buckland, Franklin County, Massachusetts, and aids in the administration of the National Flood Insurance Act of 1968 and the Flood Disaster Protection Act of 1973. This study will be used to convert the Town of Buckland to the regular program of flood insurance by the Federal Insurance Administration (FIA). Local and regional planners will use this study in their efforts to promote sound flood plain management. In some states or communities, flood plain management criteria or regulations may exist that are more restrictive or comprehensive than those on which these Federally-supported studies are based. These criteria take precedence over the minimum Federal criteria for purposes of regulating development in the flood plain, as set forth in the Code of Federal Regulations at Z4 CFR, 1910.1 (d). In such cases, however, it shall be understood that the state (or other jurisdictional agency) shall be able to explain these requirements and criteria. Authority and Acknowledgements The source of authority for this Flood Insurance Study is the National Flood Insurance Act of 1968 and the Flood Disaster Protection Act of 1973. The hydrologic and hydraulic analyses for this study were performed by Anderson-Nichols 6c Company, Inc. for the Federal Insurance Administra- tion under Contract No. H—4524. This study was completed in August 1978. Coordination Streams requiring detailed study were selected in a meeting attended by representatives of the FIA, Anderson-Nichols 6c Company, Inc., and officials of the Town of Buckland in November 1977. The New England Basins Commission, the U.S. Geological Survey (USGS); the U.S. Department of Agriculture, Soil Conservation Service (SCS); the 2.0 AREA 2.1 Massachusetts Department of Water Resources, Public Works, Commerce and Development, and Highways; and the New England Power Company were all contacted for pertinent information. During the course of work by Anderson-Nichols, specific information on peak discharge-frequency relationships, flood control channel and dam improve- ments, previous flood hazard evaluations, recent and potential flood plain development, and the extent of historical flooding were obtained, reviewed, and discussed with various community and state officials and local residents. An intermediate coordination meeting was held on September 6, 1978, where the initial results prepared by Anderson-Nichols were presented to town officials. On May l, 1979, the draft of this report and associated maps were reviewed at a final coordination meeting attended by personnel from the FIA, officials of the community of Buckland, and representatives of Anderson-Nichols. The study was acceptable to the community. STU DIED Scope of Study This Flood Insurance Study covers the incorporated area of the Town of Buckland. The area of study is shown on the Vicinity Map (Figure 1). The areas studied by detailed methods were selected with priority given to all known flood hazard areas, and areas of projected development or proposed construction for the next five years, through August 1983. Approximate methods of analysis were used to study those areas having a low development potential or minimal flood hazards. The scope and methods of study were proposed to and agreed upon by the FIA and the Town of Buckland. Flooding caused by the overflow of the Deerfield River and Clesson Brook was studied in detail. The Deerfield River was studied from the New England Power Company Dam No. 3 to a point 50 feet upstream from State Route 2; and from the New England Power Company Dam No. 4 to the Charlemont town line. Clesson Brook was studied from its confluence with the Deerfield River to Ashfield Road near the southernmost intersection of Upper Road. Although originally selected for detailed study, Bray Brook was examined by approximate methods because it did not meet FIA topwidth criteria for detailed study streams, which states that the 100-year flood plain topwidth should be greater than 200 feet in developed areas. Portions of the Deerfield River, Clesson Brook, Tributaries B and D, Shepherd Brook, Ruddock Brook, Upper Branch Maynard Brook, and other unnamed streams and swampy areas were also studied by approximate methods. Studies were .22 >:z_2> I: 52.2.5 1 p E <2 25:2: “E 23E. R Th Llli j w _ wwflz up w w o v ===2§=__= 2=§=w= S» 2 I . . F w._em2=5 .255‘ 2% Q’ 1 t . _ p _ O \ \ O ~ 1 ifi z GUWT _. \ Kn 0G _ o _ 1/ z: D . Q \ i a / I _ m 1 Y O Q \ U 5/ J I \~\ . \\. . on .. 