U.S. Department of the Interior U.S. Geological Survey
IN COOPERATION WITH THE VERMONT AGENCY OF NATURAL RESOURCES, DEPARTMENT OF ENVIRONMENTAL CONSERVATION
Application of a Sediment-Transport Model to Evaluate the Effect of Streambed-Management Practices on Flood Levels and Streambed Elevations at Selected Sites in Vermont
By Scott A. Olson
Open-File Report 00-55
Pembroke, New Hampshire 2000 U.S. DEPARTMENT OF THE INTERIOR BRUCE BABBITT, Secretary
U.S. GEOLOGICAL SURVEY Charles G. Groat, Director
The use of firm, trade, and brand names in this report is for identification purposes only and does not constitute endorsement by the U.S. Geological Survey.
For additional information write to: Copies of this report can be purchased from:
District Chief U.S. Geological Survey U.S. Geological Survey Information Services New Hampshire/Vermont District Box 25286 361 Commerce Way Federal Center Pembroke, NH 03275-3718 Denver, CO 80225 or through our website at http://nh.water.usgs.gov CONTENTS
Abstract ...... ^ 1 Introduction...... _^ 1 Purpose and Scope ...... 2 Description of Investigated Reaches...... 2 Acknowledgments...... _^ 12 Methods of Field Data Collection...... 12 Fixed-bed Water-surface Profiles...... 12 Sediment-transport Model...... 13 Model Calibration...... 13 Simulation of the Effects of Streambed-management Practices...... 16 Summary and Conclusions...... 17 Selected References ...... 19 Appendixes: A. Pre- and Post-1997 Flood Cross Sections...... A-l B. Pre- and Post-flood of 1997 Profiles from Fixed-bed Models ...... B-l C. Movable-bed Model Results Profiles ...... C-l D. Peak Water-surface Elevations from the Movable-bed Models in Tabular Form...... D-l E. Movable-bed Model Results Cross-sections...... E-l F. Elevation Reference Marks ...... F-l
FIGURES 1-6. Maps showing: 1. Locations of investigated reaches...... 3 2a-b. Locations of cross sections in study reach in Montgomery, Vt...... 4 3a-c. Locations of cross sections in study reach in Wolcott, Vt...... 6 4a-c. Locations of cross sections in study reach in Cambridge, Vt...... 9 5. Estimated hydrographs for the 1997 flood at the downstream end of the study reaches for the Trout River, Montgomery, Vt.; Wild Branch, Wolcott, Vt.; and Lamoille River, Cambridge, Vt...... 15 6. Synthetic 10- and 100-year flood hydrographs at the downstream end of the studied reach for the (A) Trout River, (B) Wild Branch, and (C) Lamoille River...... 18
TABLES 1. Range of roughness coefficients (n) used in the Trout River, Wild Branch, and Lamoille River models...... 12 2. Summary of the differences between water-surface profiles computed by fixed-bed models and the profile of the existing flood-insurance studies in Vermont...... 13 3. Variables set during the calibration of the BRI-STARS model for the Trout River, Wild Branch and Lamoille River, Vermont...... 14 4. Magnitude of flood discharges used in model simulations of the Trout River, Wild Branch and Lamoille River, Vermont...... 15 5. Peak discharges and approximate recurrence intervals at selected U.S. Geological Survey stream-gaging stations in Vermont...... 16
Contents III CONVERSION FACTORS, SEA LEVEL, OTHER ABBREVIATIONS
Multiply By To obtain
inch (in.) 25.4 millimeter (mm) foot (ft) 0.3048 meter square foot (ft2) 0.09290 square meter mile (mi) 1.609 kilometer square mile (mi 2 ) 2.590 square kilometer cubic feet per second (ft /s) 0.02832 cubic meter per second foot per mile (ft/mi) 0.1894 meter per kilometer
Temperature in degrees Fahrenheit (°F) can be converted to degrees Celsius (°C) as follows: °C = 5/9 (°F - 32).
Sea Level: In this report "sea level" refers to the National Geodetic Vertical Datum of 1929 (NGVD of 1929) a geodetic datum derived from a general adjustment of the first-order level nets of both the United States and Canada, formerly called Sea Level Datum of 1929.
OTHER ABBREVIATIONS
BM Bench Mark C-RM Cambridge, Vermont, elevation reference mark ft/ft foot per foot FEMA Federal Emergency Management Agency M-RM Montgomery, Vermont, elevation reference mark yr year RR EXIT Railroad exit section USGS U.S. Geological Survey W-RM Wolcott, Vermont, elevation reference mark XS cross section NOAA National Oceanic and Atmospheric Administration
In this report, the words "right" and "left" refer to directions that would be reported by an observer facing downstream.
IV Contents Application of a Sediment-Transport Model to Evaluate the Effect of Streambed-Management Practices on Flood Levels and Streambed Elevations at Selected Sites in Vermont
By Scott A. Olson
Abstract INTRODUCTION In a study of sediment transport in three On July 25,1997, the President declared a major river reaches in northern Vermont affected by the disaster to exist in an area covering five counties in the State of Vermont as a result of widespread damage flood of July 1997, three streambed management caused by excessive rainfall and flooding that began practices were evaluated to see what, if any, effect July 14, 1997. The storm produced between 4 and the practices had on the river channels during a 8 in. of precipitation in northern Vermont, with the 10- and 100-year recurrence interval flood. heaviest rainfall occurring during the early morning Results of the B Ridge Stream Tube model for hours of July 15, 1997 (Federal Emergency Manage ment Agency, 1997). The precipitation station Alluvial River Simulation indicated there were operated by NOAA on Jay Peak, Jay, Vt., recorded some decreases in the mean water-surface profile 6.58 in. of rainfall (National Oceanic and Atmospheric when a streambed-management practice of Administration, 1997). The intense rainfall resulted in channel dredging 2 feet below the thalweg, prior rapid runoff and severe flooding, especially in regions of steep topography. During the storm, streambed and to flooding, was followed as opposed to streambank erosion and deposition were significant at restricting the removal of any bed materials. The several locations within the declared disaster area. model, however, also showed severe erosion Many citizens and local officials reported that the under some bridges during a flood if dredging was sediment deposited in stream channels constricted practiced. There were only minor differences, water flow and contributed to channel migration and elevated flood levels. Others attested that the amount less than 1.5 feet on average, in the resulting of gravel in the channels would have little effect on the water-surface profile between the models where conveyance of such a large flood. scalping (removing) bars or other areas of Since 1986, the State of Vermont's policy on decreased channel capacity was done prior to streambed management restricts the removal of flooding and where the removal of bed material alluvial material (sand and gravel) from channels. The extent to which the policy affects flooding conditions was restricted. during events of various magnitudes is unknown. The All profiles evaluated in this study did not U.S. Geological Survey (USGS), in cooperation with result in changes that could be observed on the Vermont Agency of Natural Resources, Depart existing maps. Thus, flood-boundary maps ment of Environmental Conservation, began a study in October 1997, to evaluate the effect of various provided by Federal Emergency Management streambed-management practices on future flood Agency's flood-insurance studies are considered hazards, and more specifically, the effect of restricting to be valid. the extraction of alluvial material from stream
Abstract 1 channels. Three stream reaches that had been affected Description of Investigated Reaches by the flood of July 1997, for which a flood-insurance- study model was available, and which covered a wide The Trout River (fig. 1) flows northwest through range of basin characteristics common to Vermont Montgomery, Vt., and is best defined as an upland were selected for the study (fig. 1). The reaches stream of the Green Mountain physiographic region in selected were (1) a 4.3-mi reach of the Trout River in the north-central part of the State. The mean channel Montgomery, Vt., from 2,500 ft downstream of the State Route 118 bridge in Montgomery Center to the slope of the reach investigated is 19 ft/mi; however, the State Route 118 bridge in the Village of Montgomery; headwaters are steep and extend to Jay Peak, which (2) a 6.5-mi reach of the Wild Branch in Wolcott, Vt., has an elevation of 3,860 ft. Montgomery Center has from the mouth to the upstream corporate limit; and an elevation of approximately 530 ft. The drainage (3) the entire 15.4-mi reach of the Lamoille River area of the Trout River at the State Route 118 crossing within Cambridge, Vt. in Montgomery Center (fig. 2b) is 23.9 mi2 and Purpose and Scope increases to 71.6 mi2 at the State Route 118 crossing downstream of the Village of Montgomery (fig. 2a) This report describes the results of sediment- (Federal Emergency Management Agency, 1980). transport modeling to estimate the changes in channel Bed material is primarily gravel and cobble with some configuration and degradation in three river reaches in sand and some exposed bedrock. Vermont. Included in the report are estimated profiles The Wild Branch (fig. 1) flows south through of the peak-water surface for the 10- and 100-yr floods Wolcott, Vt., along a relatively steep slope, averaging that would result from the implementation of three streambed management practices including the effect 40 ft/mi, and drains into the Lamoille River at an of restricting the extraction of alluvial materials from elevation of about 670 ft. Wolcott is in the north- the stream channels. central part of Vermont in the New England Upland Cross sections were re-surveyed in the same physiographic province. The drainage area of the locations as the cross sections of the existing flood- Wild Branch is 20.8 mi2 upstream of North Wolcott > > insurance studies for the three study reaches (Federal (fig. 3c) and increases to 39.5 mi at its mouth (fig. 3a) Emergency Management Agency, 1980 and 1982a-d). (Federal Emergency Management Agency, 1982d). The water-surface profiles for the 10-yr and 100-yr recurrence-interval floods were recomputed using the Bed material ranges from sand to boulders with new cross-section data to verify the water-surface several locations of exposed bedrock. profiles of the existing flood-insurance studies. Next, The Lamoille River (fig. 1) flows west through changes in channel configuration between the older Cambridge, Vt., along a relatively mild slope, cross sections and the newly surveyed cross sections averaging 2.3 ft/mi, with wide flood plains and steep were documented. The sediment-transport model, valley walls. Cambridge is in the northwestern part of BRIdge Stream Tube model for Alluvial River Simula the state within the Green Mountain physiographic tion (BRI-STARS; Molinas, 1997) was then calibrated to simulate these changes in channel configuration. province. The river valley has an elevation of Finally, the post-flood cross sections were used 460-470 ft and the headwaters and tributaries of the as input into the calibrated BRI-STARS model and the Lamoille River are best described as steep upland model was used to estimate channel aggradation and streams. The drainage area of the Lamoille River degradation, and the peak water-surface profile for the upstream of the confluence of the North Branch of the > > 10- and 100-yr floods that would result from the Lamoille River (fig. 4c) is 402 mi and increases to implementation of three different streambed- 520 mi2 at the downstream corporate limit (fig. 4a) management practices. The three practices included (Federal Emergency Management Agency, 1982a-c). (1) no removal of bed material, (2) "scalping" or removing bars and other alluvial materials to increase Bed material ranges from silt to coarse gravel with the channel capacity, and (3) dredging the entire several sections having some cobbles or exposed channel to two feet below the thalweg. bedrock.
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Figure 1. Locations of investigated reaches.
