Flood Mitigation Strategies for Communities

This is how China is designing flood-resistant cities. They are using modern technology that can be replicated in flood-affected areas around the globe. With a focus on innovative engineering and sustainable practices, Chinese urban planners are implementing advanced drainage systems, green spaces, and permeable surfaces to mitigate flooding risks. In cities like Zhengzhou, which experienced devastating floods in 2021, authorities are taking proactive measures by constructing elevated walkways, improving water retention areas, and incorporating natural features into urban landscapes. These strategies aim to absorb excess rainwater and reduce runoff, enhancing the resilience of urban infrastructure. Additionally, smart technologies such as real-time data monitoring and AI-driven predictive models are being integrated into city planning. These tools enable quick responses to weather changes, allowing for timely evacuations and better resource allocation during flooding events. China's approach not only addresses immediate flood risks but also promotes sustainable development by prioritizing environmental harmony. By sharing these technologies and strategies with other nations, China is leading the way in global efforts to combat climate change and protect vulnerable communities from the impacts of flooding. This comprehensive approach showcases the potential for innovation in urban planning, setting a precedent for flood resilience worldwide. ©: Business Insider

When every risk feels urgent, how do you know where to act first? That was the challenge in Honolulu’s Ala Wai watershed—where flood risk, urban development, and aging infrastructure collided. The stakes were high, but resources weren’t unlimited. Working with 3Rwater, Inc., we helped identify where action would make the biggest impact—and how to move forward: ✔️ Mapped flood and water quality risk hotspots to target solutions where they mattered most. ✔️ Integrated green stormwater infrastructure (GSI) to reduce runoff and improve resilience. ✔️ Prioritized high-impact interventions so funding went where it would deliver real results. The result? Immediate flood risk reduction in key areas, smarter investments by tackling high-risk zones first, and a data-backed strategy that turned plans into action(!!). Too often, resilience planning stops at reports. This is what it looks like when it leads to real change. How is your community making resilience actionable? #Resilience #FloodRisk #DisasterPlanning #ClimateAdaptation #WaterManagement #CommunityResilience #GreenInfrastructure Lauren C. Roth Venu Kinga Stryszowska-Hill, Ph.D.

𝐍𝐚𝐤𝐮𝐫𝐮’𝐬 𝐒𝐩𝐨𝐧𝐠𝐞 𝐂𝐢𝐭𝐲 𝐑𝐞𝐯𝐨𝐥𝐮𝐭𝐢𝐨𝐧 – 𝐃𝐚𝐭𝐚-𝐃𝐫𝐢𝐯𝐞𝐧 𝐑𝐞𝐬𝐢𝐥𝐢𝐞𝐧𝐜𝐞 𝐢𝐧 𝐀𝐜𝐭𝐢𝐨𝐧 Nakuru County in Kenya is setting a bold precedent in urban water management with its transformative Sponge City initiative, launched under the Water as Leverage (WaL) program. This innovative approach isn’t just about flood mitigation—it’s about redefining how cities interact with water, nature, and communities. 𝐖𝐡𝐚𝐭 𝐌𝐚𝐤𝐞𝐬 𝐍𝐚𝐤𝐮𝐫𝐮’𝐬 𝐒𝐩𝐨𝐧𝐠𝐞 𝐂𝐢𝐭𝐲 𝐔𝐧𝐢𝐪𝐮𝐞? Governor Susan Kihika’s administration is leveraging nature-based solutions to combat flash floods, droughts, and groundwater loss. Key features include: • Porous “smart pavements” with IoT sensors for real-time water absorption • Rain gardens reducing floods and enabling urban farming—creating 1,200+ green jobs • Urban wetlands treating wastewater and supporting endangered Rothschild’s giraffes • Blue-green infrastructure like rooftop gardens and ponds to recharge aquifers and provide water in dry spells In partnership with the Netherlands Enterprise Agency, UN-Habitat, and Vitens Evides International, Nakuru is combining cutting-edge technology and local knowledge to create tailored, resilient solutions. 𝐁𝐲 𝐭𝐡𝐞 𝐍𝐮𝐦𝐛𝐞𝐫𝐬: 𝐍𝐚𝐤𝐮𝐫𝐮’𝐬 𝐒𝐩𝐨𝐧𝐠𝐞 𝐂𝐢𝐭𝐲 𝐖𝐢𝐧𝐬 • 62% drop in flood-related displacement, protecting 300,000+ residents • $20M raised in carbon credits for wetland conservation • 7 key hotspots absorbing 500+ liters/hour/m² of stormwater • 80+ stakeholders—from slum communities to Dutch engineers—co-designed interventions at the Nature as Leverage workshop 𝐀 𝐂𝐨𝐥𝐥𝐚𝐛𝐨𝐫𝐚𝐭𝐢𝐯𝐞 𝐕𝐢𝐬𝐢𝐨𝐧 𝐟𝐨𝐫 𝐖𝐚𝐭𝐞𝐫 𝐑𝐞𝐬𝐢𝐥𝐢𝐞𝐧𝐜𝐞 The Nature as Leverage workshop united farmers, urban planners, engineers, and local leaders to co-design strategies for seven key areas across Nakuru. Examples include: • Rain gardens in informal settlements reducing flood risks while enabling agriculture. • Sponge parks in the city center repurposing stormwater for public spaces. 𝐖𝐡𝐲 𝐍𝐚𝐤𝐮𝐫𝐮’𝐬 𝐒𝐩𝐨𝐧𝐠𝐞 𝐂𝐢𝐭𝐲 𝐌𝐚𝐭𝐭𝐞𝐫𝐬 𝐍𝐨𝐰 As climate change accelerates, Nakuru’s sponge city model offers a replicable, data-driven blueprint for other fast-growing cities: • Carbon sinks: New wetlands and green roofs offset 15,000+ tons of CO₂ annually. • Economic resilience: Properties near sponge infrastructure see 7–15% value premiums. • Scalability: Nakuru’s 2025–2027 plan targets 45% urban zone coverage and 90% stormwater reuse. As Governor Kihika said at the 2024 launch: “Floods are not enemies; we can make friends with floods.” Nakuru isn’t just adapting—it’s pioneering a community-powered, climate-resilient future for the Global South. 𝐘𝐨𝐮𝐫 𝐭𝐚𝐤𝐞: Could localized metrics like “gallons absorbed per capita” become the new standard for measuring urban resilience? Let’s discuss! #UrbanPlanning #SpongeCities #WaterResilience #ClimateAdaptation #NatureBasedSolutions #DataDriven #NetZero

