Groundwater around the world: a geographic synopsis

Abstract

1 Introduction 2 Groundwater in the global water cycle 2.1 Water below the ground surface 2.2 How much groundwater participates in the water cycle? 2.3 Groundwater and surface water: How are they related? 2.4 Groundwater is prominent in the water cycle of dry regions 3 Geography of the world's groundwater systems 3.1 Two key aspects of the subsoil: Composition and structure 3.2 Global hydrogeological panorama 3.3 The Earth's mega aquifer systems 3.4 Main aquifer types 3.5 A different angle of view: Groundwater provinces and global groundwater regions 4 Groundwater resources 4.1 Groundwater: A natural resource, but only partially exploitable 4.2 Which exploitation strategies? 4.3 Natural groundwater quality 4.4 Groundwater-related ecosystems 4.5 Geography of groundwater resources 4.6 The particular case of non-renewable groundwater resources 4.7 How to get access to groundwater and withdraw it 4.8 Fragility and vulnerability of the resources 4.9 Can the groundwater resources be augmented? 5 Groundwater withdrawal and use 5.1 Groundwater: A special and often preferred source of water 5.2 How much groundwater is withdrawn and where is withdrawal most intensive? 5.3 Evolution of groundwater withdrawals during the twentieth century 5.4 The contribution of groundwater reserves 5.5 Purposes for which groundwater is used 5.6 Contribution of groundwater to water supply in different sectors 5.7 Socio-economic implications 6 Growing needs for groundwater resources management interventions 6.1 Why should groundwater resources be managed? 6.2 Human activities modify groundwater levels and fluxes 6.3 Current state of the pressures produced by groundwater withdrawal 6.4 Pressures produced by climate change and sea level rise 6.5 Groundwater quality degradation 7 Groundwater resources management 7.1 Elements of groundwater resources management 7.2 Groundwater resources management in practice: Examples and comments 7.3 Actual state of groundwater resources management around the world 8 Final comments 8.1 About the information and knowledge on the world's groundwater 8.2 About the key features of groundwater, its role and observed trends 8.3 About groundwater resources management Appendix 1: Glossary Appendix 2: Statistics on renewable water resources - by country Appendix 3: Some data on the world's mega aquifer systems Appendix 4: Brief description of the global groundwater regions Appendix 5: Groundwater abstraction estimates by country Appendix 6: Suggestions for additional reading