Futureproofing infrastructure for disruptive events: Flooding

Transcription

1 Futureproofing infrastructure for disruptive events: Flooding Will McBain Associate Director, Arup 23 January 2014

2 Flooding already severely impacts on the nation s infrastructure assets Ulley Dam, 2007 Walham substation, Gloucestershire, 2007 courtesy Geodesign Barriers Ltd Cumbria, 2009

3 3 The 2007 floods alone cost the UK economy over 4 billion, and the damage specifically to critical infrastructure was valued at about 674 million.

4 Presentation structure Arup s work in the field of flood risk management; Brief overview of approaches currently taken to future proof our designs for projected increases in flood risk; Future proofing success criteria and the impact use of these can have on options selection; Challenges associated with improving the flood resilience of interconnected legacy infrastructure systems; Thoughts on future focus.

5 Arup s work in flood risk management

6 Industry guidance developed by Arup CIRIA C624 Development and Flood Risk; guidance for the construction industry, 2004 PPS25 Development and Flood Risk Practice Guide, 2007 Cityflood Guidance Document on Urban Surface Water Management Planning On line training in flood risk assessment for EA development control staff 6

7 7

8 8 Design approaches

9 Overall approach Understand the problem at catchment scale Align with other drivers and development needs Identify partners and understand their priorities Build a shared case for investment and action; Delivery, maintenance, evaluation, feedback.

10 Hazard assessment now and in the future Sources Mechanisms Pathways Depths, durations, velocities

11 Vulnerability and consequences now and in future People, Property and Infrastructure Social, heritage and environmental assets

12 Options development All costs and benefits expressed as Present Values based on whole life costs over appraisal period (usually 100 years) 12

13 SOURCE CONTROL - measures which reduce the likelihood of high flows/water levels occurring. FLOOD RISK MANAGEMENT MEASURES PATHWAY MODIFICATIONS - measures which modify or block the pathways taken by floodwater to a site. RECEPTOR RESILIENCE - measures which reduce the vulnerability of receptors to the impacts of a flood. Land use policies Sustainable drainage - Detention basins - Filter drains/strips - Flow control systems - Infiltration basins/ trenches - Permeable paving - Retention ponds - Soakaways/Swales - Wetlands - Green roofs/walls Rainwater harvesting Attenuation reservoirs River regulation River restoration and floodplain rehabilitation Attenuation within the drainage network. Ground raising Construction of floodwalls and embankments Tidal surge barriers, gates and sluices Construction of diversion channels or tunnels Removal or modification of existing structures Demountable flood defences Temporary flood defences Designing drainage networks for exceedance, eg overland flow routing Managed realignment to make space for water Flood resistance measures (dry-proofing). Business continuity management Flood risk identification and mapping Planning policies and development control Risk transfer (eg flood insurance) Flood forecasting and warning Improved emergency response procedures Enhanced preparedness Desk top incident management exercises Feedback from lessons identified Flood resilience measures (wet-proofing). Based on CIRIA, C688 Flood resistance and resilience for critical infrastructure, McBain et al, 2010.

14 Futureproofing resources UK Climate Impacts Programme & Toolkit National Planning Policy Framework EA/Defra Guidance to flood defence operating authorities 14

15 15 Example - projected increases in river flow

16 Precaution vs managed adaptation

17 Examples

18 18 Example of a managed adaptive approach

19 New transport infrastructure a precautionary approach Designed for climate anticipated at the end of the century using parameters in National Planning Policy Framework Technical Guidance; Eg Viaduct soffits provide a freeboard above the 1 in 100 annual probability event assuming a c. 20% increase in the magnitude of peak river flows, as a minimum; Challenging to adopt managed adaptive approach because of future enforcement of conditions. 19

20 Suggested future proofing success criteria for use in options identification and appraisal Resilient - able to withstand shocks and recover quickly; Passive not reliant on operator intervention; Fail soft - won t fail catastrophically; Fail safe - won t make situation worse if it fails to operate; Flexible & Adaptive can be readily adapted if understanding of risks change; Robust - not overly sensitive to design assumptions; No regrets - won t close-off potentially attractive alternatives; Self-reinforcing - works with, rather than against, natural processes.

21 These success criteria can steer options selection in the direction of more ecologically-based solutions

22 Designing with water for people

23 and wildlife Beam Parklands, Dagenham, London 56 Ha park created within flood storage reservoir, incl. 12 Ha BAP habitat.

24 Off-setting the carbon footprint of capital schemes 1,900 properties protected by 3 km of refurbished walls and embankments 60 Ha BAP habitat created off setting 80% the carbon footprint of the defences over their lifetime Stainforth FAS and Fishlake Biodiversity Action Plan Habitat Creation, River Don, Yorkshire

25 Retrofit futureproofing of legacy infrastructure

26 CIRIA Publication C688 Flood resilience and resistance for critical infrastructure Research contractor: Funders:

27 Resilience retrofit simple principles Problem flooding in 2007 Solution

28 But numerous interdependencies.

29 Coordination role for Local Resilience Forums

30 Cross sector collaboration required to achieve best overall value for money in boosting protection to communities Cross-sector flood resilience workshop for CIRIA C688, London, 2009.

31 What standards? Indicative design standard Target asset performance level (1 in x annual chance) Unaffected Restricted operation Safe but not operational Near failure CAT CAT 2 CAT CAT 3 CAT 2 CAT ,000 CAT 4 CAT 3 CAT 2 CAT 1 > 1,000 CAT 5 CAT 4 CAT 3 CAT 2 CAT5-CAT 3 Critical National Infrastructure CAT2-CAT0 National Infrastructure (from CIRIA C688, 2010)

32 Key challenges associated with resilience retrofit Regulatory complexity; Resources and capacity; Understanding the detailed nature of the hazard; Design standards and performance levels compatible across sectors; Business case, affordability and willingness to pay; Lack of incentives to collaborate.

33 Conclusions and thoughts on future focus Future proofing flood parameters are now more embedded and guidance is available for developers and infrastructure planners/designers; Future proofing success criteria are not formally embedded into existing options appraisal processes; Opportunities for cross sector win win solutions have never been greater; Capacity and resources to achieve such solutions is dwindling; There is therefore a need to achieve efficiencies by working more smartly.

34 Questions/discussion