Did you know vegetation reduces the velocity of water runoff by up to 90%, preventing flash floods from building destructive force? ⬇️🌳 1. Dense root systems provide more time for water to seep into the ground by functioning as organic speed bumps. 2. Up to 60% of rainfall can be stored in wetlands and healthy trees. 3. Over 40,000 gallons of water can be absorbed annually by a single mature oak tree. 4. Because roots retain soil particles, erosion on slopes can be reduced by up to 80%. 5. Up to 50% less flooding occurs in forested areas. The easiest solution is to: 🌱 Restore wetlands, which can absorb up to 30 times as much water as agricultural land; 🌿 Reforest degraded areas, which can store 20,000 gallons of stormwater per hectare; and 🏙 Green urban spaces, which can reduce runoff by up to 40% by planting trees and rain gardens in urban areas. Credit: Tamma Carel (PIEMA, FIIRSM, fCMgr, MBA, MSc, BSc)

ASCE 24 and RiskFootprint(tm) 500-year Flood Maps! ASCE 24 standard, developed by the American Society of Civil Engineers, is a critical guideline for designing and constructing buildings in flood-prone areas. It establishes minimum requirements to ensure structures are resilient against flooding. Its importance lies in reducing flood-related damages, protecting lives, and enhancing community resilience. The recent update to ASCE 24-24 introduces significant changes, including a shift to the 500-year flood event as the design standard for most structures. This means that buildings are now designed to withstand floods with a 0.2% annual chance of occurrence, rather than the previous FEMA 100-year flood standard (1% annual chance). This change reflects the increasing frequency and severity of flooding events (including extreme rainfall) due to climate change and aims to better protect communities. The new RiskFootprint(tm) Version 17 includes the Fathom (Swiss Re) 500-year flood maps for pluvial, fluvial, and coastal flooding. Key updates in ASCE 24-24 include: Expanded Flood Hazard Areas: Now includes the 500-year floodplain, offering broader protection. Elevation Requirements: Structures must be elevated based on their flood design class, with critical facilities requiring even higher standards. Climate Change Considerations: Incorporates sea level rise and other future climate impacts into floodplain calculations. Enhanced Dry Floodproofing: Updates to materials, inspection, and maintenance requirements for floodproofing measures. These updates represent a proactive approach to flood prevention, aiming to reduce economic losses and safeguard communities against increasingly severe flooding events. Our RiskFootprint(tm) Resilience Sherpas will help you make your new or existing buildings safer and more resilient. Find out more at RiskFootprint dot com. American Society of Civil Engineers FEMA ASTM International Urban Land Institute Bryan Christopherson, CFM, LIA

🏗️ What if development worked with nature instead of against it? Traditional site design often prioritizes maximizing buildable area—but at what cost? Increased runoff, flooding risks, and higher maintenance expenses are just a few of the challenges that arise. Low-Impact Development (LID) flips the script. By using nature-based solutions, LID: 🌿 Reduces runoff with permeable surfaces and green infrastructure 💧 Improves water quality by filtering pollutants before they enter waterways 🏘️ Enhances community spaces with green buffers, rain gardens, and natural drainage At Olsson, we’ve seen firsthand how LID strategies can create more resilient, cost-effective, and aesthetically pleasing developments. Instead of treating stormwater as a problem, we turn it into an asset that enhances the site. Some of our favorite LID techniques include: ✔️ Bioswales that slow, filter, and direct stormwater naturally ✔️ Permeable pavers that allow rain to seep into the ground instead of overwhelming storm drains ✔️ Rain gardens that provide both function and beauty, reducing runoff while adding greenery The result? Smarter, more sustainable development that benefits both people and the environment. 💡 What LID strategies have you seen successfully implemented in your projects? Let’s discuss! ⬇️ #SustainableDevelopment #GreenInfrastructure #SmartGrowth #CivilEngineering #WeAreOlsson

