FLOODS OF APRIL 1979, MISSISSIPPI, ALABAMA, AND GEORGIA Report prepared jointly by the U.S. Geological Survey and the National Oceanic and Atmospheric Administration U.S. DEPARTMENT OF THE INTERIOR U.S. DEPARTMENT OF COMMERCE U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1319 Floods of April 1979, MISSISSIPPI, ALABAMA, AND GEORGIA FRONTISPIECE. Sequence of photographs showing the destruction of the bridge on State Highway 50 over the Tallapoosa River below Martin Dam near Tallassee, Ala., about 1630 CST, April 14, 1979. Photographs courtesy of H. H. Weldon, Electic, Ala. FLOODS OF APRIL 1979, MISSISSIPPI, ALABAMA, AND GEORGIA By GEORGE W. EDELEN, JR., K. V. WILSON, and JOE R. HARKINS, U.S. Geological Survey, and JOHN F. MILLER and EDWIN H. CHIN, National Weather Service, National Oceanic and Atmospheric Administration U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1319 Report prepared jointly by the U.S. Geological Survey and the National Oceanic and Atmospheric Administration UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1986 UNITED STATES UNITED STATES DEPARTMENT OF THE INTERIOR DEPARTMENT OF COMMERCE DONALD PAUL MODEL, Secretary MALCOLM BALDRIDGE, Secretary NATIONAL OCEANIC AND GEOLOGICAL SURVEY ATMOSPHERIC ADMINISTRATION Dallas L. Peck, Director Anthony J. Calio, Administrator Library of Congress Cataloging in Publication Data Main entry under title: Floods of April 1979, Mississippi, Alabama, and Georgia (Geological Survey professional paper; 1319) "Report prepared jointly by the U.S. Geological Survey and the National Oceanic and Atmospheric Administration." Bibliography: p. 45 1. Floods Mississippi. 2. Floods Alabama 3. Floods Georgia I. Edelen, George W. II. Geological Survey (U.S.) III. United States. National Oceanic and Atmospheric Administration. IV. Series. GB1399.4.M7F55 1984 551.48'0976 84-600097 For sale by the Books and Open-File Reports Section, U.S. Geological Survey, Federal Center, Box 25425, Denver, CO 80225 CONTENTS Glossary VIII Reservoirs 28 Abstract 1 Major river basins of eastern Gulf of Mexico 29 Introduction 1 Coosa River basin 29 Acknowledgments 3 Tallapoosa River basin 29 Meteorological setting 4 Alabama River basin 29 Antecedent conditions 4 Tombigbee River basin 30 Early spring storms 4 Tombigbee River upstream from Gainesville, Ala 30 March 3-4 4 Tombigbee River downstream from Gainesville, Ala 31 March 10-11, 14, and 21 5 Pascagoula River basin 33 March 23-24 5 Pearl River basin 33 April 1-4 7 Lower Mississippi River basin 39 April 8-9 9 Big Black River basin 39 Major storm event: April 11-13 11 Flood-crest stages 39 500-mb features 11 Streamflow velocities 40 850-mb features 11 Velocity changes during peak discharges 40 Surface weather features 14 Velocity distribution through bridge openings 40 Satellite imagery 15 Flood hydrograph data 41 Precipitation distribution 17 Ground-water fluctuations 42 General description of floods 19 Numbering system for wells 44 Magnitude of floods 23 Salinity and temperature data, Mobile Bay and Gulf of Mexico - 44 Flood damages 23 Aerial photography 44 Flood frequency 24 Selected references 45 ILLUSTRATIONS FRONTISPIECE. Sequence of photographs showing the destruction of the bridge on State Highway 50 over the Tallapoosa River below Martin Dam near Tallassee, Ala, about 4:30 p.m., April 14,1979. FIGURE 1. Area affected by floods on the Alabama, Big Black, Chattahoochee, Chickasawhay, Coosa, Pearl, and Tombigbee Rivers and their tributaries in April 1979 2 2. Significant meteorological features associated with the storm of March 3-4,1979 5 3. Isohyetal analysis of storm rainfall March 3-4,1979 6 4. Significant meteorological features associated with the storm of March 23-24,1979 7 5. Isohyetal analysis of storm rainfall, March 23-24, 1979 8 6. Significant meteorological features associated with the storm of April 1-4,1979 9 7. Isohyetal analysis of storm rainfall, April 1-4, 1979 10 8. 500-mb analyses: A. 0600 CST, April 11,1979 12 B. 1800 CST, April 11,1979 12 C. 0600 CST, April 12,1979 12 D. 1800 CST, April 12,1979 12 E. 0600 CST, April 13,1979 12 F. 1800 CST, April 13,1979 12 9. 