THE LIBRARY OF THE UNIVERSITY OF NORTH CAROLINA THE COLLECTION OF NORTH CAROLINIANA C387 P62t V UNIVERSITY OF N.C. AT CHAPEL HILL 00044674316 This book must not be taken from the Library building. Form No. 471 Digitized by the Internet Archive in 2013 http://archive.org/details/floodsonpigeonriOOtenn ant FLOODS ON PIGEON RIVER Vicinity of CANTON % CLYDE, North Carolina TENNESSEE VALLEY AUTHORITY DIVISION O F WATER CONTROL PLANNING TENNESSEE VALLEY AUTHORITY DIVISION OF WATER CONTROL PLANNING FLOODS ON PIGEON RIVER IN VICINITY OF CANTON & CLYDE, NORTH CAROLINA REPORT NO. 0-5866 KNOXVILLE TENNESSEE FEBRUARY 1959 CONTENTS Preface i I. Past Floods on Pigeon River Vicinity of Canton and Clyde, North Carolina Summary of Flood History 2 Pigeon River Valley 3 Pigeon River Watershed 5 Developments in the Flood Plain 9 Bridges 11 Encroachments on Natural Floodway 13 Flood Protection Works of Champion Paper and Fibre Company 15 Lake Logan on West Fork 16 Flood Situation 17 Flood Records 17 Flood Stages and Discharges 17 Flood Occurrences 19 Rate of Rise and Velocities in Large Past Floods on Pigeon River 19 Flooded Area on August 30, I9I4O 20 Flood Profiles . 20 Valley Cross Sections 21 Flood Descriptions 21 1810 22 June 15, 1876 22 September 12, 1893 • 23 May 21, 1901 2h February 28, 1902 2h August 31, 1910 2^ July 16, 1916 25 October 2£, 1918 . 26 ^ August 16, 1928 26 v> August 13, 19 h0 . 29 \ August 30, 19U0 33 CONTENTS— (Continued) June 16, 19h9 37 Acknowledgments iiO H. Past Floods on Streams in Canton-Clyde Region Maximum Known Regional Floods hi Pigeon River vs. Regional Flood Discharges hh Flood Heights for Various Discharges hh Acknowledgments hS III. Maximum Probable Flood Determination of Maximum Probable Flood 1*6 Observed Storms hi Observed Floods lj.8 Maximum Probable Flood Discharges h9 Frequency l±9 Possible Larger Floods h-9 Flood Heights and Velocities h9 Flood Crest Profiles and Overflow Areas h$ Velocities and Rates of Rise 50 Acknowledgments $h TABLES I Table 1 Bridge Elevations and Clearances — Vicinity of Canton and Clyde, North Carolina ... 11 2 Flood Crest Elevations and Discharges-- Pigeon River at Canton, North Carolina 18 3 Maximum Known Discharges on Streams in General Region of Canton-Clyde, North Carolina U2 h Relative Flood Heights for Various Discharges — Pigeon River at Canton and Clyde h$ TABLES— (Continued) Table 5 Selected Maximum Observed Storms hi 6 Selected Maximum Observed Floods ii8 PLATES Follows Plate Page 1 Pigeon River Watershed $ 2 Flood Crests — Pigeon River, Vicinity of Canton-Clyde, N. C 19 3 Stage Hydrographs — Pigeon River at Canton, North Carolina 19 It Pigeon River Basin — Storm of Mid-August 19k0 .... 29 5> Pigeon River Basin — Storm of Late August 19li0 .... 3h 6 Maximum Known Flood Discharges — Region of Canton-Clyde, N.C kk 7 Flooded Areas — Pigeon River, Vicinity of Canton-Clyde, N. C % 8 Area Flooded at Canton— August 30, 19^0 Jft 9 High Water Prof iles- -Pigeon River, Vicinity of Canton-Clyde, N. C, ^ 10 Valley Cross Sections — Pigeon River, Vicinity of Canton -Clyde, N. C %k FIGURES Figure Page 1 August 30, 19^0, Flood at Canton Frontispiece 2 After the Mid-August 19^0 Flood on Pigeon River 32 3 Canton Street Flooded August 30, 19l*0 32 h June 19 h9 Flood in Clyde 39 £ High Water in Canton, June 19li9 39 FIGURES- - ( C ont inued ) Figure Page 6 Park Street, Canton, Could Be Deeply F!_0 OdG d 0000000000000090000000 ^1 7 Waterfront of the Champion Paper and Fibre 8 Water Street, Canton, Is Well Named . 52 9 Ceilings in Fibreville Could Be Submerged 52 10 Depot Street in Clyde, Looking East 53 11 Pigeon River Flows Between Clyde School and Its Gymnasium 53 X-26^1 COVER PHOTOS I Upper left photo shows the yard of the Champion Paper and Fibre Company in Canton during the flood of August 30, 19^0, with the water 1^ feet below the crest. Lower right photo is in the Fibreville section of Canton during the flood of August 13, 19i|0. PREFACE Tennessee Valley Authority- Division of Water Control Planning PREFACE This is a report on the flood situation along Pigeon River in the vicinity of Canton and Clyde, North Carolina. It is one of a series of reports that TVA is preparing to aid communities in the Tennessee Valley (l) in the solution of local flood problems which are not eliminated by TVA's reservoir system and (2) in the best utilization of lands subject to overflow. These reports are based on work that TVA has been carrying on since its beginning in connection with its water resources operations throughout the Tennessee Valley. TVA has assembled information on rainfall, runoff, historical and current flood heights, and other technical data bearing on the occurrence and magnitude of floods in localities throughout the region. These data provide the basis for preparation of flood histories of many streams so that this information may be made available to states, communities, and groups which are interested in local flood problems. This report has been prepared at the renuest of the Mayor and Board of Aldermen of the towns of Canton and Clyde, through the Board of Water Commissioners of the State of North Carolina. Flood problems in the two communities and in their vicinities are chiefly the result of high water on the Pigeon River. This report discusses floods on this stream. The Carolina Division of the Champion Paper and Fibre Company at Canton and much of the commercial and residential developments in both Canton and Clyde are located in the flood plain of Pigeon River and have been subject to inundation during large floods in the past. Main highways through Canton are blocked by overflow and local traffic is interrupted in both towns during floods. The many buildings on the flood plain at Canton, together with fills that have been made and the several highway and railway bridges located in the town, have materially encroached upon the natural waterway that was once available for flood flows. As a result flood heights are higher than they would be under prior natural conditions. The same is true to a lesser extent at Clyde. ii The largest known flood on Pigeon River in the Canton-Clyde vicinity occurred on August 30, 19 feet lower than the August 30, 19^0, flood crest. Floods above bankfull stage on the Pigeon River at Canton and Clyde have fortunately not been freouent and have occurred on an average of about one every 8 years. The most serious floods have occurred in the summer months. During past large floods, Pigeon River has risen above bankfull stage at a rate of about 2 feet per hour. There are a large number of residences in the flood plains at Canton and Clyde so that there may be danger to life from such rising floods on Pigeon River especially if the flood occurs at night. Velocities in the main channel average 8 to 10 feet per second during floods such as those of August 19U0 with maximum velocities up to 15 feet per second. During such floods, overbank depths range from 3 to 6 feet on the streets of Canton and Clyde and velocities range up to h feet per second. During the Maximum Probable Flood on Pigeon River, velocities in the channel at Canton and Clyde would approach 20 feet per second and in the overflow areas 7 feet per second. Velocities of these magnitudes create hazardous conditions. iii This report is in three parts^ (l) a history of past floods on Pigeon River in the vicinity of Canton and Clyde, (2) a description of past floods on streams of similar physical characteristics in the general geographical region of Canton and Clyde, and (3) a discussion of the Maximum Probable Flood that has been estimated as possible of occurrence on the upper Pigeon River at some future time. The first section of the report brings together a record of the largest known floods at Canton and Clyde. Profiles are presented showing the high water crests of the largest known flood, that of August 30, 19U0, and of the mid-August 19^0 flood. Maps show the area that was inundated in the late August flood. The second section of this report treats of the largest floods known to have occurred on streams of similar physical characteristics located in the same general geographic region as that of Canton and Clyde and not more than 60 miles away. Floods in this category, which have been experienced on streams having characteristics similar to and located in the same general region as Canton and Clyde, together with the Maximum Probable Flood, described in Section IU of this report, indicate the magnitude of the floods that may reasonably be expected to occur in the future on Pigeon River at Canton and Clyde. The third section of the report relates to the Maximum Probable Flood. Floods of this magnitude on most streams are considerably larger than any that have been experienced in the past. They are the floods of infrequent occurrence that are considered in planning protective works, the failure of which might be disastrous. Such floods are used by TVA in the design of physical features of reservoirs, dams, powerhouses, and local flood protection works. Such floods should be considered in the utilization of the unprotected flood plains at Canton and Clyde where the occurrence of such a flood would result in large losses and should also be considered in development of the reach between the two communities. The profile for this flood is shown in this report and the areas which would be inundated by such a flood are shown on the maps. In problems concerned with the control of developments in the flood plain, it is important to give appropriate consideration to the iv occurrence of floods of the magnitude of those that are recognized as possible of occurrence at Canton and Clyde, The facts should be weighed with regard to such floods in reaching decisions for the utilization of the lands in the flood plain along the reach covered by this report. This report does not include plans for the solution of flood problems. Rather, it is intended to provide a basis for further study and planning on the part of Canton and Clyde in arriving at solutions to minimize vulnerability to flood damages. This might involve (l) construc- tion of flood protection works, (2) local planning programs to guide developments by controlling the type of future use made of the flood plain by zoning and subdivision regulations, or (3) a combination of the two approaches. The maps in the report show the extent of the flooded area and the profiles show elevations of high water through the reach of the Pigeon River covered by this report. Elevations of the ground are shown by contours on the maps. Cross sections also show ground elevations along the line of each section. From these data the depth of probable flooding by either recurrence of the largest known historic flood or by occurrence of the much larger Maximum Probable Flood at any location may be ascer- tained. Having this information, floor levels for buildings may be planned either high enough to avoid flood damage or at lower elevations with recognition of the chance and hazards of flooding that are being taken. Probably most large developments would have site maps made by private engineering firms. Such maps would show ground elevations in considerably greater detail than do maps in this report and, in conjunction with the maps and profiles in this report, would provide the necessary basis for the development of any site. X. PAST FLOODS ON PIGEON RIVER VICINITY OF CANTON AND CLYDE, NORTH CAROLINA O X! • o ■P oJ ra 0) CD o U o o 0) a o H cT o 1 o\ o p rH -p 1 ee o o CO -P rH CVI CI h EH o3 CQ o P C5 CD o •H PL, ■P a 0 miles. Principal access points