July 26, 2017, by lgzsam1

Urban Flooding and Sponge Cities Workshop, 3-5 July 2017, China

In his blog, Sangaralingam Ahilan reports on the UK-China joint workshop on ‘Urban Flooding and Sponge Cities’ at the 2017 annual conference of the International Institute for Infrastructure Resilience and Reconstruction (IIIRR) held on 3-5^th July 2017 at Shenzhen, China.  The workshop was co-ordinated by University of Exeter, UK and Tsinghua University, China and funded by the British Council, Newton Researcher Links programme and the National Natural Science Foundation of China.  The workshop had contributions from leading UK and Chinese academics, water professionals and early career researchers.  This blog post mainly focuses on the opening day of the conference.

 

 

Sponge Cities keynote speeches

On the first day, water professionals and academics delivered keynote speeches on urban flood management and the Sponge Cities concept:

• The evolution of Shenzhen over the last 35 years, from a coastal village with a population of 30,000 to a modern metropolis consisting of 11 million inhabitants, was discussed by Prof Yuntao Guan from Tsinghua University, China. To minimise the impact of rapid urbanisation on water shortages and pollution; Shenzhen is committed to adopting the “Sponge City” programme.  Guan outlined Shenzhen flood control initiative through “Shenzhen Water Strategy” with emphasis on the protection of water resources, the recovery of water in the environment, the guarantee of water safety and the enhancement of visible water.
• Prof Paul Leinster from Cranfield University (former Chief Executive of the Environment Agency, UK) emphasised the need for a paradigm shift from ‘flood prevention’ to ‘flood management’ for sustainable stormwater management. He presented a number of UK catastrophic flood incidents and addressed practical challenges as new lessons to be learned from every flood event.  Prof Leinster stressed the importance of reliable flood mapping, forecasting and warning.
• Prof Janaka Ruwanpura from the University of Calgary, Canada presented a network modelling approach for planning and mitigation of natural disasters. Ruwanpura used the 2004 Tsunami coastal flooding in Sri Lanka to illustrate how the model parameters have been systematically devised based on expert opinions.  The network-based modelling approach enables to the categorisation of disasters and supports disaster planning. 
• Prof Mooyoung Han from Seoul University, Korea delivered a talk on the challenges and opportunities in rain and flood management in Korea. He introduced the Seoul City rainwater regulations and management strategy to cope with the unbalanced water status due to urbanisation and climate change.
• Prof Haifeng Jia from Tsinghua University talked about challenges in sustainable urban water and sanitation in China. He presented an onsite source separation toilet system that can be used to minimise the sanitation crisis in developing countries.  Jia also touched upon the ‘water-energy’ nexus to strike a balance in urban water and sanitation management, emphasising the need for the restoration of the extinct river systems.
• Prof Nigel Wright from De Montfort University, Dr Faith Chan from the University of Nottingham (Ningbo Campus) and Dr Sangaralingam Ahilan from University of Exeter represented the ‘Urban Flood Resilience Consortium’ at the workshop.  Prof Wright delivered the overview talk on ‘How do we put urban flood resilience into practice?’, introducing the Engineering Physical Sciences Research Council (EPSRC) ‘Achieving Urban Flood Resilience in an Uncertain Future’ research project.
• Dr Faith Chan presented his research work on the Ningbo sponge cities pilot study by reporting empirical evidence and findings on the hydrological modelling from a study site at East New Town, Ningbo. Chan stressed that municipal authorities have a significant role in achieving the dual goals of more sustainable water-usage and better flood control being targeted by the Sponge Cities code of practice.  Ahilan presented the long-term hydro-morphodynamic modelling and simulation of the Blue-Green features.  He demonstrated how floodplain restoration and stormwater pond influence the flow and sediment dynamics in the urban catchment through two case studies.

Take-home messages

• Think big and act early
• The importance of reliable flood mapping, forecasting and warning
• Plan for unthinkable future scenarios, as future never rely on past disasters and its consequences
• The importance of recognising interoperability of the infrastructure and interdependency of the river, groundwater and pluvial flooding
• Providing people with the effective risk communication
• The importance of linking urban water with sanitation
• Long-term performance of the Blue-Green infrastructures

Closing talks

On the final day, Prof Dragan Savic from Exeter University, delivered the keynote speech on ‘Has high-resolution, two-dimensional flood modelling come of age?’

• Prof Savic introduced a generic 2D flood modelling tool (CADDIES), which uses a new concept of ‘Cellular Automata’ to capture the dynamics of 2D surface flow, using the readily available high-resolution digital terrain models and commonly available desktop computers.
• Dr Albert Chan presented his research work on flash modelling in urban areas. He discussed the challenges in modelling flash floods, including spatial-temporal varied rainfall distribution, urban micro features and drainage networks and sponge city measures.  Chan also outlined potential solutions to overcome these challenges.  With a next generation flood models, the impact of flash flooding can be accurately and efficiently evaluated such that the decision makers can develop effective adaptation strategies to enhance the city’s resilience to flash floods.

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