The hydrogeology of the northwestern bajada region of the Sultanate of Oman Item Type Thesis-Reproduction (electronic); text Authors Aubel, James William. Publisher The University of Arizona. Rights Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. Download date 26/09/2021 18:10:04 Link to Item http://hdl.handle.net/10150/191877 THE HYDROGEOLOGY OF THE NORTHWESTERN BAJADA REGION OF THE SULTANATE OF OMAN by James William Aubel A Thesis Submitted to the Faculty of the DEPARTMENT OF HYDROLOGY In Partial Fulfillment of the Requirements For the Degree of MASTER OF SCIENCE In the Graduate College THE UNIVERSITY OF ARIZONA 1985 STATEMENT BY AUTHOR This thesis has been submitted in partial fulfillment of requirements for an advanced degree at the University of Arizona and is deposited in the University Library to be made available to borrowers under rules of the Library. Brief quotations from this thesis are allowable without special permission, provided that accurate acknowledgement of source is made. Requests for permission for extended quotation from or reproduction of this manuscript in whole or in part may be granted by the head of the major department or the Dean of the Graduate College when in his/her judgement the proposed use of the material is in the interests of scholarship. In all other instances, however, permission must be obtained from the author. SIGNED: laALS2-- APPROVAL BY THESIS DIRECTOR his thesis has been approved on the date shown below: EUGENE S. SIMPSON Date Professor of Hydrology and Water Resources ACKNOWLEDGEMENTS I wish to express my gratitude to the following persons who assisted in completing the required field work: Margaret Chapman, Peter Quinlan, and Zahir Al Adawy. Special thanks goes to Abdullah Mohammed Salim Al Barwany for his many months of hard work and dedication to collecting field data. Bill Spong was of valued assistance in supervising the drilling and in the compilation of data. Mike Foley was very helpful in spending many hours editing and proof reading the final manuscript. I also wish to thank His Majesty Sultan Qaboos Bin Said, Sultan of Oman, for having financed the work which led indirectly to this thesis. TABLE OF CONTENTS Page LIST OF ILLUSTRATIONS vi LIST OF TABLES viii ABSTRACT ix 1. INTRODUCTION 1 Purpose and Scope 3 Location and Geographic Setting 5 Physiography, Topography and Geology 5 Cultural Features and Natural Resources 10 Climate 12 Methods of Investigation 12 Previous Investigations 16 Accessibility and Operating Conditions 17 Hydrologic Data Point Identification System 18 Romanization of Arabic 20 2. GEOLOGY 21 Stratigraphie Sequence in the Northwestern Bajada 23 General Geology 23 Geomorphology 30 3. HYDROGEOLOGY 32 Pre-Tertiary System 32 Hawasina Complex-Permian to Middle Cretaceous 32 Aruma Group-Upper Cretaceous 33 Tertiary System 34 Hadhramaut Group-Paleocene to Middle Eocene 34 Fars Group-Oligocene to Pliocene 36 Taqa Formation-Oligocene to Lower Miocene 37 Undifferentiated Clastics and Evaporites-Middle Oligocene to Pliocene 39 Quaternary System 41 Surficial Deposits-Pleistocene to Recent 41 Summary of Hydrogeologic Conditions 44 iv TABLE OF CONTENTS--Vontinued Page 4, HYDROLOGY AND WATER RESOURCES 47 Fars Group/Quaternary Aquifer 47 Source 48 Occurrence 48 Hydraulic Properties 50 Water Table and Ground-Water Movement 56 Recharge and Discharge of Ground Water. , 64 Storage of Ground Water 70 Chemical Quality of Water 73 Water Use 80 5. CONCLUSIONS AND RECOMMENDATIONS 83 Governing Conditions of the Aquifer 83 Potential of Ground Water Supply 85 Additional Exploration Drilling 86 Artificial Recharge 88 Improvement of the Water Budget 91 Water Resources Planning and Management 93 APPENDIX A: THE ROLE OF THE AFLAJ IN OMANI ECONOMY 95 APPENDIX B: INVENTORY OF WELLS, BORINGS, AFLAJ, AND SEISMIC UPHOLES IN THE STUDY AREA 106 APPENDIX C: RESULTS OF THE PAWR EXPLORATION DRILLING 121 APPENDIX D: REPRESENTATIVE GRAPHS OF THE AQUIFER TESTS 124 REFERENCES 130 LIST OF ILLUSTRATIONS Figure Page 1. General Map of Oman and the Location of the Study Area 2 2. Detailed Geographic and Cultural Map of the Study Area 6 3. Map of the Geographic Zones of Oman and the Study Area 7 4. Map of the Major Surface Drainage Patterns of the Northwestern Bajada 9 5. Map of the Drainage Catchment Area of the Northwestern Bajada 13 6. Map Showing the Locations and Type of the Hydrologic Data Sites 15 7. Numbering System of Hydrologic Data Points 19 8. Regional Geology and Main Physical Features of Northern Oman and Vicinity 26 9. Detailed Geologic Map of the Study Area 27 10. Generalized Fence Diagram of the Study Area 29 11. Diagrammatic Sketch of the Movement of Water in the Study Area 49 12. Isopachous Map of the Saturated