will be at Wagon Road Gap, Balsam Gap, and Soco Gap. Railroads --The Murphy Branch of the Southern Railway crosses the basin from east to west. The line enters the basin at the low gap in Canton, crosses the Pigeon River in Canton, runs south of the river through Clyde to Lake Junaluska, then follows Richland Creek to Waynesville and goes out of the basin at Balsam Gap. The line's principal business is with the Champion plant at Canton, hauling the larger part of the pulp wood required by the plant and hauling finished paper, pulp, and other products to the main line at Asheville . Drainage Areas --Drainage areas at points of interest in the Pigeon River watershed are as follows; Drainage Stream and Location Mile Area sq.mi. Pigeon River At mouth 689 At bridge in Clyde 57.6 162 At Main Street, Canton 63.7 13U At Junction East and West Forks 69.5 118 East Fork Pigeon River £2,8 West Fork Pigeon River At mouth 6iio8 At Lake Logan Dam - 33.3 9 Developments in the Flood Plain The Champion Paper and Fibre Company plant, a good part of Canton's business districts and some 100 of the city's residences are in the flood plain of Pigeon River. All of the plant buildings are located on the bottom land on the right bank of the river, occupying an area of some h0 acres. An area nearly as large on the left bank opposite the manufacturing plant is taken up by a wood storage yard which supplies the plant. Business places occupy most of the bottom land between the Southern Railway bridge and the Main Street bridge. On the right bank these are along Park, Sorrells, Water, and Main Streets, Some, twenty establishments are here, including a theatre, the City Library, a large supermarket, two garages, three service stations, a bus station, a barber shop, a diner, a dry cleaner, a laundry, a coal and fuel business, an appliance store, a tire recapping plant, and a feed store. Nine establish- ments on the left bank are subject to flooding: three automobile agencies, a drive-in restaurant, a hotel, a lumber yard and builders' supply, an auto parts supply, a plumbing shop, and a cabinet shop. Many of these on the left bank have been located here since the record flood of August 30, 19li0. The 100 or more residences presently in the flood plain at Canton are distributed approximately as follows: ten scattered throughout the business district between Park Street and Main Street, eighteen in the Highland Park section on the right bank along Valley, Conley, and Vance Streets, six on the left bank above Main Street bridge, and sixty-five in the Fibreville section. The houses in the Fibreville section were built by the Champion Paper and Fibre Company for use by their employees. The houses are now being sold to the occupants and will soon all be in private ownership. The athletic field for the Canton High School, the National Guard Armory Building, and the Memorial Recreation Park and Swimming Pool are on the left bank flood plain near the upper city limits. Canton, since 1910, has obtained its principal water supply from an intake on Rough Creek, a tributary of Beaverdam Creek, four and one-half miles north of the town. A 6-inch pipeline feeds by gravity to a reservoir at the north corporation limit. Mains through the town are fed by gravity 10 from this reservoir. In 1936 an intake was put in on Pigeon River from which the supply is supplemented during periods of low flow at Rough Creek. The intake and pumping station is located on the left bank of the river at Mile 61u57, just upstream from the present upper city limit. The floor of the pump house is at elevation 2$91.k» A filter plant is located on the hill above the pumping plant and a treated water reservoir is located on top of the hill above the plant. Capacity of the treatment plant is one million gallons per day. Large floods enter the pump house, making it necessary to shut down the treatment plant and rely on the Rough Creek supply plus water in storage. No hardship results since in time of good streamflow, the Rough Creek supply is ample for the town needs. Storm and sanitary sewers from Canton have their outlets at various places along Pigeon River and are affected by backwater in large floods. Canton has no sewage treatment works, but a study is being made of the problem. In Clyde all the business section is in the flood plain except that which has sprung up in the last few years along the new location of U. So Highway 19 and 23. Business and commercial buildings now on the flood plain include a bank, two food stores, a hardware store, a drug store, the fire department, the post office, and two service stations. Approximately sixty houses are subject to flooding. The Clyde School is on the left bank of the river and has a large gymnasium on the right bank. All school buildings are subject to flood damage, the gymnasium being at the lowest elevation. Clyde has used Conner Mill Creek as a water supply since 1925, when an intake and treatment plant were installed just south of the Clyde city limits. Three wells have been drilled in recent years to supplement the supply. Two of these are at the treatment plant and are well above possible flood height. Well No. 3 is just out of the flood plain on the right bank of Pigeon River opposite the business district. The floor of the well house is 37 feet above the elevation of the record flood of August 30, 19^0. Storms and sanitary sewers empty into the river at several points in Clyde and a number of houses have basement drains which lead directly to the river. All these lines are subject to backwater. 11 Bridges In the eight-mile reach of Pigeon River covered by this investi- gation there are six existing highway bridges, two railroad bridges, and one footbridge. The following Table 1 lists the pertinent elevations at the bridges. TABLE 1 BRIDGE ELEVATIONS AND CLEARANCES VICINITY OF CANTON AND CLYDE, NORTH CAROLINA Flood Underclearance Mile Stream Crest Above Below Above Bed Floor Aug. 30, Aug. 30, Aug. 30 Mouth Identification Elev. Elev. Elev. 19U0 191*0 feet feet feet feet feet feet 57. 5h Footbridge 2525.5 2530.7 252li.5 6.2 57.65 Clyde 2508.2 2531.1 2531. h 2529.7 1.7 62.92 Fibreville 2581.6 2580.8 2578.0 2.8 63.15 C.P.&F. Co. RR 2560.8 2582.5 2581*. 3 2579.2 5.1 63.33 C.P.&Fo Co. Pipeline 2566.6 2612.0 2585.9 2602.0 16.1 (under construction) 63.55 Southern Railway 2566.0 2591.5 2588.7 2583.1 5.6 63.60 U. S. 19, 23 2568.7 2588.0 2588.9 2583.U 5.5 63.71 Main Street 2565.0 2590.5 2589.8 2589.0 0.8 6k. $1 Bridge 2577.2 2599.0 2599.8 2597.0 1.8 6U.78 Bridge 2579.0 2598.8 2600.6 2596.8 3.8 None of the bridges has an underclearance elevation which is high enough to pass a flood of the magnitude of the flood on August 30, 19l*0. At two of the highway bridges floor elevations are a little higher than the crest elevation reached in that flood but at both of these the bridge approaches are subject to overfloxtf. Depth of overflow is sufficient to put the bridges out of service during large floods, with the result that none of the highway bridges in the Canton-Clyde area is usable during major floods. A bridge structure is being built over Pigeon River on the Champion Paper and Fibre Company property in Canton to support pipelines to the waste treatment plant. It will have an underclearance elevation 16.1 feet above the August 30, 191*0, flood. 12 The Southern Railway bridge at Canton has a top-of-rail eleva- tion 2.8 feet higher than the August 30, 19U0, flood. The bridge approaches are not overflowed at this stage but the bottom of the main-span girder is 5.6 feet lower than the elevation of the flood crest so that the span could be endangered by a heavy pile up of debris against the span such as might occur in a large flood. The U. S. 19 and 23 bridge, a reinforced concrete structure just upstream from the Southern Railway bridge in Canton, has a floor elevation 0.9 foot below the August 30, 191*0, flood crest elevation at that point. The clearance elevation is feet under the 19^0 flood crest. The steel truss bridge at Main Street, next upstream from the highway bridge, has its floor just above the August 30, 19l|0, flood elevation and a clearance elevation which is 0»8 foot lower. The new bridge over Pigeon River in the Fibreville section of Canton has a floor level which averages three feet higher than the old bridge at the site, but the floor slopes and the left end would be under water in a repetition of the August 30, 19l|0, flood. Fibreville Street, which runs parallel to the river at the left end of the bridge, is seven feet lower than the bridge floor. The railroad bridge at the Champion Paper and Fibre Company plant, which connects the plant area with the wood storage yard on the left bank, has a top-cf-rail elevation 1.8 feet lower than the August 30, 19ii0, flood which overflowed most of the plant area and wood yard. The levees and channel improvement work done through the plant area after the floods experienced in 19^0 have altered flood flow conditions materially. The effect of these changes is set forth in a succeeding paragraph in this section of this report. The Champion Company is now building a four-span steel-truss bridge over Pigeon River near the upper end of their property. This bridge will be used to carry pipe lines which will transport the plant's waste effluent to a sewage treatment plant which is to be built on the left bank. Plate 8 shows the location of this bridge and the planned waste treatment plant. The clearance elevation of the pipe line bridge will be some sixteen feet above the August 30, 19^0, flood crest profile. 13 The two highway bridges just above the Canton Corporation Limit are steel girder structures with floor elevations a foot or more lower than the flood crest elevation reached at the sites on August 30, 191*0. At the lower of these two structures high banks confine flood flows to the bridge opening and considerable heading up occurs. The steel truss bridge at Clyde has its floor at just about the same elevation as that reached by the flood of August 30, 1°U0. The under clearance elevation is about two feet lower. Wide overflow occurs on both banks and heading up at the bridge is negligible under present conditions. A suspension type footbridge at the Clyde School provides access to the athletic field and gymnasium on the right bank opposite the main school buildings. The bridge floor is one foot lower than the August 30, 19^0, flood crest at the center and some six feet lower at the ends of the span. Encroachments on Natural Floodway The description of the extensive developments in the flood plain makes it evident that the natural valley of Pigeon River has been encroached upon by works of man which impair the natural flood-carrying capacity of the stream. The effect of these encroachments is more important at Canton than at Clyde. Plates 7 and 8 show the extent of encroachment on the flood plain at Canton by buildings and bridges. Nearly all the buildings shown would interfere to some extent with overbank flow during an occurrence of a flood as high or higher than the flood of August 30, 19^0. Plate 9i the profile of Pigeon River, gives some indication of the interference to flood flow in the river channel by the bridges in the Canton-Clyde reach. The bridge at Main Street offers less interference to flood flow than the other bridges at Canton- The flood of August 30, 19 1*0, reached the floor of the bridge. Considerable building has taken place on the flood plain at the left end of the bridge since 19ii0 and the flood crest profile would probably be higher at this point in a recurrence of