4 P19) fi o fl- y _ / h? p v Q @ .. a , 7 . 2 n ._._ _ ‘ ., . 1 , M . . ,1 1. \ . A . \ \ / O _ _0 m I o s V \ 0 o , p 1., \ 1 uwm 0 .. 0 QQ ‘l 0 . A .2 \ _.» .9 , v . m . . h. a a Q .\ . . .; 1 . . 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O _\ 4b 1 O\ nwwb 1 a , \ \ o v Q .. \ w. _@ /~@ D E . o o , a / _ = . ... Q ._ ._ _ o _ m i \ _ . p a O/Q\\1 a 0 a. 4 0 \1. ¢ o 0.. §1_ . OA. g \ , . a / a - . o a 0o .. A . _ u \ Q 1/ , . a fieb a 0 I o u G ~. O 2.2 generally terminated where the 100-year flood plain was less than 200 feet. Tributary E was studied by the approximate method, but because the 100- year flood plain was less than 200 feet, this area is considered a minimal flood area. Community Description The Town of Buckland occupies 19.9 square miles in the west-central part of Franklin County in northwestern Massachusetts. It is located approximately 10 miles northwest of Greenfield and 46 miles northeast of Pittsfield. Buckland is bordered by Charlemont to the north, Conway and Shelburne to the east, Ashfield to the south, and Hawley to the west. The 1976 population was 1,890, giving a population density of about 95 persons per square mile. The population has remained essentially constant since the 1970 census (Reference 1). The economy of Buckland is based upon dairying, fruit growing, and retail trade. Buckland is located along the scenic Mohawk Trail, and thus has excellent possibilities for development as both a summer and winter recreation center (Reference 1). The climate of the region is characterized by widely ranging temperatures and generally uniform precipitation. The average temperature of the area is approximately 45 degrees Fahrenheit (F.) with January temperatures averaging 23 degrees F. and July temperatures averaging 70 degrees F. (Reference 1). Three major types of storms bring precipitation to northwestern Massachusetts. Continental storms f'rom the west continually move across the region. These low pressure systems may be either fast- moving intense storms or slow—moving frontal systems. Coastal storms moving into New England from the south constitute a second type. Hurricanes reaching Massachusetts in the late summer or early fall are the most severe of these coastal storms. Finally, local convective action induces thunderstorms on warm, humid summer days, causing locally heavy rainfall. The average annual precipitation is 47 inches (Reference 1). Buckland is located on mountainous terrain with ice—shaped bedrock hills and a narrow level plain of deep sand and gravel along the Deerfield River. The geomorphology of Buckland indicates the influence of glacial and riverine forces (Reference 2). Two major soil associations are found in Buckland. The foothills in the central section of the town contain well-drained and somewhat excessively drained sandy and gravelly soil, characteristic of the Berkshire Mountains, and the remaining areas contain shallow and deep, well-drained and moderately well-drained soils with a dull brown or olive subsoil, character- istic of the Connecticut River Valley (Reference 3). Elevations range from approximately 410 feet at the Deerfield River to 1,618 feet at the summit of Snow Mountain, the highest point in the town. ' Vegetative cover is found mainly in wooded areas. The tree stands consist of broad leaf species of sugar maple, red maple, yellow birch, white birch, black birch, beech, white ash, and red oak interspersed with coniferous species of white pine and hemlock (Reference 3). 