INTRODUCTION 3 72°37'30«
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1 USGS 7.5 minute quadrangle, Richford, VT, 1986 Joins Figure 2b Contour Interval 6 meters EXPLANATION CROSS SECTION A ELEVATION REFERENCE MARK NORTH 1000 0 1000 Figure 2a. Locations of cross sections in study reach in Montgomery, Vt. FEET Joins Figure 2a INTRODUCTION 72°27'30» 72°30 Joins Figure 3b
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. 44°33' a> 3 to USGS 7.5 minute quadrangle, Wolcott, VT, 1986 Contour Interval 6 meters EXPLANATION A CROSS SECTION A ELEVATION REFERENCE MARK NORTH 1000 0____1000 FEET ^ Figure 3a. Locations of cross sections in study reach in Wolcott, Vt. 72°30' 72°27'30* Joins Figure 3c .44°35'30" _44°35 ( 31 § USGS 7.5 minute quadrangle. Wolcott. VT. 1986 Joins Figure 3a C Contour Interval 6 meters O EXPLANATION o A CROSS SECTION A ELEVATION REFERENCE MARK NORTH 1000 * I0 1000 Figure 3b. Locations of cross sections in study reach in Wolcott, Vt.-Continued. FEET 72°30 00 w > 3 o m o ll3" {& « 3 % g §5 f »J£ s 3 m o < 3 0) ~ C I 1 cr 2. .44°36' (O (0 2-. USGS 7.5 minute quadrangle, Wolcott, VT, 1986 Joins Figure 3b Contour Interval 6 meters EXPLANATION A CROSS SECTION A ELEVATION REFERENCE MARK NORTH 1000 0_____1000 Figure 3c. Locations of cross sections in study reach in Wolcott, Vt.-Continued. FEET = 72°55' 72°52'30" 44°39- 44°38' USGS 7.5 minute quadrangles, Gllson Mountain, VT, 1980, and Jeffersonville, VT, 1948 Contour Interval 20 feet EXPLANATION A CROSS SECTION A ELEVATION REFERENCE MARK Figure 4a. Locations of cross sections in study reach in Cambridge, Vt. NORTH 1000 0 1000 * ' FEET 72°50' 72°52Oenir m 0 3 0) (0 m 44°39' m 44°38'30 USGS 7.5 minute quadrangle, Jeffersonville, VT, 1948 Contour Interval 20 feet EXPLANATION A CROSS SECTION A ELEVATION REFERENCE MARK Iw NORTH 1000 0 1000 Figure 4b. Locations of cross sections in study reach in Cambridge, Vt.-Continued. "FEET 72°47'30" 72°45' 44°40< 44°39' O USGS 7.5 minute quadrangle, Jeffersonville, VT, 1948 O Contour Interval 20 feet O EXPLANATION A CROSS SECTION A ELEVATION REFERENCE MARK NORTH Figure 4c. Locations of cross sections in study reach in Cambridge, Vt.-Continued. 1000 0 1000 "FEET Acknowledgments FIXED-BED WATER-SURFACE PROFILES This report is the culmination of an intensive The cross sections surveyed after the 1997 flood effort by dedicated personnel of the USGS. The were used as input to a fixed-bed step-backwater following employees provided significant help model to verify the existing flood insurance study collecting and analyzing the data and (or) preparing profiles for the study reaches. Water-surface profiles the report: Erick M. Boehmler, Robert O. Brown, for the 10- and 100-yr floods were updated by use of Ronda L. Burns, Michael F. Coakley, Jon C. Denner, the Model for Water-Surface PROfile (WSPRO) Computations (Shearman, 1990). Robert H. Flynn, Debra H. Foster, Robert E. Hammond, Michael A. Ivanoff, The 10- and 100-yr flood discharges used in the Richard G. Kiah, William H. Kirby, Laura Medalie, WSPRO models were taken from existing flood- insurance-study models (Federal Emergency Manage Joseph R. Olimpio, Ann Marie Squillacci, ment Agency, 1980 and 1982a-d). Starting water- Jerry E. Vaill, Jr., Emily C. Wild, and Chester Zenone. surface elevation at the downstream end of each model was assumed to be normal depth for the Wolcott and Cambridge computations. Normal depth was METHODS OF FIELD DATA COLLECTION computed by means of the slope-conveyance method outlined in the user's manual for WSPRO (Shearman, Following the July 1997 Hood, the USGS, in 1990). The slope used was the energy-grade-line cooperation with FEMA, flagged and surveyed high- slope of the existing flood-insurance study at the water elevations throughout the three study reaches. appropriate section 0.00429 ft/ft for the Lamoille These data were crucial to the model calibrations. River and 0.00814 ft/ft for the Wild Branch. The Post-flood channel geometry was surveyed, starting water surface for the Montgomery computa insofar as possible, at the same location as the cross tion was taken from a model (Robert Flynn, U.S. sections of the existing flood-insurance study of the Geological Survey, oral commun., April 1999), for the corresponding community. The cross-section data reach of the Trout River in Montgomery immediately from the existing flood-insurance study and the newly downstream of the sediment-transport study area. surveyed data will be referred to as the pre- and post- Cross-section roughness factors (Manning's flood cross sections, respectively. This re-surveying of "n") were taken from the existing flood-insurance- the cross sections allowed comparison of channel study models and were updated at many of the sections geometry and documentation of changes. There were on the basis of field observations, following the limitations that affected this comparison. First, the general guidelines of Arcement and Schneider (1989). exact location of the pre-flood cross sections were The range of roughness values used can be found in difficult to determine, especially at sections that did table 1. The resulting 10- and 100-yr water-surface not have a nearby landmark such as a bridge, road, or profiles are compared to the 10- and 100-yr water- channel bend. Secondly, the geometry of many of the surface profiles of the existing flood-insurance study pre-flood cross sections was determined by aerial in Appendix B. The comparisons of the water-surface photography techniques, and the streambed indicated profile computed from the re-surveyed cross section to was actually the water surface with some sections the existing profile in the flood-insurance studies are having adjustments for depth. The pre- and post-1997 shown in table 2. Although some local, significant flood cross sections are shown in Appendix A. Bed material size distribution was also Table 1. Range of roughness coefficients (n) used in the Trout River, Wild Branch, and Lamoille River models determined at each cross section. At sections in which the median grain size of the bed material was greater Studied reach Channel Overbank than about 4 mm, the particle-size distribution was n-values n-values determined using a pebble count technique (Hayes, 1993). At sections with a median grain size less than Trout River, Montgomery, Vt. 0.035-0.055 0.035-0.095 4 mm, the particle-size distribution was determined by Wild Branch. Wolcott, Vt. 0.030-0.060 0.030-0.100 sieving a grab sample collected at that section. Lamoille River, Cambridge, Vt. 0.028-0.050 0.035-0.200 12 Application of a Sediment-Transport Model to Evaluate the Effect of Streambed-Management Practices on Flood Levels and Streambed Elevations at Selected Sites in Vermont Table 2. Summary of the differences between water-surface profiles computed by fixed-bed models and the profile of existing flood-insurance studies in Vermont [ft, foot; + indicates an elevation increase; river locations are shown on figure 1] Maximum increase in peak Maximum decrease in peak Average change with respect Studied reach and event water surface water surface to existing profile (ft) (ft) (ft) Trout River, 10-year flood 3.1 2.8 +0.1 Trout River, 100-year flood 4.3 2.7 +0.0 Wild Branch, 10-year flood 4.2 2.8 +0.4 Wild Branch, 100-year flood 3.7 1.0 +0.8 Lamoille River, 10-year flood 2.8 1.2 +1.3 Lamoille River, 100-year flood 3.6 t).5 +1.6 discrepancies between the profiles are evident, the independent channel, hydraulic variables are average difference between the water-surface elevation computed and sediment is routed through each tube. at corresponding cross sections ranged from 0.0 to At the end of these computations, bed-material 1.6 ft (table 2). compositions are revised and channel-bed elevations Changes in the water-surface profile cannot be are updated. attributed entirely to changes in the channel geometry. Because computer modeling of sediment The HEC-2 model (U.S. Army Corps of Engineers, transport is still in its developmental stages, the ability 1977) was used to compute the profile for the existing of models such as BRI-STARS to accurately simulate flood-insurance studies and WSPRO was used to sediment transport processes and effects is limited. compute the water-surface profiles with data from the Some limitations are as follows: (1) computer-based re-surveyed cross sections. The two models do have models currently available do not incorporate an some differences, particularly in the techniques used adequate treatment of armoring processes (Richardson to compute a water-surface profile through a bridge and others, 1990); (2) BRI-STARS is not capable of opening. These different techniques used at bridges is computing pressure flow through bridges when the the primary cause for the increase in the peak water water surface is in contact with the low chord of the surface in the Cambridge, Vt. water-surface profile of bridge; and (3) lateral movement and the formation of the Lamoille River. meander bends and bed forms cannot be adequately simulated. Data requirements for BRI-STARS include SEDIMENT-TRANSPORT MODEL channel geometry, bed-material distribution, water temperature, a flood hydrograph, a stage-discharge The sediment-transport model BRI-STARS was relation, a sediment-transport equation, and channel used to evaluate the effect of streambed-management roughness data. These factors will be discussed in the practices on future flood hazards. BRI-STARS is a following sections. A sediment-inflow hydrograph at movable bed model that can be applied to route water the most upstream section also is needed; however, and sediment through natural river channels (Molinas, BRI-STARS can develop a sediment-inflow 1997). The model is composed of the following three hydrograph based on the user-specified sediment- major components: (1) step-backwater computations, transport equation (Hilmes and Vaill, 1997). (2) stream-tube computations, and (3) sediment- routing computations. Computations are defined by a hydrograph divided into time steps. At each time step, Model Calibration backwater computations are carried out for the entire reach. With the computed water-surface profile, The first step in modeling sediment transport lateral locations of each stream tube in each section with BRI-STARS was to calibrate the models to are determined. With each stream tube treated as an simulate the channel changes observed between the SEDIMENT-TRANSPORT MODEL 13 pie-flood and post-flood cross sections. The accuracy The recurrence intervals of the estimated 1997 of this simulation is limited by the lack of streambed flood discharges are unknown; however, a comparison definition in some of the pre-flood cross sections and between these discharges and frequency data from the the assumption that all observed channel modifications flood insurance studies (Federal Emergency Manage occurred during the July 1997 flood. Although signif ment Agency, 1980 and 1982a-d) indicates that the icant channel modifications were observed following Trout River and the Wild Branch study reaches experi the July 1997 flood, the pre-flood sections were enced a flood greater than a 100-yr event and the flood collected for flood insurance studies that were on Lamoille River in Cambridge was between a 10- published in 1980 and 1982, and it is likely that some and 100-yr event. Peak discharges of the 1997 flood at changes in channel configuration between the early USGS stream-gaging stations near the study areas and 1980's and 1997 occurred during hydrologic events the corresponding recurrence intervals of these peaks other than the July 1997 flood. However, these data are listed in table 5 for comparison. are the only information available, and the cross The sediment-transport equation used for each sections from the existing flood insurance studies of the models was the Meyer-Peter Muller equation (Federal Emergency Management Agency, 1980 and (Shen and Julien, 1993). This equation produced the 1982a-d) were used as the pre-flood condition in the best results and is the preferred equation when dealing BRI-STARS calibration. The models were also with sediment that is relatively coarse such as gravel calibrated to the high-water profile of the July 1997 and cobble. flood. With the pre- and post-streambed