Devastating flooding, such as Iowa's Flood of 2008, motivated a team of researchers from the University of Iowa and Iowa Flood Center to analyze a hydrologic model with the potential to predict the extent of flooding based on predicted rain patterns
Devastating floodwaters such as those experienced during Iowa's Flood of 2008 -- which swamped many Iowa communities, along with ten square miles of Cedar Rapids -- are notoriously difficult to predict.
So a team of University of Iowa mathematicians and hydrologists collaborating with the Iowa Flood Center set out to gain a better understanding of flood genesis and the factors impacting it. They were able to do this by zeroing in on the impacts of certain rainfall patterns at the smallest unit of a river basin: the hillslope scale.
This week in the journal Chaos, from AIP Publishing, the team describes how they analyzed the nonlinear dynamics of a recently proposed hydrological model at the hillslope-scale under fluctuating precipitation. The study appears as one of a special collection of related articles in the March issue of the journal, which is focused on "Nonlinear Dynamics for Planet Earth." See http://tinyurl.com/kl28r53
The proposed hydrological model that is the subject of the new study "describes a mass balance among volumes of water at the hillslope scale," said Rodica Curtu, an associate professor in the Department of Mathematics at the University of Iowa, working on the project with Morgan Fonley, a graduate student. "Some of these volumes are easily observed, such as ponded water and streamflow, while others such as water in unsaturated areas and saturated zones of soil are more difficult to observe."
When this model is brought to equilibrium, it exhibits a natural tendency to amplify some oscillations but dampen others. "The deciding factor about this behavior is the frequency at which the oscillations are applied to the model via precipitation patterns," she pointed out.
If the hillslope system "experiences a certain frequency of rainfall, the soil becomes the least likely to take in water -- and instead puts it all in the nearest river so the streamflow exhibits large spikes of water," Curtu said. The mathematics involved tap into methods from the theory of nonlinear dynamical systems.
The key significance of this work? Mechanistic description and mathematical investigation of physical processes "can be more enlightening than model calibration, when studying nonlinear phenomena," Curtu said. This is because, she explained, mechanistic, physics-based equations “may not only simulate processes under investigation, but also uncover some of their underlying properties."
"In this case, by using physical parameters to describe a realistic hillslope, we found a pattern of precipitation that yields the greatest -- most amplified -- runoff coefficient, which determines the manner and how fast water will reach the river link."
The team's research sets up a framework by which future hillslope-soil models can be analyzed to predict the worst possible rain pattern that could lead the hillslope to flood, Curtu noted. This can be used to predict the extent of flooding possibilities based on predicted rain patterns.
Next up, the researchers will consider the effects of these streamflow oscillations once they reach the river network. Because the oscillations are occurring separately at each river link, "streamflows interact in ways that can amplify or destroy the oscillations as they combine in the river network," said Curtu.
Since this is a framework for soil models, Curtu and colleagues offer further improvements to the soil model to create a more accurate representation of water in the soil. "Using this framework, we can potentially find other factors that impact the extent of flooding both at the small hillslope scale and at the larger river catchment scale," she added. "Our work will continue in this direction with our Iowa Flood Center collaborators -- Witold Krajewski, Ricardo Mantilla and Scott Small."
The article, "Nonlinear response in runoff magnitude to fluctuating rain patterns," by Rodica Curtu and Morgan Fonley will be published in the journal CHAOS on March 10, 2015 (DOI: 10.1063/1.4913758). After that date it can be accessed at: http://scitation.aip.org/content/aip/journal/chaos/25/3/10.1063/1.4913758
This work received funding from the National Science Foundation (Award Number DMS-1025483).
ABOUT THE JOURNAL
Chaos: An Interdisciplinary Journal of Nonlinear Science is devoted to increasing the understanding of nonlinear phenomena and describing the manifestations in a manner comprehensible to researchers from a broad spectrum of disciplines. See: http://chaos.aip.org
Jason Socrates Bardi, AIP
Jason Socrates Bardi, AIP | newswise
Ice cave in Transylvania yields window into region's past
28.04.2017 | National Science Foundation
Citizen science campaign to aid disaster response
28.04.2017 | International Institute for Applied Systems Analysis (IIASA)
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
28.04.2017 | Event News
20.04.2017 | Event News
18.04.2017 | Event News
28.04.2017 | Medical Engineering
28.04.2017 | Earth Sciences
28.04.2017 | Life Sciences