2.3 2.4 The principal watercourse in the Town of Buckland is the Deerfield River, which originates in Stratton, Vermont, and follows a winding couse in a southerly direction for about 30 miles to the Vermont—Massachusetts state line. It continues about 7 miles into Massachusetts and then turns and follows a meandering but generally easterly couse for about 36 miles to its confluence with the Connecticut River. The river forms the corporate boundary between Buckland and Charlemont for 5.6 miles and between Buckland and Shelburne for 3.6 miles. The river has a total fall of about 2,900 feet, including 1,100 feet in its upper 7 miles. Numerous tributaries feed the Deerfield River throughout its course to the Connecticut River, the more important including the Cold, Chickley, North, and Green Rivers. The Deerfield River drainage area totals 664 square miles, 317 square miles lying in Vermont and 347 square miles in Massachusetts. The drainage area contributing to the study area is 498 square miles above the Shelburne Falls Dam (Reference 3). Clesson Brook originates at Cox Pond in Hawley, Massachusetts, and flows in a northeasterly direction until it empties into the Deerfield River. Its total drainage area is 21.3 square miles. Development in Buckland is concentrated in the Shelburne Falls area, particularly the area enclosed within the borders of Bray Road, Sears Street, and the Mohawk Trail. Minor residential and commercial development has occurred within the 100-year flood plain along the Deerfield River. Principal Flood Problems The major floods in Buckland have resulted from rainfall or rain combined with snowmelt. The flood records at gages on the Deerfield River reveal the history of flooding in the town. Upstream from Buckland, at the USGS gage in Charlemont on the Deerfield River, the September 1938 flood is the flood of record. A discharge of 46,300 cubic feet per second (cfs) was recorded for this flood. The estimated return period for this flood is approximately 100 years. The gage, operated since 1914, also recorded major floods in July 1915, March 1921, November 1927, March 1936, and December 1949. The discharges associated with these events were 38,200 cfs, 32,400 cfs, 36,000 cfs, 32,200‘cfs, and 42,600 cfs, respectively. The estimated return periods for these floods are 39 years, 25 years, 33 years, 25 years, and 50 years, respectively. A second t USGS gage on the Deerfield River is located downstream from Buckland near West Deerfield. The gage in West Deerfield began operation in 1941. The larger floods measured occurred in December 1949, June 1951, October 1956, and December 1974, with the 1949 flood being the flood of record. The discharges associated with these events are 48,500 cfs, 34,800 cfs, 43,700 cfs, and 32,200 cfs, respectively. The estimated return periods for these floods are 65 years, 20 years, 44 years and 15 years, respectively. Figures 2 and 3 show future flood heights on the Deerfield River and Clesson Brook. Flood Protection Measures The Town of Buckland has no flood control structures. Some flood attenuation occurs in Buckland as a result of the hydro-power facilities FIGURE 2 — Future flood height, State Route 2 crossing of Deerfield River upstream of New England Power Company Dam No. 4. mmfluon 1. “ FIGURE 3 - Future flood height, Ashfield Road crossing of Clesson Brook near Cross Street. 3.0 located at the Harriman and Somerset Reservoirs in the upstream reaches of the Deerfield River. There are several dams on the Deerfield River above and within the Town of Buckland controlled by the New England Power Company, including the Shelburne Falls Dam and New England Power Company Dam No. 4, but they offer minimal flood protection. Flashboards on these dams are designed to fail when the river reaches flood stage. The Town of Buckland has no formal flood protection or emergency evacuation plans. ENGINEERING METHODS For the flooding sources studied in detail in the community, standard hydrologic and