Groundwater Resources for Lusaka and selected Catchment Areas T ECHNICAL R EPORT N O . 4 HYDROGEOLOGY OF THE TOWN AREA OF SOLWEZI - BASELINE STUDY ON HYDROGEOLOGY AND HYDROCHEMISTRY by Max Karen, Dr. Tobias El-Fahem and Levy Museteka Lusaka, December 2015 REPUBLIC OF ZAMBIA Ministry of Water Development, Sanitation and Environmental Protection Author: Max Karen (GReSP), Dr. Tobias El-Fahem (BGR), Levy Museteka (WARMA) Commissioned by: Federal Ministry for Economic Cooperation and Development (Bundesministerium für wirtschaftliche Zusammenarbeit und Entwicklung, BMZ) Project: Groundwater Resources for Lusaka and Selected Catchment Areas BMZ-No.: 2011.2010.2 BGR-No.: 05-2361-01 BGR-Archive No.: Date: December 2015 Page 2 of 57 TABLE OF CONTENTS LIST OF TABLES ........................................................................................................................................ 4 LIST OF FIGURES ...................................................................................................................................... 4 Acronyms, abbreviations and units ........................................................................................................ 5 List of reports compiled by the project in Phase III ................................................................................ 6 Summary ................................................................................................................................................. 7 Executive Summary ................................................................................................................................. 8 1. Introduction .................................................................................................................................. 10 2. Project Objective ........................................................................................................................... 11 3. Physiography ................................................................................................................................. 11 3.1 Topography and Drainage .................................................................................................... 11 3.2 Climate .................................................................................................................................. 12 3.3 Vegetation ............................................................................................................................. 13 4. Geology and Hydrogeoloy ............................................................................................................. 13 4.1 Overview and Structure ......................................................................................................... 13 Mine Series ........................................................................................................................... 15 Kundelungu ........................................................................................................................... 15 Basement and Undifferentiated Metamorphic Rocks ............................................................ 16 4.2 Main Aquifers ........................................................................................................................ 16 The Solwezi Schists ................................................................................................................ 16 The Chafugoma Marbles ........................................................................................................ 18 The Basement and Undifferentiated Metamorphic Rocks ...................................................... 22 4.3 Groundwater Levels and Recharge ....................................................................................... 23 4.4 Groundwater Flow ................................................................................................................ 26 4.5 Groundwater flow around the wellfield areas ...................................................................... 26 4.6 Groundwater flow link between Lake Kimasala and mine dewatering ................................ 28 5. Groundwater Hydrochemistry and Water Quality ....................................................................... 30 5.1 Hydrochemical Overview ...................................................................................................... 31 5.2 Contamination of Shallow Wells ........................................................................................... 35 5.3 Wellfield Contamination ....................................................................................................... 37 5.4 Mining Contamination .......................................................................................................... 40 5.5 Shallow well contamination close to the mine ..................................................................... 41 6. Environmental Isotopes ................................................................................................................ 43 6.1 Occurrence of Deuterium and Oxygen‐18 ............................................................................. 43 6.2 Stable Isotopes in Precipitation and Surface Water .............................................................. 44 6.3 Stable Isotopes in Groundwater ............................................................................................ 45 7. Groundwater Protection ............................................................................................................... 47 7.1 Inner Zone (Zone 1) ............................................................................................................... 47 7.2 Outer Zone (Zone 2) .............................................................................................................. 48 7.3 Total Catchment (Zone 3) ...................................................................................................... 48 8. Protection Zones for Water Supply Wellfields .............................................................................. 49 8.1 Kifubwa Wellfield .................................................................................................................. 49 8.2 College Wellfield ................................................................................................................... 50 8.3 Kabitaka Wellfield ................................................................................................................. 51 9. Future Groundwater Development .............................................................................................. 52 10. Conclusions ................................................................................................................................... 53 11. Recommendations ........................................................................................................................ 55 12. References .................................................................................................................................... 57 Page 3 of 57 LIST OF TABLES Tab. 1: Solwezi simplified Stratigraphy ....................................................................................................... 15 Tab. 2: Rainwater isotope composition from Chongwe, Lusaka and Ndola. .............................................. 45 LIST OF FIGURES Fig. 1: Location map .................................................................................................................................... 10 Fig. 2: Drainage map of the Upper Kafue Catchment ................................................................................. 12 Fig. 3: Geology and topography .................................................................................................................. 14 Fig. 4: Schematic Geological Cross Section ................................................................................................. 15 Fig. 5: Weathered Zone – Schematic Description ....................................................................................... 17 Fig. 6: Karst Hydrogeology (after GOLDSCHEIDER AND DREWS, 2007) ............................................................. 18 Fig. 7: Karst secondary permeability ........................................................................................................... 19 Fig. 8: Kansanshi cross section (First Quantum Mining Limited) ................................................................ 21 Fig. 9: Location of wellfields ........................................................................................................................ 22 Fig. 10: Groundwater flow in different seasons ......................................................................................... 23 Fig. 11: Water levels and rainfall (Data source: PWO records) ................................................................... 24 Fig. 12: Groundwater flow around the college wellfield ............................................................................ 27 Fig. 13: Sub regional groundwater flow around the mine .......................................................................... 29 Fig. 14: Hydrochemical water types ............................................................................................................ 32 Fig. 15: Type I young water ......................................................................................................................... 33