Beyond Pumps: Blending Blue, Green, and Grey Infrastructure to Reduce Flooding and Optimize Resilience in New Orleans

Purpose: - Understand the Integration of Blue-Green Stormwater Infrastructure (BGSI) with Traditional Grey Infrastructure: Learn how combining nature-based solutions with traditional infrastructure can enhance flood management, reduce pressure on drainage pump stations, and improve urban resilience in flood-prone areas. - Evaluate and Prioritize Flood Management Projects: Gain insights into the criteria and methodologies used to assess and prioritize flood management projects, focusing on hydraulic benefits, cost-effectiveness, community impact, and partnership opportunities to optimize flood risk reduction and urban sustainability. Benefits: This presentation on flood management in Greater New Orleans demonstrates a comprehensive approach that integrates blue, green, and grey infrastructure solutions to enhance the city's resilience to flooding. By addressing the root causes of flooding and incorporating nature-based solutions, it offers practical insights and innovative techniques for sustainable flood risk reduction. The presentation also highlights the collaborative efforts with city partners and the strategic prioritization of projects to ensure cost-effective investments that benefit both the community and the environment. Introduction Flooding remains a critical issue in Greater New Orleans, particularly as overwhelmed drainage pump stations (DPS) face increasing strain. This project adopts a comprehensive hydrologic and hydraulic (H&H) approach to prioritize a suite of projects that blend blue, green, and grey infrastructure. By strategically integrating nature-based and traditional solutions, we aim to reduce flood risk without overburdening the city's vital pump systems. New Orleans Flood Vulnerability and Challenges New Orleans' unique geography and climate make it particularly vulnerable to flooding. The city's reliance on DPS to manage stormwater is becoming less sustainable due to aging infrastructure and the growing intensity of storm events. Traditional grey infrastructure, while effective, often fails to address the root causes of flooding and can be costly to maintain. In contrast, blue and green infrastructure solutions offer sustainable, cost-effective alternatives that enhance the city's resilience to flooding. Figure 1. Overview of Flow Paths Study Focus and Methodology The study focused on the Lakeview, Lake Vista, and Lake Shore neighborhoods, chosen due to their history of flooding. This project employed advanced H&H modeling techniques to assess flood risks and identify priority areas for intervention. By integrating nature-based solutions, urban green spaces with traditional infrastructure upgrades, we aim to create a balanced and sustainable flood management system. This approach will reduce pressure on DPS, enhance system redundancy and reliability, and optimize maintenance and operations. Figure 2. Existing Conditions Flood Collaboration with City Partners to Develop BGSI Toolbox While improving DPS capacity and reviewing the conveyance system were beyond the study's scope, the focus was on addressing the lack of storage through blue-green stormwater infrastructure (BGSI) and conveyance improvements. BGSI opportunities were identified by creating a BGSI toolbox, developing site typologies, GIS analysis, and overlaying hot spots from existing conditions modeling. The BGSI toolbox includes practices like wet ponds, dry detention basins, underground detention, bioretention areas, and permeable pavements, which provide benefits such as flood reduction, water quality improvement, and urban heat island mitigation. Site typologies and feasibility were considered based on information provided by CNO and collected during the BGSI workshop conducted with the City. Ultimately, 12 project concepts were selected for further development, modeling, and scoring, focusing on areas with the greatest flood depths and opportunities for strategic storage solutions. These projects aim to reduce flooding while enhancing community resilience and urban aesthetics. Concept Development and Prioritization Process To score the twelve proposed concepts, six scoring criteria were developed to evaluate their holistic benefits. These criteria included annual operations and maintenance (O&M) costs, hydraulic benefits, infrastructure connectivity, enhancement of community amenities and equity, proximity to partnership opportunities, and cooling potential. The criteria were weighted based on their importance to the City of New Orleans, as determined in our BGSI workshop. Figure 3. Concept Prioritization - Weighted Benefit versus Cost Graph This study has identified BGSI concepts that can help manage flooding in the Lakeview study area, and the projects are sorted into Tiers in Figure A-2. However, a combination of BGSI and gray infrastructure investments is necessary to significantly reduce flooding and risk. The recommendations emphasize phased implementation to maximize immediate benefits, overall cost-effectiveness, and synergy with other neighborhood investments. - Prioritize Tier 1 High-impact Concepts: Project that will have had the greatest hydraulic benefit with reasonable cost. - Prioritize Tier 2 Investments Concepts: Projects that could reduce flood but require and investment. - Opportunistically Pursue Tier 3 Concepts: Project to be pursued based on opportunities available including partnering with active projects. - Optimize or Defer Inefficient Tier 4 Concepts: Projects that are not cost-effective in their current configurations. Further modeling may identify more efficient solutions. - Address Persistent Surcharging: Implement conveyance improvements to address surcharging unrelated to pump capacity limitations, providing additional relief to hot spot areas. - Enhance Storage and Conveyance: Integrate BGSI with conveyance improvements to enhance storage and reduce flood risk. - Conduct Further Investigations: Investigate the stormwater collection system's capacity and necessary DPS upgrades to address backwater conditions and increase flood depth reductions. Conclusion & Value of Balanced BGSI Solutions Through strategic investments and stakeholder collaboration, we can reduce flood risk, improve system efficiency, and ensure the long-term sustainability of New Orleans' flood management infrastructure. This presentation will explore innovative techniques, balancing system efficiency, and discuss how targeted infrastructure investments can improve resilience in flood-prone urban areas.