Using a Scenario-Neutral Framework to Avoid Potential Maladaptation to Future Flood Risk

Area of Science:

• Hydrology and Climate Science
• Environmental Risk Assessment
• Water Resource Management

Background:

• Future flood risk assessment is challenged by climate change uncertainties and the potential for maladaptation.
• A scenario-neutral approach is employed to assess the sensitivity of Irish catchments to projected climate change impacts on fluvial flooding.

Purpose of the Study:

• To develop a framework for identifying catchment types at high risk of maladaptation to future flood risk.
• To quantify the sensitivity of Irish catchments to climate change using a range of temperature and precipitation scenarios.
• To classify catchments based on their physical attributes and sensitivity to flooding.

Main Methods:

• Utilized a scenario-neutral approach to examine catchment sensitivity to fluvial flooding under national climate change allowances.
• Simulated 20-year flood magnitudes using GR4J and NAM rainfall-runoff models across predefined sensitivity domains.
• Employed clustering and discriminant analysis to develop a catchment sensitivity typology and classify data-sparse catchments.

Main Results:

• Hydrological model uncertainty significantly influences flood sensitivity, more so than climate model ensemble bias.
• A national flood risk allowance of 20% offers variable protection against projected climate uncertainties.
• Catchments with lower storage capacity are particularly sensitive to amplified seasonal precipitation cycles, indicating a high risk of maladaptation.

Conclusions:

• Standardized national or regional flood allowances may lead to ineffective local adaptation strategies.
• Catchment-specific assessments are essential for robust flood risk management under climate change.
• Identifying and prioritizing catchments sensitive to precipitation seasonality is critical for mitigating future flood maladaptation.