the 19U0 floods today. Ill At the U. S. Highway 19 and 23 bridge at Park Street the bottom of the bridge girders is 5«5 feet under the crest of the flood of Aug- ust 30, 19^0. Flood discharges of about 19,000 cubic feet per second reach these girders. The bridge floor is overtopped at discharges of 30,000 cubic feet per second. The top of the bridge guard rail is 3«6 feet above the bridge floor. At discharges which overtop the bridge floor overflow extends about 500 feet to the left and 750 feet to the right of the bridge. Plates 7 and 8 show the heavy concentration of buildings vhich reduce the flood- carrying capacity of this overbank area. Considerable filling has been done in the left overbank area over the years. At the Southern Railway bridge a long fill cuts off all overbank flow for any floods which have occurred at Canton in the memory of man. A discharge of about 35,000 cubic feet per second will overtop the bridge and fill. The bottom of the bridge girders is reached by a discharge of about 19,000 cubic feet per second. Between these two discharges heading up is caused by the restricted opening under the bridge. The water supply intake dam for the Champion plant just below the Southern Railway bridge is four feet high. It backs up water a distance of 0.6 mile under low-flow conditions but has a negligible effect on large floods. The reinforced concrete bridge at Fibreville is three feet lower at the left end than at the right end. The bridge floor ranges from one foot below to two feet above the crest elevation of the August 30, 19^0, flood. The under clearance of the bridge is at an elevation equal to that flood crest at the right end and 3? feet lower at the left end. Discharges of 25,000 cubic feet per second, equal to the flood of August 13, 191*0, reach the lower end of the bridge girders. At Clyde there has been relatively little change in the flood- carrying capacity of the valley bottom up to this time. Filling has been negligible and although there has been much building on the left bank, at the point where this has the greatest effect on flood flow, at the center of town, the right bank flood plain is lower than the left and carries the larger part of overbank flow. Because of the wide overflow, the bridge at Clyde has no noticeable effect on flood heights. In the 15 record flood of August 30, 19l*0, water was just above the bridge floor but overflow extended for iiOO feet in the business section on the left bank and for £00 feet on the right bank where the depth was as much as six feet. Flood Protection Works of Champion Paper and Fibre Company After the costly flood damage experienced in the two floods in August 19^0, the Champion Paper and Fibre Company took steps to reduce its flood hazard. The channel through the plant area was enlarged, several small islands were removed and levees were constructed along both banks of the river. Flood gates were built where the railroad tracks leave the lower end of the plant property and at both ends of the company's railroad bridge over Pigeon River. A levee was constructed along the bank of Camp Ground Branch, where it flows along the north edge of the plant area, to prevent overflow into the plant at that point by high flows in the branch or by backwater from Pigeon River. Gates were installed on plant sewers at critical points in the area. When an important rise in the river is threatened, the plant must be shut down but serious flooding of the plant can be prevented by closing the gates on the sewer lines and by dropping the flood gates into place at the railroad tracks if the rise continues to those elevations. A profile was developed by the Flood Control Branch of TVA for the improved reach for a discharge equal to that of the record flood of August 30, 19 hO. This is shown on Plate 9» The pumps at the water intake plant at the upper end of the plant property can be used to remove surface water from the plant area. Some portions of the plant area are two feet lower than the ground at the pumping plant and there is no provision for pumping out this lower area. Confining all flood flow to the channel section through the plant area will cause the Champion railroad bridge to have a greater effect on flood heights than was the case when wide overflow occurred at the site. Heading up at this bridge for a discharge equal to that of August 30, 19h0, would amount to about two and one-half feet now as compared with about half a foot when the flood occurred. Thus the flood height would be affected all the way upstream to the Southern Railway bridge, partially nullifying the beneficial effect of the channel improvement work which has been done in this reach. The study shows that the flood would probably overtop the flood wall at the Champion pumping 16 plant by about one foot under present conditions. Above the Southern Railway bridge there would be no adverse effect on flood heights as a result of the flood protection works on the Champion plant property. Lake Logan on West Fork Lake Logan Dam was built on West Fork of Pigeon River by the Champion Paper and Fibre Company in 1931 to create a reservoir to provide storage to supplement water supply for the plant during periods of low flow. The dam is a concrete arch structure impounding water to a depth of 1*5 feet at the dam and creating a reservoir with a surface area of 8£ acres and a storage volume amounting to 2000 acre=>feet at the present normal full pool level. The spillway section of the dam is 1*£0 feet in length. A length of l£0 feet at the center of the dam was built one foot lower than the rest of the spillway. Flashboards were added to the low section to bring the pool level up to the elevation of the higher spillway section. In November 191*1 the pool level was raised 18 inches more by the addition of flashboards across the full spillway. In August 195>3 the boards were altered to raise the pool level an additional 12 inches, so that the pool level is now maintained at an elevation 1*2 inches above the low section of the spillway as constructed in 1931« This level is 3.5 feet below the elevation of the short non-overflow sections at the ends of the dam. The flashboards are permanently mounted and are not intended to go out during periods of high spillway discharge. The lake is maintained at the level of the top of the flash- boards except for the periods when releases are necessary to supplement low streamflow during droughts or when severe freezes reduce streamflow available at the plant intake at Canton. Under this plan of operation flood peaks on West Fork below the dam are normally reduced to some extent by Lake Logan as water goes into storage as the lake fills above the initial water level in the lake. Storage in Lake Logan amounts to ll*0 acre-feet for a head of 1.5 feet on the present flashboards and 1*20 acre -feet for a head of 1* £ feet on the flashboards. The loss of all or any part of the flashboards during a flood would alter conditions. During the two floods in August 191*0, 12-inch flashboards were in place on the lower spillway section and in the flood of June 19 1*9 flashboards 17 were 18 inches higher than in 19U0„ The boards remained in place throughout these floods. FLOOD SITUATION Flood Records The U. S. Geological Survey has maintained records of stream- flow on Pigeon River at Canton continuously since December 6, 1928. Until January 3, 1929, observations were made on a staff gage. Records since that date are from a recording gage Intermittent observations of river stages were made from a staff gage at the Main Street bridge, O.U mile downstream from the present gage site, between May 25, 1907, and June 30, 1909. Investigations by engineers of the Hydraulic Data Branch were made immediately after their occurrence for the floods of August 13 and August 30, 19k0 f and June 16, 19^9, to obtain flood heights and pertinent information for each of these floods . Local residents who possess knowl- edge of past floods were interviewed to obtain data regarding floods that occurred prior to the keeping of gage records on Pigeon River. A thorough search was made by Hydraulic Data Branch engineers throughout the Pigeon River flood plain for high water marks of past floods. In addition, research was carried out for flood information in available files of newspapers and historical documents. Flood Stages and Discharges Table 2 lists dates of occurrence, crest elevations, order of magnitude, and peak discharges for floods which have exceeded bankfull stage of 12.0 feet at the Canton stream gage. The list is complete for the period since continuous streamflow records were begun in December 1928. Floods shown prior to 1928 are those found in the flood history research and no doubt this list is incomplete, especially for the lesser floods of which there is no record or memory. Where crest stages are shown for these prerecord floods they have been estimated from high water marks, newspaper accounts, or other historical information. 18 TABLE 2 FLOOD CREST ELEVATIONS AND DISCHARGES PIGEON RIVER AT CANTON, NORTH CAROLINA This table includes all known floods which have exceeded bankfull stage of 12.0 feet at the U. S. Geological Survey gaging station on Pigeon River at River Mile 61^.1 at Canton, North Carolina. Drainage area at gaging station site is 133 square miles. Zero elevation of gage is 2572.22 feet above sea level. Order Date o f Crest Gage Stage Height Elevation of Magni- tude Peak Discharge Per Amount Sq. Mi. feet feet cubic feet cubic feet per second per second Approximately 1810 20+ 2592 2 29,800 22h June 15, 1876 18.3 2590.5 3 25,700 193 September 12, 1893 17.8 2590.0 5 2h, 700 185 May 21, 1901 12.0 10 12,500 91* February 28, 1902 12.5 258Uo7 9 13,1*00 101 August 31, 1910 12.0 2581u2 11 12,500 91* October 25, 1918 13.0 2585.2 8 11*, 300 107 August 16, 1928 16.1* 2588.6 6 21,500 162 August 13, 191*0 18.0 2590.2 li 25,100 189 August 30, 19U0 20.75 2593.0 1 31,600 238 June 16, 19U9 15.U1* 2587.7 7 19,500 11*7 19 Flood Occurrences Plate 2 shows the crest stage and month of occurrence of known floods on Pigeon River at Canton . The monthly distribution of these floods is as follows: January July February 1 August h March September 1 April October 1 May 1 November June 2 December _0 10 This shows that floods on Pigeon River in the past have been most likely to occur in the summer months when thunderstorm conditions prevail or when storms occur which originate in tropical hurricane disturbances. In the history of the Pigeon River floods there have been no known winter floods that were serious in the Canton-Clyde area. Rate of Rise and Velocities in Large Past Floods on Pigeon River The rate of rise during large floods on Pigeon River at Canton and Clyde is illustrated by the stage hydrographs, Plate 3, for the floods of mid-August and late August 1°U0 at Canton. The late-August flood is the highest known on Pigeon River at Canton and Clyde and the mid-August flood is the fourth highest known. The rate of rise of each of these floods above bankfull stage was about 2 feet per hour at practically a uniform rate. The mid-August flood rose to 6 feet above bankfull in about 3 hours } the rise above bank- full beginning about 10s 00 a.m. on the 13th. The late August flood came out of banks in the night about 2:00 a.m. on the 29th and rose sharply 8.75 feet to a crest about 6:30 a.m. The rapid rise during this latter flood coming in the night hours could be hazardous to people sleeping in residences on the flood plain. Fortunately no such loss of life occurred in l?h0. During floods of the