850-mb analyses: A. 0600 CST, April 11,1979 - B. 1800 CST, April 11,1979 - C. 0600 CST, April 12,1979 - D. 1800 CST, April 12,1979 - E. 0600 CST, April 13,1979 F. 1800 CST, April 13,1979 VI CONTENTS FIGURE 10. Surface analyses: Page A. 0600 CST, April 11,1979 16 B. 1800 CST, April 11,1979 16 C. 0600 CST, April 12,1979 16 D. 1800 CST, April 12,1979 16 E. 0600 CST, April 13,1979 16 F. 1800 CST, April 13,1979 16 11. Analysis of hourly observations at 1500 CST, April 12, 1979 17 12. GOES visual image for 0730 CST, April 12,1979, with major features of surface weather map superimposed 18 13. Enhanced GOE S infrared images (Mb curve): A. 0000 CST, April 12,1979 20 B. 0230 CST, April 12,1979 21 14. Radar summary map: A. 0535 CST, April 12,1979 22 B. 1435 CST, April 12,1979 22 15. Rawinsonde plot, 1800 CST, April 12,1979: A. Jackson, Miss. 23 B. Centreville, Ala. 23 16. Isohyetal analysis of storm rainfall, April 11-14, 1979 24 17. Rainfall mass curves 25 18. Map showing location of flood determination sites - 26 19. Comparison of April 1979 peak discharges with maximum known flood peaks in Mississippi and Alabama -- 28 20-23. Hydrographs of discharge at selected gaging stations: 20. Coosa River basin in Alabama, April 1-16,1979 29 21. Tallapoosa River basin in Alabama, April 3-22,1979 30 22. Cahaba River basin in Alabama, April 10-22, 1979 30 23. Noxubee River at Macon, Miss., and near Geiger, Ala., and Sucarnoochee River at Livingston, Ala., April 2-23, 1979 31 24. Photograph showing overflow of Tombigbee River at Demopolis, Ala., April 19,1979 32 25-27. Hydrographs of discharge at selected gaging stations: 25. Valley Creek in the Black Warrior River basin in Alabama, April 2-21, 1979 33 26. North River and Black Warrior River in Alabama, April 2-21,1979 34 27. Pearl River basin at and upstream from Jackson, Miss., March 2 to April 28,1979 34 28-31. Photographs showing: 28. Housing development in flooded area along Hanging Moss Creek in northern part of Jackson, Miss., April 16, 1979 35 29. Inundated residential area in the vicinity of Westbrook Road in northern part of Jackson, Miss., April 16, 1979 36 30. Business district of Jackson, Miss., inundated by Pearl River overflow, April 16,1979 37 31. Flooded fairgrounds enclosed by levee, Jackson, Miss., near crest of Pearl River flood, April 16, 1979 38 32, 33. Hydrographs of discharge at selected gaging stations: 32. Pearl River near Monticello, Miss., and near Bogalusa, La., April 1-30, 1979 39 33. Big Black River at West, Miss., and near Bovina, Miss., April 1-30,1979 39 34. Graph showing changes in point velocity, mean velocity, stage, and discharge of Alabama River near Montgomery, Ala., April 13-20, 1979 40 35-43. Graphs showing velocity distribution and cross sections: 35. Alabama River at U.S. Highway 31 north, near Montgomery, Ala., April 15,1979 41 36. Mulberry Creek at highway bridge at Jones, Ala., April 14,1979 41 37. Hashuqua Creek near Macon, Miss., April 12,1979 41 38. Noxubee River at U.S. Highway 45 bypass near Macon, Miss., April 14,1979 42 39. Noxubee River at State Highway 17 near Geiger, Ala., April 15,1979 42 40. Tombigbee River at Gainesville, Ala. (main channel), April 15, 1979 42 41. North River near Samantha, Ala., April 13, 1979 43 42. Pearl River at Interstate Highway 55 at Jackson, Miss., April 17, 1979 43 43. Zilpha Creek at State Highway 35 near Kosciusko, Miss., April 12,1979 43 44, 45. Hydrographs of water levels in observation wells: 44. At Centreville, Ala. (Centreville Gin and Cotton Co.), March-April 1979 44 45. Near Pickensville, Ala., in the Tombigbee River basin, March-April 1979 44 46. Map showing location of specific-conductance sampling sites along the Intracoastal Waterway at the mouth of Mobile Bay, April 28-29, 1979 -- 45 47. Map showing location of flight lines along streams where aerial photographs were obtained on or near the crest of the flood, April 1979 - - 46 CONTENTS VII TABLES [All tables