Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


'Just Right' Plant Growth May Make River Deltas Resilient


Research by Indiana University geologists suggests that an intermediate amount of vegetation -- not too little and not too much -- is most effective at stabilizing freshwater river deltas.

The study, "Optimum vegetation height and density for inorganic sedimentation in deltaic marshes," was published online Aug. 24 by Nature Geoscience. The findings may help guide restoration of river deltas, such as those near the mouth of the Mississippi River, which are under threat as sea levels rise.

Elizabeth Olliver, Indiana University

This image shows freshwater marsh vegetation in Wax Lake Delta, La. Aquatic vegetation on low-elevation marshes is pictured in the foreground, while woody vegetation occupies a levee on the left. The open water in the distance is a deltaic distributary channel.

Authors are William Nardin, a postdoctoral fellow in the Department of Geological Sciences in the IU Bloomington College of Arts and Sciences; and Douglas A. Edmonds, who holds the Robert R. Shrock Professorship in Sedimentary Geology and is an assistant professor of geological sciences.

Vegetation on marsh surfaces in river deltas can slow the flow of water and cause more sediment to be deposited, helping prevent sea-level rise from drowning sensitive marshlands. But the study finds that, if the vegetation is too tall or dense, it diverts water into the river channel, resulting in less sediment being deposited on the marsh.

“In river deltas the effect of vegetation on sedimentation seems to follow the Goldilocks principle,” Edmonds said. “You want the amount of vegetation that is just right -- not too much, but also not too little.”

The world’s river deltas are rich and productive and are home to about 10 percent of the world’s population. But they are threatened by an array of forces, including population growth, pollution, development and erosion, as well as sea-level rise associated with climate change.

Edmonds wrote in a 2012 Nature Geoscience article that river deltas can be restored, but it will take a better understanding of the processes involved in their formation and destruction. The current study suggests vegetation could play a role in designing effective river delta restoration.

In tidal saltwater marshes, research has shown that vegetation enhances sedimentation. But scientists know less about how vegetation affects sedimentation in freshwater marshes that are common in river deltas. Nardin and Edmonds used sophisticated computer modeling to study how marsh vegetation influences the transport and deposition of sediment in river deltas. They conducted 75 simulations involving varying scenarios of vegetation height and density and rates of water flow.

They found that vegetation of intermediate height and density results in the greatest deposition of sand and mud. However, if the plants are too tall or densely packed, sediment tends to remain in the river channel, bypassing marshes and being carried directly to the sea.

The researchers also analyzed remote-sensing data collected from Wax Lake Delta in Louisiana. The analysis showed the delta exhibits a hydrodynamic response to the presence of vegetation that corresponds with what the researchers found with their model.

The rate at which sediment is delivered to marshes in river deltas is strongly influenced by storms and flooding, as well as the construction of engineered diversions. The research suggests the resilience of river deltas will depend on the timing of floods and storms relative to the seasonal growth of vegetation. And of course, scientists can’t control or even predict when floods will occur.

“That unpredictability adds an interesting twist to the problem,” Edmonds said. “The time that the flood wave arrives does not always coincide with the timing of vegetation growth and decay. Those two have to line up just right for vegetation to really enhance deposition of sand and mud.”

Funding for the research came from a National Science Foundation Frontiers in Earth Systems Dynamics grant and from the Alfred P. Sloan Foundation. To speak with Edmonds or Nardin, contact Steve Hinnefeld with IU Communications, 812-856-3488 or

Steve Hinnefeld | newswise
Further information:

Further reports about: Geoscience Nature River construction floods marshes marshlands sedimentation storms

More articles from Earth Sciences:

nachricht Oasis of life in the ice-covered central Arctic
24.10.2016 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung

nachricht Receding glaciers in Bolivia leave communities at risk
20.10.2016 | European Geosciences Union

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Oasis of life in the ice-covered central Arctic

24.10.2016 | Earth Sciences

‘Farming’ bacteria to boost growth in the oceans

24.10.2016 | Life Sciences

Light-driven atomic rotations excite magnetic waves

24.10.2016 | Physics and Astronomy

More VideoLinks >>>