Delta Alliance - Comparative assessment of the vulnerability and resilience of 10 deltas

Tom Bucx (Deltares)

tom.bucx@deltares.nl

8 June 2011 EEA Expert meeting Methods and tools for

assessing coastal vulnerability to climate change

Comparative assessment of the vulnerability andresilience of 10 deltas

Provide a first step towards a comprehensive overview of the current and future state of deltas

Provide a ‘Delta assessment framework’: integrating scientific, social and management knowledge and addressing future data collection on key-indicators

Support decision-making process on adaptive strategies and measures towards resilient and sustainable deltas

Deltas studied

CaliforniaBay-Delta

Mississippi

Incomati

Nile

Rhine-MeuseDanube

Ganges-Brahmaputra-Meghna Yangtze

Mekong

Ciliwung

DPSIR + Spatial layers approach

Framework for assessment

Impacts | Responses

Towards indicators of change

Delta descriptions

Delta description - format

Drivers of change

Pressures / potential problems

• Land and water use (occupation layer)

• Infrastructure (network layer)

• Natural resources (base layer)

Governance (institutional and organisation aspects)

Adaptive measures

Technical methods and tools

Needs for knowledge exchange and research gaps

Lessons learned

Score card

Delta description – qualitative and quantitative info

Example: Drivers of change in Rhine-Meuse delta:

Climate change – higher peak river discharges (winter)long drought periods (summer)sea-level rise ≤ 0.65 to 1.3 m in 2100

Subsidence – Tectonic subsidence ~10 cm/century≤10 mm/year surface-lowering due to peatcompaction and oxidation

Presure on space – population density ~500 inhabitants/km2; high pressure on space

Vulnerability to flooding – high safety levels: 1/1250 (river dikes) to 1/10,000 years (coastal defense); sea-level rise and growing investments will increase flood risk

Freshwater shortage – rising sea levels will increase salt water seepage and will cause local freshwater shortages

Delta description – qualitative and quantitative info

Example: pressures on occupation layer in Rhine-Meuse delta:

Delta description – quantative main indicators

Example: main indicators (draft) for Rhine-Meuse Delta:

Scorecard and related indicators

Scorecard – ‘weighting method’

Assessment of the current and future state of the delta

Comparative overview of delta score cards

resilience/sustainability: ++ (very good), + (good), 0 (medium), - (low), -- (very low)

Comparative overview of delta score cards - Conclusions

For most of the deltas current resilience and sustainability is not satisfactory

Reasons differ per delta but some general mechanisms:

. An imbalance between demands and supply with regard to land and water use;

. An inadequate or ageing infrastructure in the delta;

. Disruption of the natural delta processes;

. Inadequate governance to address problems and implement solutions.

For a number of deltas the challenge is defining a comprehensive

(multi-sectoral) delta plan

The combined DPSIR-layer approach has proven to be useful

What’s next?

. Develop set of key (quantitative) indicators

. Optimize scoring and ranking method

. Work out scenarios in more detail

. Include more deltas (Rhone, Po, Thames, …)

. Work out concrete collaborative research ideas/proposals across deltas

Website - downloads

www.delta-alliance.org

Background information

Documents to download:

• Synthesis report

• Working document (with full delta descriptions)

Thank you

Questions?

Project team