magnitude of those of August 19h0, average velocities in the Pigeon River channel at Canton are from 8 to 10 feet per PLATE 2 1810 i 1870 i 1880 l 1890 1900 1 1910 1920 1930 1940 J. 1950 u AO 'l N CD t- 1 < UJ S3 u. (J O fvj z 1 UJ u. cc O 2 cc UJ o O u < 4 o 1- and on the profile, Plate 9. The cross sections not reproduced are available from the Hydraulic Data Branch of TVA to anyone who may have need for them. Each cross section shows the elevation and limits of overflow for the August 30, 19U0, flood and also for the Maximum Probable Flood. The Maximum Probable Flood is discussed in Section III of this report. Section 12 at Mile 63.59 is taken along Park Street in Canton and shows first floor and basement elevations for business and other buildings located along that street. Many of these were inundated by the late August 19k0 flood and all are below the elevation of the Maximum Probable Flood. FLOOD DESCRIPTIONS The following descriptions cover the more important floods that have occurred on Pigeon River in the vicinity of Canton and Clyde for which information is available. The flood descritpions are based on investi- gations made by TVA Hydraulic Data Branch engineers, on information furnished by local residents, on newspaper accounts of past floods, and on historical documents. In the absence of actual records of stream heights and discharges, 22 local residences, diaries, and newspaper accounts are the best available sources of information covering past floods. The Asheville "Citizen- Times" files were reviewed back to 1889 including files of the Asheville "Gazette -News." Available files of the "Canton Enterprise" and the "Waynesville Mountaineer" were both searched for flood information at Canton and Clyde. Each newspaper account has been reviewed to present only material that appears to give a correct portrayal of the flood being reported. 1810 Two old residents of the upper Pigeon River basin who have been interviewed mentioned a flood which occurred somewhere around 1810 to 1820. Mr. Will Moore, who was born near Woodrow in 1871, stated that his father told him of hearing a woman, who was one of the earliest residents of the basin, talk of wading through shoulder-deep water in getting out of her house on what is now the Forest Justice farm. The house referred to was said to be located on the lower end of West Fork Pigeon River at a point where overflow reached depths of about five feet in the flood of August 30, 19UC . Mr. Moore said that it was his recollection that this flood was supposed to have occurred in 1817. Mrs. R. E. Sentell recalls that her father-in-law used to talk of this flood as having occurred in 1810. No other leads on the flood could be found and its relation to later floods could not be established with any greater accuracy. However, the information obtained indicates that this early flood approached closely the height reached by the flood of August 30, 19U0. A height of about 20 feet at Canton is reasonable for this great flood and it is ranked second among known floods at Canton. June 15, 1876 Known as "The June Freshet," this flood is the greatest known along much of East Fork Pigeon River. Through Canton it was apparently a little higher than the August 13, 19^0, flood and was exceeded only by the 1810 flood and the flood of August 30, 19li0. A diary kept by Mr. W. H. Hargrove, one of the early residents of the Canton vicinity, contains a description of the flood "which includes the following: 23 We all planted our crops as usual and on the night of l£th of June had a freshet in Pigeon River which run over much of the bottom lands doing a great deal of damage but still continued to rain until the morning of 17th Saturday and the river came down two feet higher which run over almost all the bottom land on the river and doing more or less damage to near all except my own and a few more. Mr. John Holtzslaw was able to point out where the flood reached in the vicinity of the Main Street bridge at Canton. Mr. James Anderson showed how high the flood was at a tree in the Fibreville section and Mr. Joe Thompson was able to show the height reached at Thompson Ford below Canton. A high water mark found at the old Morgan Mill at the lower edge of Clyde shows that the I876 flood height at Clyde has about the same relation to other known floods as at Canton. September 12, 1893 Above Canton this flood is known as the "Sam's Knob Flood" because of the large slides which occurred on the peak in the West Fork drainage as the result of the cloudburst rains. At the Morgan Mill at Clyde this flood was 10 inches lower than the I876 flood. Through Canton the flood was about half a foot under the I876. The Asheville "Daily Citizen" of September 13, 1893, contains the following account of the flood at Canton, the earliest newspaper account of floods on Pigeon River: FLOOD NEWS Pigeon River Way Up - Logs Lost In The Tuckasegee Canton, N. C, Sept. 12 - Pigeon River was higher last night than at any time since the memorable June freshet of I876. No serious damage was done in this locality but farther up the river considerable damage was done . The old store of Captain W. S. Jerrell at Sonoma was washed away together with a small quantity of goods, plunder, etc., also a great deal of hay and other farm products, and some stock. His family were, when heard from this morning at nine o'clock, in the upper story of his house, the water being several feet deep over the premises and no way of getting out. 2k May 21, 1901 This was a lesser flood on the upper Pigeon River but was one which overflowed banks in the Canton area, as shown by the following abstract from the "Asheville Citizen" of May 23, 1901* AT CANTON Canton, N. C, May 22 - Owing to the recent rains, Pigeon River at Canton yesterday afternoon at 5> o'clock was out in the field and some crops were considerably damaged. For about two hours the railroad bridge was the center of attraction as the water was getting very close to the cross- ties on the bridge. The field at Canton which is referred to is probably the river bottoms which were later occupied by the plant of the Champion Paper and Fibre Company, when construction of the plant was begun in 1906. February 28, 1902 This was a severe flood on the lower reaches of Pigeon River, but was not so important at Clyde and Canton. Very heavy flood flow from Richland Creek and Johnathans Creek contributed to the flood below Clyde. The only mention found of the flood in the upper Pigeon River basin is in the March 7, 1902, issue of the "Asheville Citizen": WAYNESVILLE DID NOT SUFFER GREATLY Wayne sville, N. C, March 7 - The rainfall here was not excessive and would not have raised the waters to the danger point except for the melting snow in the mountains. .... The damage in this county was not to be compared with that suffered in other places. Only one bridge, the iron bridge across Pigeon River at the mouth of Fines Creek, which was washed from its piers, is so far reported damaged. The account of the August 31, 1910, floods states that that flood "did not quite reach the height of 8 years ago." 2$ August 31, 1910 Newspaper accounts are the only reference to this flood. The following account puts the flood as slightly lower than the flood of February 1902. Water in some rooms of the Champion Paper and Fibre Company apparently was surface water and not overflow from Pigeon River. From the Asheville "Gazette -News" for September 1, 1910; THE RAINS DESCENDED AND THE FLOODS CAME CONSIDERABLE DAMAGE IS DONE THROUGHOUT WESTERN NORTH CAROLINA oooeo o o o o o News From Canton A telephone message to the Gazette News this morn- ing from Canton stated that the Champion Fibre Company was forced to shut down more than half its operations yesterday on account of the floods. The waters from the hills gathered to a depth of 2 to 3 feet in some of the rooms of the plant. Pigeon River did not quite reach the height of 8 years ago. It flooded many bottoms and the damage will be great. July 16, 1916 This was a record flood on the upper French Broad River, but the hurricane rains that caused the floods there did not get over the mountains into the Pigeon River watershed. As a result only a modest rise occurred on the upper Pigeon. The "Asheville Citizen" for July 19, 1916, contains the following reference to the Pigeon River j CANTON LITTLE DAMAGED AND CHAMPION FIBRE COMPANY IS UNINJURED .... Pigeon River has been high for the past 10 days but little property damage has been caused. The only damage sustained by the Champion Fibre Company was caused by cutting off of the mill from supplies. (Due to interruptions to rail service.) No actual shut-down resulted from delays of shipments. 26 October 2£, 1918 The "Asheville Citizen," October 26, 1918, reported: NO SERIOUS DAMAGE RESULTED FROM FLOOD GREATEST RAINFALL IN HISTORY OF WEATHER STATION What is believed to have been the heaviest rainfall in a 2i;-hour period is recorded for the 2k hours ending yester- day afternoon. The official figures given out by the local weather department show that in this time a total rainfall of 8.2ii inches came down since Thursday afternoon. .... Two or three bents in the trestle over the Pigeon River at Canton were washed away. . . . August 16, 1928 This flood was the sixth highest known at Canton. It was not a serious one on West Fork, but on the East Fork the flood was the highest since I876 and was slightly higher than the August 30, 19^0, flood but was not so severe as the flood of August 13, 19^0. Two storms of tropical origin brought heavy rainfall over the Pigeon River basin in August 1928. The center of the first storm passed southeast of the basin, through Charlotte, North Carolina, on August 11- 12 and brought rains which put many streams out of banks in the mountain region. The second storm moved from Florida northward, along the Alabama- Georgia line, on August llj-l6 and brought rains to the upper Pigeon River basin which produced a flood which was the sixth in order of magnitude of floods known in the Canton and Clyde vicinity, ranking below the two 19lj0 floods and the floods of 1810, I876, and 1893. The crest was some four feet lower than the record flood of August 30, 19h0, but the flood is notable in that it was the first flood to cause appreciable damage and inconvenience since the start of the industrial development of Canton in 1906. Water did not invade the plant buildings but flood water caused curtailment of operations on two days. The railroad trestle that connects the plant area with the wood storage yard on the left bank was washed out, other trackage was affected and pulp wood was washed away. The steel bridge at Fibreville was lost, houses in the Fibreville area were surrounded, and water supply to the area was cut off. The Canton business district was affected by 27 overflow. In Clyde water blocked the highway at both ends of town and flooded a number of houses. Accounts of the flood are found in three issues of the "Ashe- ville Citizen" and one issue of the "Canton Enterprise." The "Asheville Citizen," August 16, 1928, states: HIGHWAYS ARE BLOCKED FROM SLIDES, FLOODS With highways blocked in all directions and train service suspended between Asheville and Spartanburg and Asheville and Salisbury, Western North Carolina this morn- ing faced one of the worst traffic tie-ups in recent years as a result of slides and flood waters from streams swollen by nearly 36 hours of continuous rainfall. The stream reaching the highest level last night was the Pigeon River with a flood tide of 20 feet above its normal level. Fifteen