hydraulic study methods were used to determine the flood hazard data required for this study. Flood events of a magnitude which are expected to be equalled or exceeded once on the average duri.ng any 10-, 50-, 100-, or 500—year period (recurrence interval), have been selected as having special significance for flood plain management and for flood insurance premium rates. These events, commonly ‘termed the 10-, 50-, 100-, and 500—year floods, have a 10, 2, 1, and 0.2 percent chance, respectively, of being equalled or exceeded during any year. Although the recurrence interval represents the long term average period between floods of a specific magnitude, rare floods could occur at short intervals or even within the same year. The risk of experiencing a rare flood increases when periods greater than one year are considered. For example, the risk of having a flood which equals or exceeds the 100-year flood (one percent chance of annual occurrence) in any 50- year period is about 40 percent (four in ten), and for any 90-year period, the risk increases to about 60 percent (six in ten). The analyses reported here reflect flooding potentials based on conditions existing in the community at the time of completion of this study. Maps and flood elevations will be amended periodically to reflect future changes. 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 flooding source studied in detail affecting the community. A statistical analysis of gage data was used to develop the 10-, 50-, 100-, and 500—year peak flows at the USGS gage no. 01170000 on the Deerfield River near West Deerfield, Massachusetts (37 years of record), and USGS gage no. 01168500 on the Deerfield River in Charlemont, Massachusetts (51 years of record). The shorter term Deerfield gage record was extended using a regression analysis with the longer term record at the Charlemont gage. The flood flow frequency analysis followed the standard log—Pearson Type III distribution (Reference 4). Discharges for individual stream stations were calculated by transposing the gage-based peak flows according to the formula: 3.2 where Q, Qg are the discharges at the station and the gage, respectively; and A, Ag are the drainage areas at these locations (Reference 5). 3—g z 0.75 Final peak discharges were based on a weighted average of equivalent years of record between the two gages. Because Buckland has no flood control structures, no hydrologic routings were performed. Discharges for Clesson Brook were derived using regional discharge- frequency equations (Reference 6) and adjusted by weighted averages with USGS stream gage no. 01165300 on Moss Brook (59 years of record). The regional equations relate topographical and precipitation characteristics to streamflows. The Moss Brook gaging station was chosen from a nearby basin because of similar hydrologic characteristics. No flood discharges for areas of approximate study were developed in this study. Peak discharges for the 10-, 50-, 100-, and 500—year floods of each flooding source studied in detail in the community are shown in Table 1. Hydraulic Analyses Analyses of the hydraulic characteristics of the streams in the community are carried out to provide estimates of the elevations of the floods of the selected recurrence intervals along each flooding source studied in detail. Overbank and channel cross sections were obtained by field survey (Reference 7). Bridge plans were used to obtain elevation data and structural geometry for bridges over the stream studied in detail. Bridges were surveyed where plans were unavailable or out of date. Cross sections for the backwater analyses of the detailed study stream were located at close intervals above and below bridges in order to compute the significant backwater effects of these structures in the developed areas. In long reaches between structures, appropriate valley cross sections were also surveyed. Locations of selected cross sections used in the hydraulic analyses are shown on the Flood Profiles (Exhibit 1). For stream segments for which a floodway was computed (Section 4.2), selected cross section locations are also shown on the Flood Boundary and Floodway Map (Exhibit 2). Roughness coefficients (Manning's "n") for the streams were estimated by field inspection at each cross section. Coefficients for the Deerfield River ranged from 0.045 to 0.05 for the channel and from 0.08 to 0.1 for the overbanks. For Clesson Brook, coefficients ranged from 0.03 to 0.04 for the channel and from 0.06 to 0.08 for the overbanks. =>».