Project Deep City in China

1. Workshop on geomatics technology for the monitoring of natural hazards, August 23th 2010 Project Deep City in China LI Huanqing, phD student EPFL GEOLEP: Laboratory of Engineering and Environmental Geology REME: Research Lab in Economics and Management of Environment

2. OUTLINE • Project scheme and methodology • Target discussion on land subsidence • The vision in underground resources management

3. Project scheme and methodology Project « Deep City » : A global concept for sustainable urban underground resources management “Urban underground, 4 main resources, a system”

4. Matrix of interactions betweenresources D’après Blunier

5. Examples of synergies and conflicts Synergy between space and geothermic: Energetic geostructures integrated in underground space (parking) Synergy between space and geomaterial: Valorisation of excavated material Sorting and reuse

6. Conflict between groundwater and space: Over-exploitation of groundwater causes land subsidence Conflict between space and groundwater: Subway construction against water protection zone

7. Multi-use methodology: aim to exploit the full potential of the urban underground in a sustainable way by integrated management

8. Project Development: • Deep City project in Switzerland (PNR54) published in 2010 - Case study in Geneva • Deep City project in China (SSSTC) 2009-2012 collaboration with Nanjing University – IUSG (Institute of Underground Space and Geo-environment) and Jiangsu Land Resources Bureau - Case study in Suzhou, test the applicability - Generalization the methodology to the othermetropolis in Chineseterritory, based on four main types of urban underground conditions

9. OBJECTIFS économique économique social social environnemental environnemental Projet Deep City Suisse Projet Deep City Chine

10. Phase 1 of Deep City project - Case study in Suzhou • Target scale • The city of Suzhou, in Jiangsu Province (Yangtze Delta city clusters) Steps: • Evaluation of global resourcespotentialbased on 3D geological and hydrogeological model (conflicts and synergies) 2. Global economic and social cost-benefitanalysisbased on a specificdevelopmentproject 3. Optimization for long term exploitation 4. Intergrationintourban planning

11. 3D geological model of target area deep to 100m: (provisional) • Layers of unconsolidated alluvial sediments  difficult underground engineering conditions, especially soft soil layers are main challenges during excavation • Layers of aquifer system  rich in groundwater resource • FromphDstudent L. Cao (NJU-IUSG)

12. Phase 2 of Deep City project – Generalization Typological network in Chinese main cities

13. Identification of the main conflictsfromurban underground resources exploitation in Chinesebigcities:

14. Land subsidence in Suzhou • History of groundwater over-exploitation (before 2000) • Control policyfrom central government ( from 2000 to 2005) • Reasonableplanning for long term exploitation • Prevention of riskcaused by underground engineering works

15. Over-exploitation Control  planning  future risk • Unconsolidated Porous aquifers system: 2 shallow unconfined aquifers, 3 deep confined aquifers . 2nd confined aquifer as main exploitation layer (good quantity and quality for drinking use)

16. Intensive pumping: within the same time, the same area and the same layer! • Reason: strong industrial demand for water, surface water pollution and insufficient water supply infrastructures Land subsidence velocity from 1995 to 2000 (InSAR results)

17. Land subsidence Monitoring system and GIS plateform for spatial analysis Vertical land deformation in the center of Suzhou

18. Over-exploitation Control  planning  future risk • From 2000 to 2005, local authority completely banned the groundwater pumping, groundwater level is restored. Groundlevel Ban Policy Center South North Groundwater observation boreholes

19. Over-exploitation Control  planning  future risk • The Ban policy for exploitation is not a permanent solution for groundwater resource management • To maintain the deep groundwater quality and quantity by • zoning policy (protection zone, exploitation zone) • Control water supply  target to drinking use • technical requirement for underground structures • Shallow groundwater have high potential for exploitation: • Good natural recharge conditions • Suitable water quality for industrial and agricultural use • Improve technology for water supply system

20. Over-exploitation Control  planning  future risk • Recently, another important risk for land subsidence is underground construction work in saturated soft soil area. • Severe accidents during metro line excavation in Yangtze Delta: • Shanghai: 2003, metro line 4 • Nanjing: 2007, metro line 2 • Hangzhou: 2008, metro • Lessons to learn for metro construction in Suzhou city!!

21. Vision from Deep City • Consider the whole underground resources system during urban planning, with the priority to promote the synergies and avoid the conflicts • Coordinate the governance among different bodies such as urban constructors, water supply, energy supply, legislators and land developers, in order to decide the best development scenarios • Evaluate the development project based on global cost-benefit analysis, to maximize social, economic and environmental objectives

22. THANK YOU!