Luận án Tiến sĩ: Ứng dụng Địa Vật lý tìm kiếm nước ngầm ở Lào

VIETNAM NATIONAL UNIVERSITY HANOI UNIVERSITY OF SCIENCE _______________________ VIENGTHONG XAYAVONG APPLICATION OF GEOPHYSICAL EXPLORATION METHODS FOR GROUNDWATER INVESTIGATION IN LAOS DOCTORAL THESIS IN PHYSICS Hanoi – 2023 VIETNAM NATIONAL UNIVERSITY HANOI UNIVERSITY OF SCIENCE _______________________ VIENGTHONG XAYAVONG APPLICATION OF GEOPHYSICAL EXPLORATION METHODS FOR GROUNDWATER INVESTIGATION IN LAOS Major: Physics of The Earth Code: 9440130.06 DOCTORAL THESIS IN PHYSICS Scientific Supervisor: Assoc. Vu Duc Minh Hanoi – 2023 Statutory declaration I hereby declare that this thesis is my own research work under the direction of Assoc. Vu Duc Minh. The results stated in the thesis project are honest and have never been published in any other works.

Thesis author Viengthong Xayavong Acknowledgements To complete this thesis, I would like to express my deepest gratitude to my supervisor, Assoc. Vu Duc Minh for giving me the opportunity to enter the world of research and working with groundwater problems in Laos; for his invaluable feedback in the writing process of articles and the thesis to complete my PhD study program. I would also like to express my sincere thanks to Dr. Nguyen Anh Duong and Dr.

Vu Minh Tuan, who helped me with their suggestions, valuable discussions, encouragement when reading and editing some draft manuscripts. Thanks to Dr. Do Anh Chung, Dr. Pham Thanh Luan, Prof.

David Gomez-Ortiz, Dr. Eldosouky for their important contributions to my articles. A special thanks to Professor Roland Roberts and Professor Thomas Kalscheuer, Department of Earth Sciences, Uppsala University, Sweden for reviewing the article. My sincere appreciation goes to the anonymous reviewers for taking their time to contribute with constructive criticism and improve my articles.

Special thanks go to my field work team, Dr. Sonexay Xayheuangsy and Mr. Thiengsamome Sounsuandao and BSc students in geophysics in Physics Department, Faculty of Natural Science, National University of Laos for the hard fieldwork assistance. I gratefully acknowledge the funding of the International Programme in the Physical Sciences (IPPS), Uppsala University, Sweden with grateful thanks to Prof.

Carla Puglia and Dr. Barbara Brena, Director and Deputy Director of the IPPS respectively. Many thanks also go to Assoc. Ernst Van Groningen and Prof.

Lennart Hasselgren, past Director of the IPPS for giving me the chance to obtain this research fund. The author would like to thank the VNU University of Sciences, Training Department, Faculty of Physics, Department of Physics of the Earth for supporting course fee and the SuperSting R8/IP (USA) to geophysical data acquisition. Special thanks go to the International Center of Physics, Institute of Physics, Vietnam, Grant number ICP.09 for research grant in this research work. Finally, I send my loving thanks to my family, relatives and friends and especially to my wife, Bouakham Douangpanya and my daughter, Valatthaya Xayavong for encouraging and supporting me throughout my work.

Thesis author Viengthong Xayavong TABLE OF CONTENTS Page STATUTORY DECLARATION ACKNOWLEDGEMENTS TABLE OF CONTENTS 1 LIST OF SYMBOLS AND ABBREVIATIONS 3 LIST OF TABLES 4 LIST OF FIGURES 5 INTRODUCTION 9 CHAPTER 1: AN OVERVIEW OF GROUNDWATER RESEARCH USING GEOPHYSICAL METHODS 1. Geophysical methods for groundwater investigation 13 1. Reason for choosing the thesis title 24 CONCLUSION OF CHAPTER 1 25 CHAPTER 2: GEOPHYSICAL EXPLORATION METHODS APPLIED TO SURVEY GROUNDWATER IN THE RESEARCH AREAS 2. Basic resistivity theory 27 2.

Basic induced polarization theory 33 2. Traditional Electrical Exploration Methods 35 2. Improved Multi-electrode Electrical Exploration Methods 38 2. Basic theories of seismic refraction 50 CONCLUSION OF CHAPTER 2 60 CHAPTER 3: GROUNDWATER SURVEY RESULTS IN CENTRAL LAOS 3.