~ ¢N~.m @»m.m ¢H¢“>w @H@.m@ m~@.¢@ m“H @¢@.N ¢wN.N ¢m¢.mm @m¢.>@ ¢@@.~@ m> QOCQDFwCOO w< moomm zowwmqo 2E2 wfifiomhoo Emwbwm: 3» w .02 EwQ .00 Lwzom wcfiwcm >52 3w m .02 Ema .00 530m wcfiwcm 262 ~< mmfim mqfimmmmo ZOEQOOQ QZ< momsom 0250012 4.0 Starting water-surface elevations for the Deerfield River were taken from stage-discharge rating curves developed at the Shelburne Falls Dam and New England Power Company Dam No. 4 in Buckland. Starting water—surface elevations for Clesson Brook were determined through normal depth analysis. Water—surface elevations of floods of the selected recurrence intervals were computed for the stream in the study area through use of the U.S. Army Corps of Engineers (COE) HEC—2 step-backwater computer program (Reference 8). Flood profiles were developed showing computed water-surface elevations to an accuracy of 0.5 foot for floods of the selected recurrence intervals (Exhibit 1). The information shown on the Flood Hazard Boundary Maps has been deemed adequate for areas of approximate study with the exception of the delineation of Clesson Brook (Reference 9). Topwidths determined in this report show the 100—year delineation for Clesson Brook to be confined by State Route 112. Adjustments to the Flood Hazard Boundary Map delineation upstream of the detailed study limit are necessary. The hydraulic analyses for this study are based only on the effects of unobstructed flow. The flood elevations as shown on the profiles are, therefore, considered valid only if hydraulic structures, in general, remain unobstructed and if channel and overbank conditions remain essentially the same as ascertained during this study. All elevations are referenced from National Geodetic Vertical Datum of 1929 (NGVD); elevation reference marks used in the study are shown on the maps. FLOOD PLAIN MANAGEMENT APPLICATIONS The National Flood Insurance Program encourages state and local governments to adopt sound flood plain management programs. Therefore, each Flood Insurance Study includes a flood boundary map designed to assist communities in developing sound flood plain management measures. 4.1 Flood Boundaries In order to provide a national standard without regional discrimination, the IOU-year flood has been adopted by the FIA as the base flood for purposes of flood plain management measures. The BOO-year flood is employed to indicate additional areas of flood risk in the community. For each stream studied in detail, the boundaries of the 100-year and the 500—year floods have been delineated using the elevations determined at each cross section; between cross sections the boundaries were interpolated using topographic maps at a scale of b24000, with a contour interval of 10 feet (Reference 10). Approximate 100-year boundaries are delineated on the Flood Hazard Boundary Map for the Town of Buckland (Reference 9). 