The Rio Puerco arroyo, located in north-central New Mexico, has been the source of high sediment loads entering the middle Rio Grande since the mid-1800s. In the early 1900s, sediment delivered from the Rio Puerco led to aggradation of the channel bed in the Rio Grande valley and exacerbated flooding issues. Saltcedar (Tamarix spp.) was introduced to the arroyo in the 1920s to stabilize the arroyo bottom, reduce wall erosion, and reduce sediment loads transported into the Rio Grande. As in many riparian systems of the West, the tamarisk became invasive, supplanting native vegetation, and is now the target of eradication efforts. In September 2003, a 12-km reach of the lower Rio Puerco arroyo was sprayed with herbicide by aircraft for the purpose of saltcedar control. A large flood in August 2006 caused extensive erosion in the sprayed reach, but not in an untreated reach downstream, suggesting the tamarisk serves as an effective erosion control. USGS scientists are quantifing the efficacy of invasive tamarisk in reducing sediment loads in the Rio Puerco using remotely sensed data to understand potential trade-offs associated with invasive weed management.
USGS scientists previously documented volumes of sediment erosion and deposition within the arroyo during and after the 2006 flood using aerial lidar survey data from 2005 and 2010 to supplement mapping from historical aerial photographs, satellite imagery (2006), and data from high-precision (Real Time Kinematic) GPS surveys (2002, 2007, and 2010). A second, much larger flood occurred in September 2013, and field observations suggest that this flood also caused substantial geomorphic change. Satellite imagery made available under the National Geospatial-Intelligence Agency’s NextView License agreement includes images of the lower Rio Puerco arroyo acquired shortly after the 2013 flood. Archived high-resolution (0.5-m ground sample distance), pan-sharpened natural color imagery acquired by the WorldView-2 satellite in January 2014 were obtained through DigitalGlobe’s EnhancedView Web Hosting Service (https://evwhs.digitalglobe.com/). Using this imagery, scientists can map geomorphic change over large areas and assess whether vegetation control efforts in 2003 continue to cause increased erosion in the sprayed reach compared to the untreated reach downstream.
http://dx.doi.org/10.1007/s00267-009-9314-8 (Vincent et al., 2009)
http://dx.doi.org/10.1016/j.geomorph.2013.10.025 (Griffin et al., 2014)
http://dx.doi.org/10.1130/B31046.1 (Friedman et al., 2015)
Rio Puerco arroyo wall locations mapped from 2005 imagery (red dashed line) and a 2010 lidar DTM (light blue line) overlaid on a WorldView-2 image acquired shortly after the September 2013 flood, on January 5, 2014 (DigitalGlobe, Inc.). The New Mexico Highway 6 crossing was the downstream limit of the sprayed reach. The northern limit of the untreated reach used for comparison of flood effects is the AT&SF Railway bridge. The red arrow points to a location where valley-fill sediment in the 10.6-m-high arroyo wall eroded another 13 m south toward the highway between March 2010 and January 2014.