Geological characteristics of the research area 62 3. Network of survey profiles and used geophysical methods 70 3. Results and Discussions 78 CONCLUSION OF CHAPTER 3 99 CONCLUSIONS AND RECOMMENDATIONS 103 LIST OF SCIENTIFIC WORKS OF THE AUTHOR RELATED 1 TO THE THESIS 106 REFERENCES 108 2 LIST OF SYMBOLS AND ABBREVIATIONS Abbreviations Full name VES Vertical Electrical Sounding IES Improved Electrical Sounding MEE Multi-Electrode Electrical Exploration IMES Improved Multi-Electrode Electrical sounding AMES Advanced Multi-Electrode Electrical Sounding IMEE Improved Multi-Electrode Electrical Exploration MRS Magnetic Resonance Sounding ERT Electrical Resistivity Tomography 2D ERT 2D Electrical Resistivity Tomography 2D ERI 2D Electrical Resistivity Imaging SRT Seismic Refraction Tomography TDS Total Dissolved Solids EC Electrical Conductivity of water pH Potential of Hydrogen SP Self-Potential method IP Induced Polarization method EM Electromagnetic method Ra Radiometric method GPR Ground Penetrating Radar method M Magnetic method S Seismic method G Gravity method E Electrical resistivity method WHO World Health Organization USEPA United State Environmental Protection Agency JICA Japan International Cooperation Agency 3 LIST OF TABLES No. Caption Page Table 1.

Geophysical methods and relevant measured geophysical 13 1 parameter 2 Table.2 Geophysical exploration applications 14 3 Table 2. Resistivity of various earth materials 33 4 Table 2. The chargeability of various earth materials 36 5 Table 2. The P-wave velocity of various earth materials 55 6 Table 3.

Stratigraphy of Khorat Plateau and Vientiane Basin 68 Table 3. The surface geophysical methods and relevant physical 72 7 properties Table 3.3: The geophone and seismic shot for the first seismic 75 8 spread Table 3. Comparison between drilling results at BH 1 and results 81 9 of IMEE model Table 3. Comparison between drilling results at BH 2 and results 85 10 of IMEE model 11 Table 3.6: Comparison between drilling results at BH 1 and seismic 91 results of seismic velocity model 4 LIST OF FIGURES No.

Caption Page 1 Figure 2. The current flow lines from a point source and the resulting 29 equipotential distributions 2 Figure 2. The generalized form of the electrode array used in 30 resistivity measurements 3 Figure 2. The Wenner electrode array 36 4 Figure 2.

The arrangement of electrode system for a 2D- ERT survey 37 for electrode spacing of “1a” 5 Figure 2. The arrangement of electrode system for a 2D- ERT survey 37 for electrode spacing of “2a” 6 Figure 2. The arrangement of an improved symmetric multi-electrode 41 array (with the distance of first AB in the position 27 and 28 7 Figure 2. The arrangement of an improved symmetric multi-electrode 42 array (with the distance of first AB in the position 26 and 29) 8 Figure 2.

The arrangement of an improved dipole–dipole multi- 42 electrode array (with the distance of first AB in the position 14 and 15) 9 Figure 2. The arrangement of an improved dipole–dipole multi- 43 electrode array (with the distance of first AB in the position 13 and 16) 10 Figure 2. The traditional definition of the inverse problem 44 11 Figure 2. ERT data processing and inversion flow chart for 46 RES2DINV software 12 Figure 2.

Diagram for inversion flow chart for EarthImager 49 software 13 Figure 2. Successive positions of the expanding wave fronts for 51 direct and refracted waves through a two-layer model 14 Figure 2. Travel-time curves for the direct wave and refracted wave 52 from a single horizontal refractor. The relationship of seismic velocity and density to porosity 56 16 Figure 2.

Flow chart of seismic refraction data processing 57 17 Figure 2. Example of picking first arrival times for one seismic 58 spread 18 Figure 2. Example of traveltime curves for seismic profile 59 19 Figure 2. Example of velocity models for seismic profile 59 20 Figure 3.

Map of the Khorat and the SakonNakon basins on the 64 Khorat Plateau, Thailand 21 Figure 3. Geology of the Vientiane Basin, key map shows the extent 66 of Khorat Plateau and the site locations 22 Figure 3. Detailed geology of the study region in Khammouan 70 Province overlaid with the boundaries of the province and districts 23 Figure 3. Map of geophysical survey profiles in Vientiane Province 72 24 Figure 3.