10 4.2 , The boundaries of the 100-year and 500—year floods are shown on the Flood Boundary and Floodway Map (Exhibit 2). Small areas within the flood boundaries may lie above the flood elevations, and, therefore, not be subject to flooding; owing to lack of detailed topographical information or to limitations of the map scale, such areas are not shown. In cases where the 100—year and the 500-year flood boundaries are close together, only the 100- year boundary has been shown. Certain areas shown on the Flood Hazard Boundary Map (Reference 9 ) were determined to be areas of minimal flooding and, as such, have not been included on the Flood Boundary and Floodway Map and the Flood Insurance Rate Map. Floodways Encroachment on flood plains, such as artificial fill, reduces the flood- carrying capacity, increases the flood heights of streams, and increases 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 flood hazard. For purposes of the National 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 a 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 may be carried without substantial increases in flood heights. Minimum standards of the FIA limit such increases in flood heights to 1.0 foot, provided that hazardous velocities are not produced. The floodways presented in this study were computed using Method 1 and Method 6 encroachment analyses of the COE HEC-2 computer program (Reference 8). No encroachment was attempted for cross sections at bridges. Encroachment limits were based on equal conveyance reduction which would produce a surcharge in water surface related to a corresponding maximum 1.0-foot surcharge in energy grade line or water-surface elevation. Because of the effects of downstream encroachment on energy grade line and water-surface elevations upstream, there may be numerous cross sections where minimal encroachment can be permitted without elevation increases of more than 1.0 foot. This "domino" effect, therefore, imposes an additional constraint on flood plain encroachment. The results of these computations were tabulated at selected cross sections for each stream segment for which a floodway was computed (Table 2). The floodway analysis includes both sides of a stream. Thus, a portion of the floodway of the Deerfield River lies outside of the corporate limit of Buckland. 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O 0.0 0N0¢ 0. 8.. 0N0¢ T0 0mm m0 mwmd 0 50 0.05» ~35. v.m0¢ _..¢ 0mm 00w 0mN.0 < x0000 zowwmju Fwm": ~0>0Z0 .Q>0Z. AO>02. Admmfiwwk Em“. .600 Chm“: ><>>QOO4m 02300041 >._._UO|_m> > q muz<._.w_n zoiuww wwomo wm> PDOI.P_>> >IOP<4D0wE zmJw wo> D0040 mm<>>QOO|E wumaow 02500.7. Under certain flow conditions, as the cross sectional flow area is reduced, the local effect is to lower the water-surface elevation and increase velocity. The water-surface elevation drops because potential energy is converted to kinetic energy to accelerate the flow through the restricted section. Though the local effect of such an encroachment is a reduction of water-surface elevation, the increased velocity usually results in an increase in water-surface elevation at some point upstream. If further encroachment were allowed at the restricted section, the water-surface would continue to drop and the velocity would continue to increase, causing rises greater than one foot in either the energy grade line or the water-surface elevation at upstream sections. As shown on the Flood Boundary and Floodway Map (Exhibit 2), the floodway boundaries were determined at cross sections; between cross sections, the boundaries were interpolated. In cases where the boundaries of the floodway and the 100-year flood are either close together or collinear, only the floodway boundary has been shown. 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 4. |> ‘IOO —YEAR FLOOD PLAIN FLOODWAY _ FRINGE ~ FLOODWAY —g>< STREAM CHANNE L FLOOD ELEVATION WHEN CONFINED WITHIN FLOODWAY ENCROACHMENT ENCROACHMENT "r c D i TI .11» N! +++W W $f+ I8 AREA OF FLOOD PLAIN THAT COULD _ BE USED FOR DEVELOPMENT BY ' FLOOD ELEVATION RAISING GHOUND 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) OF. LESSER AMOUNT IF SPECIFIED BY STATE. FIGURE 4 — Floodway Schematic The floodways in this report are recommended to local agencies as minimum standards that can be adopted or that can be used as a basis for additional studies. 14 5.0 INSURANCE APPLICATION In order to establish actuarial insurance rates, the FIA 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 (FHF), and flood insurance zone designations for each flooding source affecting the Town of Buckland. 