appear at end of report] Page TABLE 1. Supplementary rainfall data, storm of April 11-13, 1979 49 2. Summary of flood stages and discharges 54 3. Summary of flood damages on main streams and principal tributaries, March 1979 and April 1979 floods 67 4. Summary of stages and contents of storage reservoirs 69 5. Flood-crest st^a^g>es iii 6. Streamflow velocities, Alabama River near Montgomery, Ala, April 12-20, 1979 7. Gage height, discharge, and accumulated runoff, flood of April 1979 8. Ground-water levels in selected observation wells in Alabama and Mississippi, April 1979 197 9. Specific conductance and temperature of samples at selected sites along the Intracoastal Waterway at the mouth of Mobile Bay, April 28-29, 1979 209 10. Aerial photographs obtained at or near the crest of the flood, April 1979 212 CONVERSION OF INCH-POUND UNITS TO INTERNATIONAL SYSTEM OF UNITS (SI) Most units of measure used in this report are inch-pound units. The following factors may be used to convert inch-pound units to the Inter national System of Units (SI). Inch-pound to SI SI to Inch-pound Length inch (in.) 25.4 mm millimeter (mm) 0.03937 in. foot (ft) 0.3048 m meter (m) 3.2808 ft mile (mi) 1.6093 km kilometer (km) 0.6214 mi Area square mile (mi2) 2.5900 km2 square kilometer (km2) 0.3861 mi2 acre 4046.86 m2 square meter (m2) 0.000247 acre Volume cubic foot (ft3) 0.0283 m3 cubic meter (m3) 35.3147 ft3 acre-foot (acre-ft) 1233 m3 m3 0.00081 acre-ft Velocity mile per hour (mph) 1.6093 km/h kilometer per hour (km/h) 0.6214 mph foot per second (ft/s) 0.3048 m/s meter per second (m/s) 3.2808 ft/s Flow rate cubic foot per second (ft3/s) 0.02832 m3/s cubic meter per second (m3/s) 35.3147 ft3/s (ft3/s)/mi2 0.01094 (m3/s)/km2 (m3/s)/km2 91.40768 (ft3/s)/mi2 Pressure [The National Weather Service uses millibar (mb) as customary unit for atmospheric pressure.] inch of mercury at 32°F (in. Hg) = 33.8639 mb mb 0.02953 in. Hg Temperature degrees Fahrenheit (°F) 9/5(°C)+32 degrees Celsius (°C) 5/9(°F-32) VIII GLOSSARY GLOSSARY Acre-foot (acre-ft). The volume of water required to cover 1 acre to a K index. A measure of the airmass moisture content and stability. depth of 1 ft. It equals 43,560 ft3 (cubic feet), 325,851 gal (gallons), K = <T850-T500> + Td,850-<T700-Td,700>' where T «* Td «" or 1,233 m3 (cubic meters). temperature and dewpoint, respectively, in degrees Celsius (°C); Aquifer. A water-bearing formation. subscripts denote pressure levels. Contents. The volume of water in a reservoir or lake. Content is com Knot. A velocity of 1 nautical mile per hour. puted on the basis of a level pool or reservoir backwater profile Lifted index. Difference in degrees Celsius between the observed and does not include bank storage. 500-millibar (mb) temperature and the computed temperature a Cubic feet per second (ft3/s). A rate of discharge. One cubic foot per parcel characterized by the mean temperature and dewpoint of second is equal to the discharge of a stream of rectangular cross the 50-mb-thick surface layer would have if it were lifted from sec 1 ft wide and 1 ft deep, flowing at an average velocity of 1 ft/s. 25 mb above the surface to 500 mb. It equals 28.32 L/s (liters per second) or 0.02832 m3/s (cubic Low. Center of low barometric pressure. meters per second). Millibar (mb). A unit of pressure equal to 1,000 dynes per square Cubic feet per second per square mile [(ft3/s)/mi2]. The average number centimeter. of cubic feet per second flowing from each square mile of area National Geodetic Vertical Datum (NGVD). Formerly called Sea drained by a stream, assuming that the runoff is distributed uni Level Datum of 1929. A geodetic datum derived from a general formly in time and area. One (ft3/s)/mi2 is equivalent to adjustment of the first order level nets of both the United States 0.0733 (m3/s)/km2 (cubic meters per second per square kilometer). and Canada. In the adjustment, sea levels from selected tide sta Cyclone. An atmospheric low-pressure system around which the tions in both countries were held as fixed. The