Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New technique tracks 'heartbeat' of hundreds of wetlands

17.03.2016

For two University of Washington researchers, the real test came as they walked across a barren-looking field.

They were on the Columbia Plateau with two state wetland ecologists, searching for a 1-acre body of water identified and mapped for the first time using a new method they developed. But when the group arrived at the expected coordinates, map in hand, the soil was dry and cracked and there wasn't a wetland in sight.


This is a wintertime view of wetlands in Douglas County, Washington.

Credit: Meghan Halabisky/University of Washington

Then, one of the ecologists sunk a shovel into the ground, looked at the characteristics of the soil, and put everyone's worries to rest: The wetland was there, all right -- it just happened to be in a dry phase.

"I remember getting goosebumps when I realized our method worked," said L. Monika Moskal, an associate professor in the UW's School of Environmental and Forest Sciences.

This fine-tuned knowledge is the result of a new approach to better understand the hydrology of Eastern Washington's wetlands. Now, researchers have an abundance of data about how these wetlands behave seasonally, which will also help monitor how they change as the climate warms.

"One of the things that makes wetlands so hard to study is their dynamic nature, the patterns of flooding and drying," said Meghan Halabisky, a UW doctoral student in environmental and forest sciences and lead author of a new paper appearing in the May edition of Remote Sensing of Environment.

"That element is also the thing that makes wetlands so fascinating and so unique. They have really high levels of biodiversity and unique species you won't find anywhere else."

In Washington and elsewhere, wetlands hold water on the landscape and help prevent flooding. They also filter and remove sediment and excess nutrients from entering rivers and larger bodies of water like Puget Sound, and they provide an important water source for grazing animals and migrating species.

Across the U.S. and particularly in Washington state, very little is known about the acreage, yearly flooding cycles and even the actual locations of wetlands. Even hazier is what could happen to these vital ecosystems under climate change.

To get at these questions, Halabisky and collaborators used open-access satellite images (through Landsat, a joint effort by the U.S. Geological Survey and NASA) taken every 16 days from 1984 to 2011 in Washington's Douglas County. Though these images are shot with impressive regularity and can show changes over time, the resolution is coarse. One Landsat photo pixel is roughly 30 square meters (100 square feet), making it impossible to see wetlands smaller than that size.

They used high-resolution images from the same region to train a computer algorithm to "see" structural elements of wetlands and delineate them from other parts of the landscape. For example, water absorbs light differently than sagebrush or other plants, giving the water in a wetland a unique, identifiable signature.

"Each material has a unique pattern of absorbing and reflecting light. And based on those unique patterns, we can deconstruct each Landsat pixel and find out how much water, sage steppe and other vegetation is composed within that pixel," Halabisky said.

The researchers applied this method to satellite images taken on about 200 dates over the same areas on the landscape, producing flooding and drying patterns (called hydrographs) for 750 wetlands in Eastern Washington.

"This method is unique because it's essentially taking the pulse of the landscape -- the time-series data (graphs) look like a heartbeat as the water in wetlands fills up, then goes down. We can track this for decades now," said Moskal, senior author on the paper and director of the UW's Remote Sensing and Geospatial Analysis Laboratory.

They also are able to identify wetlands, particularly small ones, that weren't previously on the radar of land managers and other stakeholders who use the semi-arid landscape in Douglas County. The wetlands in this region are an important resource for cattle ranchers, tribes and organizations like Ducks Unlimited.

Researchers with the UW's Climate Impacts Group will use these data in their models to make projections on how individual wetlands in Eastern Washington could behave under climate change. Halabisky, who has worked in the region for years and revisited a number of the same sites, is sometimes surprised by what she sees.

"I think there's an assumption that wetlands in arid regions are just going to dry out. In two of my study areas that wasn't the case at all," she said. "That may change under climate change when we do that modeling."

Halabisky is leading an effort in Douglas County to convene land managers and stakeholders in planning for the future of wetlands as the climate warms. Their first workshop in early March drew upon the new seasonal data available for each wetland in the region.

Little is known about wetlands in Western Washington as well, and the researchers hope to use other remote-sensing techniques such as Lidar to characterize their locations and seasonal patterns. Shadows from tree cover west of the Cascades make it hard to use the method described in this paper.

###

Other co-authors are Alan Gillespie of the UW's Earth and space sciences department and Michael Hannam of the Smithsonian Environmental Research Center in Maryland. Hannam is a recent graduate of UW who worked with Moskal and Kern Ewing, a professor of environmental and forest sciences.

This research was funded by the U.S. Geological Survey, the U.S. Department of the Interior's Northwest Climate Science Center and the UW's Precision Forestry Cooperative.

For more information, contact Halabisky at halabisk@uw.edu and Moskal at lmmoskal@uw.edu or 206-221-1510.

Grant number: GS276A-AUSGS

Related paper: http://www.sciencedirect.com/science/article/pii/S0034425716300682

Media Contact

Michelle Ma
mcma@uw.edu
206-543-2580

 @UW

http://www.washington.edu/news/ 

Michelle Ma | idw - Informationsdienst Wissenschaft

More articles from Earth Sciences:

nachricht New Study Will Help Find the Best Locations for Thermal Power Stations in Iceland
19.01.2017 | University of Gothenburg

nachricht Water - as the underlying driver of the Earth’s carbon cycle
17.01.2017 | Max-Planck-Institut für Biogeochemie

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Helmholtz International Fellow Award for Sarah Amalia Teichmann

20.01.2017 | Awards Funding

An innovative high-performance material: biofibers made from green lacewing silk

20.01.2017 | Materials Sciences

Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery

20.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>