Development of well-balanced strategies to enhance flood resilience

Transcription

1 Development of well-balanced strategies to enhance flood resilience Forum Inondations 2017 Herman van der Most (Deltares)

2 Some background on Deltares institute Independent research institute on water, soil and infrastructure Doing applied research and specialized consultancy Making use of unique in-house research facilities and software Ca. 850 employees, about 15 % international from > 30 countries Some (part-time) professors; guidance of numerous PhD and MSc students Working (inter)nationally for public and private sector; Strong relationships with national government Campus in Delft

3 Outline of presentation Planning based on joint fact-finding and common knowledge base: experiences from Room for the River project / Delta Programme Risk-informed decision-making for a proportionate response to risk: framework for policy analysis and planning methods and tools for analysis (risk analysis / critical infrastructure) Evaluation of full range (cascade) of possible measures: some reflections on different types of measures : green infrastructure, early warning, multi functional defences, etc. 24 oktober 2017

4 Trigger for Room for the River programme (1) (Near) flooding and evacuation in oktober 2017

5 Trigger to Room for the River programme (2) Two one in 30/60 years events within 14 months (Dec 93; Jan 95) people evacuated Large impact, media attention, etc Increase in design discharge from 15,000 to 16,000 m3/s 24 oktober 2017

6 Loss of room along river Rhine ( ) urban expansion over decades has taken away room from the river Rhine (e.g. at Arnhem and Nijmegen) Arnhem 1830 Arnhem 2000

7 Room for the River measures Lowering of floodplains Lowering of groynes Deepening of main channel Floodway Dike relocation Removal of obstacles

8 Projects within Room for the River programme different projects within Room for the River programme

9 River bend near Nijmegen (old and new) Nijmegen old situation Nijmegen new situation 24 oktober 2017

10 Governance and timeline of programme Joint approach of national government, regional authorities and other partners 2 ministries 7 provinces 8 waterboards 30 municipalities NGO s and Interest groups Ministry of Infrastructure and Environment responsible for overall programme development (in consultation with ) Actual implementation in separate projects by local authorities (under supervision of Ministry) 24 oktober 2017

11 Experiences from the Programme Large infrastructural programme implemented within time and budget: Integrated approach (safety and spatial quality) with strong community involvement (process of joint fact-finding) Planning Kit (DSS) to screen individual measures and design strategies and to connect local ambitions to scientific sound results (common knowledge base) Nice blend of a strategic approach looking for a coherent strategy and local / regional stakeholder engagement to connect to other developments 24 oktober 2017

12 Proactive approach of Dutch Delta Programme 2008: advice by State Committee (after Katrina) 2010: Delta Programme: with the aim of keeping the Netherlands a safe and attractive place to live and work Two main goals : Safe now and in future ( ) Fresh water supply guaranteed in dry periods Not in response to a disaster but proactively to be prepared and trying to avoid it

13 Delta Programme approach Involve all levels of government in a transparent decision-making process in line with their responsibilities Stimulate horizontal and vertical coordination Three values: solidarity, flexibility and sustainability Joint fact-finding with involvement of stake-holders and interest groups

14 Delta Act to ensure continuity of Delta Programme Legal base established in 2011 Delta Fund to guarantee long term financial stability (1 billion Euro/year) Government Commisionner for the Delta Programme (responsible for progress and coherence) New approach on integration of administrative vertical and horizontal divisions, which addresses financial and policy continuity with participation of all stakeholders

15 Adaptive (Delta) Planning Incorporating long-term objectives in short-term decisions Connect short term decisions (in physical domain) with long term water challenges Link with (short term) investment agenda s in other domains Ability to speed up or slow down, flexibility to change to another strategy No regret, avoid lock in Co-creation of integrated solutions Spatial reservations for possible future interventions

16 Development new flood protection standards Behind the levee More people, assets More value to protect In front of the levee Sea level rise Larger peak discharges New insights Strength of levees Consequences of levee breaches

17 Principles of new flood protection policy 1. Provide a basic level of safety (1 in 100,000 years) for every one behind dikes through risk mitigation measures in areas with large individual risk 2. Counteract societal disruption: provide additional protection for areas which would experience a large number of casualties or large economic damage in case of flooding 3. Establish protection of vital and vulnerable infrastructure to enhance the functioning of an area during and after a flood disaster. 24 oktober 2017

18 Economic efficient protection standards Costs (euro) Optimal protection when marginal benefits equal marginal costs Total costs Investment costs Expected damage cost Levee height (cm) 18

19 Basic safety based on Local Individual Risk (LIR) Local Individual risk: probability per year of drowning in a flood at a certain location (taking into account preventive evacuation) Calculate from: Flood scenarios Flood probabilities Mortality = f(h, dh) Preventive evacuation