families were moved out of their homes at Clyde and heavy damage was felt at Canton. The "Asheville Citizen," August 17, 1928, states: CHAMPION FIBRE COMPANY SHUT DOWN Canton, N. C, August 16 - Champion Fibre Company's large pulp mill was paralyzed here today on account of flood waters from yesterday's heavy rains. It was expected that some operation would be resumed sometime tonight. .... Pigeon River was estimated to be from 9 to 10 feet higher than normal. The "Asheville Citizen," August 18, 1928, carried the following report: PIGEON RIVER HIGH Wayne sville, N. C, August 17 - Lenoir Gwyn, of Wayne sville, who is spending the summer at ... . Springdale on Route No. 2Qk, the highway from Waynesville to Brevard and which crosses the Pigeon River at Woodrow and follows the course of the East Fork of the Pigeon for some distance, reports that 28 the Pigeon River was higher in that section (the East Fork at Springdale) Wednesday and yesterday than it has been in £0 yearsj that it overflowed its banks The "Canton Enterprise" for August 17, 1928, describes the flood more detail. CANTON IS VISITED BY HEAVIEST RAIN IN YEARS SWOLLEN STREAMS GREATLY DAMAGE CROPS AND PROPERTY IN PATH, HIGHWAYS BLOCKED The continuous downpour of rain here Wednesday from early morning till night, caused damage to property in this section such as has not been witnessed in a great number of years. Pigeon River began rising at a rapid rate early in the after- noon, and by midnighj, had swept out a number of small buildings and bridges and damaged crops along its path to a great extent. Business places and dwellings nearby were much endangered by the rising waters, and in many instances the occupants moved to safety. Cars from the Felment and Russell Motor Company garages were moved for safe keeping, and a number of the Fibreville residents left on account of their homes being surrounded by water. Fibreville was practically cut off when the iron bridge across the river was swept away and water and sewer connections were put out of service . Relief was soon given, however, when the water supply was temporarily restored, and plans for a walkway across the river is being made. The main road from Fibreville will be through the Phillipsville section and on to the No. 10 Highway until the bridge is rebuilt. The Champion Fibre Company suffered heavy losses when the trestle across the river used for transportation of wood was swept away, together with a considerable amount of the track- way and pulp wood. Work in many sections of the plant was suspended during the night and did not start until late in the day Thursday. Considerable damage is reported from the East Fork and Woodrow sections also. The Dick's Creek bridge, two small houses and some outbuildings are said to have been swept away, while other buildings and property were greatly damaged. Clyde is said to have been completely cut off by the No. 10 Highway being flooded at both ends of the town and a number of the residents nearest the river were forced to move out, taking their stock with them for safe keeping. A number of houses were said to have been flooded also. 29 August 13, l£jtO On August 13, 19^0, a West Indian hurricane, which had swept inland, resulted in an intense storm over the eastern section of the Tennessee Valley which produced high floods on streams in that area. On the Pigeon River at Canton and Clyde the flood was very nearly equal to the flood of June I876, the highest prior flood about which any appreciable amount of information is available. The flood slightly exceeded the flood which occurred in September 1893. It was about two feet under the best estimate that can be made for the height of the flood of 1810. The August 13, 19^0, flood was by far the most damaging up to that period in the history of Canton and Clyde. The plant of the Champion Paper and Fibre Company was flooded. Production was lost and equipment was damaged. A large part of the business section of Canton was flooded and houses which were flooded or surrounded by water totaled Qh at Canton and 17 at Clyde. TVA Hydraulic Data Branch engineers began investigations immediately after the flood and assembled extensive data on the rainfall amounts and distribution, the storm runoff, extent of flooding, and the flood damages. The storm of mid-August 19^0 was of tropical origin, as had been the storm which caused the flood of August 1928. This storm developed in the Atlantic Ocean east of the Bahamas and was of hurricane intensity when it moved inland over Georgia and South Carolina late on August 11, I9I4O. As it moved overland the storm rapidly lost its hurricane winds but its intense activity and high moisture content were retained as the storm center moved first over Atlanta, then swung in a slow circle over Knoxville, Bristol, and then Greensboro, North Carolina, in a period of some three and a half days. As the storm moved parallel to the Southern Appalachian Mountains on August 12 and 13, very heavy rainfall occurred, particularly to the east and northeast of the storm center. Plate h shows the storm rainfall over the Pigeon River basin. At Beech Gap, at the head of West Fork, a rainfall catch was located which totaled 16,8 inches for the storm. In Haywood Gap, at the head of Middle Prong of West Fork, a TVA recording rain gage showed 12„88 inches for the storm. At Wagon Road Gap, at the head of East Fork, the storm total was 12. hi inches and at Mt. Pisgah the rainfall exceeded the lU-inch capacity of the PLATE 4 30 recording rain gage. From these points on the basin rim, amounts for the storm graduated downward to 8 inches at the confluence of East Fork and West Fork at Woodrow. At Canton the storm total was Uo55 inches. From Canton to Walters Dam rainfall totals dropped off to about 2\ inches. The principal part of the rain over the Pigeon River basin fell in a period of £0 hours and the maximum hourly intensity rate was slightly under 1 inch per hour. Rural areas throughout the Pigeon River basin suffered heavy damage to corn, tobacco and potato crops. Practically every bridge on East Fork was washed away. Highways were damaged extensively throughout the storm area. At Canton, the Pigeon River began to rise slowly at 6 a.m. on Monday, August 12, and continued to rise at an irregular rate to a 10-foot stage at 6:30 a.m., August 13. At that time the river began a much more rapid rise, at a rate of about 1.3 feet per hour. The banks were overflowed and a considerable portion of the business section was flooded, along with adjoining residential areas. Upwards of 100 families were driven from their homes, the plant of the Champion Paper and Fibre Company was flooded and was forced to close down. The rise crested at 12: h0 p.m. on August 13, at a stage of 18.00 feet. The crest stage held for only a short time and by 9 p.m. the river was back within its banks. At the Champion plant, water entered low buildings on the morning of August 13, flooding motors and stopping operations. When water reached pump motors in the water treatment plant, the water supply to the mill was interrupted and the entire plant was shut down. As the water continued to rise other buildings were flooded until three quarters of the plant had been affected. Many motors were raised ahead of the rising water, but some 200 motors were reached by the water and had to be removed, cleaned and dried out. Machine shop equipment had to be torn down, cleaned and reassembled. Other machinery and controls were damaged by the mud and water. Pulp and paper in storage at low elevations was moved above the flood waters and was not damaged. Water surrounded coal stored in the plant yard and the coal was damaged by loss of fines and deposit of silt. Close to a thousand cords of pulp wood was lost from the wood storage yard on the left bank and a like quantity was left lodged against the company's railroad bridge at the lower end of the yard. Work lost by plant employees 31 due to the enforced shutdown totaled thousands of man-hours. Figure 2 is a scene in the Champion plant after the flood waters had receded. In the Canton business section supplies and machinery were damaged and a 21* -hour shutdown resulted at Canton Laundry on the right bank below Park Street. Flood water reached a depth of 32 inches in the plant. Stock was damaged at the Smoky Mountain Candy Company and seme damage was caused by mud and water at the Champion Motor Company and at Spears Inn. Heavy coal caffs were run onto the Southern Railway bridge as a protection against loss of the structure when water and debris piled up against the bridge. Similar precautions had been taken at the railro.ad bridge on the Champion property. Water over U. S. Highway 19 and 23 closed that route to traffic for 3 hours. Overflow on the approaches prevented use of Main Street bridge as well. Water entered or surrounded Qh houses in Canton. Of these £9 were in the Fibreville section,, owned by the Champion Paper and Fibre Company, 16 were in the Highland Park section, at Valley, Vance, and Conley Streets, on the right bank above Main Street bridge, and 9 were scattered through the downtown section. Flooding in Fibreville is pictured on the cover at the lower right. Depths of flooding ranged from a few inches to more than five feet. Since the rise came during daylight hours, it was possible to organize the evacuation of persons with some efficiency, preventing a possible loss of life. At Clyde the low-lying residential section was flooded. Water entered basements of 13> private homes but did not reach the floor level of any. Extensive damage was done to furniture and buildings when water entered the Pines Tourist Rooms. Water was up to h feet deep on U. S. Highway 19 and 23 and through traffic was stopped for several hours. The suspension footbridge at the Clyde School was damaged by drift and the high water. Communications were interrupted throughout the storm area. Because of the heavy damage to secondary roads and bridges, several schools were forced to close for periods up to two weeks. Mail service was disrupted to many areas and power service interruptions were common. Damages from the flood totaled $102,300 at Canton and $2,200 at Clyde. Adjusting these figures for the increased construction, 32 Figure 2 . - -AFTER THE MID-AUGUST 19^0 FLOOD ON PIGEON RIVER Inside the plant of the Champion Paper and Fibre Company at Canton. The late August flood was about 3 feet higher than the flood line shown in the picture. IIn , m . n\ (Photo courtesy Asheville Citizen-Times ; Figure 3- --CANTON STREET FLOODED AUGUST 30, 19^0 On Park Street, Canton, North Carolina, business and commercial establishments were flooded by the late August I9J4-O flood. 