Formation of arroyos in the late 1800s greatly increased erosion across the southwestern United States. Since the 1930s, however, this erosion has decreased, partly because of bank stabilization by introduced saltcedar. With Isleta Pueblo Indian Nation, the Aquatic Systems Branch developed a new sediment dating method using saltcedar tree rings. We applied the method in a landmark study of arroyo filling along the Rio Puerco, New Mexico. We then showed how aerial application of herbicide to control saltcedar accidentally renewed erosion. This erosion may now be amplified by a beetle introduced for saltcedar control.
Below are other science projects associated with this project.
Riparian Ecology
- Overview
Formation of arroyos in the late 1800s greatly increased erosion across the southwestern United States. Since the 1930s, however, this erosion has decreased, partly because of bank stabilization by introduced saltcedar. With Isleta Pueblo Indian Nation, the Aquatic Systems Branch developed a new sediment dating method using saltcedar tree rings. We applied the method in a landmark study of arroyo filling along the Rio Puerco, New Mexico. We then showed how aerial application of herbicide to control saltcedar accidentally renewed erosion. This erosion may now be amplified by a beetle introduced for saltcedar control.
Channel change and saltcedar introduction along the Rio Puerco, NM. Flooding from 1880-1930 caused erosion of an arroyo, an incised channel in fine sediments (clay to sand) over 200 km long, 100 m wide and 10m deep. Channel narrowing and arroyo filling after the 1930s was associated with spread of saltcedar, planted to control erosion in 1926 (Friedman et al. 2015). Public domain.
Erosion of the Rio Puerco arroyo caused siltation downstream in Elephant Butte Reservoir. After arrival of saltcedar, the loss of storage capacity in Elephant Butte Reservoir slowed by about a factor of 5. Removal of saltcedar could accelerate reservoir sedimentation again. Public domain.
Herbicide was applied by helicopter to control saltcedar in a 12-km reach of the Rio Puerco in 2003. A flood in 2006 caused substantial erosion in the spray zone. This photo was taken in October 2006 by Kirk Vincent, USGS. Gray stems left of the channel are dead saltcedar. Public domain.
Extreme erosion occurred in the herbicide spray zone, but not upstream or downstream (Vincent et al. 2009, Griffin and Friedman 2016). Public domain.
A beetle introduced to the US to control saltcedar has dispersed to the Middle Rio Grande. This natural-color image by DigitalGlobe, Inc. on July 18, 2016 shows saltcedar defoliated by the beetle (purple) at the confluence of the Rio Puerco and the Rio Grande. If the beetle kills large areas of saltcedar, subsequent floods could accelerate erosion in tributaries, leading to siltation along the Rio Grande and in Elephant Butte Reservoir. Public domain.
Anatomical changes in rings of buried stems can be used to date stratigraphy. Saltcedar stem cross-section cut 2.8 m below the ground surface. Following initial burial of 68 cm in 1969, ring-width decreased, vessel size increased, and annual transitions became less distinct. After a second burial by 41 cm in 1972, annual transitions became indistinguishable. (Friedman and others 2005, 2015). Public domain.
Trench stratigraphy dated using tree rings of buried saltcedar, Rio Puerco near Highway 6, New Mexico (Friedman et al. 2005, 2015) Public domain.
Buried cottonwood along the Rio Puerco, NM. Public domain. - Science
Below are other science projects associated with this project.
Riparian Ecology
Riparian ecologists at the Fort Collins Science Center study interactions among flow, channel change, and vegetation along rivers across the western United States and worldwide. Our work focuses on issues relevant to the management of water and public lands, including dam operation, climate change, invasive species, and ecological restoration. Investigations take place on a range of scales. For... - Publications
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