profiles and The final variables modified in calibration were 1997 flood water-surface profile known, the flood the energy-loss coefficients. Because each reach discharges, the time step of the computations, the studied had several bridges and the bridge routines in roughness coefficients, the coefficients of expansion BRI-STARS can handle only one bridge per model and contraction, the sediment-transport equation, and run, those routines were not utilized. In addition, BRI-STARS' bridge routines cannot account for the local energy-loss coefficients were selected to pressure flow when the water surface is in contact improve the simulation (table 3). with the bridge deck. Instead of using the bridge The final estimated discharges for the July 1997 routines, an option that incorporates user-supplied flood determined from the calibration runs are listed in local energy-loss coefficients at the bridge section was table 4. BRI-STARS also requires a flood hydrograph. used. This technique was recommended for the A synthetic flood hydrograph was developed using the BRI-STARS model before the bridge routines were Soil Conservation Service dimensionless hydrograph incorporated (Molinas, 1989). The coefficients were (U.S. Bureau of Reclamation, 1974). For these intense adjusted until the losses through a bridge computed by events, the lag time, estimated by Snyder's method BRI-STARS either matched the losses observed from (Bedient and Huber, 1988), was assumed to approxi the surveyed profile of the July 1997 flood or matched mate the time to the peak used in the time ratio of the the results of the WSPRO model calibrated to the dimensionless hydrograph. The resulting hydrographs July 1997 flood at the bridge. Coefficients at bridges are shown in figure 5. ranged from 0.0 to 1.5. Table 3. Variables set during the calibration of the BRI-STARS model for the Trout River, Wild Branch, and Lamoille River, Vermont [Meyer-Peter/Muller sediment-transport equation is from Shen and Julien, 1993] Variable Trout River, Montgomery Wild Branch, Wolcott Lamoille River, Cambridge Coefficient of expansion 0.3 0.5 0.5 Coefficient of contraction 0.1 0.1 0.1 Time step length, hours 0.8 1.5 2.5 Water temperature, °F 70 70 70 Number of stream tubes 1 1 3 Sediment transport equation Meyer-Peter/Muller Meyer-Peter/Muller Meyer-Peter/Muller 14 Application of a Sediment-Transport Model to Evaluate the Effect of Streambed-Management Practices on Flood Levels and Streambed Elevations at Selected Sites in Vermont Table 4. Magnitude of flood discharges used in model simulations of the Trout River, Wild Branch and Lamoille River, Vermont [mi2, square miles; ft3/s, cubic feet per second; locations are found in figures 1 -4] 10-year 1 00-year July 1997 flood _. .. Drainage area 3 discharge discharge Flooding source (mi. . 2)> < (ft^s) (ft3/s) Trout River Downstream of West Hill Brook 71.6 9,400 18,000 28,000 Upstream of West Hill Brook 59.0 7,600 14,500 22,000 Upstream of Black Falls Brook 48.4 6,100 11,500 17,500 Upstream of South Branch Trout River 23.9 3,550 7,600 12,000 Wild Branch At mouth 39.5 3,100 6,340 8,400 Upstream of Tamarack Brook 27.6 2,410 4,930 6,800 Upstream of North Wolcott 20.8 1,980 4,050 4,800 Lamoille River At downstream corporate limit 520 16,000 29,250 22,000 Upstream of Seymour River 489 15,000 26,250 19,000 Upstream of Brewster River 464 14,500 25,250 18,000 Upstream of North Branch Lamoille River 402 13,100 22,900 17,000 Q 3D,OOOr i i i i i i i i i - | 25,000; /\ 1OOT7 flood hydnograph for the Trout Rver, Montgomery, VI T - - 1997 flood hydrograph for the Wld Braxh, Wblcott, VI : L. 20,000- 1 \ / X .... 1997flocdh/drographfortheLarrdlleRwer, Can-bridge, VI ~ % % S 1san' I \ '' - jj= 10,000- I \/ - I 5i00°7 / ' \>- -.. - c\'L<' , . . i , . T- I i_H~ r- 0 10 20 30 40 50 60 7 "HIVE, IN HOURS Figure 5. Estimated hydrographs for the 1997 flood at the downstream end of the study reaches for the Trout River, Wild Branch, and Lamoille River. SEDIMENT-TRANSPORT MODEL 15 Table 5. Peak discharges and approximate recurrence intervals at selected U.S. Geological Survey stream-gaging stations in Vermont [mi , square mile; ft/s, cubic foot per second; (Coakley and others, 1998; Robert Hammond, U.S. Geological Survey, oral commun., March 16, 1998)] 1997 Event peak Approximate Gaging station Gaging Drainage area discharge recurrence station No. (mi2) («g.i) (ft3/s) interval, in years Lamoille River at Johnson, Vt. 04292000 310 12,900 10 to 25 Missisquoi River at North Troy, Vt. 04293000 131 8,940 100 to 200 Missisquoi River at East Berkshire, Vt. 04293500 479 17,500 25 to 50 Additional data required in the models, but not accuracy, trends and patterns of aggradation and adjusted for calibration purposes, were the stage- degradation were similar to what was observed after discharge relation at the section farthest downstream the flood of 1997. and the bed-material-size distribution. The stage-discharge relation was assumed to be normal depth at any given rate of streamflow. The normal Simulation of the Effects of Streambed- depth was computed on the basis of the instantaneous management Practices slope of the energy-grade line at the downstream-most section of the study reaches. The slope of the energy Fluvial processes, such as erosion and deposi grade line was estimated from hydraulic data for the tion of materials by flowing water, are complex. A 1997 flood. complete description of the fluvial processes in the three study reaches was beyond the scope of this The bed-material-size data entered into the investigation and beyond the capabilities of the model. models were determined from the grain-size analysis Management of a channel in regards to this study of bed samples collected at each cross section after the refers only to the removal of streambed materials. 1997 flood. The bed material in the Trout River reach Bank protection and other channel improvements were was primarily gravel and cobble with some sand and not considered. Three streambed-management some exposed bedrock. The bed material in the Wild practices were selected for evaluation in this study. Branch reach ranged from sand to boulders with The first practice was based on current State policy several locations of exposed bedrock. The bed that restricts the removal of streambed materials from material in the Lamoille River reach ranged from silt channels. The second practice evaluated was based on to coarse gravel with several sections having some typical channel alterations and practices prior to 1986, cobbles or exposed bedrock. when the current State policy took effect. The third The simulation results from the calibrated practice was based upon the popular opinion that models are considered adequate. For the Trout River, channels need to be dredged. The BRI-STARS model the model simulated the final thalweg within 3.3 ft at was used to determine the peak water-surface and the 80 percent of the cross sections and the 1997 peak final streambed profiles for a 10- and a 100-yr flood in water surface within 2.8 ft at 80 percent of the cross each reach that would result from the implementation sections. For the Wild Branch, BRI-STARS estimated of each of the management practices. the final thalweg within 3.2 ft at 76 percent of the cross With the calibrated models established, the sections and the 1997 peak water surface within 1.3 ft model input was modified to reflect the current at 79 percent of the cross sections. For the Lamoille channel geometry, a pre-flood streambed-management River, the model estimated the final thalweg within practice, and the 10- and 100-yr flood hydrographs. 4.0 ft at 74 percent of the cross sections and the 1997 All other variables were kept constant. Modifying the peak water surface within 0.6 ft at 88 percent of the model to reflect the current channel geometry was cross sections. Although BRI-STARS could not simply done by using as input the cross sections simulate the actual conditions with 100 percent surveyed following the July 1997 flood. This 16 Application of a Sediment-Transport Model to Evaluate the Effect of Streambed-Management Practices on Flood Levels and Streambed Elevations at Selected Sites in Vermont modification represented the first streambed- elevations between restricting removal of bed material management practice no removal of bed material. and scalping bars and dredging are also included in the The second management practice included tables. "scalping" or removing bars and other deposits in Appendix E shows the cross-section geometry channels above the water surface a common practice as it was following the 1997 flood, and the predicted prior to the 1986 statute restricting such extraction. To channel geometry following a synthesized 10- and simulate this practice, the model input was modified 100-yr flood for the three streambed-management by editing cross-section geometry points of the model practices. Channel geometries shown in Appendix E described in the previous paragraph on the basis of are after the event has occurred; channel geometry descriptions written by the surveyors and the elevation during the peak discharge may be different. of the water surface at the time of the survey. The Appendix F contains the elevations and descriptions of surveying was done during relatively low water. Elevation Reference Marks used in the study and The third streambed-management practice to be displayed in figures 2-4. simulated was dredging of the entire channel. In the simulation, each channel was dredged two vertical feet below the thalweg and across the width of the channel, SUMMARY AND CONCLUSIONS with side slope of 1.5 ft horizontal to 1.0 ft vertical. With additional input for each cross section, A sediment transport study by the U.S. Geolog BRI-STARS has the capability to modify channel ical Survey, in cooperation with the Vermont Agency geometry to simulate this dredging prior to running the of Natural Resources, began in October 1997, to sediment transport routines (Albert Molinas, Hydrau- evaluate the State of Vermont's policy on streambed Tech, Inc., written commun., June 10, 1998). management, which restricts the extraction of The only other modification to the calibrated streambed materials from channels. The reaches models was the hydrograph. The 10- and 100-yr peak included in this study were a 4.3-mi section of the discharges were taken from the flood-insurance Trout River in Montgomery, Vt., all 6.5 mi of the Wild studies for each river reach (Federal Emergency Branch in Wolcott, Vt., and the entire 15.4-mi reach of Management Agency, 1980 and 1982a-d). These peak the Lamoille River in Cambridge, Vt. All three discharges can be found in table 4. The hydrographs reaches were affected by the July 1997 flood in of the 10- and 100-yr floods were synthesized using northern Vermont. The current state policy on the Soil Conservation Service dimensionless streambed management, as well as alternative hydrograph (U.S. Bureau of Reclamation, 1974) and practices, were evaluated using a sediment-transport were used as input to the models. The same time-to- model. The BRIdge Stream Tube model for Alluvial peak as estimated for the July 1997 flood was used for River Simulation was used to estimate degradation and the 10- and 100-yr hydrograph synthesis. The aggradation of the streambed and to compute peak hydrographs used in the models are displayed in water-surface elevations for 10-yr and 100-yr figure 6. recurrence-interval floods. Results of the model runs can be found in the The model was calibrated using data for the Appendixes C-F. Appendix C contains, for each study flood of July 14-16,1997, including channel-geometry reach, profiles of the current streambed thalweg, the data available at 110 cross sections for dates before 10- and 100-yr water surfaces from the fixed-bed and after the July 1997 flood. The calibrated model models, the 10- and 100-yr peak water surfaces for the was then used to estimate aggradation, degradation, three streambed-management practices, and the and the water-surface profile in each of the three study streambed following 10- and 100-yr floods for the reaches for a 10- and a 100-yr flood following three three streambed-management practices. Elevations of different streambed-management practices: no the water-surface profiles are listed in Appendix D. removal of bed material, removal of bars and other The tables in Appendix D show the peak water-surface alluvial materials that reduce channel area, and elevations that could result at each cross section for a dredging the entire channel to 2 ft below the thalweg. 