33 equipment, and labor costs of 1959 and making a moderate allowance for the increased development which has taken place in the flood plain gives damage figures for a recurrence of the August 13, 191*0, flood under present conditions which amount to about $1*00,000 at Canton and $8,000 at Clyde. August 30* 19 b0 Two and a half weeks after the flood of August 13, 19l;0, the upper Pigeon River watershed was again deluged with very heavy rainfall which resulted in Pigeon River rising to its greatest known heights at Canton and Clyde. The storm differed greatly from the first August 19^0 storm, but the flood Tiahich resulted on the Pigeon River was more devastat- ing than the first. Two lives were lost when a house was swept away on a tributary of West Fork Pigeon River above Lake Logan. Through Canton and Clyde the flood was 2 to 3 feet higher than the flood of August 13, 19l*0. Industries and businesses which were just beginning to recover from the first flood were again hit. Other businesses and homes, previously thought to be above flood danger, were flooded this time. When overflow began, store goods, equipment, and furniture were raised to above the elevation of the first flood, only to see the water continue to rise, sub- merging everything that was thought safe,, TVA Hydraulic Data Branch engineers again went throughout the flood area investigating rainfall, runoff, and damages, and outlining the flood crest profile. The storm of August 29-30, 19l|0, was much different from the storm of August 12-13. Where the first storm was due to a tropical hur- ricane which moved inland, the second storm originated in a purely local meteorological disturbance. The first storm had covered a wide area, including ihe eastern part of the Tennessee River Basin from the head- waters of the Clinch River to the headwaters of the Little Tennessee River, and in addition, a large area in North and South Carolina and Virginia. The second storm was primarily confined to the North Carolina portion of the Tennessee River Basin, extending from Mt. Mitchell in the headwaters of the Nolichucky River in Mitchell County, to the headwaters of the Little Tennessee in Jackson and Macon Counties. The Pigeon River Basin lies in the region where these two storm areas overlapped and had 31* severe floods from both storms. The August 29-30, 19^0, storm seemed to develop over the immediate area affected. There were no definite indica- tions of the intensity of this storm on the surface weather maps either prior to or subsequent to the appearance of the storm over the Southern Appalachian Mountains. A broad and relatively deep current of moist tropical air had been flowing over the area for a number of days, producing scattered showers and thunderstorms. During the night of August 29-30, a mass of cold polar air moved southward along the Atlantic coast. The presence of these air masses, along with a strong southerly current, lifted the moisture- laden tropical air and produced the heavy shower activity. Undoubtedly the rough physiographic conditions over the area also aided in initiating the release of shower activity. Such a catastrophic rainstorm, when being of a local nature such as this one, cannot be accurately forecast for any long period in advance, with the present knowledge and available sources of data on developing conditions. Plate 5 shows the storm rainfall over the Pigeon River basin for the August 29-30 period. Distribution of rainfall was somewhat more uniform than for the mid-August storm, with amounts decreasing gradually from the headwaters to the mouth of the river. The East Fork and West Fork drainage basins received about the same total precipitation, with amounts in excess of 11 inches along the high divide of the watershed, dropping off to about 9 inches one -third of the way to the confluence of the forks and 6£ inches at the Junction at Woodrow. At Canton the storm total was 6.36 inches. At Waterville the storm total had dropped off to 3.1|7 inches. The tributary watersheds of Richland Creek, Jonathans Creek, and Crabtree Creek each had $^ to 6 inches of rain. The storm lasted 20 to 22 hours as compared to 5>0 hours for the August 12-13 storm. The maximum hourly recorded intensity rate was about 2^ inches per hour. Although the total precipitation amounts for the storm were about the same on East Fork and on West Fork, the intensity rate must have been greater on West Fork. The flood there was 2 to h feet higher than on August 13, while on East Fork the crest was ]^ to 2 feet lower than in the first flood. Many bad mountain slides were observed in the head of West Fork above Lake Logan, which indicate very high intensity rates. On Big Creek and Right Hand Prong slides were found which started PLATE 5 35 near the basin divide and continued to the mouth of the streams, vhere huge piles of drift and debris were left. It was on Big Creek that the Reverend and Mrs. Bill Hampton lost their lives when their home was carried away as they slept. Mrs. Hampton's body was located below Lake Logan two days after the flood.. The body of Mr. Hampton was lodged in a pile of drift a quarter of a mile below the mouth of Big Creek and was not found until a week after the flood. Roads and bridges repaired after the first flood were washed out or damaged again, land was scoured and crops were lost at some points where they had survived the first flood. Traffic was interrupted by high water and by washed out roads and bridges. Power service and communications were disrupted. At Canton, the Pigeon River began a sharp rise at 7 a.m. Thurs- day, August 29, and continued at a rate of 1 to 2 feet per hour to a crest of 20.75 feet at 6;30 a.m. the following morning. This was 2.75 feet higher than the crest reached on August 13. Plate 8 shows the area over- flowed in Canton. Ninety-six homes were flooded and the occupants were forced to evacuate from many more. The Champion Paper and Fibre Company, scarcely back to normal operation after the first flood, was again heavily damaged. Water was 3 to k feet deep in the heart of the Canton business district, the bridge at Fibreville was washed out, and other bridges or their approaches were damaged. At the Champion Paper and Fibre Company water flowed through or around all the plant buildings except the office, as seen on Plate 8. The upper left cover picture shows conditions in the railroad yard of this plant. Employees worked throughout the night Thursday as the river rose raising hundreds of motors to what they thought was a safe height, only to see them submerged as the waters went 3 feet higher through the plant than on August 13. In all, some 500 motors were covered by the water. Chemicals were lost or damaged when touched by the water. A large quantity of pulp and finished paper was damaged in basements and other storerooms. Damage to the stock increased as the piles tipped over into the water when the bottom cartons or bundles became water- soaked. In other cases water seeped upward from one package to the one above and caused damage above the water line. Trackage and equipment in the plant yard were damaged and additional 36 coal in storage in the yard was affected. About 1^00 cords of pulp wood was washed from the wood yard. The shutdown period averaged 100 hours for the plant as a whole. All motors reached by the water had to be removed, dried out, and cleaned,, Damaged pulp and paper stock was salvaged and reworked where possible. Loss in payroll to the employees due to the enforced shutdown again was large . A total of 22 commercial establishments in Canton were damaged by the flood. Figure 3 shows flooding on Park Street. Water was 6 feet k inches deep in the plant and office of the Canton Laundry, resulting in a shutdown of 36 hours for the plant. Additional damage was done to supplies and equipment. An ice plant, operated in conjunction with the laundry, was shut down a week as a result of the flood. The Smoky Mountain Candy Company lost almost their full stock of candy when water reached a 3^— foot depth in the building. Many places were flooded this time which had escaped the first flood. Rugs and seats were damaged in the Colonial Theatre. Water stood 26 inches deep in the barber shop in the theatre building and 3g feet deep in the adjoining Colonial Restaurant, causing a shutdown there that extended over the busy Labor Day weekend. At the Union Clothing Company no precautions had been taken since water did not enter the store in the August 13 flood. Water was 2 feet deep in the store this time, causing heavy damage to suits, clothing accessories, and equipment. Six service stations and six garages were flooded. The Spears Inn suffered more damage and the Pines Tourist Home had heavy damage to floors and furniture. In the Highland Park section water entered 12 homes and surrounded 3 others. In central Canton 18 houses were flooded and 5 had water around them. In Fibreville a total of 6l houses were flooded, with water standing up to the eaves of several houses. Figure 1, the frontispiece, shows the flood on Pigeon River at Fibreville. Two houses were moved off their foundations. Town policemen, firemen, and volunteers had worked through Thursday night evacuating the people and such furniture as time would allow. The Fibreville bridge went out at 6 a.m. on Friday, taking with it the water line which served the community. Water was 8 feet deep in the National Guard Armory near the Canton School, marooning two members of the Guard unit overnight. Walls were damaged when a corner of the building was undercut by the flood waters. 37 Damage to the left bank approach fill and a trestle section of the Southern Railway bridge in Canton interrupted train service for 3 days. At Clyde, as at Canton, residents made preparations for a flood similar to the August 13 flood when they saw the river breaking overbank. They were entirely unprepared for a flood which rose 3 feet higher. Twenty homes were flooded, where none had been before, and 23 others were surrounded by water or had their basements flooded. Traffic through the town was halted when water reached a depth of k feet on U. S. Highway 19 and 23. The steel truss bridge over Pigeon River in Clyde, a landmark for 50 years, was washed out. The footbridge at the Clyde School was heavily damaged and building materials were carried away from the construction site of a school addition. Three service stations and a machine shop were flooded. Water lines were broken and streets and sewers were damaged. Damages from this flood totaled $303,100 at Canton and $l£,600 at Clyde. Adjusting these figures to 195>9 costs and values and allowing for the increased development in the flood plain gives estimates of damage if the August 30, 19i|0, flood were to recur today which amount to about $1,200,000 at Canton and $£5,000 at Clyde. June 16, 19U9 This was the highest flood which has occurred since 19U0 and the only flood in that period to overtop the banks at Canton and Clyde. TVA Hydraulic Data Branch engineers made investigations immediately following the flood. From 6 to 12 inches of rain fell over the Pigeon River above Canton, much of it in the last 2l± hours of the storm. East Fork Pigeon River near Cruso rose three feet higher than in the highest of the two floods in 19^0, due to very heavy contribution from the two tributaries, Pisgah Creek and Crawford Creek, Houses were flooded at Woodrow and in the Fibreville section of Canton, Crops, highways, and bridges had heavy damage . A widespread storm, accompanied by the passage of a cold front and squall line over the mountain area, produced heavy rain over the headwater regions of the French Broad, Pigeon, Little Tennessee, and Hiwassee Rivers. The greatest amounts fell during the night of June 1$ 38 and the daylight hours of June 16. By the afternoon of the 15 th rainfall totaling 3 inches had fallen along the high rim of the Pigeon River basin. Up to 9 inches fell in the next 2i;-hour period, ending at 6 p.m. on June 16. Rainfall for the storm totaled 5.1 inches at Canton and %,h inches at Chambers Mountain near Clyde. East Fork Pigeon River was out of banks from 10 a.m. to 6 p.m. on June 16. High velocities scoured secondary roads and farm lands. East Fork at Woodrow was about as high as on August 30, 19^0. Eight houses were flooded to depths ranging from 0.5 foot to h feet. West Fork Pigeon River did not reach serious flood stages and the Pigeon River between