Balancing multiple stakeholder objectives for floodplain reconnection and wetland restoration

Area of Science:

• Environmental Science
• Hydrology
• Ecological Restoration

Background:

• Floodplain reconnection and wetland restoration are key nature-based solutions for enhancing flood resilience.
• These projects offer co-benefits like nutrient storage and improved habitats.
• Stakeholder objectives for riverside land use can be complex and sometimes conflicting.

Purpose of the Study:

• To develop and illustrate a decision-support tool for simulating floodplain restoration scenarios.
• To quantify and assess trade-offs between multiple stakeholder objectives in restoration design.
• To enable planners to identify optimal restoration designs that balance competing goals.

Main Methods:

• A simple ranking approach using an n-dimensional objective function was developed.
• The approach was applied to a watershed in central Vermont, USA.
• Eleven restoration modifications were simulated using the 2D Hydrologic Engineering Center's River Analysis System (2D HEC-RAS) across six scenarios, plus a baseline.

Main Results:

• Floodplain restoration scenarios showed modest peak flow attenuation due to the watershed's steep and flashy nature.
• Several scenarios successfully met or exceeded annual phosphorus load reduction targets for Total Maximum Daily Load (TMDL) implementation.
• The ranking approach effectively prioritized scenarios based on multiple stakeholder objectives.

Conclusions:

• The decision-support tool aids planners in evaluating and visualizing the effectiveness of different restoration designs.
• The approach facilitates consensus-building among stakeholders by quantifying trade-offs and justifying design choices.
• While peak flow reduction was limited, floodplain restoration proved effective for nutrient management in this watershed.