ESTIMATED DEPTH TO THE WATER TABLE AND ESTIMATED …

ESTIMATED DEPTH TO THE WATER TABLE AND ESTIMATED RATE OF RECHARGE IN OUTCROPS OF THE CHICOT AND EVANGELINE AQUIFERS NEAR HOUSTON, TEXAS

U.S. GEOLOGICAL SURVEY Water-Resources Investigations Report 96?4018

Prepared in cooperation with the

HARRIS-GALVESTON COASTAL SUBSIDENCE DISTRICT

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ESTIMATED DEPTH TO THE WATER TABLE AND ESTIMATED RATE OF RECHARGE IN OUTCROPS OF THE CHICOT AND EVANGELINE AQUIFERS NEAR HOUSTON, TEXAS

By J.E. Noble, P.W. Bush, M.C. Kasmarek, and D.L. Barbie U.S. GEOLOGICAL SURVEY Water-Resources Investigations Report 96?4018

Prepared in cooperation with the HARRIS-GALVESTON COASTAL SUBSIDENCE DISTRICT

Austin, Texas 1996

U.S. DEPARTMENT OF THE INTERIOR BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY Gordon P. Eaton, Director

Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

For additional information write to:

District Chief U.S. Geological Survey 8011 Cameron Rd. Austin, TX 78754?3898

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Copies of this report can be purchased from:

U.S. Geological Survey Branch of Information Services Box 25286 Denver, CO 80225?0286

CONTENTS

Abstract ................................................................................................................................................................................. 1 Introduction ........................................................................................................................................................................... 1

Purpose and Scope ..................................................................................................................................................... 2 Geology and Hydrogeology ...................................................................................................................................... 2 Acknowledgments ..................................................................................................................................................... 2 Estimated Depth to the Water Table ..................................................................................................................................... 2 Seismic-Refraction Method and Field Application ................................................................................................... 5 Water-Table Depth from Seismic Refraction ............................................................................................................ 5 Estimated Rate of Recharge .................................................................................................................................................. 8 Method of Computing Recharge Rate Using Environmental Tritium ....................................................................... 8 Field Application of the Method and Computation of Recharge Rate ...................................................................... 12 Evaluation of Recharge Rate ..................................................................................................................................... 17 Conclusions ........................................................................................................................................................................... 18 References Cited ................................................................................................................................................................... 18

PLATE

(Plate is in pocket)

1. Map showing estimated depth to the water table near Houston, Texas, 1989?90.

FIGURES

1. Map showing location of study area and outcrops of the Chicot and Evangeline aquifers near Houston, Texas ...................................................................................................................................................... 3

2. Correlation chart showing geologic and hydrogeologic units in the study area near Houston, Texas .................. 4 3. Diagrams showing (A) sound-wave propagation in unsaturated and saturated zones and detection

at land surface, and (B) the corresponding time-distance curve ........................................................................... 6 4. Hydrographs of water-table wells (A) LJ?65?02?311, (B) LJ?65?12?725, and (C) TS?60?45?803

completed in the Chicot aquifer near Houston, Texas ........................................................................................... 9 5. Map showing location of tritium sampling sites near Houston, Texas .................................................................. 13 6. Graph showing sample depth below the water table as a function of tritium concentration in samples

from selected wells in the Chicot and Evangeline aquifers near Houston, Texas, 1989?90 ................................. 14

TABLES

1. Measured and seismic-computed water-table depths at seismic-verification sites near Houston, Texas .............. 7 2. Environmental tritium concentrations in samples from selected wells in the Chicot and Evangeline

aquifers near Houston, Texas, 1989?90 ................................................................................................................ 15

Abbreviations:

ft, foot ft2/d, square foot per day ft/s, foot per second in/yr, inch per year mi2, square mile Mgal/d, million gallons per day pCi/L, picocurie per liter TU, tritium unit

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