5.1 5.2 5.3 Reach Determinations 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 difference does not have a variation greater than that indicated in the following table for more than 20 percent of the reach. Average Difference Between 10- and 100-year Floods Variation Less than 2 feet 0.5 foot 2 to 7 feet 1.0 foot 7.1 to 12 feet 2.0 feet More than 12 feet 3.0 feet The locations of the reaches determined for the Town of Buckland are shown on the Flood Profiles (Exhibit 1) and are summarized in the Flood Insurance Zone Data Table (Table 3). Flood Hazard Factors The FHF is used to correlate flood information with insurance rate tables. Correlations between property damage from floods and their FHFs 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. Flood Insurance Zones After the determination of reaches and their respective FHFs, the entire incorporated area of the Town of Buckland was divided into zones, each having a specific flood potential or hazard. Each zone was assigned one of the following flood insurance zone designations: 15 6.0 Zone A: Special Flood Hazard Areas inundated by the 100-year flood, determined by approx- imate methods; no base flood elevations shown or FHFs determined. Zones A3, A13: Special Flood Hazard Areas inundated by the 100-year flood, determined by de- tailed methods; base flood elevations shown, and zones subdivided according to FHF. Zone B: 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; and areas subject to IOU-year flooding from sources with drainage areas less than 1 square mile. Zone B is not subdivided. Zone C: Areas of minimal flooding. Table 3, "Flood Insurance Zone Data," summarizes the flood elevation differences, FHFs, flood insurance zones, and base flood elevations for each flooding source studied in detail in the community. 5.4 Flood Insurance Rate Map Description The Flood Insurance Rate Map for the Town of Buckland 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 FIA. OTHER STUDIES Preliminary coordination has resulted in complete agreement between this study and the Flood Insurance Studies for the adjacent Towns of Charlemont, Conway, and Shelburne (References 11, 12, and 13). A local publication detailing flood hazards on Clesson Brook was reviewed and coordinated with this study (Reference 14). 16 E55 =32: . 52¢ EH55: <._.<= “=3 5.2%.“; HEQ: I: __:.__===_ <2 .222: 3 =33 ===E~w_=_.=_.< Q2528:- 3.23m >953 hzusmwu=$=usw .2555 TABLE 3 ._.OOu_ Emu/Dz 0.... awozaomm wo< nwkzoms? ._mz_ mh_ wmwlwmzm<> m< m5 N._. md: mél OPOO P IU_ www|mmzm<> MP< mmO ¢.m 7N! 1m: QwOqmoOO N 10.4mm n_<_>_ wwwlwflm<> MP4‘ mwO mfim TNI mdl OFOO F 10.4mm 52m Qn-MEEMMO Efiwwwam. E.$. Efiié: mo5<¢ . o? *2 muwwwwwfiw wzo~ om<~w._m 7.0 8.0 A Flood Hazard Boundary Map has been. published by the Federal Insurance Administration (Reference 9). The differences between the Flood Hazard Boundary Map and this study are justified due to the more detailed nature of this Flood Insurance Study. This report either supersedes or is compatible with all previous studies published on streams studied in this report and should be considered authoritative for the purposes of the National Flood Insurance Program. LOCATION OF DATA Survey, hydrologic, hydraulic and other pertinent data used in this study can be obtained by contacting the office of the Federal Insurance Administration, Regional Director, 15 New Chardon Street, Boston, Massachusetts 02114. REFERENCES AND BIBLIOGRAPHY 1. Massachusetts Department of Commerce and Development, Massachusetts Profile of Buckland, Shelburne Monograph, Boston, Massachusetts, 1976. 2. U.S. Department of Agriculture, Soil Conservation Service, Soil Survey, Franklin County, Massachusetts, February 1967. 3. U.S. Army Corps of Engineers, New England Division, Connecticut River Basin Comprehensive Water And Related Land Resources Investigation, 1970, Appendices A-M. 4. U.S. Water Resources Council, Bulletin No. 15, A Uniform Technique for Determining Flood Flow Frequencies, Washington, D.C., December 1967. 