10- and 100-yr flood after the streambed-management In general, some decrease in the water-surface practice of restricting removal of bed material. For elevation was realized when channel maintenance was comparison, the differences of the peak water-surface done. In Montgomery, the water-surface elevations for SUMMARY AND CONCLUSIONS 17 20,000 15,000 - Synthetic 100-yr flood hydrograph for Trout River, Montgomery, Vt. Synthetic 10-yr flood hydrograph 10,000 - for Trout River, Montgomery, Vt. 5,000 - Q Z O o LU CO 8,000 cc B. LU Q. h- 6,000 LJJ Synthetic 100-yr flood hydrograph LU for Wild Branch, Wolcott, Vt. LJL 4,000 Synthetic 10-yr flood hydrograph O for Wild Branch, Wolcott, Vt. 00 => O 2,000 z III O 1 2 8 10 12 14 16 18 20 22 24 26 28 30 CC I< o 30,000 CO Q Synthetic 100-yr flood hydrograph 20,000 - for Lamoille River, Cambridge, Vt. Synthetic 10-yr flood hydrograph for Lamoille River, Cambridge, V 10,000 - 25 30 35 40 TIME, IN HOURS Figure 6. Synthetic 10- and 100-year flood hydrographs at the downstream end of the studied reach for the (A) Trout River, (B) Wild Branch, and (C) Lamoille River. 18 Application of a Sediment-Transport Model to Evaluate the Effect of Streambed-Management Practices on Flood Levels and Streambed Elevations at Selected Sites in Vermont the simulation with bar material scalped or removed restricting the removal of any bed materials. The were, on average lower (-0.1 and -0.2 ft) than the model, however, showed severe erosion under some water-surface elevations of the model with no channel bridges during a flood if dredging was practiced. maintenance on the Trout River for the 10- and 100-yr There were only minor differences, less than 1.5 ft on floods, respectively. The average water-surface average, in the resulting water-surface profile between elevation for the simulation in which the channel was the models where scalping (removing) bars or other dredged was lower (-1.5 and -1.1 ft) than the channel areas of decreased channel capacity was done prior to with no maintenance for the 10- and 100-yr floods, flooding and where the removal of bed material was respectively. restricted. All profiles evaluated in this study did not In the town of Cambridge, the average differ result in changes that could be observed on existing ence in the water-surface elevation of the Lamoille maps. Thus, flood-boundary maps were not developed River between the simulation in which bar material and the flood-boundary maps provided by Federal was scalped and the simulation with no channel Emergency Management Agency's flood-insurance maintenance was -0.1 ft for the 10- and 100-yr floods. studies are considered to be valid. The average difference in the water-surface elevation The models used in this study provide informa between the simulation in which the channel was tion on the effect of streambed-management practices dredged and the simulation with no channel mainte on the water-surface profile of a flood and on the bed nance was -1.4 and -1.0 ft for the 10- and 100-yr profile following a flood. The management practices floods, respectively. evaluated in this study would have local effects on The Wild Branch models for Wolcott did not flooding that are beyond the scope of this study. have decreased water-surface elevations at the cross Investigations of channel stability and stream restora sections, on average, that the other modelled reaches tion are currently being undertaken by the Vermont had for the simulated practices of channel manage Agency of Natural Resources. ment. The average difference in the water-surface elevation between the model with scalped bars and the model with no channel maintenance was +0.1 and SELECTED REFERENCES 0.0 ft for the 10- and 100-yr events, respectively. The average difference in the water-surface elevation Arcement, G.J., Jr., and Schneider, V.R., 1989, Guide for between the model, for a dredged channel and the selecting Manning's roughness coefficients for natural model with no channel maintenance was 0.0- and channels and flood plains: U.S. Geological Survey -0.5 ft for the 10- and 100-yr floods, respectively. Water-Supply Paper 2339, 38 p. Rivers continually change position and shape as Barnes, H.H., Jr., 1967, Roughness characteristics of natural a result of hydraulic forces. Rates of change are channels: U.S. Geological Survey Water-Supply Paper variable. Furthermore, a river may maintain stability 1849, 213 p. for long periods of time and then experience rapid Bedient, P.B., and Huber, W.C., 1988, Hydrology and movement. For example, the sinuosity, width, and floodplain analysis: Reading, Mass., Addison-Wesley depth of a channel can change to compensate for an Publishing Company, 650 p. unusually large hydrologic event. The effect of the Coakley, M.F., Kiah, R.G., Keirstead, Chandlee, and changes in the channel geometry on the peak water- Brown, R.O., 1998, Water Resources Data, New Hampshire and Vermont, Water Year 1997: U.S. surface elevations can vary, however. Comparing Geological Survey Water-Data Report NH-VT-97-1, average change in water surface between the pre- and p. 106-111. post-1997 flood fixed-bed models of the study area, Colby, B.R., 1961, Effect of depth of flow on discharge of the profiles are not significantly affected by the change bed material: U.S. Geological Survey Water-Supply in channel geometry. This was expected, because Paper 1498-D, 12 p. most of the flood waters are conveyed by the flood Federal Emergency Management Agency, 1980, Flood plains, especially during the larger 100-yr flood. insurance study, Town of Montgomery, Franklin From the movable-bed models, there were some County, Vermont: Washington, D.C., June 1980, 17 p. decreases in the mean water-surface profile when a 1982a, Flood insurance study, Town of Cambridge, streambed-management practice of channel dredging, Lamoille County, Vermont: Washington, D.C., prior to flooding, was followed as opposed to December 15, 1982, 18 p. SELECTED REFERENCES 19 1982b, Flood insurance study, Village of Richardson, E.V., Simons, D.B., and Julien, P.Y., 1990, Cambridge, Lamoille County, Vermont: Washington, Highways in the river environment: Federal Highway D.C., December 1, 1982, 15 p. Administration Publication FHWA-HI-90-016. 1982c, Flood insurance study, Village of Jefferson- Ritter, D.F., 1984, Process geomorphology: Debuque, Iowa, ville, Lamoille County, Vermont: Washington, D.C., WC. Brown Co., 603 p. December 15, 1982, 15 p. Shearman, J.O., 1990, User's manual for WSPRO -a 1982d, Flood insurance study, Town of Wolcott, computer model for water-surface profile computa Lamoille County, Vermont: Washington, D.C., tions: Federal Highway Administration Publication February 2, 1982, 17 p. FHWA-IP-89-027, 187 p. -1997, Mitigation strategy report in response to the Shearman, J.O., Kirby, W.H., Schneider, V.R., and July 25, 1997 Disaster Declaration for the State of Flippo, H.N., 1986, Bridge waterways analysis model; Vermont: Boston, Mass., July 1997. research report: Federal Highway Administration Publication FHWA-RD-86-108, 112 p. Hayes, D.C.,1993, Site selection and collection of bridge- scour data in Delaware, Maryland, and Virginia: Shen, H.W., and Julien, P.Y., 1993, Erosion and sediment U.S. Geological Survey Water-Resources Investiga transport in Maidment, D.R., ed., Handbook of tion Report 93-4017, 23 p. Hydrology: New York, McGraw Hill, chap. 12, p. 12.1-12.55. Hilmes, M.M., and Vaill, J.E., 1997, Estimates of bridge U.S. Army Corps of Engineers, 1977, HEC-2 Water-surface scour at two sites on the Virgin River, Southeastern profiles, Generalized Computer Program, Davis, Calif., Nevada, using a sediment-transport model and histor Hydrologic Information Center. ical geomorphic data: U.S. Geological Survey Water- U.S. Bureau of Reclamation, 1974, Design of small dams: Resources Investigations Report 97-4073, 72 p. U.S. Government Printing Office, p. 38-93. Lagasse, P.P., Schall, J.D., Johnson, F, Richardson, E.V., U.S. Geological Survey, 1948a, Gilson Mountain, Vermont, Chang, F, 1995, Stream stability at highway 7.5-minute series quadrangle map: U.S. Geological structures: Federal Highway Administration Hydraulic Survey Topographic Map, Photorevised 1980, scale Engineering Circular No. 20, Publication FHWA-IP- 1:24,000. 90-014, 144 p. 1948b, Jeffersonville, Vermont, 7.5-minute series Maidment, D.R., 1992, Handbook of hydrology: New York, quadrangle map: U.S. Geological Survey Topographic McGraw-Hill, Inc. Maps, scale 1:24,000. Molinas, Albert, and Santoro, V.C., 1989, Bri-Stars Model 1986a, Jay Peak, Vermont, 7.5-minute series and its applications, in Proceedings of the bridge scour quadrangle map: U.S. Geological Survey Topographic symposium: Federal Highway Administration Map, scale 1:24,000. Publication FHWA-RD-90-035, p. 256-271. 1986b, Richford, Vermont, 7.5-minute series Molinas, Albert, and Wu, Baosheng, 1997, User's primer quadrangle map: U.S. Geological Survey Topographic for Bri-Stars (BRIdge Stream Tube model for Alluvial Map, scale 1:24,000. Simulation): Fort Collins, Colo., Federal Highway 1986c, Wolcott, Vermont, 7.5-minute series Administration Project No. DTFH61-93-C-00068, quadrangle map: U.S. Geological Survey Topographic Hydrau-Tech, Inc., 43 p. Map, scale 1:24,000. National Oceanic and Atmospheric Administration, 1997, Yuzyk, T.R., 1986, Bed material sampling in gravel-bed Climatological data, New England, July 1997: streams: Environment Canada Water Survey of National Climatic Data Center, v. 109, no. 7. Canada Publication IWD-HQ-WRB-SS-86-8, 47 p. 20 Application of a Sediment-Transport Model to Evaluate the Effect of Stream bed-Management Practices on Flood Levels and Stream bed Elevations at Selected Sites in Vermont APPENDIX A: Pre- and Post-1997 Flood Cross Sections EXPLANATION Cross section from the 1980 or 1982 Flood Insurance Study Cross section as surveyed following the 1997 flood Pre- and Post-1997 Flood Cross Sections Trout River, Montgomery, Vermont 450 450 - 440 440 100 200 400 600 800 800 900 1,000 1,100 1,200 1,300 480 490 SECTION XS235 SECTION B LU LU 470 480 LL 460 470 LU 450 LLI 460 440 450 200 300 400 500 600 700 100 200 300 400 500 600 490 ! yTTTITTT. . | 1 I I STATE ROUTE 118 480 470 460 LLI 430 450 -200 -100 100 200 300 100 200 300 400 500 600 480 470 460 450 440 430 100 200 300 400 500 600 200 400 600 700 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX A 22 Pre- and Post-1997 Flood Cross Sections Trout River, Montgomery, Vermont 500 500 i i SECTION D SECTION G 490 490 480 480 470 470 460 460 450 450 100 200 300 400 500 200 300 400 500 600 700 500 490 480 470 460 450 100 150 200 250 300 350 400 200 300 400 500 600 700 UJ 450 460 100 200 300 400 500 800 900 1,000 1,100 1,200 1,300 500 510 500 VINCENT BRIDGE 490 490 480 480 470 470 460 460 450 450 0 100 200 300 400 80° 90° 1 '000 1 ' 100 1 '200 1>30° DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX A 23 Pre- and Post-1997 Flood Cross Sections Trout River, Montgomery, Vermont 500 510 SECTION J 505 SECTION N 490 500 480 495 490 470 485 460 480 800 900 1,000 1,100 1,200 1,300 200 300 400 500 600 700 520 SECTION O LLJ LLJ 510 LJL 500 LLJ LLJ 490 LLJ 480 CO 100 200 300 400 500 1,000 1,100 1,200 1,300 1,400 1,500 LLJ 510 O SECTION L CD 500 490 480 LLJ _l 470 LLJ 460 490 3()0 400 500 600 700 8C 700 800 900 1,000 1,100 1,200 520 510\J I \J ; SECTION M ; 515 - 500 510 490 505 H^\^-=^3**"^/ r : 500 480 495 A7f\ 490 1,300 1,400 1,500 1,600 1,700 1,800 300 400 500 600 700 800 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX A 24 Pre- and Post-1997 Flood Cross Sections Trout River, Montgomery, Vermont 550 SECTION U 540 530 520 iu 505 LU iu 500 510 LL 100 200 300 400 500 600 1,200 1,300 1,400 1,500 1,600 _T 540 550 LU SECTION S STATE ROUTE 118 UJ 530 540 S 520 530 LU 510 O 520 CO 500 510 O 100 200 300 400 500 600 1,000 1,100 1,200 1,300 1,400 1,500 h- 540 560 SECTION T SECTION V LiJ 535 550 LU 530 525 540 520 530 515 510 520 600 700 800 900 1,000 1,100 