Rising Tides
With climate-related catastrophes becoming a growing threat, properly preparing against them is becoming a major issue. One category of risk driven by climate change is flooding due to changing weather patterns and increasingly frequent and powerful hurricanes. This might become an ever-larger issue if sea levels rise significantly.
For a long time, topographic maps were used only to estimate the risk of floods. More recently, computer simulations started to be used to model how floods could impact different zones.
Urban areas are one type of area where simulations tend to perform poorly. This is largely due to the complexity of the landscape, which includes many buildings, pipes, sewage systems, etc. Not only is this complex environment hard to record properly, but it is even harder to predict how it will react to a flood.
This is a problem for many actors, from public authorities to insurance companies and real estate owners, as urban areas are the zone where properly preparing for flooding is the most crucial. For example, when Hurricane Harvey hit in 2017, it cost $132B in damages to Galveston, Texas, after $36B in damages from Hurricane Ike in 2008.
Source: Texas A&M
Modeling Urban Environments
This problem is what researchers at Texas A&M University have tried to solve.
The work was multidisciplinary, involving the Landscape Architecture and Urban Planning, Department of Computer Science and Engineering, Department of Multidisciplinary Engineering, Department of Geography, and the Section of Visual Computing & Interactive Media.
For now, a few methods have been used to try to simulate urban areas and their reactions to floods:
- 3D models using high-resolution terrain data
- The problem with using it for simulations is that it is too computing-intensive, making it unusable for large areas.
- Using Unreal 3D engine, a videogame engine, to create a simulation of an urban area.
- This too requires a lot of computing power, and also a lot of technical expertise in high demand by the video game industry.
- High-resolution Digital Elevation Models (DEMs).
- But these fail to capture the complexities of urban flooding.
Trying to solve the issues with previous modeling tentatives, the Texas A&M researchers used Galveston as a model study.
The city has been offered to build the “Ike Dike” for $31B to try to mitigate future flooding disasters.
A Novel Approach
The researchers first recognized that the city has a non-standardized first-floor level, changing the damage flooding would do to different buildings.
They then found a compromise between too vague approximations and ultra-detailed models, which were too demanding in terms of computer power.
Instead, they focused on 3 points:
- Pinpointing the building entrance, aka where the water will enter the building and cause damages.
- Using door flooding as a damage indicator.
- They integrated their model with the US government and FEMA”s GIS (Geographic Information Systems) flood impact analysis, making it more likely to be useful to government agencies and first responders.
This focus on “practical damages” allows the model to predict the financial damages caused by flooding relatively accurately. It also allows us to model the impact of flooding-related costs that building Ike Dike would have.
Practical Applications
The first direct application is for homeowners and insurance companies. Correctly assessing risks allows them to properly decide what leverage of coverage is adequate for an individual building.
The next step will be to apply this method beyond the prototype of Galveston and to other Texas coastal communities.
Once such a model exists, a real-time actualization of expected risks and damages can be created depending on the latest weather forecasts. This could be especially impactful in properly preparing community buildings like schools and stores.
Beyond Texas
This method can be applied everywhere flooding, and extreme weather events can threaten buildings and infrastructures.
A good example is the ongoing battle between Canadian Provincial and Federal governments over the Chignecto Isthmus. This 24km narrow strip of land connects Nova Scotia to New Brunswick and to the rest of Canada.
Source: CBC
The connection is at threat from extreme weather events and requires a $650M investment to secure the road and railroad passing by it. A vital infrastructure for the region, with $35B worth of inter-provincial trade passing by it every year.
The provinces want the Federal government to cover the whole cost, but the Federal government is only willing to pay half.
Proper flooding simulations could help here, making clear which weather event would cause which level of damage to the important land bridge. This way, officials could have a clearer vision of what needs to be done and what risks will be prevented.
Coastline Protection Companies
1. Hohonu
Hohonu is an American company providing real-time nationwide monitoring of water levels.
This includes tidal levels, road flooding detection, flood reporting, and analysis.
The system relies on ultra-low power consumption sensors powered by small solar panels, usually installed on docks and pier of harbors.
Water levels are measured either with radar or ultrasonic sensors. Water quality can also be monitored, including temperature, dissolved oxygen, chlorophyll, etc. It sends back data either through a cell network or satellite, refreshing the measurement every 6 minutes.
Hohonu currently has 120 locations across 15 US states and growing, already working with the city of Boston, Annapolis (Maryland), Hilton Head Island (South Carolina), and Palm Beach County (Florida).
Source: Hohonu
The data are integrated into a dedicated app working in iOS.
The National Weather Service uses the company’s API’s to validate model outputs for storm surge events, making it a key partner to prevent damage during floodings, including from hurricanes.
This data-centric approach to disaster management could benefit from integrating into their system and app models like the one developed by the Texas researchers, combining real-time water measurement with 3D models predicting potential damage and areas at risk.
2. Reefy
Healthy marine ecosystems are often key in buffering the effects of extreme weather events. For example, it is well known that mangrove forests are a key factor in avoiding land erosions from storms in tropical areas, including in Florida.
Another ecosystem that can break waves and increase biodiversity all at once is coral reefs.
The company Reefy builds concrete blocks that lock on each other to build breakwater barriers, limiting the impact of waves on the coastline.
Source: Reefy
What makes the Reefy breakwater system unique is that it doubles as a natural habitat replicating the effect of natural coral reefs.
Over time, the concrete gets replaced by living coral. So this not only reduces flooding and waves but also retains sediments (limiting erosion) and becomes a self-sustaining barrier boosting sea life biodiversity.
Source: Reefy
A key part of Reefy’s technology is combining 2 different types of blocks.
The first one is ReefBlock, which has a modular and hydrodynamic design. Specific surface roughness and texture provide the substrate on which corals or oysters can start growing.
The second one is the Eco-block, which can be configured to provide the right habitat for specific species. This includes the whole block (macro level) as well as tunnels and caves (micro level).
Eco-block can be used to pre-seed coral reef-building species right into the breakwater structure built with ReefBlock, speeding up the process of turning the artificial reef into self-sustaining.
Source: Reefy
This system can limit the consequences of floods. It can also boost tourism by improving the marine ecosystem and providing a site that will be a prime destination for divers once it is fully mature.
The system can also be used for offshore installations like foundations of wind turbines or to protect cables, while delivering ecological benefits at the same time.