year indicates the wind blows in a counterclockwise direction in the Northern Hemi time of the last general adjustment. This datum should not be sphere and clockwise in the Southern Hemisphere. confused with mean sea level. Dewpoint (or dewpoint temperature). The temperature to which a Nautical mile. A distance of 6,080.20 feet (1.853 km). given parcel of air must be cooled at constant pressure and con Occluded front (occlusion). A composite of two fronts, formed as a stant water-vapor content in order for saturation to occur. cold front overtakes a warm front or a quasi-stationary front. Drainage area of a stream at a specific location. The area measured This is a common process in the late stages of cyclone develop in a horizontal plane, bounded by topographic divides. Drainage ment. area is given in square miles. One square mile is equivalent to Planck's law. One of the fundamental laws of physics that gives the 2.590 km2 (square kilometers). intensity of radiation emission at a specific wavelength as a func Fall line. A narrow zone between resistant rocks and the softer for tion of the temperature of a black-body. mations of the coastal plain, characterized by steepened gra Precipitable water. The amount of water contained in an atmospheric dients and by waterfalls, locally. column if all the vapor between two levels (usually the surface Flood. Any high streamflow that overtops natural or artificial banks and 500 mb) were condensed. of a stream and overflows onto land not usually under water or Radiosonde. A balloon-borne instrument package for measuring and ponding caused by precipitation at or near the point it fell. transmitting meteorological data. Flood peak. The highest value of the stage or discharge attained by Rawinsonde. A meteorological data-collection system including a a flood. radiosonde and reflectors for measuring winds by radar. Flood profile. A graph of the elevation of water surface of a river in a Recurrence interval. As applied to flood events, the average number flood plotted as ordinate; against distance plotted as abscissa. of years within which a given flood peak will be exceeded once. Flood stage. The approximate elevation of the stream when overbank Runoff. That part of the precipitation that appears in surface flooding begins. streams. Front. The interface or transition zone between two airmasses of Sounding. A single complete radiosonde observation of the upper different density. atmosphere. Gage height. The water-surface elevation referred to some arbitrary Specific conductance. The measure of the ability of water to carry an gage datum. electric current and, therefore, an indication, within rather wide Gaging station. A particular site on a stream, canal, lake, or reser limits, of the dissolved-solids concentration or salinity of a solu voir where systematic observations of gage height or discharge tion. Specific conductance is expressed in mhos/centimeter. In are made. most waters, conductance is so low that micromho is used as the GOES. Geostationary Operational Environmental Satellite. unit of expression. GMT. Greenwich mean time. Stage-discharge relation. The relation between gage height and the High. A center of high barometric pressure. amount of water flowing in a stream channel. Hydrograph. A graph showing stage, flow, velocity, or ground-water Time of day is expressed in 24-hour time. For example, 12:30 am. level of water, with respect to time. Instability. Areas of instability as referred to in this report are areas is 0030 hours, and 1:00 p.m. is 1300 hours. Central standard time (CST) is used throughout this report unless stated otherwise. where the lifted index is less than four. Isohyet. A line connecting points of equal precipitation. Trough. An elongated area of relatively low atmospheric pressure. FLOODS OF APRIL 1979, MISSISSIPPI, ALABAMA, AND GEORGIA By GEORGE W. EDELEN, JR., K. V. WILSON, and JOE R. HARKINS, of the U.S. GEOLOGICAL SURVEY and JOHN F. MILLER and EDWIN H. CHIN of the NATIONAL WEATHER SERVICE, NATIONAL OCEANIC and ATMOSPHERIC ADMINISTRATION ABSTRACT The report presents analyses of the meteorological settings of the storms, the distribution of rainfall, and supplementary rainfall data A major storm brought large amounts of rainfall over the south that have not been published elsewhere. It also gives summaries of eastern United States April 11-13. 