200 300 400 500 600 700 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX A 25 Pre- and Post-1997 Flood Cross Sections Wild Branch, Wolcott, Vermont 705 695 r 655 665 100 200 300 400 450 50 100 150 200 250 300 350 695 700 RAILROAD BRIDGE SECTION D LU LU 685 690 LL 675 680 LU LU 665 670 LLJ 655 660 CO 0 50 100 150 200 250 300 100 150 200 250 300 350 400 LLJ 695 710 O SECTION B SECTION E CO 685 700 675 690 LLJ 665 _l 680 LJJ 655 670 50 100 150 200 250 300 350 800 900 1,000 1,100 710 TOWN HIGHWAY 2 700 690 680 670 50 100 150 200 250 300 350 700 800 900 1,000 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX A 26 Pre- and Post-1997 Flood Cross Sections Wild Branch, Wolcott, Vermont 710 730 SECTION F SECTION J 700 720 690 710 680 700 670 690 700 800 900 1,000 900 1,000 1,100 1,200 710 730 TOWN HIGHWAY 15 720 710 700 LU 680 690 L CO 200 250 300 350 400 450 500 300 350 400 450 500 550 600 LU 720 730 O CD SECTION K 710 720 700 710 LU _l 690 700 LLI 680 690 50 100 150 200 250 300 350 400 450 500 550 600 650 700 715 740 SECTION L 730 705 720 695 710 685 700 ^ 50 100 150 200 250 300 300 350 400 450 500 550 600 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX A 27 Pre- and Post-1997 Flood Cross Sections Wild Branch, Wolcott, Vermont 750 760 SECTION P 740 750 730 740 720 730 710 720 200 250 300 350 400 450 500 50 100 150 200 250 300 350 750 760 SECTION N LJJ LJJ 740 750 U_ 730 740 LU > 720 LJJ 730 710 «-* LJJ 720 V) 200 250 300 350 400 450 500 350 400 450 500 550 600 650 STATION LJJ 750 780 O PRIVATE BRIDGE CO 740 770 730 760 LJJ 720 _J 750 LJJ 710 740 300 350 400 450 500 550 600 100 150 200 250 300 350 400 750 790 SECTION S SECTION O 745 780 740 735 770 730 760 725 720 750 250 300 350 400 450 500 550 150 200 250 300 350 400 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX A 28 Pre- and Post-1997 Flood Cross Sections Wild Branch, Wolcott, Vermont 800 810 SECTION T SECTION W 790 800 780 790 770 780 760 ^ 770 200 250 300 350 400 450 500 250 300 350 400 450 500 550 800 810 SECTION U SECTION X LU LU 790 800 Li. 780 790 LU LU 770 780 760 ' ' ' ' ' ' ' ' ' LU 770 CO 50 100 150 200 250 300 350 400 450 500 550 600 650 700 LU 810 820 O SECTION V CD SECTION Y 800 810 i 790 800 LU _l 780 790 LU 770 780 250 300 350 400 450 500 550 550 600 700 800 850 770 150 200 250 300 350 400 450 50 100 150 200 250 300 350 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX A 29 Pre- and Post-1997 Flood Cross Sections Wild Branch, Wolcott, Vermont 860 890 SECTION AA 850 880 840 870 830 860 820 850 L 250 300 350 400 450 500 550 200 250 300 350 400 450 500 860 890 SECTION AB SECTION AF1 LLJ LLJ 850 885 UL - 840 880 LLJ 830 LLJ 875 LLJ 820 L 870( CO 300 400 500 600 650 50 100 150 200 250 300 350 LLJ 865 905 O SECTION AC CO PRIVATE BRIDGE 855 895 O 845 885 g LLJ 835 _J 875 LLJ 825 865 450 500 550 600 650 700 750 50 100 150 200 250 300 350 910 SECTION AF 900 890 880 870 50 100 150 200 250 300 350 100 150 200 250 300 350 400 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX A 30 Pre- and Post-1997 Flood Cross Sections Wild Branch, Wolcott, Vermont 920 950 SECTION AG PRIVATE BRIDGE 910 940 900 930 890 920 880 910 300 400 500 600 700 0 100 200 300 400 500 600 930 SECTION AH LJJ LLI 920 910 _J LLI > 900 920 m 890 910 W 200 250 300 350 400 450 500 300 350 400 450 500 550 600 LLI > 940 950 O CO SECTION AL < 930 940 2 O p 920 930 < LU 910 920 LLI 900 910 100 200 300 350 200 250 300 350 400 450 500 950 SECTION AJ 940 930 920 910 ' ' ' ' ' ' ' ' ' ' ' ' ' 200 250 300 350 400 450 500 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX A 31 Pre- and Post-1997 Flood Cross Sections Lamoille River, Cambridge, Vermont 470 410 100 200 300 400 500 1,200 1,300 1,400 1,500 1,600 1,700 470 LLJ 460 111 450 440 LLJ 430 LLJ 420 LLJ 410 410 CO 2,000 2,100 2,200 2,300 2,400 2,500 900 1,000 1,100 1,200 1,300 LLJ O CO i LLJ LLJ 410 2,700 2,800 2,900 3,000 3,100 3,200 1,700 1,800 1,900 2,000 2,100 2,200 470 SECTION E 460 450 440 430 420 420 410700 800 900 1,000 1,100 1,200 1 '400 1 '500 1 '600 1 '700 1 '800 1 '900 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX A 32 Pre- and Post-1997 Flood Cross Sections Lamoille River, Cambridge, Vermont 480 480 470 SECTION VD 460 450 440 430 420 430 1,500 1,600 1,700 1,800 1,900 2,000 1,300 1,400 1,500 1,600 1,700 1,800 420 1,300 1,400 1,500 1,600 1,700 1,800 100 200 300 400 500 600 490 SECTION K 480 470 460 450 LU 440 420 430 700 800 900 1,000 1,100 1,200 400 500 600 700 800 900 480 490 SECTION H 480 STATE ROUTE 15 470 470 460 460 450 450 440 440 430 430 200 300 400 500 600 700 1 '200 1 '300 1 '400 1 '500 1 '600 1 '700 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX A 33 Pre- and Post-1997 Flood Cross Sections Lamoille River, Cambridge, Vermont 490 490 SECTION L SECTION O 480 480 470 470 460 460 450 450 440 440 430 430 1,400 1,500 1,600 1,700 1,800 1,900 2,600 2,700 2,800 2,900 3,000 3,100 430 1,400 1,500 1,600 1,700 1,800 1,900 1,200 1,300 1,400 1,500 1,600 1,700 480 RAILROAD EXIT 460 440 420 LLJ 430 400 1,900 2,000 2,100 2,200 2,300 2,400 500 600 700 800 900 1,000 480 STATE ROUTE 108 470 460 450 440 430 420 2,100 2,200 2,300 2,400 2,500 2,600 ouu800 90° 1 '000 1 ' 100 1 '200 1>30° DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX A 34 Pre- and Post-1997 Flood Cross Sections Lamoille River, Cambridge, Vermont 490 480 SECTION S 470 460 450 440 430 430 1,100 1,200 1,300 1,400 1,500 1,600 500 600 700 800 900 1,000 490 490 COVERED BRIDGE EXIT SECTION T LLJ 480 480 LLJ U_ 470 470 460 460 LLJ 450 450 LLJ 440 440 LLJ 430 430 CO 200 300 400 500 600 700 800 900 1,000 1,100 1,200 LLJ 490 O CO 480 SECTION U 470 460 450 LLJ _l LLJ 440 430 430 100 200 300 400 500 600 1,500 1,600 1,700 1,800 1,900 2,000 490 480 SECTION R 470 460 450 440 430 430 100 200 300 400 500 600 100 200 300 400 500 600 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX A 35 Pre- and Post-1997 Flood Cross Sections Lamoille River, Cambridge, Vermont *fyu ^fyu SECTION W - : SECTION Z : 480 480 470 - - 470 ^ 460A O/\ 460 - ____ -_ 450 l- \^^^ ^ K 450 440 7 -__ LU ' V^/ | m 440Ml \J LL 8()0 900 1,000 1,100 1,200 1,300 1,«)00 2,000 2,100 2,200 2,300 2/too Z P 4QO wl "wV/ 4QO^&\J LU : SECTION x : SECTION AA : > 480 480 < 47o - - 470 -_ ^\ UJ /ion ~ ^n ^-DU '^ J/"^"^^"^ 460 YV / ~ ^ 450 r ^^^^^v / -- 450 \^7^ J § 440 440 -i -7 T-OU 430 | L2 00 1,300 1,400 1,500 1,600 1,700 2,0 00 2,100 2,200 2,300 2,400 2,500 < 490 490 : SECTION Y : SECTION AB : L1J 480 480 '- m 470 470 I___ v y^ 460A O/"V 460 450 \ ^^ 1,' 1 00 1,200 1,300 1,400 1,500 1,( 00 43°7()0 800 900 1,000 1,100 1,2 00 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX A 36 APPENDIX B: Pre- and Post-flood of 1997 Profiles from Fixed-bed Models Pre- and Post-Flood of 1997 Profiles from Fixed-Bed Models 510 TROUT RIVER, MONTGOMERY, VERMONT 500 490 Covered Bridge 480 LU LL 470 Vincent Bridge 460 LU LU 450 Pre-flood thalweg Post-flood thalweg Pre-flood 10-year water surf ace Post-flood 10-year water surface LLJ 440 Pre-flood 100-year water surface Post-flood 100-year water surface C/D LLJ 430 § 7,000 8,000 9,000 10,000 11,000 12,000 13,000 14,000 15,000 16,000 17,000 18,000 19,000 CO 540 TROUT RIVER, MONTGOMERY, VERMONT O 530 I 520 LLJ 510 LLJ 500 490 Section Q TJ TJ m 480 Pre-flood thalweg Post-flood thalweg D Section M Pre-flood 10-year water surface Post-flood 10-year water surface X 470 CD Pre-flood 100-year water surface Post-flood 100-year water-surf ace 460 19,000 20,000 21,000 22,000 23,000 24,000 25,000 26,000 27,000 28,000 29,000 30,000 31,000 RIVER DISTANCE, IN FEET, FROM DOWNSTREAM CORPORATE LIMIT Pre- and Post-Flood of 1997 Profiles from Fixed-Bed Models WILD BRANCH, WOLCOTT, VERMONT . Pre-flood thalweg Post-flood thalweg - Pre-flood 10-year water surface Post-flood 10-year water surface Town Highway 2 Bridge . Pre-flood 100-year water surface Post-flood 100-year water surface 9,000 WILD BRANCH, WOLCOTT, VERMONT o o m . Pre-flood thalweg Post-flood thalweg o x . Pre-flood 10-year water surface Post-flood 10-year water surface DO ' Private Bridge . Pre-flood 100-year water surface Post-flood 100-year water-surface u CO 700 9,000 10,000 11,000 12,000 13,000 14,000 15,000 16,000 17,000 18,000 RIVER DISTANCE, IN FEET, FROM MOUTH Pre- and Post-Flood of 1997 Profiles from Fixed-Bed Models 850 840 WILD BRANCH, WOLCOTT, VERMONT 830 820 LU L Section AA LU 810 LL 800 790 L Section Z LU > 780 LU . Pre-flood thalweg Post-flood thalweg 770 . Pre-flood 10-year water surface Post-flood 10-year water surface L Tamarack Road LLI 760 Bridge . Pre-flood 100-year water surface Post-flood 100-year water surface CO LLI 750 18,000 19,000 20,000 21,000 22,000 23,000 24,000 25,000 26,000 27,000 O CO 930 920 WILD BRANCH, WOLCOTT, VERMONT O 910 I 900 LLI LLI 890 880 870 a 860 a m . Pre-flood thalweg Post-flood thalweg 850 1 Post-flood 10-year water surface x . Pre-flood 10-year water surface o 840 . Pre-flood 100-year water surface Post-flood 100-year water-surface 830 27,000 28,000 29,000 30,000 31,000 32,000 33,000 34,000 35,000 36,000 RIVER DISTANCE, IN FEET, FROM MOUTH Pre- and Post-Flood of 1997 Profiles from Fixed-Bed Models 460 LAMOILLE RIVER, CAMBRIDGE, VERMONT 450 440 LU 430 UJ 420 LJJ Pre-flood thalweg Post-flood thalweg - Section C < 410 Pre-flood 10-year water surface Post-flood 10-year water surface LJJ Pre-flood 100-year water surface Post-flood 100-year water surface C/D LU 400 > 5,000 10,000 15,000 20,000 25,000 30,000 35,000 40,000 45,000 O CO ^^ 480 Z LAMOILLE RIVER, CAMBRIDGE, VERMONT O 470 - Railroad Bridge > 460 LJJ LU 450 440 Section W L Section AA o 430 m Pre-flood thalweg Post-flood thalweg s x l ' Covered Bridge O Pre-flood 10-year water surface Post-flood 10-year water surface X 420 _ - Route 108 CD Pre-flood 100-year water surface Post-flood 100-year water-surface 410 45,000 50,000 55,000 60,000 65,000 70,000 75,000 80,000 85,000 RIVER DISTANCE, IN FEET, FROM DOWNSTREAM CORPORATE LIMIT APPENDIX C: Movable-bed Model Results Profiles Movable Bed Model Results 510 10-YEAR FLOOD ON THE TROUT RIVER, MONTGOMERY, VERMONT 500 Current thalweg . . . 10-year water surface-fixed bed model 490 Post-flood thalweg-no bed material removed Peak water surface-no bed material removed Post-flood thalweg-bed material scalped . _ _ . Peak water surface-bed material scalped 480 LU Post-flood thalweg-channel dredged Peak water surface-channel dredged LU 470 -Route 118 r Bridge 460 LU 450 LU 440 LU C/D 430 LU 7,000 8,000 9,000 10,000 11,000 12,000 13,000 14,000 15,000 16,000 17,000 18,000 19,000 O CO 540 10-YEAR FLOOD ON THE TROUT RIVER, MONTGOMERY, VERMONT 530 : Current thalweg . 10-year water surface-fixed bed model 520 Post-flood thalweg-no bed material removed Peak water surface-no bed material removed Post-flood thalweg--bed material scalped . _ _ . Peak water surface-bed material scalped LU 510 _l Post-flood thalweg-channel dredged ..... Peak water surface-channel dredged LU 500 490 Section Q o o 480 x o 470 - Section M 460 19,000 20,000 21,000 22,000 23,000 24,000 25,000 26,000 27,000 28,000 29,000 30,000 31,000 RIVER DISTANCE, IN FEET, FROM DOWNSTREAM CORPORATE LIMIT Movable Bed Model Results 510 100-YEAR FLOOD ON THE TROUT RIVER, MONTGOMERY, VERMONT 500 Current thalweg . . 100-year water surface-fixed bed model 490 Post-flood thalweg-no bed material removed Peak water surface-no bed material removed Post-flood thalweg-bed material scalped . _ _ . Peak water surface-bed material scalped 111 480 Post-flood thalweg-channel dredged Peak water surface-channel dredged 111 470 460 HI Vincent Bridge 450 HI Route 118 440 Bridge Covered Bridge LLJ CO 430 LLJ 7,000 8,000 9,000 10,000 11,000 12,000 13,000 14,000 15,000 16,000 17,000 18,000 19,000 O CO 540 100-YEAR FLOOD ON THE TROUT RIVER, MONTGOMERY, VERMONT 530 Current thalweg i . . 100-year water surface-fixed bed model 520 Post-flood thalweg-no bed material removed Peak water surface-no bed material removed LU 510 Post-flood thalweg-bed material scalped . - - Peak water surface-bed material scalped _l Post-flood thalweg-channel dredged Peak water surface-channel dredged LLJ 500 490 TJ Section Q TJ m 480 o X o 470 - Section M 460 19,000 20,000 21,000 22,000 23,000 24,000 25,000 26,000 27,000 28,000 29,000 30,000 31,000 RIVER DISTANCE, IN FEET, FROM DOWNSTREAM CORPORATE LIMIT Movable Bed Model Results 740 730 10-YEAR FLOOD ON THE WILD BRANCH, WOLCOTT, VERMONT 720 Gulf Road Bridge 710 - 700 - LU 690 680 670 HI Current thalweg . 