A research team from the Institute of Industrial Science, The University of Tokyo has conducted a detailed analysis of the uncertainties associated with flood risk modeling at the global scale. They found large uncertainties were mainly associated with runoff data.

Flood magnitude is large in wet regions, but uncertainties in flood depth is larger in dry and mountainous regions affected by rare, extreme floods. The results of the study can be used to identify the key areas for improvement in hydrological modeling and improve future predictions of flood risk.

Assessment of the risk of rare and extreme floods is essential for disaster management and recovery planning at international, national, and regional levels. However, the accurate assessment of flood risk is limited by the number of observations possible, and relies on hydrological modeling which has limited performance.

Theoretical flood hazard maps, which are relied on by governments, regional planners, insurance services, and other stakeholders, are an important part of understanding the potential extent of flood risk. However, they are subject to high levels of uncertainty, especially at the large scale.

"The main problem is that the creation of accurate flood hazard maps relies on excellent flood frequency analysis," explains study co-author Dr. Wenchao Ma, "and the main limitation of that is its reliance on assumptions about the underlying distribution of flood events, which is hugely variable among different regions of the world. There is no single solution that can be applied everywhere."

The research team found that uncertainties in runoff inputs contributed more than 80% of the total uncertainty. Overall uncertainties were highest in Africa, but exposure risk was greatest in Asia. "We found that land susceptible to rare floods - called 1-in-100-year floods - accounts for 9.1% of the global area, excluding Antarctica," says study lead author Dr. Xudong Zhou. "In addition, the numbers show 13.4% of the population may be exposed to such a flood event, with a potential economic impact of up to 14.9 trillion US dollars to global GDP."

More adjustments are needed to flood hazard maps to ensure their accuracy. Further data are needed to take into account the efforts made by flood defenses and dam regulations and to improve inputs for areas with large uncertainties, such as Africa. Such improvements would reduce these uncertainties and improve these resources for use under future climatic conditions.

Research Report: "The uncertainty of flood frequency analyses in hydrodynamic model simulations"

Related Links
Institute Of Industrial Science, The University Of Tokyo
Bringing Order To A World Of Disasters
When the Earth Quakes
A world of storm and tempest

Tweet

Thanks for being here; We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain. With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords. Our news coverage takes time and effort to publish 365 days a year. If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor $5 Billed Once credit card or paypal		SpaceDaily Monthly Supporter $5 Billed Monthly paypal only

Australia begins 'long haul' to recovery as floodwaters recede
Londonderry, Australia (AFP) March 25, 2021
Thousands of flood-stricken residents along Australia's east coast began a massive clean up effort Thursday, as waters receded revealing damaged homes, piles of debris and mud-caked roads. The region has been devastated by widespread flooding brought on by a torrential downpour, inundating towns, destroying farmland and leaving two people dead. On Thursday, David Williams stepped back inside his home in flood-hit Londonderry, to find waters lapping just below his knees and "gut-wrenching" destru ... read more