FLOOD OF MAY 19-20, 1990, IN THE VICINITY OF HOT SPRINGS, ARKANSAS By Rodney E. Southard U.S. GEOLOGICAL SURVEY Water-Resources Investigations Report 92-4007 Prepared in cooperation with ARKANSAS POWER AND LIGHT COMPANY, the ARKANSAS SOIL AND WATER CONSERVATION COMMISSION, and the U.S. ARMY CORPS OF ENGINEERS Little Rock, Arkansas 1992 U.S. DEPARTMENT OF THE INTERIOR MANUEL LUJAN, JR., Secretary U.S. GEOLOGICAL SURVEY Dallas L. Peck, Director For additional information Copies of this report can write to: be purchased from: District Chief U.S. Geological Survey U.S. Geological Survey Books and Open-File Reports Section 2301 Federal Office Building Federal Center, 700 West Capitol Box 25425 Little Rock, Arkansas 72201 Denver, Colorado 80225 CONTENTS Page Abstract................................................................................................................................................ 1 Introduction ......................................................................................................................................... 2 Methods ................................................................................................................................................ 2 Description of storm ............................................................................................................................ 4 Flood damage ....................................................................................................................................... 8 Flood characteristics ............................................................................................................................ 8 Peak stages and discharges ............................................................................................................. 8 Flood profiles .................................................................................................................................... 11 Flood hydrographs ........................................................................................................................... 11 Summary.............................................................................................................................................. 21 Selected references .............................................................................................................................. 22 Appendix 1. Names and locations of stations within the study area ............................................... 1-1 Appendix 2. High-water-mark elevations in the vicinity of Hot Springs for the flood of May 19-20, 1990.............................................................................................................................. 2-1 ILLUSTRATIONS Figure 1. Map showing study area and location of streamflow-gaging stations ............................. 3 2. Map showing cumulative rainfall for the storm of May 19-20, 1990, in the vicinity of Hot Springs, Arkansas.................................................................................................. 5 3. Graph showing cumulative rainfall at selected stations for May 19-20, 1990 ................ 7 4. Map showing location of streams with flood profiles in the study area ........................... 12 5-12. Graphs showing: 5. Water-surface profile of Ouachita River for the May 19-20, 1990, flood.................. 13 6. Water-surface profile of Gulpha Creek for the May 19-20, 1990, flood.................... 14 7. Water-surface profile of Hot Springs Creek from station 1500 to station 14000 for the May 19-20, 1990, flood............................................................................... 15 8. Water-surface profile of Hot Springs Creek from station 14000 to station 26000 for the May 19-20, 1990, flood .............................................................................. 16 9. Water-surface profile of Whittington Creek for the May 19-20, 1990, flood ............ 17 10. Stages for Caddo River near Caddo Gap (07359610) and Caddo River at Glenwood (07359700) for the May 19-20, 1990, flood.......................................... 18 11. Stages for Lake Hamilton near Hot Springs (07358500) and Lake Catherine at Jones Mill (07359000) for the May 19-20, 1990, flood......................................... 19 12. Stages for Antoine River at Antoine (07361500) and Ouachita River at Arkadelphia (07360000) for the May 19-20, 1990, flood...................................... 20 in TABLES Page Table 1. Recorded rainfall totals for May 19-20, 1990, and recurrence intervals for the 24-hour rainfall totals of May 20, 1990........................................................................... 