To better predict long-term flooding risk, scientists at the Department of Energy's Oak Ridge National Laboratory developed a 3D modeling framework that captures the complex dynamics of water as it flows across the landscape. The framework seeks to provide valuable insights into which communities are most vulnerable as the climate changes, and was developed for a project that's assessing climate risk and mitigation pathways for an urban area along the Southeast Texas coast.
The modeling framework offers a powerful tool for urban planning by providing robust estimates of both frequent and rare flood events. By modeling the physical processes that transform rainfall into runoff, the framework accounts for factors such as land cover, soil properties and slope of the land.
These elements, incorporated alongside population density data, provide a unique perspective on flood risk across vast areas such as river basins. This comprehensive approach is detailed in a study published in the Journal of Hydrology.
"This new state-of-the-art model not only estimates the streamflow magnitude of rare events such as a 100-year flood, but it also quantifies its associated flood depth, allowing us to assess the impact on the population directly," said Gabriel Perez, who co-led the work as a postdoctoral researcher in ORNL's Watershed Systems Modeling group, and is currently an associate professor at Oklahoma State University.
"That's a very unique framework, that can help us better understand how flood risk is evolving due to climate change and urbanization." In developing such a model, "it becomes much more important to rely on the underlying physics of flooding because those are true throughout time, as opposed to a model that's calibrated under today's conditions and might not be right in tomorrow's climate or tomorrow's cities," said Ethan Coon, project co-lead, senior R&D staff, and principal investigator for ORNL's research for the Southeast Texas Urban IFL.
The new framework incorporates the Amanzi-ATS software, an integrated surface-subsurface hydrological model developed by ORNL, Los Alamos National Laboratory, Lawrence Berkeley National Laboratory and Pacific Northwest National Laboratory. Amanzi-ATS provides a holistic view of hydrological systems.It captures subsurface flows, considering complex geology and soil properties, and accounts for unique topography, including the representation of water infrastructure and disturbances such as changes in land use by accelerated urbanization. Results may identify new flood-prone areas, specifically pinpointing risks for area populations.
"We're able to replicate a wide range of observations, including streamflow, vegetation effects, soil moisture content and even groundwater changes. These initial results boost our confidence in capturing flood processes and enhance our ability to quantify flood changes over the coming decades. This approach is crucial to meeting the mission of the Urban IFLs," Perez said.
"What's different here is that we're not just analyzing precipitation," Coon said. "We're computing stream flows, but we're also computing inundated areas and tying that to population data so we understand what these events mean for people on the ground."
"Models calibrated mostly on precipitation have a goal of predicting conditions in the next 30 days, and that is very useful for short-term flood planning," Coon added. "But for our longer horizon, it's important to lean on physics-based models. You don't want to make a 10- or 20-year plan based on today's events and infrastructure. You need different statistics and an idea of what conditions will be in the decades ahead."
Next, the scientists will apply the new modeling capability to a larger section of the Beaumont-Port Arthur region. One of their objectives is to simulate flood responses that reflect various future climate projections and land use changes. Among the challenges will be modeling compound flooding, an event in which multiple hazards interact, from coastal storm surges to river flooding, simulating the influence of precipitation on impervious surfaces in urban corridors and how water infrastructure interacts with flood events.
Sources:
PHYS.ORG
https://phys.org/news/2024-07-scientists-human-element-term.html .
Provided by the IKCEST Disaster Risk Reduction Knowledge Service System
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