When water is coming from all sides
Date:
January 13, 2022
Source:
University of Texas at Austin, Texas Advanced Computing Center
Summary:
Researchers have developed the first three-dimensional operational
storm surge model. The model simulates compound surge and flooding -
- especially hard in transition zones where the river meets the sea.
Since April 2021, NOAA has run daily 2D and 3D compound flood models
on the Frontera supercomputer. During Tropical Storm Claudette
(June 2021), the three-dimensional, real-time storm surge model
closely matched observations across the Gulf Coast.
FULL STORY ==========================================================================
When Hurricanes Harvey (2017) and Florence (2018) hit, it was not solely
the storm surge from the Gulf of Mexico and Atlantic Ocean that led
to flooding.
Inland sources, like rain-swollen rivers, lakes, and suburban culverts
also contributed significantly. These factors were missed by many computer models at the time, which underestimated the flood risk.
========================================================================== "People don't care as much as to whether flooding is coming from the
river or the ocean, especially when both contribute to water levels,
as they want to know, 'Is my house going to be flooded?'" said Edward
Myers, branch chief of the Coastal Marine Modeling Branch, located in
the Coast Survey Development Laboratory at the National Oceanographic
and Atmospheric Administration (NOAA).
Myers and his colleagues at NOAA are collaborating with Y. Joseph Zhang
from the Virginia Institute of Marine Science (VIMS) at William & Mary
to develop and test the world's first three-dimensional operational
storm surge model.
"We started with the right attitude and the right core algorithm,"
joked Zhang, research professor at the Center for Coastal Resources
Management. "Over the years, we've re-engineered the dynamic core multiple times and that led to the current modeling system." Now in its third incarnation, the Semi-implicit Cross-scale Hydroscience Integrated System
Model (SCHISM) forecasts coastal flooding in Taiwan, at agencies across
the European Union, and elsewhere. It is being considered for operational
use by NOAA. (The researchers described the system in the Nov. 2021 issue
of EOS, the science news magazine of the American Geophysical Union.)
SCHISM is designed to serve the needs of a wide range of potential users.
"Compound surge and flooding is a world-wide hazard," Zhang said. "It's notoriously challenging, especially in the transition zone where the river meets the sea. Lots of factors come into play and interact non-linearly." Surrounding the hydrodynamic core of SCHISM are numerous modules that
simulate other phenomena important to flooding. These include air-sea
exchange, vegetation, and sediment. Other modules adapt the system
for specific events, like oil spills, or to predict conditions, like
water quality.
========================================================================== Unlike other coupled inland-coastal flooding models, SCHISM incorporates
very fine scale features, like engineered structures, culverts, and
narrow gates, into its forecasts.
"We see the SCHISM model as a candidate for what we want to do in terms of linking models," Myers said. "It handles very fine scales very well, and
we can run it efficiently. Of course, it still requires high performance computing, which is why the Texas Advanced Computing Center [TACC] has
been instrumental." Zhang started using TACC systems in 2010. "Since
then, TACC's HPC resources and facilities have greatly improved. The
size of the problem we can tackle has dramatically improved. We've gotten
into uncharted territory," Zhang said.
"TACC has been continuously pushing the limits." VERIFYING THE MODEL To confirm the accuracy of SCHISM, Zhang has been focusing on hindcasts --
a way of testing a mathematical model by inputting estimates from past
events and seeing how well the model output matches the known results.
========================================================================== Writing in Natural Hazards and Earth System Sciences in June 2021,
Zhang, Myers, and their collaborators described a study of compound
flooding during Hurricane Florence that impacted a large swath of North Carolina in September 2018. The study found that barrier islands played
an important role in compound surges.
"Barrier islands somehow can amplify or dampen surge, depending on
what direction the surge is coming from," Zhang said. They also found
that the wave effects are significant near the barrier islands and have contributed to some observed over-toppings and breaches.
Applying each of the three major forcing factors -- oceanic, fluvial
(from rivers), and pluvial (from surface flooding) -- separately, they
were able to produce a "dominance map" that shows which factors are most important for a specific site. The map clearly demonstrated significant compound effects in most of the affected coastal watersheds, estuaries,
and back bays behind the barrier islands.
The model's ability to resolve small-scale features in some watershed
areas turned out to be critical for capturing the observed high-water
marks locally.
The research was enabled by William & Mary Research Computing, the Extreme Science and Engineering Discovery Environment (XSEDE), which allocated
time on TACC's Stampede2 system, and the NASA High-End Computing (HEC)
program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center.
REAL-TIME FLOOD FORECASTING The NOAA and VIMS team started their
interaction with TACC after NOAA Storm Surge Modeling Team lead Saeed
Moghimi connected with individuals from DesignSafe, an NSF program
for natural hazards, that relies on advanced computing capabilities at
TACC. The center initially provided a small allocation to develop and
test the first SCHISM prototype on TACC systems.
That relationship quickly blossomed. Since April 2021, NOAA has run
daily 2D and 3D compound flood models for the East and Gulf Coasts on
Frontera, the fastest academic supercomputer in the world and the 13th
fastest overall.
Early indications suggest the Inland-Coastal Flooding Operational Guidance System is working well. During Tropical Storm Claudette (June 2021), the researchers compared water level results between the three-dimensional operational storm surge model and NOAA's current model.
"We were quite pleased with the results," Zhang said. "They corroborated
with inundation observations at Shoreline Park, Mississippi, and in
Slidell, Louisiana, and the forecasts were all done in real-time."
Myers concurred. "We're really impressed with how the model is
performing in terms of its accuracy, computational efficiency, and
robustness. For NOAA to put a model into operations, it needs to
be very reliable. SCHISM has shown itself to be extremely robust."
"Having this test going a full year to make sure everything is
going well is hugely important," said Moghimi. "Even if we put this
version of the system into production, having a shadow application
of what we have at NOAA would be extremely valuable and provide
an opportunity for agile upgrading of the system in the future." ========================================================================== Story Source: Materials provided by University_of_Texas_at_Austin,_Texas_Advanced_Computing Center. Original written by Aaron Dubrow. Note: Content may be edited for style and length.
========================================================================== Journal Reference:
1. Fei Ye, Wei Huang, Yinglong J. Zhang, Saeed Moghimi, Edward Myers,
Shachak Pe'eri, Hao-Cheng Yu. A cross-scale study for
compound flooding processes during Hurricane Florence. Natural
Hazards and Earth System Sciences, 2021; 21 (6): 1703 DOI:
10.5194/nhess-21-1703-2021 ==========================================================================
Link to news story:
https://www.sciencedaily.com/releases/2022/01/220113111436.htm
--- up 5 weeks, 5 days, 7 hours, 13 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)