10-year water surface-fixed bed model 660 Town Highway 2 Bridge Post-flood thalweg--no bed material removed Peak water surface-no bed material removed |j 650 - -Route 15 Post-flood thalweg~bed material scalped - - Peak water surface-bed material scalped HI 640 Post-flood thalweg-channel dredged Peak water surface-channel dredged C/D 630 HI 0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 CQ 790 -" -, 780 - 10-YEAR FLOOD ON THE WILD BRANCH, WOLCOTT, VERMONT 770 - Section R o Current thalweg ,. 10-year water surface-fixed bed model o m Post-flood thalweg~no bed material removed Peak water surface-no bed material removed o ' Private Bridge Post-flood thalweg-bed material scalped .. Peak water surface-bed material scalped X o Post-flood thalweg-channel dredged Peak water surface-channel dredged 680 9,000 10,000 11,000 12,000 13,000 14,000 15,000 16,000 17,000 18,000 RIVER DISTANCE, IN FEET, FROM MOUTH Movable Bed Model Results 860 850 10-YEAR FLOOD ON THE WILD BRANCH, WOLCOTT, VERMONT 840 830 820 HI HI 810 L LJL Section AA 800 790 L Section Z HI 780 Current thalweg 10-year water surface-fixed bed model HI Post-flood thalweg--no bed material removed Peak water surface-no bed material removed 770 - _ _ . Post-flood thalweg-bed material scalped Peak water surface-bed material scalped Tamarack Road HI 760 Bridge ...... Post-flood thalweg-channel dredged Peak water surface-channel dredged C/D 750 §HI 18,000 19,000 20,000 21,000 22,000 23,000 24,000 25,000 26,000 27,000 CO 940 930 10-YEAR FLOOD ON THE WILD BRANCH, WOLCOTT, VERMONT 920 910 Ill 900 _l Private Bridge 111 890 Section AH 880 870 Current thalweg 10-year water surface-fixed bed model TJ TJ 860 m Post-flood thalweg~no bed material removed Peak water surface-no bed material removed o 850 Private Bridge - Post-flood thalweg-bed material scalped Peak water surface-bed material scalped x o 840 Post-flood thalweg-channel dredged Peak water surface-channel dredged 830 27,000 28,000 29,000 30,000 31,000 32,000 33,000 34,000 35,000 36,000 RIVER DISTANCE, IN FEET, FROM MOUTH Movable Bed Model Results 740 730 100-YEAR FLOOD ON THE WILD BRANCH, WOLCOTT, VERMONT Gulf Road 720 Bridge 710 tn 700 LU 690 LL 680 670 __Town Highway 2 LU ^ Current thalweg 100-year water surface-fixed bed model 660 Bridge LU Post-flood thalweg-no bed material removed Peak water surface-no bed material removed 650 . _ _ . Post-flood thalweg-bed material scalped Peak water surface-bed material scalped a 640 Post-flood thaiweg-channel dredged Peak water surface-channel dredged CO 630 LU 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 O CO 790 780 100-YEAR FLOOD ON THE WILD BRANCH, WOLCOTT, VERMONT 770 760 LU 750 LU 740 730 720 TJ _ Current thalweg 100-year water surface-fixed bed model m 710 Post-flood thalweg-no bed material removed Peak water surface-no bed material removed g Private Bridge x 700 .. Post-flood thalweg-bed material scalped Peak water surface-bed material scalped o 690 Post-flood thalweg-channel dredged Peak water surface-channel dredged 680 9,000 10,000 11,000 12,000 13,000 14,000 15,000 16,000 17,000 18,000 RIVER DISTANCE, IN FEET, FROM MOUTH Movable Bed Model Results 860 850 100-YEAR FLOOD ON THE WILD BRANCH, WOLCOTT, VERMONT 840 830 fc 820 LU 810 Section AA 800 790 Section Z LU 780 __ Current thalweg 100-year water surface-fixed bed model LU Post-flood thalweg--no bed material removed Peak water surface-no bed material removed 770 . _ . Post-flood thalweg--bed material scalped Peak water surface-bed material scalped LU 760 Tamarack Road Post-flood thalweg-charmel dredged Peak water surface-channel dredged Bridge CO 750 LU 18,000 19,000 20,000 21,000 22,000 23,000 24,000 25,000 26,000 27,000 § CO 940 930 100-YEAR FLOOD ON THE WILD BRANCH, WOLCOTT, VERMONT O 920 910 1LU 900 _J LU 890 Private Bridge Section AH 880 870 . Current thalweg 100-year water surface-fixed bed model 860 - Post-flood thalweg~no bed material removed Peak water surface-no bed material removed 3 Private Bridge x 850 . Post-flood thalweg-bed material scalped Peak water surface-bed material scalped o 840 Post-flood thalweg-channel dredged Peak water surface-channel dredged 830 27,000 28,000 29,000 30,000 31,000 32,000 33,000 34,000 35,000 36,000 RIVER DISTANCE, IN FEET, FROM MOUTH Movable Bed Model Results 470 10-YEAR FLOOD ON THE LAMOILLE RIVER, CAMBRIDGE, VERMONT Route 108 460 - Route 15 450 fc 440 LU LL 430 420 Route 15- LU Current thalweg . 10-year water surface-fixed bed model > 410 LU - Section C Post-flood thalweg--no bed material removed - Peak water surface-no bed material removed Post-flood thalweg~bed material scalped . Peak water surface-bed material scalped 400 LJJ Post-flood thalweg-channel dredged Peak water surface-channel dredged CO 390 LJJ 10,000 15,000 20,000 25,000 30,000 35,000 40,000 45,000 48,000 O CO 480 10-YEAR FLOOD ON THE LAMOILLE RIVER, CAMBRIDGE, VERMONT 470 O Railroad Bridge 460 ILJJ 450 _l LJJ 440 Section W L Section AA o 430 o __ Current thalweg - 10-year water surface-fixed bed model m o 420 Post-flood thalweg-no bed material removed Peak water surface-no bed material removed" x L Covered Bridge o - - Post-flood thalweg-bed material scalped . _ _ . Peak water surface-bed material scalped 410 Post-flood thalweg-channel dredged Peak water surface-channel dredged 400 50,000 55,000 60,000 65,000 70,000 75,000 80,000 85,000 RIVER DISTANCE, IN FEET, FROM DOWNSTREAM CORPORATE LIMIT Movable Bed Model Results 470 100-YEAR FLOOD ON THE LAMOILLE RIVER, CAMBRIDGE, VERMONT Route 10! 460 -Route 15 450 r fc 440 LU LL 430 420 Route 1£J LJJ Current thalweg 100-year water surface-fixed bed model 410 - L LJJ Section C Post-flood thalweg-no bed material removed Peak water surface-no bed material removed Post-flood thalweg-bed material scalped Peak water surface-bed material scalped 400 LJJ Post-flood thalweg-channel dredged Peak water surface-channel dredged CO 390 LJJ 10,000 15,000 20,000 25,000 30,000 35,000 40,000 45,000 48,000 g CO 480 100-YEAR FLOOD ON THE LAMOILLE RIVER, CAMBRIDGE, VERMONT 470 r Railroad Bridge 460 LU 450 _J LU 440 L Section AA 430 Section W _ Current thalweg 100-year water surface-fixed bed model g 420 Post-flood thalweg-no bed material removed Peak water surface-no bed material removed" X - - Post-flood thalweg-bed material scalped . _ _ . Peak water surface-bed material scalped o Covered Bridge 410 Post-flood thalweg-channel dredged Peak water surface-channel dredged 400 50,000 55,000 60,000 65,000 70,000 75,000 80,000 85,000 RIVER DISTANCE, IN FEET, FROM DOWNSTREAM CORPORATE LIMIT APPENDIX D: Peak Water-surface Elevations from the Movable-bed Models in Tabular Form The tables in Appendix D display the peak water-surface elevation at each cross section for a 10- and 100-yr flood occurring after the streambed management prac tices in which removal of bed material is restricted. For comparison, the differ ences of the peak water-surface elevations between the practices restricting removal of bed material and the scalping of bars and dredging are also included. Table D1. Peak water-surface elevations at each cross section following the three streambed managment scenarios on the Trout River, Montgomery, Vt. Change in 10-yrpeak Change in 10-yr Change in 10-yr 100-yr peak Change in 100-yr peak 0 .. water-surface, no peak water- peak water- water-surface, no 100-yr peak Section . ... water-surface, . . 4... removal of bed surface, bed surface, bed removal of bed water-surface, identifier . . , bed material material material scalped dredged material bed dredged scalped (ft) (ft) (ft) (ft) (ft) (ft) XS24 452.0 0.0 0.0 454.6 0.0 0.0 XS235 455.7 .0 -1.0 458.4 .0 -.8 Route 118 456.3 .0 -.8 458.9 .0 -.6 XS22 456.6 .0 -1.2 460.2 .0 -1.6 A 460.7 .0 -1.9 463.5 .0 -1.0 B 464.7 .0 -1.6 466.4 .0 -1.1 Route 118 465.4 .0 -1.4 467.1 .0 -1.0 C 465.9 .1 -1.8 468.0 .0 .0 D 466.6 -.1 1.1 470.8 .0 -.3 Covered 472.8 .0 -2.9 475.0 .0 -.4 E 474.4 .0 -4.7 476.5 .0 -.4 F 474.5 .0 -3.6 476.1 .0 -.5 G 476.6 .0 -1.8 480.9 .0 -.7 H 477.3 .0 -1.3 481.1 .0 -.7 I 477.9 .0 -1.2 481.5 .0 -.6 Vincent 477.9 .0 -1.2 481.5 .0 -.6 J 477.9 .1 -.7 481.5 .0 -.7 K 480.4 -.6 -1.6 482.6 -.1 -.7 L 481.9 -.2 -1.1 484.1 .0 -.4 M 486.5 .0 -.7 488.3 .0 -.4 N 491.3 .0 -.9 493.0 .0 -.5 O 495.9 -.2 -.7 498.0 -.2 -.7 P 499.1 -.5 -.7 500.9 -.2 .1 Q 503.7 -1.0 -.6 505.6 -.9 -.4 R 508.6 .0 -.9 511.0 -.6 -.2 S 511.8 .2 -1.7 516.3 .4 -2.1 T 519.3 .2 -2.4 523.5 -2.7 -4.8 U 524.3 .2 -2.8 525.6 .0 -3.8 Route 118 525.5 -.2 -2.6 527.5 -1.8 -4.6 V 527.8 -.1 -2.0 531.1 -.1 -2.1 Average -.1 -1.5 -.2 -1.1 APPENDIX D 54 Table D2. Peak water-surface elevations at each cross section following the three streambed managment scenarios on the Wild Branch, Wolcott, Vt. 1 0-yr peak Change in 1 0-yr Change in 10-yr 100-yr peak Change in 100-yr Change in 100-yr _ . water-surface, peak water-surface, peak water- water-surface, peak water-surface, peak water-surface, -i *-.c- no removal of bed material surface, bed no removal of bed material identifier . . . . , , . bed dredged bed material scalped dredged bed material scalped (ft) (ft) (ft) (ft) (ft) (ft) A 676.0 0.3 0.3 678.2 -0.3 -1.1 Railroad 677.4 .5 .6 683.1 .0 0.6 B 681.5 -2.0 2.2 685.2 .0 .6 C 681.5 -2.0 2.2 685.2 .0 .6 Route 15 681.4 -1.9 2.2 685.0 .0 .7 D 682.1 -.2 1.9 686.0 .0 .3 E 684.9 2.7 .1 687.0 .1 -.2 TH2 685.0 2.5 .4 686.9 2.1 1.8 F 686.8 1.0 2.4 689.3 1.5 1.4 G 690.6 -.7 -.4 693.5 1.4 -1.0 H 695.2 -.3 -.6 698.4 -.5 -1.1 I 698.7 .0 -.1 702.0 -.1 -.5 J 704.8 .0 .2 708.9 .1 -.4 TH15 704.9 .0 .9 709.5 -.1 -.6 K 704.9 -.1 .9 710.1 -.2 -1.0 L 714.0 -.3 -.9 715.6 .0 -.2 M 724.9 -.1 -3.6 727.0 -.3 -2.5 N 121.1 -1.3 -2.3 730.2 -1.7 -3.1 Bridge PI 731.6 .9 -1.7 731.3 .8 2.2 O 732.9 1.0 .2 733.2 .3 2.2 P 734.5 .0 -1.0 735.4 .0 .3 Q 737.0 -.2 -.5 738.5 -.1 -.4 R 755.4 -1.0 -1.0 757.4 -.6 -.6 S 760.9 -.8 -1.4 762.7 -.4 -.6 T 774.0 .3 -.1 776.9 .1 -.1 U 777.8 .2 .0 781.6 .0 -2.0 V 782.7 .4 .6 787.8 .1 -2.2 THIS 784.1 .0 .9 788.6 -.1 -.9 W 787.0 -.2 4.2 792.6 -.1 -2.1 X 791.2 .2 .3 793.8 -.6 -.9 Y 797.9 .4 -1.6 799.2 .1 -.1 Z 807.7 -.1 -.2 808.8 .2 -.4 AA 831.0 -.6 .2 833.6 -.6 -.5 AB 837.3 -1.1 .5 840.2 .0 -2.5 AC 841.5 -.2 -.4 843.7 2.0 -2.0 AD 854.6 .3 -.3 857.7 1.3 -2.7 AE 861.1 .9 .1 861.4 .9 -1.6 API 876.6 -1.6 -2.9 879.2 -3.0 1.6 Bridge P2 875.6 3.8 2.2 886.7 -2.8 -1.9 AF 880.7 1.9 .2 888.9 -.8 .1 AG 890.4 -.1 -1.6 891.6 .2 -.7 AH 908.7 -.2 -1.8 909.7 .2 .1 AI 912.2 -.7 -1.9 912.9 -.3 -1.1 AJ 915.4 -.6 -.9 919.9 -3.8 -.7 Bridge P3 919.6 .9 1.3 920.3 1.6 -.1 AK 920.8 .9 1.4 921.5 1.8 -.5 AL 928.2 -.4 -.1 929.8 -.4 -.9 Average .1 .0 .0 -.5 APPENDIX D 55 Table D3. Peak water-surface elevations at each cross section following the three streambed managment scenarios on the Lamoille River, Cambridge, Vt. 10-yrpeak Change in 10-yr Change in 10-yr 100-yrpeak Change in 100-yr Change in 100-yr water-surface, peak water- peak water- water-surface, no peak water- peak water- Section no removal of surface, bed surface, bed removal of bed surface, bed surface, bed identifier bed material material scalped dredged material material scalped dredged (ft) (ft) (ft) (ft) (ft) (ft) C 442.6 0.0 0.0 447.1 0.0 0.0 D 443.3 .0 -.2 447.9 .0 -.1 X39 443.3 .0 -.2 447.9 .0 -.1 E 443.4 .0 -.2 448.0 .0 -.1 VA 443.9 .0 -.4 448.3 .0 -.2 VB 444.4 .0 -.5 448.6 .0 -.2 VC 444.7 -.1 -.6 448.7 .0 -.4 Route 15 445.5 -.1 -.7 449.0 .0 -.3 VD 446.0 -.1 -1.0 449.7 .0 -.4 F 447.2 -.1 -.8 450.7 .0 -.5 G 447.5 .0 -.8 451.0 .0 -.5 H 447.9 .0 -.8 451.4 .0 -.5 I 448.9 .0 -1.0 452.3 .0 -.7 J 451.0 .0 -1.2 454.2 .0 -.9 K 452.7 .0 -1.5 456.0 .0 -1.0 Route 15 452.7 .0 -1.5 455.9 .0 -1.0 L 453.1 .0 -1.5 456.6 .0 -1.1 M 453.5 .0 -1.6 457.0 .0 -1.2 N 454.9 -.1 -1.8 458.3 -.1 -1.3 Route 108 454.8 -.1 -1.9 458.2 -.1 -1.3 O 455.8 -.1 -1.9 459.6 -.1 -1.6 P 457.4 -.2 -2.6 460.8 -.1 -1.7 RR Exit 458.1 -.2 -2.6 461.4 -.1 -1.6 Railraod 457.9 -.1 -2.6 461.2 -.1 -1.6 Q 458.1 -.2 -2.6 461.5 -.1 -1.7 Exit 458.5 -.2 -2.5 462.1 -.1 -1.6 Covered 458.4 -.2 -2.4 461.9 -.1 -1.6 R 458.7 -.2 -2.5 462.3 -.1 -1.6 S 459.2 -.1 -2.4 462.9 -.1 -1.5 T 459.6 -.1 -2.1 463.2 -.1 -1.4 U 460.2 -.1 -1.6 463.8 -.1 -1.2 V 460.6 -.1 -1.5 464.1 -.1 -1.2 w 461.4 -.1 -1.5 464.7 -.1 -1.2 X 462.2 -.1 -1.5 465.4 -.1 -1.2 Y 462.6 -.1 -1.5 465.6 -.1 -1.2 Z 463.3 -.1 -1.4 466.2 -.1 -1.1 AA 