Flood Prevention: How to Reduce Risks for Your City

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August 11, 2020

5 minute read

Flood prevention is critical to any city’s master planning process. Especially considering the recent wave of heavy rainstorms around the world, bringing to light the grave problem of severe urban flooding.

Not only do torrential rainstorms cause injuries and damage to infrastructure, but they also bring entire cities to a standstill. The repercussions of this—in terms of both finances and sanitation—are humongous.

To put things into perspective, did you know — In 2017 Hurricane Harvey, which is considered as the most significant rainfall in U.S history—cost the economy between $125 and $180 billion USD, making it second most costly storm in the history of the country?

The point — extreme rainfall and flooding are not to be taken lightly.

Good news! There is a way to minimize, if not avoid, the damage caused to a city by flooding after a torrential rainstorm.

Understanding Root Causes of Floods and the Trends/Patterns to Watch Out For

Torrential rainstorms around the world are unlikely to take a breather anytime soon and that should ring warning bells for a lot of cities and towns around the world. The reason we say this is because most urban communities around the world are not planned adequately enough to avoid flooding after heavy rainfall.

As you probably already know, inadequate flood management has multiple root causes such as:

  • Inaccurate or outdated floodplain maps
  • Poor understanding of overland flow paths during heavy rainfall
  • Uncontrollable inflow leading to sewer surcharges

So, what is the solution? For many cities, having an updated and accurate hydrologic and hydraulic model of your system gives you a far better understanding of infrastructure resiliency in the face of intense rainfall events.

Combined with flood forecasting and near-real-time modeling techniques, cities can not only make long term flood risk mitigation plans, but also use operational data to act when flooding is imminent.

One US city did just this when disaster nearly struck.

How an Accurate Flood Model Can Make a Difference in Flood Prevention

The San Antonio River Authority (SARA) leveraged its flood warning system (FWS) built by HDR Engineering, Inc. (HDR) in InfoWorks ICM in the days leading up to Hurricane Harvey to get a predictive overview and prepare a risk mitigation plan for the City of San Antonio should Harvey 's course make its way towards it.

SARA's Wayne Tschirhart, the FWS technical director, analyzed many potential rain events based on the predicted rainfall levels recorded by the Weather Service, so that the city could know what’s coming. The course of the storm shifted and stalled over Houston, failing to make it to San Antonio.

Once Harvey's scale of damage was known it raised the question: Would San Antonio been ready if the hurricane went in a different direction? The San Antonio City Council inquired Steve Graham, SARA’s Executive, if the effects of Hurricane Harvey could be modeled. With this very query, SARA contacted Brandon Hilbrich, PE, Project Manager and Anthony Henry, Senior Modeler at HDR.

The HDR team utilized InfoWorks ICM to perform the analysis, with a four-week deadline to produce concrete results for the downtown area. Working with this baseline, HDR could import operational data from ICMLive, steady state HEC-RAS & HEC-HMS model data, and XPSWMM 1D/2D data to get the model close to the high detail necessary to simulate Harvey.

InfoWorks ICM enabled HDR to model the specific characteristics of the USAR watershed correctly, including underground tunnels utilizing pressure flow conduits and operational control for a dam and two flood gates.

Using the same process, municipalities across the globe can use flood modeling to get a better understanding of flood risks, which in turn can lead to more accurate floodplain maps, flood prevention strategies, and emergency plans. Thus, reduces flood damage/cost, improving safety, and helping cities be more prepared.   

At Innovyze, we offer storm and flood modeling solutions to minimize the impact of torrential rainstorms on cities. Whether it is our InfoWorks ICM or ICMLive, it will generate 2D modeling for the most credible predictive analysis of a potential flood situation, helping you reduce flood damages for your city.

Get in touch with us today to know more about how we can help you.

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Tags: Flood Prevention, InfoWorks ICM, Flood Modeling