Thickness of the Fars Aquifer 51 13. Map Showing the Depth to Water in the Study Area 52 14. Generalized Flow Net Showing the Direction of Ground-Water Movement in the Study Area 58 15. Equipotential Map of the Study Area for the Winter of 1982-83 59 vi vii 16. Equipotential Map of the Study Area for the Summer of 1983 60 17. Generalized Hydrologic Cycle of the Fars Aquifer 66 18. Isosalinity Map in Micromhos/cm3 of the Ground Water in the Fars Aquifer 72 19. Plot of Stiff Diagrams on a Map of the Study Area 77 20. Chemical Analyses of the Ground Water in the Fars Aquifer Plotted on a Trilinear (Piper) Diagram 79 21. Map Showing the Proposed Exploration Drilling Sites In the Study Area 87 22. Generalized Cross-Section of a Typical Falaj in the Bajada 97 23. Plan View of a Typical Falaj in the Bajada 98 24. Chronologie Order in Constructing a Falaj and Its Relationship to the Water Table 100 25. The Various Engineering and Construction Details of the Aflaj in Oman 101 LIST OF TABLES Table Page 1. Stratigraphie Correlation Between Oman and the Arabian-Persian Gulf 22 2. General Stratigraphie Column for the Study Area 24 3. Hydrogeologic Characteristics of the Major Geologic Units of the Study Area 45 4. Summary of the Transmissivity Values Calculated for the Study Area 55 5. Tabulation of the Ground Water Flow Calculations for the Winter 1982-83 Equipotential Map (Figure 15) 61 6. Tabulation of the Ground Water Flow Calculations for the Summer 1983 Equipotential Map (Figure 16) 62 7. Summary of the Total Ground Water Flow Calculated from the Equipotential Maps of Figures 15 and 16 64 8. Summary of Total Average Annual Volume of Rainfall and the Percentage which Enters the Study Area as Ground-Water Flow 67 9. Chemical Analyses of Water from Wells in the Study Area 74 10. Major Chemical Ratios of Sea Water, River Water and Fars Aquifer Water 78 11. Tabulation of Annual Abstraction of Ground Water by Aflaj in the Study Area 81 12. Proposed Exploration Drilling Sites and their Priorities 89 viii ABSTRACT The Northwestern Bajada of the Sultanate of Oman is an arid region which relies solely on ground water. Present abstraction, which accounts for about 70 percent of the fresh water entering the aquifer system, is almost entirely by aflaj (qanats) located near the mountain front. The results of 38 exploration boreholes drilled at 30 sites from 1982 to 1983 were analyzed along with field reconnaissance data. P110-Pleistocene sediments comprise the aquifer system which is highly heterogeneous with lithologies ranging from marine carbonates to well-sorted continental alluvium. Transmissivities range from 10 m2/d to over 2,000 m2/d. Ground-water quality is controlled by recharge, and conduc- tivities range from less than 1,000 to over 100,000 micromhos. The predominant water type is sodium chloride, owing to the mainly marine deposition of the aquifer sediments. Fresh ground water occurs as shoe-string aquifers paralleling the active wadi channels which traverse the bajada. Intrusion of poor quality water will limit ground-water development. ix CHAPTER 1 INTRODUCTION The northern interior region of Oman comprises a large area between the desert foreland and the Northern Oman Mountains (Figure 1). This area, or piedmont slope, consists of two geomorphologic parts: (1) an upper part, a pediment, which is an eroded bedrock surface with a thin veneer of alluvium; and (2) a lower part of aggradational origin which is a bajada (Thornbury, 1969; Gary, et. al., 1974; Wilkinson, 1977). A bajada consists of a series of coalescing alluvial fans which form a broad, undulating and gently sloping detrital surface. In Oman, most of the deposition probably occurred from the Late Miocene to early Pleistocene. Following the Pleistocene deposition, the bajada has been undergoing erosion causing the development several terrace levels on the older bajada surface. The northwestern region of the interior bajada is characterized by thicker detrital deposits and relatively large reserves of ground water. This region has a good potential for water resources development and was selected as the study area. There are no specific place names for this area; it is locally referred to as "the desert". For lack of a better name, therefore, the study area will be referred to as the Northwestern Bajada, or simply, the bajada. 1 IRAN ARABIAN GULF ....M. ..... ..... ....• erg... ...... ...... ....... .11•111•1 • SAUDI ARABIA I ...0 HAIMA 00' •01 .0'.0 ARABIAN .0 .0 SEA .0 .0 .0 0 80 180 320 KM 1 I i I 0 50 100 200 MI Figure 1 , General Map of Oman and the Location of the Study Area. Purpose and Scope Knowledge of the water resources of a region is essential to the proper planning of a development program.