Woodrow and Canton was 3 to k feet lower than in the record flood of August 30, 191*0. Wide overflow occurred but velocities were lower and scouring was relatively light. At Canton the crest occurred at 3 p.m. at a stage of l^.hh feet, 5.3 feet under the August 30, 19h0 3 flood. At the recreation park, built since the 19ii0 flood near the National Guard Armory, the fill and fence around the swimming pool were damaged, and the filter plant and pump were flooded. Water entered a basement at the Canton Motor Company to a depth of 3.8 feet. The basements of two nearby houses were flooded. Following its experiences in the two 19U0 floods, the Champion Paper and Fibre Company dredged the channel of Pigeon River and constructed dikes on both banks through the plant property. Flood gates were installed on the water intake and on sewer lines. The June 19U9 flood passed through the dredged channel at the plant with little damage. Without these protective measures the flood would have been 2 feet deep on the lower floors of the plant. The plant was shut down ahead of the crest of the flood, as a precautionary measure, and 8 hours of production were lost. Surface water which collected behind the dike entered the lowest floors and flooded 5 motors. At Fibreville 6 houses were flooded and a suspension type foot- bridge was washed out. Figure 5 shows flooded houses in this area. The local National Guard Company had been organized in the emergency and assisted in the evacuation of 15 families in advance of the flood. Figure k. — JUNE 19^9 FLOOD IN CLYDE Near the east city limits of Clyde, flood water overflowed U. S. Highways 19 and 23. Crest was 1.5 feet higher than the water in the photograph. The crest of the August 30, 19^0, flood was about 7 feet higher than the water in the picture. /_. „ TT . , , . ,, \ (Photo courtesy Waynesville Mountaineer ; Figure 5. --HIGH WATER IN CANTON, JUNE 19^9 Homes in the Fibreville section of Canton were overflowed on the afternoon of June l6. The crest of the flood is indicated by the dark stains on the houses. The 19^-0 flood reached nearly to the eaves of these houses. (Photo courtesy of Guy Teague, Canton, N. C.) ho Overflow began at Clyde at 2 p.m. and lasted until 6 p.m. The crest was 3 feet under that of August 30, 19^0. Water in U. S. High- way 19 and 23 blocked through traffic. Figure k shows the flooding of the highways. Water did not reach the floor level of any house, but l£ yards were flooded and water entered 33 basements in the town. At Thompsons Tourist Court, at the upper end of Clyde, 16 cabins were flooded. Water reached a 16-inch depth in the Pines Grocery, at the lower edge of Clyde. ACKNOWIEDGMENTS This section of the report has been prepared by personnel of the Hydraulic Data Branch, Division of Water Control Planning, under the general direction of Reed A. Elliot, Chief Water Control Planning Engineer and the immediate supervision of Albert S. Fry, Chief, Hydraulic Data Branch. Field investigations were made under the direction of James W. Beverage, Head of the Field Investigations Section. High water investi- gations in the field were carried out by District Engineer Myron 0. Jensen assisted by Area Engineer Joseph S. Enloe. Thomas C. Bounds, Head of the Office Engineering Unit, prepared charts and maps for the report under the direction of Paul C. Spath, Head of the Hydraulic Investigations Section. Newspaper files at Asheville, Wayne sville, and Canton were searched for flood information by Mr. Jensen and Mr. Enloe. Flood information was analyzed and this report was prepared by Mr. Jensen. II. PAST FLOODS ON STREAMS IN CANTON-CLYDE REGION Tennessee Valley Authority- Division of Water Control Planning Hydraulic Data Branch II. PAST FLOODS ON STREAMS IN CANTON-CLYDE REGION Large floods have been experienced in the past on streams in the general geographical and physiographical region of Canton and Clyde, North Carolina, as a result of heavy rainstorms that have occurred over the watersheds of these streams. Such storms, except for the vagaries of the weather, could just as well have occurred over the upper Pigeon River watershed. Had they done so, floods would have resulted on the Pigeon River comparable in magnitude to those that happened on the neighboring streams. It is therefore desirable in connection with any determination of floods that may occur on the Pigeon River in the future, to consider the floods that have occurred on streams in the Canton and Clyde region and whose watersheds are similar in physical characteristics to the upper Pigeon River watershed. Such characteristics include both topography and watershed cover. Maximum Known Regional Floods Table 3 contains a list of the maximum known floods that have been experienced on streams in the region of Canton and Clyde, which in this report is considered to be the area within 60 miles of these places. All of the floods occurred on streams whose watersheds are similar in physical characteristics to that of the upper Pigeon River. This necessarily limits the neighboring streams considered to those that lie in the Southern Appalachian Mountains since streams in other areas differ greatly in water- shed characteristics from those of the upper Pigeon River. One of the earliest floods known to have occurred in the region was that of April 1791 on Swannanoa River at Biltmore, North Carolina. Other early floods that have occurred in the region were those of March 1867 on Nantahala River at Almond, North Carolina, and of March 1875 on Little River near Walland, Tennessee. 1*2 - O CM moOH J- OJ VO VO O OA O oj H on oj oj -=*• H J- VO LTN H OJ H H H on 1 o o S3 •> O CQ I m o 1 o d o i o -P o - OA CO O O O VO CM _d _d _d H OA OA OA OA OA i— I i— I <— I i— I H ino O onvo VO O O OA O J- _d- -d- CO OA OA OA OA r— I i— I H f— I H lt\ o o vo on i— i on on i— i h -p -p -p -p CQ CQ CQ CQ 3 ? ? 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Particularly significant are , , the hurricanes of July 1916 and mid-August 19U0. The storm of July 13-17, 1916, caused record flooding along the upper French Broad River. A considerable area on the eastern French Broad watershed divide experienced over 16 inches of rain, the major portion falling in a 12-hour period on the night of July l£-l6. The greatest amount of rainfall recorded in a 2h-hour period in the Tennessee River Basin, 22.2 inches, occurred at Altapass, North Carolina, during this storm. The rainfall amounts decreased westward and northward across the Valley and only moderately heavy rains of k to 5 inches fell on the upper Pigeon River watershed. The hurricane of mid -August I9I4O produced large floods on water- sheds on the eastern Tennessee Valley divide from the Blue Ridge Mountains south to the Hiwassee Basin. In a ii8-hour period from August 11 to 13, rainfall amounts up to 1$ inches fell in the vicinity of the Watauga River watershed causing record floods in that area. A 16-inch center of rainfall at Haywood Gap on the divide between the Pigeon and French Broad Rivers south of Canton caused the highest known flood on the East Fork Pigeon River. The storm of late August 191*0 which followed the mid-August storm by only 2\ weeks was of the thunderstorm type with heavy rains along the Southern Appalachian Mountains of eastern Tennessee and western North Carolina. Rainfall amounts up to 13 inches occurred in a relatively narrow band along the Blue Ridge Mountains, In general, rainfall intensities at those stations receiving heavy rainfall were higher than in the mid-August storm. The upper Little Tennessee and its tributaries, the Tuckasegee and Cullasaja Rivers, which were only moderately flooded during the mid-August storm, rose to record heights during this storm. The Pigeon River at Canton which approached record flood heights in mid-August reached unprecedented stages during the late August flood. An average of over 9 inches of rain fell in Pigeon River watershed above Canton in approximately 2k hours. The floods that are listed in Table 3 have all occurred on physically similar watersheds in the general region of Canton and Clyde. hh This indicates that floods of like magnitude, modified to take into account differences in drainage area characteristics, may occur in the future on the Pigeon River at Canton and Clyde „ Pigeon River vs. Regional Flood Discharges The flood discharges in Table 3 have been plotted on Plate 6. This chart illustrates graphically for drainage areas of various sizes the maximum flood discharges that have been experienced on streams in the Canton and Clyde region. The key map on Plate 6 shows the locations of the streams for which the discharges have been plotted and listed in Table 3. Included on Plate 6 and in Table 3 is the maximum known discharge on the Pigeon River, that for the flood of August 30, 19^0. The flood of August 30, 19^0, is the largest that is known to have occurred at Canton since 1810. However, comparison of this flood with others in the region indicates that more severe floods have occurred on neighboring streams. In particular, higher peak discharges in relation to the drainage area have occurred on Little River at Walland, Tennessee, in 1875 (No. 3, Table 3 and Plate 6), Swannanoa River in 1791 (No. 9), East Fork Tuckasegee River on August 30, 19i;0 (No. 13), and the South Toe River on August 13, 19^0 (No. lh) . Based only on a consideration of the maximum flood discharges that are known to have been experienced on streams in the Canton-Clyde region, it is reasonable to expect future floods in the order of lil,000 cubic feet per second at Canton and k^ 3 000 cubic feet per second at Clyde . Flood Heights for Various Discharges The peak discharge for the flood of June 16, 19ii9, in the Canton-Clyde reach of Pigeon River was over bankfull in many places and considerable flooding resulted. This high water is doubtless remembered by many people who have homes, businesses, or other interests along the Pigeon River. In order to show the height of floods greater than that of 19^9 t as compared to that flood at Canton and at Clyde, Table h has been prepared. PLATE 6 is • IS _J> eg II II cc z ?3x I lO \- z D -I < < o a ad) „ i- z 5 o < 5^ u. « o 9 z o Z w u > Z 2 O z 2 X (/> UJ < i o ° z ^ Q Q : Ll. q z < O z S y o s z < o o o < J I I D L S31IW 3bVnDS Nl V3UV 30VNIVHQ TABIE k RELATIVE FLOOD HEIGHTS FOR VARIOUS DISCHARGES PIGEON RIVER AT CANTON AND CLYDE At Canton At Clyde Peak Dischage Mile 6lul Mile 57.65 At Canton Stream Gage Feet Above Feet Above Date of Flood Cubic Feet Per Second 191+9 Flood 19^9 Flood June 16, 19k9 19,500 August 30, 19U0 31,600 5.3 i.O la, 000 9.1 6.8 60,000 12.7 11.6 Maximum Probable Flood 81,000 16.7 16.3 The elevations of floods at Canton and Clyde greater than that of 19U9 are shown by ticks on the profile, Plate 9, at Mile 61*. 