4 2. Maximum rainfall totals for 6-, 12-, and 24-hour periods during May 19-20, 1990, and recurrence intervals........................................................................................ 6 3. Summary of peak stages and discharges for streams and lakes in the study area........... 9 4. Hourly stage and storage in lakes on the Ouach^ita River for May 19-20, 1990 ............... 10 IV CONVERSION FACTORS AND VERTICAL DATUM Multiply Bx To obtain inch (in.) 25.4 millimeter foot (ft) 0.3048 meter mile (mi) 1.609 kilometer square mile (mi ) 2.590 square kilometer acre-foot (acre-ft) 1,233 cubic meter 3 cubic foot per second (ft /s) 0.02832 cubic meter per second Sea level: In this report, "sea level" refers to the National Geodetic Vertical Datum of 1929--a geodetic datum derived from a general adjustment of the first-order level nets of the United States and Canada, formerly called Sea Level Datum of 1929. FLOOD OF MAY 19-20, 1990, IN THE VICINITY OF HOT SPRINGS, ARKANSAS By Rodney E. Southard ABSTRACT Severe thunderstorms, which produced heavy rainfall in west-central Arkansas, resulted in extensive flash flooding on May 19-20, 1990. The greatest rainfall occurred in the vicinity of Hot Springs. Personnel at the Hot Springs National Park Service rainfall station in Hot Springs recorded 12.97 inches of rain within a 24-hour period. Maximum rainfall totals for the 6-, 12-, and 24-hour periods at Remmel Dam and Carpenter Dam had recurrence intervals that exceeded 100 years. Peak discharges at stations on Fourche A Loupe Creek near Hot Springs, Gulpha Creek near Hot Springs, and Valley Creek near Point Cedar exceeded the 100-year recurrence-interval discharges. Peak stages for Lake Hamilton near Hot Springs was 0.12 foot below the 100-year flood stage, and Lake Catherine at Jones Mill was 5.0 feet higher than the 100-year flood stage. Water-surface profiles were developed for Ouachita River, Gulpha Creek, Hot Springs Creek, and Whittington Creek. Stage hydrographs for four rivers and two lakes also are included in the report to indicate the duration of flooding at selected stations. INTRODUCTION Rainfall for spring 1990 generally was above normal in western Arkansas. On May 19-20, 1990, a series of severe thunderstorms developed over west-central Arkansas and produced rainfall that exceeded 10 inches at several rainfall recording stations. Severe flooding caused by the excessive rainfall damaged numerous bridges and homes and resulted in the loss of one life. The vicinity of Hot Springs in Garland County was hardest hit. Floodwaters 2 to 4 ft deep rushed through the historic downtown area of Hot Springs, causing extensive damage to private and public property. This report summarizes rainfall amounts, flood damage, peak stages and discharges, and lake-storage data for selected stations in the vicinity of Hot Springs. The study area and locations of gaging stations are shown in figure 1. Information contained in this report was provided by Arkansas Power and Light Company; National Weather Service (National Oceanic and Atmospheric Administration, 1990); The Sentinel-Record, Hot Springs, Arkansas; U.S. Army Corps of Engineers, Vicksburg District; and the U.S. Geological Survey. This report was prepared in cooperation with Arkansas Power and Light Company, the Arkansas Soil and Water Conservation Commission, and the U.S. Army Corps of Engineers. METHODS Rainfall and discharge data were used to determine recurrence intervals at selected sites to indicate the areal extent and significance of the May 19-20 flood. Rainfall data were collected at 17 sites within the study area. Recurrence intervals for rainfall intensity at these sites were determined by plotting the observed rainfall and the rainfall frequency curve for a specific duration on log-probability paper (Weather Bureau, 1961). As used in this report, the recurrence interval is the reciprocal of the probability of occurrence and is the average number of years betweert exceedences over a long period of time. This does not mean that an event will occur at uniformly spaced intervals. In fact, an event of this magnitude can be exceeded at any time during a given period. Discharge data from stations with established stage-discharge ratings were computed directly from the rating. At stations with no defined rating, indirect methods of computing peak discharge were used. For all but two of these stations, the method used was the indirect computation of discharge through contracted openings described by Matthai (1967). The contracted opening computations yielded unsatisfactory results for the Hot Springs Creek at Hot Springs station and at the Ouachita River near Malverri station. A step-backwater computation with a digital model was used to determine the peak discharge at the Hot Springs Creek at Hot Springs station. The step-backwater model