Lakewood, NY’s Grandview Stormwater Management Project is a strategic, long-term investment in water quality and flood mitigation, born from a collaboration between local government, engineers, and conservation groups. Nestled just below Grandview Estates, the site now features a network of detention ponds, constructed channels, and engineered wetlands that collectively capture and filter runoff from nearly 50 acres of land. As spring snowmelt flows down this formerly steep slope, sediment and nutrients are intercepted before reaching Chautauqua Lake—an effort designed to reduce algal blooms and downstream flooding. Even under this year’s heavier-than-usual thaw, the system handled the influx with room to spare, a promising indicator as seasonal rains approach. What sets this project apart isn’t just the infrastructure, but the ecosystem it supports. Purpose-built habitats for birds, bats, and turtles are integrated into the landscape, which doubles as a public nature trail. Educational signage, native vegetation, and careful tree preservation efforts speak to a vision that balances utility with community value. The project, six years in the making, stands as a testament to patient, systems-oriented thinking—one that blends hydrology, civic planning, and environmental stewardship into a single, scalable model. With minimal maintenance, it’s poised to deliver both ecological and recreational returns for decades. Read the article: https://lnkd.in/gi49m934

🌧️ After a devastating $1.8 billion flood in 2011, Copenhagen made a bold decision: transform into the world's first comprehensive "sponge city." What makes this remarkable? The city is combining nature-based solutions (wetlands, parks, permeable surfaces) with advanced engineering (underground tunnels, storage basins) to absorb, store, and slowly release water back into the natural cycle. The results so far: 🌊 Flood risk reduced by 30-50% in priority areas 🏗️ Hundreds of projects completed with hundreds more underway 🌍 Cities from Auckland to New York now studying Copenhagen's model The Danish/Copenhagen model has long been recognized around the world as leading best practices in climate adaptation. Cities facing any type of climate-related flooding—whether inland or coastal, riverine or sea level rise—can take note of this comprehensive approach. This is not merely about managing water—it is about reimagining what infrastructure can be. Karen Blixens Square pulses with student life while silently preparing for the next deluge. Parks become reservoirs. Bike shelters capture rainwater. Every surface, every space serves multiple masters with elegant precision. As climate chaos intensifies globally, Copenhagen stands as proof that cities need not merely endure the future—they can shape it with intention and grace. The project may not be complete (originally slated for 2032), but it is already rewriting the rules of what urban resilience can achieve. I am extraordinarily proud that Ramboll has been part of this transformative journey, helping develop climate adaptation masterplans for several areas of Copenhagen—and bringing similar expertise to cities like New York. As our colleague Christian Nyerup Nielsen notes with profound foresight: "We have to anticipate the extreme weather events a century from now." It is work like this that drew me to Ramboll. This type of multifunctional urban infrastructure represents the cities I envision across our planet's future—each with its own unique contextual interpretation of how design can serve multiple purposes simultaneously, each a testament to human ingenuity rising to meet our greatest challenge. Climate adaptation does not demand sacrifice—it can elevate everything we value about urban life. When we design with nature as our partner rather than our adversary, we do not just survive—we flourish. This is not just Copenhagen's story. This is the blueprint for how civilization adapts, evolves, and ultimately transcends the climate crisis. Many thanks to Yale Environment 360 for illuminating this extraordinary work! https://lnkd.in/evBy7pEe #ClimateAdaptation #UrbanPlanning #Sustainability #Innovation #ClimateResilience #Ramboll

Diverting floodwater from roadways ensures safe passage and protects infrastructure integrity. A successful approach includes a mix of engineered solutions and natural methods. Engineered solutions encompass constructing drainage systems like swales, catch basins, and French drains to divert runoff from roads. Elevating road levels and erecting flood barriers effectively avert flooding incidents. Incorporating green infrastructure, such as rain gardens and permeable pavements, facilitates natural absorption, reducing runoff. Regular maintenance of clear drainage channels and proactive debris removal are vital for the optimal functioning of these systems, especially during heavy rainfall periods.

The Netherlands is now pioneering an ingenious urban solution: water squares. These are not just public parks; they are brilliant, multi-purpose hubs that double as intelligent flood-control systems. In dry weather, they are lively community spaces with playgrounds and markets. But when heavy rain falls, they transform into temporary basins, capturing and storing water to prevent local flooding. This innovative approach turns flood management into a valuable community asset instead of an eyesore. Pioneered in cities like Rotterdam, these designs show that urban infrastructure can be both functional and beautiful, seamlessly blending smart engineering with everyday city life. It's a great example of how we can build more resilient, people-friendly cities for the future. #water #Resilience #Sustainability