Litani River Basin Management Support Program Groundwater Modeling Within the Upper Litani Basin Report
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LITANI RIVER BASIN MANAGEMENT SUPPORT PROGRAM GROUNDWATER MODELING WITHIN THE UPPER LITANI BASIN REPORT OCTOBER 2013 This report was produced for review by the United States Agency for International Development (USAID). It was prepared by International Resources Group (IRG) under Contract EPP-I-00-04-00024-00 order no 7. LITANI RIVER BASIN MANAGEMENT SUPPORT PROGRAM GROUNDWATER MODELING WITHIN THE UPPER LITANI BASIN Contract No.: EPP-I-00-04-00024-00 order no 7. OCTOBER 2013 DISCLAIMER The author’s views expressed in this publication do not necessarily reflect the views of the United States Agency for International Development or the United States Government TABLE OF CONTENTS EXECUTIVE SUMMARY ················································································ 1 1. INTRODUCTION ················································································ 1 2. MODELING APPROACH ······································································ 3 2.1 Data Gathering and Hydrogeological Model Conceptualization ............................................... 3 2.2 Initial Model Setup ................................................................................................................................ 4 2.3 Model Calibration and Sensitivity Analysis ..................................................................................... 4 2.4 Model Simulation and Predictions .................................................................................................... 5 3. STUDY AREA ······················································································ 6 3.1 Extent ...................................................................................................................................................... 6 3.2 Topology ................................................................................................................................................. 6 3.3 Land Use and Villages .......................................................................................................................... 6 4. HYDROGEOLOGY ············································································· 10 4.1 Hydrostratigraphy .............................................................................................................................. 12 4.1.1 Aquifers ...................................................................................................................................................................... 12 4.1.2 Low Transimissivity Aquifers and Aquicludes ................................................................................................. 17 4.2 Springs ................................................................................................................................................... 18 5. GROUNDWATER DATA ···································································· 22 5.1 Groundwater Measurments ............................................................................................................. 22 5.2 Overview of Previous Hydrogeological Investigations .............................................................. 27 6. CONCEPTUAL MODEL OF THE STUDY AREA ···································· 29 6.1 Model Geometry and Parameterization ........................................................................................ 29 6.1.1 Boundary Conditions ............................................................................................................................................. 29 6.1.2 Grid ............................................................................................................................................................................. 30 6.1.3 Hydrogeological Parameters ................................................................................................................................ 30 6.2 Preliminary Water Balance ............................................................................................................... 30 6.2.1 Inflow .......................................................................................................................................................................... 31 6.2.2 Outflow ...................................................................................................................................................................... 32 7. MODEL CALIBRATION ······································································ 34 7.1 Steady State .......................................................................................................................................... 34 7.2 Transient Flow..................................................................................................................................... 37 7.3 Sensitivity Analysis .............................................................................................................................. 38 8. PROJECTIONS ··················································································· 39 8.1 Historical Water Levels – 1970 ...................................................................................................... 39 8.2 Projection of Water Levels – 2030 ................................................................................................ 45 9. CONCLUSIONS & RECOMMENDATIONS ··········································· 56 10. REFERENCES ····················································································· 58 11. APPENDICES ····················································································· 59 Appendix A – Geological Setting .................................................................................................................. 60 Appendix B–Wells ............................................................................................................................................ 66 Appendix C– Measured Water Level in Wells ......................................................................................... 68 Appendix D – Comparison Between Wells surveyed in 2010- 2011 and Wells Used for Calibration .................................................................................................................................... 70 LIST OF TABLES Table 4 –1 Major Aquifers in the Upper Litani Basin Along With their Hydrogeological Characteristics ...................................................................................................................................... 15 Table 4 –2 Total Number of Springs Emerging from Different Types of Hydrostratigraphic Units 18 Table 4 –3 Discharge of Springs (UNDP 1970) .................................................................................. 20 Table 6 –1 Estimated Recharge to the Upper Litani Basin by Different Studies ........................... 28 Table 7 –1 Infiltration Rate ..................................................................................................................... 32 Table 8 –1 Water Balance for the Steady State Model ........................................................................ 35 Table 9 –1 Parameters Used in the Sensitivity Analysis and the Response of the Model ............. 38 Table 10 –1 Water Balance for the 1970 Model..................................................................................... 40 Table 10 –2 Computed Water Level in Observation Points in the Model Between 1970 and 2010 41 Table 10 –3 Different Scenarios Used for Projection ........................................................................... 45 Table 10 –4 Computed Water Level in Observation Points in the Four Scenarios ......................... 48 Table 10 –5 Drawdown* in Observation Points in the Four Scenarios of 2030 .............................. 49 Table 13 –1 Total Discharge(m3/day) from Public Wells Per Well and Per Aquifer ...................... 66 Table 13 –2 Coordinates of the Measured Observation Wells and Their Relative Computed and Observed Water Levels ...................................................................................................................... 68 LIST OF FIGURES Figure 3 -1 The Upper Litani Basin .......................................................................................................... 8 Figure 3 -2 Land Use/Land Cover Map of the Upper Litani Basin .................................................... 9 Figure 4 -1 Hydrostratigraphical Log of the Geological Formations ................................................ 11 Figure 4 -2 Hydrostratigraphic Units in the Study Area .............................................................. 13 Figure 4 -3 Hydrostratigraphical Cross-section of the Study Area .................................................... 14 Figure 4 -4 Location of Springs with Discharge Data ......................................................................... 19 Figure 4 -5 Location of Springs with Discharge (UNDP, 1970) ....................................................... 21 Figure 5 -1 Comparison Between UNDP 1970 Ground Water Contour Lines and Ground Elevation ............................................................................................................................................... 23 Figure 5 -2 Generated Ground Water Contour Lines for November 2010 .................................... 25 Figure 5 -3 Generated Ground Water Contour Lines for May/June 2011 ...................................... 26