SuperSting R8/IP system with 56 electrodes and Switch box 73 connection for IMEE data acquisition 25 Figure 3. Smartseis ST with 12 channels for seismic data acquisition 73 26 Figure. A typical seismic refraction data acquisition layout and 74 location of shot points for the seismic refraction survey profile 27 Figure 3. ABEM Terrameter SAS 1000 for 2D ERT data acquisition 75 28 Figure.

Map of ERT and seismic refraction profiles in Savannakhet 76 Province 29 Figure 3. Map of the ERI and SRT profiles in Khammouane 77 Province 30 Figure 3. 2D Resistivity cross sections under profiles 1 and 2 at site1 79 31 Figure 3. 2D Resistivity cross sections under profiles 1 at site1 80 (b).

Vertical geological section under borehole VBH-1 at 450 m on profile 1 32 Figure 3. 2D Resistivity and IP cross sections under profile 3 at site1 81 6 33 Figure 3. 2D Resistivity and IP cross sections under profile 4 at site 82 2 34 Figure 3. 2D Resistivity cross sections under profiles 5 and 6 at site 83 2 35 Figure 3.

2D Resistivity and IP cross sections under profile 7 at site 83 3 36 Figure 3. 2D Resistivity cross sections under profile 8 at site3 84 (b). Vertical geological section under borehole VBH-2 at 450 m on profile 8 37 Figure 3. 2D Resistivity cross sections under profiles 9 and 10 at 85 site 4 38 Figure 3.

Distribution of physical properties (TDS and EC) from 13 86 water samples in existing shallow wells 39 Figure 3. Distribution of physical properties (pH) from 13 water 86 samples in existing shallow wells 40 Figure 3. The traveltime curves and velocity models for seismic 87 profile 1 at site 1 41 Figure 3. The traveltime curves and velocity models for seismic 87 profile 2 at site 1 42 Figure 3.

The traveltime curves and velocity models for seismic 88 profile 3 at site 2 43 Figure 3. The traveltime curves and velocity models for seismic 89 profile 4 at site 2 44 Figure 3. (a) Seismic velocity model under profile 1 at site1 and 90 (b) Vertical geological section of borehole VBH-1 at 440 m along profile 1 45 Figure 3. Location of the orientation of seismic refraction survey 91 profiles compared with geophysical sites 7 46 Figure 3.

2D resistivity cross sections at profiles 1, 2, 3 and 4 92 47 Figure 3. 2D resistivity cross section at profile 5 93 48 Figure 3. 2D geoelectric cross sections at profiles 2 and 4 versus 94 seismic velocity models at profiles 1 and 2 49 Figure 3. (a) 2D geoelectric cross section at profile 2, (b) The seismic 95 velocity models at profile 1, (c) Vertical geological section of borehole SBH-1 at 100 m along ERT profile 2 and 45 m along seismic profile 1 50 Figure 3.

(a) 2D geoelectric cross section at profile 4, (b) The 95 seismic velocity models at profile 2, (c) Vertical geological section of borehole SBH-2 at 100 m along ERT profile 4 and 45 m along seismic profile 2. 2D-ERI cross sections at profiles 1, 2 and 3 96 52 Figure 3. 2D-ERI cross section at profile 4 97 53 Figure 3. 2D-ERI and SRT cross sections at profiles 1 and 2 98 54 Figure 3.

2D-ERI and SRT cross sections at ERT profile 4 and 98 profile 3. (a) 2D-ERI cross section at profile 1, 99 (b) The SRT cross section at profile 1, (c) Vertical geological cross section of borehole KBH-1 at 140 m at ERI profile 1 and 96 m at SRT profile 1. (d) Vertical geological cross section of borehole KBH-2 at 290 m at ERI profile 1 and 246 m at SRT profile 1. 8 INTRODUCTION Groundwater is an essential source of freshwater in many regions in the world.

A growing number of countries in Southeast Asia have encountered serious groundwater quantity and quality issues such as declining groundwater tables, subsidence, groundwater quality, and overexploitation leading to unsustainable management of groundwater resources. These are major problems that currently challenge hydrogeologists and relevant organizations. Groundwater is also a renewable resource with volumes that vary with the seasons and the local geological characteristics.