5. Johnstone, Don, and W. P. Cross, Elements of Applied Hydrology. New York: Ronald Press Co., 1949. 6. U.S. Geological Survey, Estimating the Magnitude and Frequency of Floods in Natural-Flow Streams in Massachusetts, S. William Wandle, 1977. 7. F. A. Hesketh and Associates, "Field Notes — Town of Buckland," January 1978. 8. U.S. Army Corps of Engineers, Hydrologic Engineering Center, HEC-2 Water-Surface Profiles, Users Manual, November 1976. 9. U.S. Department of Housing and Urban Development, Federal Insurance Administration, Flood Hazard Boundary Map, Town of Buckland, Massachusetts, May 1974, (revised) September 1976. 10. U.S. Geological Survey, 7.5 Minute Series Topographic Maps, Scale 1:24000, Contour Interval 10 feet: Ashfield, Massachusetts, 1974; Heath, Massachusetts, 1974; Shelburne Falls, Massachusetts, 1961. 18 11. 12. 13. 14. U.S. Department of Housing and Urban Development, Federal Insurance Administration, Flood Insurance Study, Town of Charlemont, Massachusetts, (in progress). , Flood Insurance Study, Town of Massachusetts, (in progress). Conway, , Flood Massachusetts, (in progress). Insurance Study, Town of Shelburne, Buckland Conservation Commission, Evaluation of Flood Hazards for Clesson Brook, Charles G- Wirth, Jr., and Thomas E. Shippee, September 1974. U.S. Geological Survey, Water-Supply Paper 867, Hurricane Floods of 1938, Washington, D.C.: U.S. Government Printing Office, 1940. 19 ELEVATION IN FEET (NGVD) 440 430 420 410 400 390 380 370 16.90 17.00 17-10 17.20 17.30 h 17.40 STREAM DISTANCE IN MILES ABOVE MOUTH 17.50 17.60 FLOOO PROFILES OEERFIELO RIVER LEGEND SOD-YEAR FLOOD 100—YEAR FLOOD 50-YEAR FLOOD 10—YEAR FLOOD STREAM BED CROSS SECTiON LOCATION 17.70 17.80 FEDERAL EMERGENCY MANAGEMENT AGENCY Federal Insurance Administration TOWN OF BOOKLAND, MA {FRANKLIN GO ] O1 ‘U 52¢ 3E5: “fizz: =2: I: ___:.=.:_ <2 .._=<:a=_ “E =32. ===_:E=__=__< 2.25.55 25E: 55$ P523522 555E .255‘ 02F 510 500 490 8 5>0Z. Em". Z- zo_»<>w._w 460 500—YEAR FLOOD 100—YEAR FLOOD 50——YEAR FLOOD 10—YEAR FLOOD STREAM BED CROSS SECTION LOCATION M 11512.0 2L8 440 21.6 21.4 21.2 21.0 20.8 20.6 20.4 20.2 20.0 19.8 19.6 STREAM DISTANCE IN MILES ABOVE MOUTH 52¢ EH55: $E2_._ =23» I: 55.2: <2 ._=_§a== S =32. =2=Ew____=___< 3=2=2__ 52:; SE3 Eigsz: 5:355 .255... 03F 0 O 0 0 3 2 1 0 5 5 5 5 E>uz. Em“. Z_ zo;<>w.m_ 490 LEGEND 500—YEAR FLOOD 100—YEAR FLOOD 50—YEAR FLOOD I0—YEAR FLOOD STREAM BED CROSS SECTION LOCATION 480 24.4 24.2 24.0 23.8 23.6 23.4 23.2 23.0 22.8 22.6 22.4 22.2 22.0 STREAM DISTANCE IN MILES ABOVE MOUTH ELEVATION IN FEET (NGVDI 520 510 500 490 480 470 460 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 STREAM DISTANCE IN MILES ABOVE CONFLUENCE WITH DEERFIELD RIVER LEGEND 500—YEAR FLOOD 100—YEAR FLOOD 50—YEAR FLOOD 10—YEAR FLOOD STREAM BED CROSS SECTION LOCATION 0.9 1.0 1.1 1.2 m u; .1 g -- a Q m z n. g w 2 w u: a _: _.| GD u. E < LI S <2 r-"Z- " EE=_. 52:5 Z ‘é"§_|"’ 53$! ‘"31 L? 55$: E5 c: w" u. zELh—- HJ Z 5T: dgZ g2; H-I Z S l- Lb 04F ELEVATION IN FEET INGVD) 580 570 560 550 540 530 520 510 LEGEND 500—YEAR FLOOD 100—YEAR FLOOD 50—YEAR FLOOD 10—YEAR FLOOD STREAM BED CROSS SECTION LOCATION 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 STREAM DISTANCE IN MILES ABOVE CONFLUENCE WITH DEERFIELD RIVER 2.2 2.3 2.4 2.5 (I! l-Hl Z -I c - 2 Q m Z =- z a a Q u; ¢ _.| _| L? u.- >- g < LAJ 3g: r-E ,_ z- w~Z Q25; é-EQ" 2...‘: >gui :22: uaam< a: Z EILI-f: 5E3 2'31 29-; HJ B $ Ll- h 05 ‘U ELEVATION IN FEET (NGVD) e40 s30 w Ll-l - E» - c Z == an n: z n. a 620 a V’ <= E3 c _| _| u Ll- s10 e00 59o S < Z g g E 5 "é d 580 z Z '7 g3 .5 < 3 LEGEND < E _| E 3 Z _z_ 500—YEAR FLOOD z ., u .4 ,. g = g 100—YEAR FLOOD g g m < 570 50—YEAR FLOOD FEE g g. 10—YEAR FLOOD E § z STREAM BED g -- c Z cnoss SECTION E '- _ LOCATION 560 E V " 2.5 2.6 2.7 2.8 2.9 3.0 3.1 3.2 3.3 3.4 3.5 3.6 STREAM DISTANCE IN MILES ABOVE CONFLUENCE WITH DEERFIELD RIVER m5 Q5454!‘ s3 "hf! » "q":- $1“?