UNITED STATES DEPARTMENT OF THE INTERIOR Harold L. Ickes, Secretary GEOLOGICAL SURVEY W. C. Mendenhall, Director Water-Supply Paper 816 MAJOR TEXAS FLOODS 1936 BY i TATE DALRYMPLE AND of Prepared in cooperation with tl FEDERAL EMERGENCY ADMINISJ OF PUBLIC WORKS I fl UNITED STATES GOVERNMENT PRINTING OFFICE WASHINGTON : 1937 For sale by the Superintendent of Documents, Washington, D. C. Price 25 cents CONTENTS Page Abstract........................................................... 1 Introduction....................................................... 2 Authorization...................................................... 3 Definition of terms................................................ 3 Administration and personnel....................................... 5 Acknowledgments.................................................... 6 Physical features of the State..................................... 7 Cause of floods.................................................... 10 Flood investigations............................................... 11 Field work..................................................... 11 Office procedure............................................... 12 Computation of discharge at gaging stations........................ 18 Precipitation...................................................... 21 The June-July flood................................................ 35 General discussion............................................. 35 Stages and discharges.......................................... 41 Guadalupe River at Victoria................................ 44 San Marcos River at Ottine................................. 45 Plum Creek near Luling..................................... 46 San Antonio River near Falls City.......................... 47 Guadalupe River above Comal River at New Braunfels......... 48 Comal River at New Braunfels............................... 48 Blanco River at Wimberley.................................. 49 Cibolo Creek near Falls City............................... 49 Neches River near Rockland.................................. 50 Neches River at Evadale.................................... 50 The September floods............................................... 52 Trinity River Basin............................................ 52 Brazos River Basin............................................. 53 Colorado River Basin........................................... 56 Colorado River flood....................................... 56 Concho River flood......................................... 58 San Saba River flood....................................... 61 Llano River flood.......................................... 62 Discussion of precipitation.................................... 62 Stages and discharges.......................................... 73 Maximum discharges......................................... 73 Brazos River near Glen Rose................................ 75 Brazos River at Waco....................................... 76 Brazos River near Bryan.................................... 77 Brazos River at Richmond................................... 78 North Bosque River near Clifton............................ 79 Bosque River at Lake Waco, near Waco....................... 80 Little River at Cameron.................................... 81 Colorado River at Ballinger................................ 82 Colorado River near San Saba............................... 83 Colorado River at Austin................................... 84 Colorado River at Smithville............................... 85 Colorado River near Eagle Lake............................. 86 South Goncho River at Christoval........................... 87 South Concho River at San Angelo........................... 88 Concho River near San Angelo............................... 89 Concho River near Paint Rock............................... 90 Middle Concho River near Tankersly......................... 91 Spring Creek near Tankersly................................ 92 North Concho River near Carlsbad........................... 93 Pecan Bayou at Brownwood................................... 94 San Saba River at Menard................................... 95 San Saba River at San Saba................................. 96 North Llano River near Junction............................ 97 Llano River near Junction.................................. 98 Llano River near Castell................................... 99 Pedernales River near Spicewood............................ 100 Trinity River at Dallas.................................... 101 Trinity River near Oakwood................................. 101 Brazos River near Palo Pinto............................... 102 Clear Fork of Brazos River near Crystal Falls.............. 102 Guadalupe River near Spring Branch......................... 103 Nueces River at Laguna..................................... 103 Frio River at Concan....................................... 104 Devils River near Juno..................................... 104 Previous floods.................................................... 112 III IV CONTENTS Previous floods Continued. Page Upper Colorado River floods.................................... 113 Concho River floods............................................ 114 Floods of September 1921....................................... 117 Floods of May 1929............................................. 117 Floods of July 1932............................................ 119 Precipitation.............................................. 120 Flood discharge............................................ 126 Rio Grande floods of September 1932............................ 126 Major floods of 1935........................................... 126 Flood-discharge records........................................ 127 Index.............................................................. 143 ILLUSTRATIONS Plate 1. Slope-area reach on the Concho River near San Angelo.... 14 2. Slope-area reach on the Concho River near San Angelo.... 15 3. A, Dry Creek near San Angelo; B, Grape Creek near Carlsbad.............................................. 16 4. A, Brazos River near Hearne; B, Brazos River near Bryan. 17 5. A, Colorado River at Winchell; B, Railroad bridge near Miles................................................. 58 6. A, Concho River near Paint Rock; B, North Concho River at San Angelo......................................... 58 7. North Concho River at San Angelo at about peak of flood of September 17, 1936................................. 58 8. North Concho River at San Angelo at about peak of flood of September 17, 1936................................. 58 9. Damage at San Angelo caused by flood of September 17, 1936, on the North Concho River....................... 58 10. A, North Concho River at San Angelo; B, Flood of August 1906 at Ballinger..................................... 59 11. Flood of August 1906 at San Angelo...................... 114 12. Guadalupe River at Kerrville. Flood of July 1, 1932.... 115 Figure 1. Map of Texas showing principal towns and streams men­ tioned in text........................................ 4 2. Map of Texas showing major topographic divisions and major drainage basins................................. 8 3. Profiles of high-water marks and sections of slope-area reach on the Concho River near San Angelo............. 14 4. Map, profiles of high-water marks, and sections for con­ tracted-opening measurement on Dry Creek near San Angelo................................................ 16 5. Stage and discharge hydrographs of the Frio River at Concan, September 16, 1936............................ 19 6. Map of Texas showing location of rainfall stations at which data were obtained for flood periods in 1936.... 22 7. Isohyetal map of Texas showing total rainfall, in inches, observed June 28 to July 1, 1936.............. 37 8. Isohyetal map of Texas showing total rainfall, in inches, observed June 28 to July 4, 1936.............. 38 9. Isohyetal map of the Guadalupe and San Antonio River Basins, showing total rainfall, in inches, observed June 28 to July 1, 1936............................... 39 10. Graph of cumulative rainfall, in inches, at Uhland, June 30 to July 1, 1936.................................... 40 11. Hydrographs of discharge, Plum Creek near Luling,. San Marcos River at Ottine, and Guadalupe River at Vic­ toria, June 29 to July 16, 1936....................... 51 12. Isohyetal map of part of the Brazos River Basin above Waco and of the Little River Basin above Cameron, showing total rainfall, in inches, observed September 25-28, 1936............................................ 54 13. Isohyetal map of Texas showing total rainfall, in inches, observed September 13-14, 1936................ 63 14. Isohyetal map of Texas showing total rainfall, in inches, observed September 13-lp, 1936................ 64 15. Isohyetal map of Texas showing total rainfall, in inches, observed September 13-18, 1936................ 65 16. Isohyetal map of Texas showing total rainfall, in inches, observed September 25-26, 1936................ 66 ILLUSTRATIONS V Page Figure 17. Isohyetal map of Texas showing total rainfall, In inches, observed September 25-28, 1936............... 67 18. Isohyetal map of Texas showing total rainfall, in inches, observed September 19-24, 1936............... 68 19. Isohyetal map of the Concho, San Saba, Llano, and parts of adjacent river basins, showing total rainfall, in inches, observed September 13-18, 1936............... 69 20. Isohyetal map of the Concho River Basin