PROTECTION AND STRATEGIC USES OF GROUNDWATER RESOURCES IN DROUGHT PRONE AREAS OF THE SADC REGION GROUNDWATER SITUATION ANALYSIS OF THE LIMPOPO RIVER BASIN FINAL REPORT This report is the final report on the project Protection and Strategic Uses of Groundwater Resources in the Transboundary Limpopo Basin and Drought Prone Areas of the SADC Region Title of Consulting Services: Groundwater Situation Analysis in the Limpopo River Basin The project was funded through a grant from The Global Environmental Facility (GEF Grant GEF-PDF TF027934 ) At the request of the World Bank a summary of the final report was prepared as a separate document by the Division of Water Environment and Forestry Technology CSIR, Pretoria, South Africa and issued as Report No. ENV-P-C-2003-047 DIVISION OF WATER, ENVIRONMENT AND FORESTRY TECHNOLOGY CSIR FINAL REPORT PROTECTION AND STRATEGIC USES OF GROUNDWATER RESOURCES IN DROUGHT PRONE AREAS OF THE SADC REGION GROUNDWATER SITUATION ANALYSIS OF THE LIMPOPO RIVER BASIN Prepared for: Southern African Development Community (SADC) Directorate for Infrastructure and Services Water Division Private Bag 0095 GABERONE Botswanao Prepared by: Environmentek, CSIR P.O. Box 395 0001 Pretoria South Africa Pretoria Project no: JQ390 October 2003 Report no: ENV-P-C 2003-026 Limpopo River Basin Groundwater Situation Analysis – Final Report CONTENTS 1. BACKGROUND TO AND PURPOSE OF THE STUDY.............................................. 1 2. OBJECTIVES AND SCOPE OF THE PROJECT........................................................ 3 3. SPECIFIC TERMS OF REFERENCE FOR THIS PHASE .......................................... 4 4. GROUNDWATER AND DROUGHT ............................................................................ 5 5. THE LIMPOPO BASIN AS STUDY AREA.................................................................. 6 5.1 Physiography ................................................................................................................ 6 5.2 Climate and Weather Patterns ..................................................................................... 7 5.2.1 Rainfall .......................................................................................................................... 9 5.2.2 Evaporation ................................................................................................................. 10 5.2.3 Aridity index................................................................................................................. 11 5.2.4 Temperature................................................................................................................ 12 5.2.5 Climate change and variability.................................................................................... 14 5.2.6 Drought........................................................................................................................ 14 5.2.7 Floods.......................................................................................................................... 17 5.2.8 Global warming ........................................................................................................... 18 5.3 Drainage Basins.......................................................................................................... 19 5.3.1 General description..................................................................................................... 19 5.3.2 Major tributaries of the Upper Limpopo River Reach................................................. 20 5.3.3 The Middle Reach....................................................................................................... 20 5.3.4 Lower Reach............................................................................................................... 21 5.4 Surface Water Resources and Hydrological Modelling of the Limpopo Basin .......... 21 6. WATER USE AND DEMAND IN THE LIMPOPO BASIN ......................................... 24 6.1 Botswana..................................................................................................................... 24 6.2 Mozambique................................................................................................................ 26 6.3 South Africa................................................................................................................. 26 6.4 Zimbabwe.................................................................................................................... 27 7. GEOLOGY.................................................................................................................. 28 7.1 Major Geotectonic Divisions ....................................................................................... 28 7.2 Western Archaean-Mesozoic Complexes and Kalahari Basin .................................. 29 7.2.1 Archaean-Early Proterozoic basement....................................................................... 30 7.2.2. Late Archaean-Proterozoic sedimentary basins and layered intrusives.................... 30 7.2.3 Palaeozoic-Mesozoic Karoo basins............................................................................ 34 7.2.4 Cenozoic Kalahari basin ............................................................................................. 34 7.2.5 Mozambique (Coastal Basin)...................................................................................... 35 8 HYDROGEOLOGY..................................................................................................... 37 8.1 Hydrogeological Regions ............................................................................................ 37 8.2 Brief description of the hydrogeology of the four countries........................................ 38 8.2.1 Botswana..................................................................................................................... 38 CSIR Environmentek Report No.: ENV -P-C-2003-026 i Limpopo River Basin Groundwater Situation Analysis – Final Report 8.2.2. Mozambique................................................................................................................ 38 8.2.3 South Africa................................................................................................................. 39 8.2.4 Zimbabwe.................................................................................................................... 40 8.3 Hydrogeological region classification of the Limpopo Basin...................................... 41 8.3.1 Unit L0: Alluvium associated with river courses........................................................ 41 8.3.2 Unit L1: Fractured Basement Complex granites ........................................................ 44 8.3.3 Unit L2: Fractured Transvaal sequence and Bushveld complex .............................. 44 8.3.4 Unit L3: Fractured Waterberg, Palapye, Soutpansberg groups ................................. 45 8.3.5 Unit L4: Central Zone of the Limpopo Mobile Belt ..................................................... 45 8.3.6 Unit L5: Zimbabwean craton...................................................................................... 45 8.3.7 Unit L6: Kaapvaal craton ........................................................................................... 45 8.3.8 Unit L7: Unconsolidated sand and coastal plain aquifers ......................................... 45 8.4 Groundwater Potential and Resources ...................................................................... 45 8.4.1 Botswana..................................................................................................................... 45 8.4.2 Mozambique................................................................................................................ 46 8.4.3 South Africa................................................................................................................. 48 8.4.4 Zimbabwe.................................................................................................................... 48 8.4.5 Groundwater quality .................................................................................................... 51 8.5 Groundwater Recharge .............................................................................................. 52 8.5.1 Base flow estimation................................................................................................... 52 8.5.2 Chloride method for recharge determination.............................................................. 54 8.6 Groundwater Levels .................................................................................................... 55 8.7 Groundwater Monitoring ............................................................................................. 56 9. SHARED WATER RESOURCES .............................................................................. 58 9.1 Introduction ................................................................................................................. 58 9.2 Limpopo Alluvial Aquifers ........................................................................................... 59 9.3 River Flow ................................................................................................................... 59 9.4 Karoo Aquifers ............................................................................................................ 59 9.5 Pollution......................................................................................................................