HYDROLOGIC ANALYSIS OF PEARL RIVER FLOODS, APRIL 1979 AND APRIL 1980, IN LOUISIANA AND MISSISSIPPI by Fred N. Lee and George J. Arcement Prepared by the U.S. Geological Survey in cooperation with Louisiana Department of Transportation and Development Office of Highways and U.S. Department of Transportation Federal Highway Administration 1981 Research Study No. 81-1-SS TABLE OF CONTENTS Abstract Introduction Description of basin Available data Analysis of data     Double-mass curve analysis     Trend analysis Effects of Ross Barnett Reservoir Effects of land use Significant floods     The 1979 flood in the Bogalusa area     The 1980 flood in the Slidell area Additional data Conclusions Selected references ILLUSTRATIONS 1. Map showing general location of Pearl River basin 2. Map showing location of precipitation stations 3. Map showing location of streamflow gaging stations 4-13. Graph showing double-mass curve of annual precipitation for:     4. Bogalusa, La     5. Brookhaven, Miss     6. Jackson, Miss     7. Monticello, Miss     8. Tylertown, Miss     9. Philadelphia, Miss     10. Edinburg, Miss.     11. Louisville, Miss     12. Canton, Miss     13. Kosciusko, Miss 14-19. Graph showing double-mass curve of annual mean discharge for:     14. Pearl River at Bogalusa, La     15. Pearl River at Monticello, Miss     16. Pearl River at Jackson, Miss     17. Tuscolameta Creek at Walnut Grove, Miss     18. Yockanookany River at Ofahoma, Miss     19. Pearl River at Edinburg, Miss 20-29. Graph showing trend curve of annual precipitation for:     20. Louisville, Miss     21. Kosciusko, Miss     22. Philadelphia, Miss     23. Edinburg, Miss     24. Canton, Miss     25. Jackson, Miss     26. Brookhaven, Miss     27. Monticello, Miss     28. Tylertown, Miss     29. Bogalusa, La 30-32. Graph showing trend curve of annual runoff for Pearl River at:     30. Edinburg, Miss     31. Jackson, Miss     32. Bogalusa, La 33. Graph showing trend curve of annual precipitation for Baton Rouge, La 34. Graph showing trend curve of annual precipitation for Calhoun, La 35. Graph showing peak discharge at Jackson versus peak discharge at Bogalusa 36. Map showing areal distribution of rainfall for April 1979 flood 37. Graph of unit peak discharge for floods of April 1979 and April 1980 38. Map showing areal distribution of rainfall for April 1980 flood 39. Map showing flood-peak discharges in the Pearl River basin during March and April 1980 40. Graph comparing mean daily discharge for 1980 to monthly average discharge, Pearl River at Bogalusa TABLES 1. Land use in Pearl River basin during 1972-73 2. Annual peak-discharge information for the Pearl River 3. Discharge measurements made during the 1961, 1979, and 1980 floods on the lower Pearl River 4. Pearl River flood frequency ABSTRACT Double-mass and trend curves of precipitation and streamflow data indicate that flooding in the Pearl River basin follows a natural, random pattern. The April 1979 flood was caused by excessive rainfall in the upper part of the basin where as much as 19.6 inches of rain fell in one storm. This caused the largest flood since 1901 in the Jackson, Miss., area, and the largest since 1938 in the Bogalusa, La., area. The Ross Barnett Reservoir, although generally not having a measurable effect on flood peaks in the Bogalusa area, may have dampened the peak discharge of the April 1979 flood in the Jackson, Miss. area by as much as 20 percent. The April 1980 flood was caused by excessive rainfall over the entire Pearl River basin, where precipitation amounts ranged from 8.6 to 15.0 inches. The coincidental timing of peak discharges of the Pearl River and the Bogue Chitto at their confluence caused a large flood peak to occur near Slidell, La. than would be expected, based on the peak discharge recorded at Bogalusa, La. Land-use statistics indicate that about 4.8 percent of the basin is urbanized. Damage to urban property during the April 1980 flood amounted to about 12.75 million dollars in the Slidell area alone. LizardTech's Djvu plug-in is needed to view these reports. CLICK HERE TO VIEW THE ENTIRE REPORT For questions or comments, contact K. Van Wilson.