Groundwater development in selected countries

1. Groundwater in big cities, use, consequences, impacts of climate change and response optionsKaren G. VillholthGroundwater Specialist, Senior ResearcherGEUS, Geological Survey of Denmark and GreenlandCopenhagen, DenmarkFAU Conference 2000Copenhagen Business School, Denmark, May 15, 2008

2. Groundwater development in selected countries Ref: Shah, 2004

3. Importance of GW for cities • Groundwater is the main source of domestic-potable water supply in most European countries (Water Economy Prospects for 1990 and 2000, 1982) • In general, GW is the primary source for domestic water supply and hence significant for most cities • Quantity-wise, GW use for cities is less than the use in agriculture

4. Reasons and advantages of using groundwater for cities • Surface water exhausted or polluted • New drilling and pumping technology • Groundwater is generally of a good, reliable and constant quality and temperature suitable for drinking water with no or little pre-treatment • Groundwater can be developed incrementally and with less capital investment

5. Groundwater Surface water

7. Groundwater flow and occurrence

8. Importance of groundwater,1

9. Importance of groundwater, 2

10. Importance of groundwater, 3

11. Importance of groundwater, 3

12. Importance of groundwater, 4

14. Impact in response to change Pre-development Post--development (T1) Post--development (T2)

16. Effect on riparian vegetation

17. Example from Dhaka, Bangladesh Δ=22% Δ=30m over 30 years

18. GWL decline, example from China Hydrograph depicting water-table elevations beneath Luancheng Agro-Ecological Research Station (Chinese Academy of Sciences), Luancheng County, Hebei Province, 1974-2002. Δ=20m over 35 years

19. Dramatic changes of depression cones in Cangzhou m m 6-1973 2-1981 6-1995 6-2000

20. GWL decline, example from Chicago

21. Saltwater intrusion • Inflow of saltwater into freshwater aquifer • Origin of saltwater: • Seawater in coastal areas • Geological saline deposits in deeper formations • Influx or accumulation from irrigated agriculture

22. In coastal areas there is a natural balance between salt and freshwater

23. GW withdrawal in coastal auifers

24. Subsidence

25. Subsidence, impacts • Gives problems for infrastructure, buildings, pipelines • Flooding and drainage patterns changed • Causes secondary GW contamination from breakage of underground pipes and tanks

26. What is subsidence? Before After

27. Example of subsidence,San Joaquin Valley GWL Landsurface level

28. Relation btw. subsidence and GWL decline

29. Example of subsidence, Texas

30. Groundwater pollution sources

31. Pollution risk Vulnerability high, but load is low low high Load is high, but vulnerability is low GW pollution risk high

32. Urbanization • Generally, urbanization decreases the recharge to aquifers (pavements, storm water drainage) • However, depending on the primary source of water supply and the means of discharging wastewaters, GWLs may be affected differently

36. Climate change • There is accumulating evidence that the climate is changing on a global scale • Exact effects not known as well as the speed, extent and local distribution of them • Some effects seem inevitable: • Water level rises due to global warming • More variability and unpredictability in climate and more ‘extreme’ events • Dry regions becoming drier • Effects compounded by other human influences (e.g. intensive water exploitation) • Most vulnerable areas: Arid areas, big coastal cities, large tropical deltas

37. Climate change on GW in cities • GW can be a drought prevention strategy but only to a certain extent • GW over-abstraction and flooding can occur at the same time • Energy intricately linked to GW exploitation • CC exacerbate existing problems of GW

38. Disaster management

39. Post-Modern Water Balance Increased Water Demand for Agriculture, People and Ecosystems Increased Pumpage to Meet Domestic, Agricultural, Industrial and Ecosystem Demands Water Contamination Ground Water Contamination Precipitation Change Precipitation/Recharge Change Cost-Effective Water Treatment and Conservation Technologies Increased Valuation/ Economic Breakpoints Virtual Water Imports And Exports Virtual Water Imports And Exports Trans- boundary Disputes Trans- boundary Flows Changes in Water Availability Changes in Water Availability Salt- water intrusion Salt- water intrusion

40. Sustainable level of ressource development with acceptalbe impacts under present conditions Total abstraction Number of wells time 1 4 0 2 3 Incipient stress an Stable development Baseline situation Significant stress Unstable development Growth of aquifer pumping, but only few local conflicts between neighbouring abstractors Simple management tools (e.g. appropriate well-spacing according to aquifer properties) High-level of abstraction, but sound balance between stakeholder interests and ecosystem needs Integrated management with high-level of user self-regulation, aquifer monitoring and assessment Excessive abstraction with irreversible aquifer deterioration and stakeholder conflicts Regulatory framework with demand managemnt and/or artificial recharge urgently needed Availability and accessibility of adequate quality groundwater greatly exceeds small dispersed demand Registration of wells required, together with maps of occurrence of usable resources Abstraction expanding rapidly with impacts on natural regime and strong dependence of stakeholders on ressource Regulatory framework needed, based on comprehensive assessment

41. Some response options • More focus on GW, monitoring, permits, • GW mgt. as an integral part of IWRM • Combine demand and supply mgt. • Awareness of general public => genuine stakeholder participation in groundwater protection • Capacity building => Research into mgt. => informed mgt. • Advocacy at the policy level => importance of GW acknowledged and incorporated into policies and institutions • Climate change a driver for GW emphasis • No blanket policy