News Detail
New data adds dimension to water picture
12/21/2009 10:23:16 AM
By Sandra Hansen, The Scottsbluff Star-Herald
A lot of research has been done on how much water is consumed by invasive species such as Russian olive and saltcedar along the North Platte River. Most of that work was done in the Southwest, especially New Mexico. New information regarding this region, gathered with updated technology, has given researchers a new look at what transpires in these riparian areas.
According to Dr. Gary Hergert at the University of Nebraska Panhandle Research and Extension Center at Scottsbluff, all of the earlier data was collected from test plots with a lot of control factors. He said this situation is different because it was not regulated, but collected from actual environments.
Hergert said the new information is another tool in managing water. It can be used with earlier work to add detail on density, crops and other factors that could impact study results.
Gary Stone, Extension educator at the Panhandle Center, said he is excited about the results. Earlier information came from the southwest, and this new technology is an opportunity to study higher altitudes.
"We wanted to bring good science, the best we could get," Hergert said Wednesday morning. "Anything you can do to save water is good."
Stone said he got interested in the project and contacted Dr. Alyse Irmak at the University in Lincoln, and the new method developed from there. She was the one who devised the means to incorporate the various data sources into one single application.
Hergert said it is all about changing water management for the better. An acre of corn in July will use a similar amount of water as an acre of Russian olive or saltcedar in July, Hergert said. "There are no exact numbers because plants are as different as people," Hergert said. "There are large and small, old and young. Each situation is different, but this gives us a more realistic look at what the ultimate water savings might be.
Previous research has indicated that a mature salt cedar plant can use up to 200 gallons of water per day, and a Russian olive tree about 150 gallons. There are 325,829 gallons in one acre-foot.
During a recent seminar at the University of Nebraska Panhandle Research and Extension Center, the latest information on the water use of these invasive species was presented in a program by Extension Educator Gary Stone.
Dr. Gary Hergert, agronomy; extension educator Gary Stone; and Dr. Robert "Bob" Wilson of the UNL Panhandle Research and Extension Center at Scottsbluff, have been involved from the beginning. Wilson's work on mapping the extent of the invasives was one of the key elements of the current study. Information gained from his research has been combined with work done by Ayse Irmak, assistant professor of the School of Natural Resources and Civil Engineering, Center for Advanced Land Management Information Technologies (CALMIT). University of Nebraska--Lincoln (UNL). Donald Rendquist, and Sunil Narumalani, professors UNL, were co-investigators with Irmak.
The goal of the project was to estimate riparian evapotranspiration (ET) by utilizing satellite and air-borne remote sensing data on major watersheds in the North Platte River. Daily and seasonal distributions of ET over riparian systems at selected watersheds along the basin were to be quantified. Water use and water availablility on riparian species by utilizing ET maps with existing air-borne based riparian species were compared.
Information was also gleaned from Landsat Satellite Images. The various sets of data were overlayed and analized by Dr. Irmak and the others. The ET data was taken from May 1 to Sept. 1, 2005, or 123 days. The project covered the North Platte between the Wyoming/Nebraska state line and Lake McConaughy. Russian olive infested 3,653 acres of the total acres mapped. Salt Cedar covered 4,855 acres, and the thistle complex infested 4,927 acres.
It was determined that seasonal ET for Russian olive for that time period averaged 26.7 inches or 2.23 acre-feet of water. The seasonal Salt Cedar ET for that time averaged 26.8 inches or 2.23 acre-feet. The average for the thistle complex in that time was 27.9 inches or 2.23 acre-feet. The thistle complex, plus reed canary grass for that time averaged 28.8 inches or 2.40 acre-feet.
The study shows that the total of 30,453 acre-feet of water equals that required for 13,410 acres of corn (27.25 inches). That same amount of water would produce 11,420 acres of alfalfa (32 inches. Both figures are at 100 percent recovery of the water formerly consumed by the invasive species. That same amount of water would provide enough for more than 66 million people, at 150 gallons per person per day. It would be enough for Nebraska domestic use for 36 days for 1.8 millioin people. However, even with the iradication of the plants, 100 percent recovery would not be achieved.
Researchers emphasize that 100 percent of the water would not be recovered, and unless otherwise enhanced, the terrain would be filled in by nature with other plant species.