1979. Heaviest rain fell over flood stages and discharges at 221 streamflow gaging stations, stages north-central Mississippi and Alabama. Although the storm extended and contents of 10 reservoirs, flood-crest stages and hydrograph data into the headwaters of the Chattahoochee River basin in northwest (gage height, discharge, and accumulated runoff at selected times) at ern Georgia, most flooding there was only moderate. A maximum of 46 gaging stations, ground-water fluctuations in 11 observation wells, 21.5 inches was observed at a site 14 miles southeast of Louisville, and water salinity and temperature at 22 sites along the Intracoastal Miss. Areal average rainfall exceeded 12 and 8 inches over the upper Waterway in Mobile Bay. The availability of aerial photography Pearl and upper Tombigbee River basins, respectively. Owing to a obtained during the flood is summarized, and flood damages are series of antecedent storms in March and April over the Mississippi- discussed. Alabama area, soils were saturated and many rivers were already bankfull. Additional rains April 21-23 in Mississippi and April 24-26 in Alabama averaged less than 2 inches over the flooded area. A max imum of 6.4 inches was reported at Ruth, Miss., about 65 miles south INTRODUCTION of Jackson, where little or no rain fell during the major storm of April 11-13. Floods in Mississippi and Alabama caused by the series of storms During March and April 1979, a series of storms in were the maximum of record at 60 streamflow gaging stations in the Coosa, Alabama, Tombigbee, Chickasawhay, Pearl, and Big Black Mississippi and Alabama resulted in recordbreaking River basins. floods on streams in the Coosa, Alabama, Tombigbee, On the Pearl River, peak discharges at main stem gaging stations Chickasawhay, Pearl, and Big Black River basins. The generally approached or exceeded those of the great flood of 1874, first storm, March 3-4, produced maximum stages and and recurrence intervals generally were greater than 100 years. discharges greater than previously observed on several On some streams, maximum stages and discharges produced by the March 3-4 storm, although greater than those previously ob streams in the Coosa, Tombigbee, and Chickasawhay served, were exceeded during the April 11-13 storm. Other storms in River basins. Some of these floods were exceeded during April extended the flood duration and added materially to the flood the major storm of the series, April 11-13, which pro volume. duced most of the recordbreaking floods. A comparison with the greatest known floods indicates that floods generally one-third greater than those in 1979 may occur in large The storms of March 23-24 and April 1-4 produced basins and that floods two or three times greater may occur in small bankfull stages on many streams. basins. Floods much greater than those observed in April 1979 or A major rainstorm occurred April 11-13, 1979, over than the greatest known floods in the area are likely to occur if the probable maximum precipitation occurs. the Southeastern United States. Rain fell over large Nine lives were reported lost. Estimated damages from the March areas of Mississippi, Alabama, Georgia, South Carolina, and April flooding totaled nearly $400 million. During April 1979, 75 Tennessee, and Arkansas. However, the heaviest rain percent of the total damage occurred in the Pearl River Basin, and 65 fell in central and northern Mississippi and Alabama percent of the damage occurred in Jackson, Miss., and vicinity. (henceforth referred to as "the two-State region" or "the Seventeen thousand people were driven from their homes in Jackson, Miss. region"), over the Tombigbee and Pearl River basins.