1 and Mile 57.65. Acknowledgments This section of the report has been prepared by personnel of the Hydraulic Data Branch, Division of Water Control Planning, under the general direction of Reed A. Elliot, Chief Water Control Planning Engineer, and the immediate supervision of Albert S. Fry, Chief, Hydraulic Data Branch. Flood studies and preparation of this section of the report were made under the direction of Willard M. Snyder, Head of the Hydrology Section, by Roger P. Betson. III. MAXIMUM PROBABLE FLOOD Tennessee Valley Authority Division of Water Control Planning Flood Control Branch III. MAXIMUM PROBABLE FLOOD The preceding sections have told about the floods that have already occurred on the Pigeon River in the vicinity of Canton and Clyde and of large floods that have occurred on other streams close to those communities. This section describes the basis for the Maximum Probable Flood that may reasonably be expected and discusses the extent of the flood plain that would be affected by this flood. Floods of this magni- tude are of the kind considered in planning the design and operation of protective works, the failure of which might be disastrous. Extreme floods on Pigeon River in the vicinity of Canton and Clyde, where the drainage areas are 133 and 162 square miles, respectively, can occur as a result of various combinations of meteorologic and hydro- logic events. Large floods have resulted from winter storms of fairly long duration when infiltration and other losses are small and, in one case, when snow was a contributing factor. The largest floods have resulted from intense storms of the cloudburst or hurricane type occurring in the summer or early fall when loss rates are high. DETERMINATION OF MAXIMUM PROBABLE FLOOD In determining the Maximum Probable Flood on the Pigeon River, consideration was given to great storms and floods that have already occurred in the Pigeon River watershed and to those which have occurred elsewhere but could have occurred in this area. This procedure helps to overcome the lack of hydrologic data in the relatively short period for which dependable records are available. Section I stated that the maximum known flood on Pigeon River occurred on August 30, 19l|0. Peak discharge for this flood is estimated 1*7 to have been 31,600 cubic feet per second at the Canton stream gage. It is reasonable to expect that greater floods than that of 19li.O will occur on the Pigeon River. Observed Storms The watershed of the Pigeon River is unusual from a meteoro- logical standpoint in that it is divided by the Appalachian Mountains. These mountains have prevented major storms from centering over the entire watershed. Storms center on the east or west side of the mountains, depending upon their source. The major portion of this watershed is to the east of the mountains. Consequently, it was assumed that critical storms will occur there. Observed storms are meteorologically transposable to the Pigeon River watershed from within a broad region extending generally from the Atlantic Ocean to the Appalachian Divide and from Florida through Pennsylvania. The moisture source for storms in this region is the warm, moist air flowing northward from the tropical Atlantic Ocean. In general, the moisture potential for a given region decreases with its distance from the moisture source. When transferring storms within the broad region to the Pigeon River watershed, appropriate adjustments were made for differences in this moisture potential and for the elevation of the surrounding mountain barrier. Table 5 lists known rainfall depths for several large storms transposable to the Pigeon River watershed. TABLE $ SELECTED MAXIMUM OBSERVED STORMS Rainfall Depth on 133 Sq. Mi. Date Location in 6 Hours inches July 1916 North Carolina 7.1 August 1939 New Jersey 8.9 October 19hl Florida 10.2 September 19^0 New Jersey 16.5 On the basis of these and other data, a rainstorm of 11. I* inches in 6 hours was adopted for computing the Maximum Probable Flood on the Pigeon River at Canton-Clyde. The unit hydrograph technique, with appropriate watershed factors, was used in this computation. Storms greater than that which would produce the Maximum Probable Flood can occur. The storm considered to be the greatest from a meteoro- logical standpoint would be approximately twice the storm adopted for the Maximum Probable Flood. Observed Floods When considering peak discharges on other streams, factors such as the meteorology of the region and flood-producing characteristics of the watershed were given consideration in determining whether their application to the Pigeon River would be appropriate. In addition to the floods listed in Table 3 of Section II, the following Table 6 lists peak discharges for observed floods on several streams of approximately the size of the Pigeon River. For comparison the discharge of the maximum known flood on the Pigeon River at Canton is listed. TABLE 6 SELECTED MAXIMUM OBSERVED FLOODS (Streams listed are approximately the size of the Pigeon River at Canton- Clyde.) Stream Elk Creek Linville River Wilson Creek Johns River Warrior Fork Watauga River Mud Creek Tuckasegee River Catawba River S.F. New River N.F. New River Pigeon River Location Elkville, N. C. Branch, N. C. Adako, N. C. Collettsville, N. C. Morganton, N. C. Drainage Area Date sq.mi. 50 191*0 65 19 1*0 66 19U0 69.1 191*0 80.5 191*0 Peak Discharge Per Amount Sq. Mi. cfs cfs 70,000 1,1*00 39,500 608 99,000 1,500 31,000 1*50 38,000 1*70 50,800 560 1*0,000 367 1*0,800 285 71,000 1*18 52,800 256 79,1*00 287 31,600 238 Near Sugar Grove, N. C. 90.8 191*0 Naples, N. C 109 1916 Tuckasegee, N„ C. 11*3 191*0 Marion, N. C. 170 191*0 Jefferson, N. C. 207 191*0 Crumpler, N. C. 277 191*0 Canton, N. C. 133 191*0 h9 Maximum Probable Flood Discharges From consideration of the flood discharges in Table 6 and of the transposition to the Canton-Clyde area of outstanding storms which have occurred elsewhere but can occur over the Pigeon River watershed, the peak discharge of the Maximum Probable Flood for this stream at the Canton gage was determined to be 81,000 cubic feet per second. The same rate was used at Clyde, downstream, because the reducing effect on the flood wave in traveling from Clyde to Canton would neutralize the addi- tional inflow which enters from the small drainage area between these places. This peak rate of discharge is about two and one -half times that of the presently known maximum flood of August 30, l°li0. Frequency The frequency of a flood of the magnitude of the Maximum Probable Flood is not susceptible of definite determination. Such a flood would occur on the average only at rather long intervals of time, but it could occur in any year. Possible Larger Floods Floods larger than any of those discussed are hydrologically possible. However, the combination of factors that would be necessary to produce such floods would occur at rare intervals, if at all. The consideration of floods of this magnitude is of greater importance in some flood problems than in others and should not be overlooked in the study of any flood problem,, Such floods, because of their extreme rarity and uncertainty of occurrence on a given watershed, need be considered only where dependence is placed on protective works, the failure of which would cause loss of life or destruction of valuable property. FLOOD HEIGHTS AND VELOCITIES Flood Crest Profiles and Overflow Areas The crest profiles computed for the Maximum Probable Flood on the Pigeon River in the vicinity of Canton and Clyde are shown on Plate 9 50 They were computed using stream characteristics for selected reaches as determined from valley cross sections and observed flood profiles. They are based on channel conditions existing in 1958. The height of the Pigeon River Maximum Probable Flood profile above elevations already experienced varies between 8 and lit feet. The height that would be reached by a Maximum Probable Flood at several locations in Canton and in Clyde is shown in Figures 6 through 11. It is impossible to foretell the destructive effect of velocities such as those described in the succeeding paragraph of this report, "Veloci- ties and Rates of Rise," on bridges over the stream and other nearby structures. In computing the profile of the Maximum Probable Flood there was no choice but to assume the survival of all structures. No clogging was assumed at bridges. The elevations shown on Plate 9 and the overflow areas shown on Plate 7 have been determined as accurately as possible consistent with the basic data, but actual elevations may vary from those shown on the profile and map. The standard contour interval of the map permits only an approxi- mate plotting of the boundaries of the flooded area. To determine flood elevations and limits with a higher degree of accuracy would require costly surveys and studies that are not warranted. Velocities and Rates of Rise During the Maximum Probable Flood, velocities in the main channel of Pigeon River would range frcm about 6 to more than 20 feet per second. In the overflow area, velocities would range from 2 to 7 feet per second. The greatest channel velocities would occur at the constricted channel sections at Mile 62.1 and Mile 65.0. The greatest overbank velocity would occur in the reach near Mile 59.5 where the overflow area is a smooth open field. The Maximum Probable Flood on the Pigeon River at the Canton stream gage, Mile 61;. 1, would rise about 32 feet above low water to its crest stage in about 8 hours. The maximum rate of rise would be about 12 feet in 2 hours. 51 Figure 6. --PARK STREET, CANTON, COULD BE DEEPLY FLOODED This view east from Pigeon River bridge along U. S. Highways 19 & 23 (Park Street) shows the depth to which the Maximum Probable Flood could inundate this part of Canton. The rod targets indicating the height of such a flood are in the centers of the white circles on photograph. (Figures 6 through 11 courtesy of Mr. James M. Deaton, The Champion Paper and Fibre Company) Figure 7 • - -WATERFRONT OF THE CHAMPION PAPER AND FIBRE COMPANY Downstream from the Southern Railway bridge, the height of the Maximum Probable Flood would range from 12 to 10 feet above the spur tracks, as shown by the rod targets. The levee built along the right bank after the 19^0 floods can be seen in left center of photograph. Figure 8 . - -WATER STREET, CANTON, IS WELL NAMED View east from riverbank along Water Street from the end, toward intersection of Main Street in background. Camera was about 5 feet below the level of the Maximum Probable Flood, which is indicated by encircled targets. Figure 9. --CEILINGS IN FIBREVILLE COULD BE SUBMERGED Northbound view of Fibreville Street at intersection of Terrace Road. The Max- imum Probable Flood level, which is about 5 feet above the edges of these porch roofs, is shown by the targets. The distant target is just beyond Avenue A. Figure 10 . - -DEPOT STREET IN CLYDE, LOOKING EAST Height of the Maximum Probable Flood at Clyde is shown by the line connecting the rod targets. The town offices and the fire station are at the end of the block near the distant rod. Figure 11. --PIGEON RIVER FLOWS BETWEEN CLYDE SCHOOL AND ITS GYMNASIUM These school buildings are accessible from each other by a footbridge concealed in background. Maximum Probable Flood lines are drawn through rod targets en- circled in white against the gymnasium, across the river, and in black against the schoolhouse. Deep, moving flood water in the overflow areas is most likely to affect people and buildings. Moderate stream velocities in combination with rapid rate of rise and deep flow would create a hazardous situation. Even low velocities combined with the buoyancy of deep flooding can be destructive. ACKNOWLEDGMENTS This section was prepared by the Flood Control Branch of the Division of Water Control Planning under the general direction of Reed A. Elliot, Chief Water Control Planning Engineer, and the immediate direction of Edward J. Rutter, Chief, Flood Control Branch. Basic hydraulic data were furnished by the Hydraulic Data Branch. Flood studies were under the supervision of B. J. Buehler, Head, Operation Studies Section. The flood discharges were determined by Donald W. Newton and the profiles were computed by Logan A. Gillett and Bevan W. 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