20 Setting a threshold value for individual risk Provide a base level of safety for every person living within a dike ring Compare to the safety standard for industrial risk: no urban development within 10-6 contour Flooding is not an industrial risk! anthropogenic vs. natural cause? Threshold value of 10-5 / year chosen for basic safety (CBA, Motion adopted in parliament)

21 New flood protection standards Combination of requirements from basic safety and economic efficiency New standards based on a risk based approach: more differentiation in standards Accepted in Parliament in July 2016 (by acclamation); in law by January 2017 New standards to be met in

22 Framework for policy analysis and planning From: WMO/GWP Guidance document (May 2017) 24 oktober 2017

23 Flood risk analysis Past floods are just realizations of possible floods Planning should deal with possible future floods: thorough risk analysis as a base for development of effective strategies Factors contributing to flooding: Rainfall depth Spatio-temporal rainfall patterns Initial soil conditions Initial reservoir conditions Ocean water levels Snowpack and melt

24 Flood risk based on joint probabilities Joint probabilities through a Monte Carlo / modeling approach: consistent framework for flood risk analysis (current / future situations) scenarios for climate change (rainfall, sea level rise) changes in reservoir operation policy Different components in place: Impacts of climate change on reservoir operation Integrated set of models through new version of SPH 24 oktober 2017

25 Impacts of flooding on critical infrastructure Understand full scope of impacts from flooding; including cascading effects Better understand the sequence of failure during a flood event to improve emergency management Impacts of flooding on critical infrastructure in Toronto (scoping workshop with stakeholders + research for quantifying resilience) 24 oktober 2017

26 Development of methodology through cases EU-research project INTACT with case studies for Port of Rotterdam and city of Cork (Ireland) Circle application for CNRS Paris (Prefecture de Police) Business continuity in Istanbul (Turkey) for World Bank Applications for various regions in NL Collaborative approach using existing expertise and experience: To create a qualitative overview in workshops with stakeholders and to gain focus for more detailed analyses To map of interdependencies of networks and objects of critical infrastructure (with Circle tool) 24 oktober 2017

27 Mapping infrastructure interdependencies Power (medium): expected to fail at 25cm water depth 24 oktober 2017

28 Cascade of FRM measures 24 oktober 2017

29 Adaptation in urban areas: overview of options Many, many options:

30 Feasibility NBFD solutions: energy and slope (=space) Dominance of Sand Softer solutions need more space! Mud

31 Perspectives of green infrastructure Growing interest in potential of green infrastructure: Nature based solutions are better adaptable to changing climate Offer ecosystem services (co-benefits) Uncertainty about effectiveness under real extreme conditions Compete with traditional engineering structures with design regulations Various pilot projects; no mainstream yet, evidence base still limited, Nature based solutions / flood defences: spearheads in research Most perspective in hybrid solutions (mix of green and grey infrastructure)?

32 Urban planning multi functional water defences

33 Flood Forecasting and Early warning Delft-FEWS based system for realtime flood forecasting: Initial stages: development by Deltares (Kénogami basins) Currently: expansion to all Québecois basins in the system by MDDELCC staff MDDELCC models integrated into new SPH Model types included: Rainfall-to-runoff, streamflow propagation: HYDROTEL Reservoir models Uncertainty estimation procedures

34 High-resolution weather forecast

35 near-real time observed streamflow

36 Hydrologic model runs: recent past, near future

37 Awareness and preparation for floods Emergency kit Appointments Search for information Sand bags flood boards Emergency plan Insurance

38 Perception of responsibilities in NL Number Individual only mainly individual individual & government mainly government government only damage reduction reduction of loss of life

39 Low regret measures (from EU FRM-plan) Establish early warning systems and risk management plans Identify and map hot spots for flash flooding Safeguard retention areas in local and regional spatial planning Restore and maintain the functionality of natural retention areas (biodiversity co-benefits) Cooperation between upstream and downstream communities Limit development in flood prone areas From Flood Risk Management Plans (EU Floods Directive) 24 oktober 2017

40 Connecting measures to other policy domains 24 oktober 2017

41 Recommendations for strategy development (1) Strategy to be embedded in vision on regional development; will facilitate to connect flood risk measures to other policies Adoption of a river basin approach will help to: Refrain of measures which significantly increase flood risk elsewhere Give proper consideration to spatial planning policy, giving room to the river, natural water retention measures and climate change Facilitate the actual implementation of measures 24 oktober 2017

42 Recommendations for strategy development (2) Thorough examination of all relevant options: Cascade of measures: menu for strategy design Find optimal mix of structural and non-structural measures Green, grey or hybrid solutions? Sufficient attention for short term actions (low regret) Adaptive approaches to minimize future regret 24 oktober 2017