464.3 .0 -1.3 467.0 -.1 -1.0 AB 466.2 .0 -1.3 468.7 .0 -.9 Average -.1 -1.4 -.1 -1.0 APPENDIX D 56 APPENDIX E: Movable-bed Model Results Cross-section Geometry EXPLANATION Cross section as surveyed following the 1997 flood Cross section following synthesized flood channel untouched prior to flood Cross section following synthesized flood channel scalped prior to flood Cross section following synthesized flood channel dredged prior to flood Cross sections are located on the following figures: Montgomery, Vt. . . . figure 2 Wolcott, Vt...... figure 3 Cambridge, Vt...... figure 4 Movable Bed Model Results 10-year flood on the Trout River, Montgomery, Vermont 480 480 SECTION XS24 SECTION A 470 470 460 460 450 440 450 430 440 100 200 400 600 800 800 900 1,000 1,100 1,200 1,300 480 SECTION B 470 460 450 440 300 400 500 600 700 100 200 300 400 500 600 490 STATE ROUTE 118 480 470 460 LLJ 430 450 -200 -100 100 200 300 100 200 300 400 500 600 480 SECTION XS22 470 460 450 440 430 100 200 300 400 500 600 100 200 300 400 500 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX E 58 Movable Bed Model Results 10-year flood on the Trout River, Montgomery, Vermont 500 500 SECTION D SECTION G 490 490 480 480 470 470 460 460 450 450 100 200 300 400 500 200 300 400 500 600 700 510 500 500 COVERED BRIDGE SECTION H LLJ 490 LLJ LL. Z 480 480 470 LLJ 460 LLJ 460 LLJ 440 450 O) 100 150 200 250 300 350 400 200 300 400 500 600 700 LLJ O CO LLJ _J LLJ 450 460 100 200 300 400 500 800 900 1,000 1,100 1,200 1,300 500 510 500 VINCENT BRIDGE 490 490 480 480 470 470 460 460 450 450 0 100 200 300 400 80° 90° 1 '000 1>10° 1 '200 1 '300 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX E 59 Movable Bed Model Results 10-year flood on the Trout River, Montgomery, Vermont 500 510 SECTION J SECTION N 490 500 480 490 470 480 460 470 800 900 1,000 1,100 1,200 1,300 200 300 400 500 600 700 510 520 SECTION O 111 500 111 510 490 500 480 HI HI 470 490 HI 460 480 CO 0 100 200 300 400 500 1,000 1,100 1,200 1,300 1,400 1,500 HI 510 520 O SECTION L SECTION P CO 500 510 O 490 500 480 g HI _J 470 490 HI 460 480 300 400 500 600 700 800 700 800 900 1,000 1,100 1,200 510 520 SECTION M 515 500 510 490 505 500 480 495 470 490 1,300 1,400 1,500 1,600 1,700 1,800 300 400 500 600 700 800 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX E 60 Movable Bed Model Results 10-year flood on the Trout River, Montgomery, Vermont oou oou ; SECTION R ; SECTION U ] 540 520 530 510 - : \fV\^t 520 X ,_ 500 510 y^f LLJ LJJ L1J 490 500 U- 1C)0 200 300 400 500 6C)0 1,2>00 1,300 1,400 1,500 1,600 2 _J 540 550 LJJ : SECTION s ; > STATE ROUTE 118 ; 540 W 530 530 § 520 - LJJ 520 > O 510 CD M 1 1 1 1 $ 500 500 Q 1()0 200 300 400 500 6C)0 1,0 00 1,100 1,200 1 ,300 1,400 1,500 < 540 ; SECTION T LJJ SECTION V ; d 53° 550 540 520 r~~~\r^ K 530 1 510 520 snn cin 600 700 800 900 1,000 1,100 200 300 400 500 600 700 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX E 61 Movable Bed Model Results 100-year flood on the Trout River, Montgomery, Vermont 480 480 SECTION XS24 SECTION A 470 470 460 460 450 440 450 430 440 100 200 400 600 800 800 900 1,000 1,100 1,200 1,300 480 480 SECTION B 470 460 450 440 700 100 200 300 400 500 600 LU 430 450 -200 -100 100 200 300 100 200 300 400 500 600 480 SECTION XS22 470 460 450 440 430 100 200 300 400 500 600 100 200 300 400 500 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX E 62 Movable Bed Model Results 100-year flood on the Trout River, Montgomery, Vermont 500 500 SECTION D SECTION G 490 490 480 480 470 470 460 460 450 450 100 200 300 400 500 200 300 400 500 600 700 510 500 500 COVERED BRIDGE SECTION H LLJ 490 LLJ LL 480 480 LLJ 470 > 460 LLJ 460 LU 440 450 CO 100 150 200 250 300 350 400 200 300 400 500 600 700 LU O GO LU _l LU 450 460 100 200 300 400 500 800 900 1,000 1,100 1,200 1,300 500 510 500 490 490 480 480 470 470 460 460 450 450 0 100 200 300 400 80° 90° 1 '000 1 ' 100 1 '200 1 '300 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX E 63 Movable Bed Model Results 100-year flood on the Trout River, Montgomery, Vermont 510 SECTION N 500 490 470 - 480 460 470 800 900 1,000 1,100 1,200 1,300 200 300 400 500 600 700 510 520 SECTION K SECTION O LJU 500 LJU 510 490 500 480 LJU LJU 470 490 LJU 460 480 CO i 100 200 300 400 500 1,000 1,100 1,200 1,300 1,400 1,500 LJU 510 520 O SECTION L SECTION P CO 500 510 490 500 480 LJU _l 470 490 LJJ 460 480 300 400 500 600 700 800 700 800 900 1,000 1,100 1,200 520 515 510 505 500 495 470 490 1,300 1,400 1,500 1,600 1,700 1,800 300 400 500 600 700 800 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX E 64 Movable Bed Model Results 100-year flood on the Trout River, Montgomery, Vermont oou oou ; SECTION R ; : SECTION U : 540 520 530 510 '- 520 X ,_ 500 Vw ; 510 -_ HI HI O HI 490 500 H. 1C)0 200 300 400 500 6C)0 1,2>00 1,300^ 1,400 1,500 1,600 Z _f 540 550 HI SECTION S ; > STATE ROUTE 118 : W 530 540 530 CO 520 HI ^^SSS3^-^ 520 0> 51 ° 510 - CO V -, 500 500 Q 1C)0 200 300 400 500 6C)0 1,0 00 1,100 1,200 1 ,300 1,400 1,500 < 540 SECTION T HI : SECTION V ; GJ 53° 550 540 520 ""I t 530 510 w 520 500 K-in i ^n 600 700 800 900 1,000 1,100 200 300 400 500 600 700 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX E 65 Movable Bed Model Results 10-year flood on the Wild Branch, Wolcott, Vermont 705 680 695 670 660 650( 665 50 100 150 200 250 300 350 50 100 150 200 250 300 350 695 .\ . , , . 700 RAILROAD BRIDGE SECTION D LU LU 685 - 690 U_ f - 680 LU '- 665 - LU r 670 ~ t ...... i...... i...... i.../ LU 660 CO 50 100 200 300 400450 100 150 200 250 300 350 400 LU 690 710 O SECTION B CO SECTION E < 680 700 670 690 W 660 680 LU 650 ' .I....I....I... .i .... i.. 670 50 100 150 200 250 300 800 900 1,000 1,100 700 710 TOWN HIGHWAY 2 SECTION C 690 700 680 690 670 680 660 r. . . .i... . i .. . . 50 100 150 700 800 900 1 ,000 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX E 66 Movable Bed Model Results 10-year flood on the Wild Branch, Wolcott, Vermont 710 730 SECTION F SECTION J 700 720 690 710 680 700 670 690 700 800 900 1,000 900 1,000 1,100 1,200 730 TOWN HIGHWAY 15 720 710 700 690 LU 670 680 CO 200 250 300 350 400 450 500 300 350 400 450 500 550 600 LU 720 730 O SECTION H CD SECTION K 710 720 700 710 LJJ 690 _J 700 LJJ 680j 690 50 100 150 200 250 300 350 400 450 500 550 600 650 700 720 740 SECTION L SECTION I 710 730 700 720 690 710 680 700 0 50 100 150 200 250 300 300 350 400 450 500 550 600 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX E 67 Movable Bed Model Results 10-year flood on the Wild Branch, Wolcott, Vermont 760 750 740 - 720 - 730 - 710 720 200 250 300 350 400 450 500 50 100 150 200 250 300 350 750 760 SECTION N SECTION Q LJJ LJJ 740 750 U_ 730 740 LJJ 720 LJJ 730 LJJ 710 720 CO 200 250 300 350 400 450 500 350 400 450 500 550 600 650 LJJ 750 780 O PRIVATE BRIDGE CD SECTION R 740 770 730 760 LJJ 720 _l 750 LJJ 710 740 300 350 400 450 500 550 600 100 150 200 250 300 350 400 790 780 770 760 710 750 250 300 350 400 450 500 550 100 150 200 250 300 350 400 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX E 68 Movable Bed Model Results 10-year flood on the Wild Branch, Wolcott, Vermont 800 810 SECTION T SECTION W 790 800 780 790 770 780 760 770 200 250 300 350 400 450 500 250 300 350 400 450 500 550 800 810 SECTION U SECTION X LJJ LJJ 790 800 LI- ~ 780 790 LJJ 770 LU 780 LJJ 760 770 CO 50 100 150 200 250 300 350 400 450 500 550 600 650 700 LJJ 800 820 O SECTION V CD SECTION Y 790 810 780 800 LJJ 770 _l 790 LJJ 760 780 ' ' 250 300 350 400 450 500 550 550 600 700 800 850 830 SECTION Z 820 810 800 770 790 150 200 250 300 350 400 450 50 100 150 200 250 300 350 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX E 69 Movable Bed Model Results 10-year flood on the Wild Branch, Wolcott, Vermont 880 SECTION AE 870 860 830 - 850 820 840 250 300 350 400 450 500 550 200 250 300 350 400 450 500 860 [ I I T -I | 1 I I I [ 890 SECTION AB 111 III 850 880 840 870 111 111 830 860 111 820 850( CO 300 350 400 450 500 550 600 50 100 150 200 250 300 350 111 865 905 o SECTION AC CD PRIVATE BRIDGE 855 895 z O 1[Z 845 885 111 835 875 111 825 865 450 500 550 600 650 700 750 50 100 150 200 250 300 350 910 i i i i SECTION AF 900 890 880 870 50 100 150 200 250 300 350 100 150 200 250 300 350 400 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX E 70 Movable Bed Model Results 10-year flood on the Wild Branch, Wolcott, Vermont 920 950 SECTION AG 910 940 900 930 - 890 920 - 880 910 400 450 500 550 600 650 700 0 100 200 300 400 500 600 930 940 SECTION AH LU SECTION AK HI 920 930 910 920 LU LU 900 910 LU 890 900 CO 200 250 300 350 400 450 500 300 350 400 450 500 550 600 LU 940 r T ^' T i 950 O 00 SECTION Al SECTION AL 930 940 920 930 LU _l 910 920 LU 900( 910 50* 100 150 200 250 300 350 200 250 300 350 400 450 500 950 SECTION AJ 940 930 920 910 900 200 250 300 350 400 450 500 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX E 71 Movable Bed Model Results 100-year flood on the Wild Branch, Wolcott, Vermont I ' ' I SECTION A 680 670 vi/ 660 r- j 650 640 665 50 100 150 200 250 300 350 50 100 150 200 250 300 350 695 . \ . 1 1 1 1 i i i i _ 700 RAILROAD BRIDGE SECTION D LU 111 685 690 LJL ______: " 675 - 680 LU - - LU 665 - 670 «J r < 660 L-' LU 655 CO 50 100 150 200 250 300 350 100 150 200 250 300 350 400 LU 710 O CO SECTION E < 700 z O 690 LU 660 - I 680 LJJ 650 670 50 100 200 300 400 800 900 1,000 1,100 710 TOWN HIGHWAY 2 700 690 665 - 680 655 50 100 700 800 900 1,000 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX E 72 Movable Bed Model Results 100-year flood on the Wild Branch, Wolcott, Vermont 710 730 SECTION F SECTION J 700 720 690 710 680 700 670 690 700 800 900 1,000 900 1,000 1,100 1,200 720 710 TOWN HJj iHWAY 15 700 690 680 670 LLJ 670 660 CO 200 250 300 350 400 450 500 300 350 400 450 500 550 600 LLJ 720 730 O CD SECTION H SECTION K 710 720 700 710 LLJ 690 _l 700 LLJ 680( 690 50 100 150 200 250 300 350 400 450 500 550 600 650 700 720 740 SECTION L 710 730 700 720 690 710 i .... i 680 700 50 100 150 200 250 300 300 350 400 450 500 550 600 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX E 73 Movable Bed Model Results 100-year flood on the Wild Branch, Wolcott, Vermont 760 SECTION P 750 740 720 - 730 710 « "' 720 L J- 200 250 300 350 400 450 500 50 100 150 200 250 300 350 750 760 SECTION N LJJ LJJ 740 750 Li- 730 740 LJJ 720 LJJ 730 LJJ 710 720 CO 200 250 300 350 400 450 500 350 400 450 500 550 600 650 LJJ 750 780 O PRIVATE BRIDGE CD SECTION R 740 770 730 760 LJJ 720 _J 750 LJJ 710 740 300 350 400 450 500 550 600 100 150 200 250 300 350 400 750 790 SECTION O SECTION S 740 780 730 770 720 760 710 i .... i 750 250 300 350 400 450 500 550 100 150 200 250 300 350 400 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX E 74 Movable Bed Model Results 100-year flood on the Wild Branch, Wolcott, Vermont 800 810 SECTION T 790 780 770 760 760 200 250 300 350 400 450 500 250 300 350 400 450 500 550 800 810 SECTION U SECTION X LJJ LJJ 790 800 LL 780 790 LJJ > 770 LJJ 780 LJJ 760 770 CO 50 100 150 200 250 300 350 400 450 500 550 600 650 700 LJJ 805 820 O SECTION V SECTION Y 00 795 810 O 785 800 < LJJ 775 _l 790 LJJ 765 780 250 300 350 400 450 500 550 550 600 650 700 750 800 850 830 SECTION Z 820 810 800 765 790 150 200 250 300 350 400 450 50 100 150 200 250 300 350 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX E 75 Movable Bed Model Results 100-year flood on the Wild Branch, Wolcott, Vermont 880 SECTION AE 870 860 830 - 850 820 ' ' 840 250 300 350 400 450 500 550 200 250 300 350 400 450 500 860 890 SECTION AB LJJ 885 LJJ 850 LL 880 840 875 LJJ 870 830 LJJ 865 LJJ 820 860( CO 350 400 450 500 550 600 650 50 100 150 200 250 300 350 LJJ 865 900 O CD PRIVATE BRIDGE < 855 - 890 Z O 880 LJJ -J 870 LJJ 860 450 500 550 600 650 700 750 50 100 150 200 250 300 350 905 SECTION AF 895 885 875 865 50 100 150 200 250 300 350 100 150 200 250 300 350 400 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX E 76 Movable Bed Model Results 100-year flood on the Wild Branch, Wolcott, Vermont 920 SECTION AG 910 900 890 880 900 400 450 500 550 600 650 700 0 100 200 300 400 500 600 930 940 SECTION AH SECTION AK LU LU 920 930 910 920 _J LU > 900 910 m 890 900 u & 200 250 300 350 400 450 500 300 350 400 450 500 550 600 LU > 940 950 O CO SECTION Al SECTION AL < 930 940 O P 920 930 > LU 910 920 LU 910 "-" 50 100 150 200 250 300 350 200 250 300 350 400 450 500 940 SECTION AJ 930 920 910 900 200 250 300 350 400 450 500 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX E 77 Movable Bed Model Results 10-year flood on the Lamoille River, Cambridge, Vermont 410 100 200 300 400 500 1,200 1,300 1,400 1,500 1,600 1,700 470 SECTION D LJJ 460 LJJ 450 440 LJJ 430 > LJJ 420 LJJ 410 410 CO 2,000 2,100 2,200 2,300 2,400 2,500 800 900 1,000 1,100 1,200 1,300 LJJ 470 O 00 SECTION VC 460 450 440 LJJ _J 430 LJJ 410 420 2,700 2,800 2,900 3,000 3,100 3,200 1,700 1,800 1,900 2,000 2,100 2,200 470 SECTION E 460 450 440 430 420 420 410700 800 900 1,000 1,100 1,200 1 '400 1 '500 1 -600 1 '700 1 '800 1 '900 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX E 78 Movable Bed Model Results 10-year flood on the Lamoille River, Cambridge, Vermont 480 SECTION I 470 460 450 440 430 420 420 1,500 1,600 1,700 1,800 1,900 2,000 1,300 1,400 1,500 1,600 1,700 1,800 480 SECTION J 470 460 450 440 430 420 1,300 1,400 1,500 1,600 1,700 1,800 100 200 300 400 500 600 490 SECTION K 480 470 460 450 111 440 420 430 700 800 900 1,000 1,100 1,200 400 500 600 700 800 900 480 SECTION H 470 460 450 440 430 420 430 200 300 400 500 600 700 1 '200 1 '300 1 '400 1 '500 1 '600 1 '700 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX E 79 Movable Bed Model Results 10-year flood on the Lamoille River, Cambridge, Vermont 490 480 SECTION O 470 460 450 440 430 430 1,400 1,500 1,600 1,700 1,800 1,900 2,600 2,700 2,800 2,900 3,000 3,100 490 SECTION M LU 480 LU 470 460 LU 450 LU 440 LLI 430 CO 1,400 1,500 1,600 1,700 1,800 1,900 1,200 1,300 1,400 1,500 1,600 1,700 LLI O CO LLI LLI 430 420 1,900 2,000 2,100 2,200 2,300 2,400 500 600 700 800 900 1,000 480 470 460 450 440 430 420 420 2,100 2,200 2,300 2,400 2,500 2,600 800 900 1,000 1,100 1,200 1,300 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX E 80 Movable Bed Model Results 10-year flood on the Lamoille River, Cambridge, Vermont 490 490 SECTION Q 480 480 SECTION S 470 470 460 460 450 450 440 440 430 430 1,100 1,200 1,300 1,400 1,500 1,600 500 600 700 800 900 1,000 490 LJJ 480 LJJ U_ 470 460 LJJ 450 LJJ 440 LJJ 430 430 CO 100 200 300 400 500 600 700 800 900 1,000 1,100 1,200 LJJ 480 490 O SECTION U 00 470 480 460 470 450 460 440 COVERED 450 LJJ BRIDGE _l LJJ 430 440 420 430 100 200 300 400 500 600 1,500 1,600 1,700 1,800 1,900 2,000 490 480 SECTION R 470 460 450 440 430 430 100 200 300 400 500 600 100 200 300 400 500 600 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX E 81 Movable Bed Model Results 10-year flood on the Lamoille River, Cambridge, Vermont 490 SECTION W 480 470 460 450 440 LLJ LLJ 430 430 LL 800 900 1,000 1,100 1,200 1,300 1,900 2,000 2,100 2,200 2,300 2,400 490 490 LLJ SECTION X SECTION AA > 480 480 LU 470 470 LU CO 460 460 LU 450 450 O CO 440 440 430 430 o 1,200 1,300 1,400 1,500 1,600 1,700 2,000 2,100 2,200 2,300 2,400 2,500 I- LJJ LJJ 430 430 1,100 1,200 1,300 1,400 1,500 1,600 700 800 900 1,000 1,100 1,200 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX E 82 Movable Bed Model Results 100-year flood on the Lamoille River, Cambridge, Vermont 470 SECTION C SECTION VA 460 450 440 430 420 410 100 200 300 400 500 1,200 1,300 1,400 1,500 1,600 1,700 470 SECTION D LLJ 460 LLJ LL 450 440 LLJ 430 LLJ 420 LLJ 410 410 CO 2,000 2,100 2,200 2,300 2,400 2,500 800 900 1,000 1,100 1,200 1,300 UJ O 00 UJ _l LLJ 410 2,700 2,800 2,900 3,000 3,100 3,200 1,700 1,800 1,900 2,000 2,100 2,200 470 SECTION E 460 450 440 430 420 410 410700 800 900 1,000 1,100 1,200 1 '400 1 '500 1 '600 1 '700 1 '800 1 '900 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX E 83 Movable Bed Model Results 100-year flood on the Lamoille River, Cambridge, Vermont 480 SECTION I 470 460 450 440 430 420 420 1,500 1,600 1,700 1,800 1,900 2,000 1,300 1,400 1,500 1,600 1,700 1,800 480 SECTION F LU 470 LU 460 450 LU 440 LU 430 420 420 1,300 1,400 1,500 1,600 1,700 1,800 100 200 300 400 500 600 490 480 SECTION K 470 460 450 111 440 420 430 700 800 900 1,000 1,100 1,200 400 500 600 700 800 900 480 500 SECTION H STATE ROUTE 15 470 480 460 450 460 440 440 430 420 420200 300 400 500 600 700 1 '200 1 '300 1 -400 1 '500 1 '600 1 '700 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX E 84 Movable Bed Model Results 100-year flood on the Lamoille River, Cambridge, Vermont 490 SECTION O 480 470 460 450 440 430 430 1,400 1,500 1,600 1,700 1,800 1,900 2,600 2,700 2,800 2,900 3,000 3,100 490 SECTION M LU 480 LU 470 460 LU 450 > LU 440 LU 430 CO 1,400 1,500 1,600 1,700 1,800 1,900 1,200 1,300 1,400 1,500 1,600 1,700 LU 480 O CO 470 460 450 440 LU _J LU 430 420 420 1,900 2,000 2,100 2,200 2,300 2,400 500 600 700 800 900 1,000 480 480 STATE ROUTE 108 460 460 - 440 440 - 420 420 - 410 410 2,100 2,200 2,300 2,400 2,500 2,600 800 900 1,000 1,100 1,200 1,300 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX E 85 Movable Bed Model Results 100-year flood on the Lamoille River, Cambridge, Vermont 480 490 SECTION 0 SECTION S 470 480 460 470 450 460 440 450 430 440 420 430 1,100 1,200 1,300 1,400 1,500 1,600 500 600 700 800 900 1,000 430 100 200 300 400 500 600 700 800 900 1,000 1,100 1,200 490 480 SECTION U 470 460 450 LLJ 440 420 430 100 200 300 400 500 600 1,500 1,600 1,700 1,800 1,900 2,000 480 470 SECTION R 460 450 440 430 420 430 100 200 300 400 500 600 100 200 300 400 500 600 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX E 86 Movable Bed Model Results 100-year flood on the Lamoille River, Cambridge, Vermont SECTION W 480 470 460 450 440 LJJ LJJ 430 430 800 900 1,000 1,100 1,200 1,300 1,900 2,000 2,100 2,200 2,300 2,400 490 490 LJJ SECTION X SECTION AA 480 480 LJJ 470 470 460 460 450 450 O CO 440 440 430 430 1,200 1,300 1,400 1,500 1,600 1,700 2,000 2,100 2,200 2,300 2,400 2,500 < 490 LJJ 480 470 460 450 440 430 1,100 1,200 1,300 1,400 1,500 1,600 700 800 900 1,000 1,100 1,200 DISTANCE, IN FEET, ACROSS SECTION FROM LEFT TO RIGHT APPENDIX E 87 APPENDIX F: Elevation Reference Marks Table F1 . Reference marks utilized in Montgomery, Vermont Elevation, in feet Identifier Description above sea level M-RM6A 431.65 Chiseled square on top of south end of the east abutment of Enosburg Town Highway 17 bridge over the Trout River. Newly established. M-RM5A 446.36 Chiseled square on top of south end of the east abutment of Longley Road bridge over the Trout River. Newly established. M-RM4A 466.86 Chiseled square on top of west end of the north abutment of State Highway 118 bridge over the Trout River just west of the Village of Montgomery. Newly established. M-RM9 466.38 Chiseled square on top of north end of the east abutment of State Highway 118 bridge over West Hill Brook. Newly established. M-RM1 470.80 Chiseled square on upstream side of wingwall of covered bridge on Town Highway 42 over Trout River, 0.3 miles west of Montgomery village green. Recovered. M-RM2 493.89 Standard USGS disk stamped "52 VT 1922", set in northeast corner of top step at front entrance of Method ist Church on Montgomery village green. Recovered. M-RM3 482.92 Vermont Agency of Transportation disk set in concrete curb on upstream side of Town Highway 41 bridge over Trout River, about 500 ft from State Route 118, 0.4 miles south on State Route 118 from village green in Montgomery. Recovered. M-RM5 493.18 Lag bolt in utility pole 8-4-40 across State Route 118 from Vermont Agency of Transportation highway maintenance garage, 1.15 miles north on State Route 118 from Community Baptist Church in Montgom ery Center. Newly established. M-RM6 500.38 Chiseled square on southwest side of concrete junction well for storm drains on the east side of State Route 118 approximately 0.8 miles north along State Route 118 from Community Baptist Church in Montgomery Center. Newly established. M-RM7 514.80 South bonnet bolt on top of fire hydrant on east side of State Route 118, 0.7 miles north along State Route 118 from Community Baptist Church in Montgomery Center. Recovered. M-RM8 533.70 Standard USGS disk stamped "S 3 1922 reset 1965" set in south end on top concrete step of Community Baptist Church at corner of State Routes 118 and 242 in Montgomery Center. Recovered. APPENDIX F 90 Table F2. Reference marks utilized in Wolcott, Vermont Elevation, in feet Identifier Description above sea level W-RM8 693.44 Chiseled square in south end of west abutment of State Route 15 bridge over Wild Branch. Recovered. W-RM7 Chiseled square in south end of east abutment of Town Highway 2 bridge over Wild Branch. Recovered. W-RM6 710.86 Chiseled square in south end of west abutment of Town Highway 15 bridge over Wild Branch. Recovered. W-RM5 731.31 Lag bolt in utility pole 40 along North Wolcott Road, immediately downstream of a private road which is 1.2 miles north along North Wolcott Road from the intersection with Town Highway 2. Newly established. W-RM4A 754.19 Lag bolt in utility pole 62 located approximately 2.1 miles north along North Wolcott Road from intersection with Town Highway 2 and 25 feet east of North Wolcott Road centerline. Newly established. W-RM4B 758.03 Center of Soil Conservation Service Disk nailed to utility pole 38/65 located approximately 2.3 miles north along North Wolcott Road from intersection with Town Highway 2 and 35 feet east of North Wolcott Road centerline. Newly established. W-RM3 787.77 Lag bolt in utility pole 79 located immediately downstream of the old Town Highway 13 crossing of Wild Branch and approximately 2.8 miles north along North Wolcott Road from intersection with Town Highway 2 and 20 feet east of North Wolcott Road centerline. Newly established. W-RM2 848.64 Chiseled square on north end of east curb of North Wolcott Road Bridge over an unnamed tributary; located approximately 3.5 miles north along North Wolcott Road from intersection with Town Highway 2. Newly established. W-RM1 923.01 Chiseled square in south end of east abutment of Private Drive bridge over Wild Branch; located approximately 4.45 miles north along North Wolcott Road from intersection with Town Highway 2 and 80 feet east of North Wolcott Road. Recovered. APPENDIX F 91 Table F3. Reference marks utilized in Cambridge, Vermont Elevation, in feet Identifier Description above sea level C-RM4 457.88 Spike in utility pole 5,25 feet south of Town Highway 66, 3,600 feet west of intersection of State Highway 104 and Town Highway 66. Recovered. C-RM5A 466.97 Top of twentieth vertical I-beam of guard rail west from a parking area on the north side of Vermont State Highway 104, directly across highway from mile marker "1040" and approximately 960 feet west along State Route 104 from the intersection with Town Highway 71. Newly established. C-RM5B 473.42 Lag bolt in utility pole 19S on north side of State Route 104, approximately 200 feet west of intersection with State Route 15. Newly established. C-RM3A 453.28 Chiseled square on the east end of the south abutment of the State Route 15 bridge over the Lamoille River in the Village of Cambridge. Recovered. C-RM6A 458.73 Lag bolt in utility pole 42 on the south side of State Route 15 approximately 0.8 miles west along State Highway 15 from the intersection with Town Highway 2. Newly established. C-RM3J 480.44 USGS disk in stone step of Soldier's Monument in the Village of Jeffersonville. Recovered. C-RM1J 465.92 State of Vermont survey disk on southwest corner of the State Route 15 bridge over the Brewster River. Recovered. C-RM8 467.98 Chiseled square on the southeast corner of St. Johnsbury and Lamoille County Railroad Bridge over Lamoille River at Cambridge Junction. Recovered. C-RM9 462.21 NGS disk in concrete post on Cambridge Junction, 251 feet west of Town Highway 23 centerline, 81 feet east of railroad switch stand, 17.1 feet south of south rail of main track, and 13 feet north of north rail of St. Johnsbury and Lamoille County Railroad. Recovered. BM490 489.56 USGS disk 0.1 miles west of a two-story house which is on south side of road stamped "H53" in boulder projecting 6 feet, 29 feet north of centerline of State Route 15, 24 feet northwest of west end of guard rail, and 10 feet south of twin trunk maple. Recovered. C-RM3 464.37 Center rivet on north end of 6-feet-diameter boiler plate culvert under St. Johnsbury and Lamoille County Railroad, and 750 feet west of Cambridge-Johnson Town line. Recovered. APPENDIX F 92