Climate and ephemeral-stream processes: Twentieth-century geomorphology and alluvial stratigraphy of the Little Colorado River, Arizona

Hereford, Richard

doi:10.1130/0016-7606(1984)95<654:caeptg>2.0.co;2

Cited by 160 publications

(130 citation statements)

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“…He stated that the effects of active degradation were unmistakable and that the geomorphic problem was one of erosion. This opinion was upheld by Hereford (1984), who also concluded that erosion was the dominant geomorphic process affecting the morphology of the river channel until the late 1940s or early 1950s. Flows of high magnitude and prolonged duration are known to produce drastic channel widening in semiarid rivers (Huckleberry, 1994).…”

Section: Channel Response To Flow Eventsmentioning

confidence: 95%

“…10). Hereford (1984) did not interpret vegetation as the driver of channel contraction on the Little Colorado River, although he noted the coincidence of channel narrowing with the spread of tamarisk. Other researchers of contracting dryland ephemeral streams have likewise concluded that channel narrowing was not initiated by the arrival of tamarisk (for example, Everitt, 1998;Cadol and others, 2011).…”

Section: Vegetation and Channel Morphologymentioning

confidence: 99%

“…Hydrologic changes also affect the establishment of riparian species because plant distributions and successions are mainly controlled by flow magnitude and frequency (Everitt, 1995;Hupp and Osterkamp, 1996;Camporeale and Ridolfi, 2006). Hereford (1984) considered tamarisk germination to be a response to a reduction in discharge and flood frequency. The spread of woody vegetation may be opportunistic, responding to and interacting with other changes in the fluvial environment, including hydrologic and morphologic changes.…”

Section: Vegetation and Channel Morphologymentioning

confidence: 99%

“…Hack further suggested that the "epicycles of erosion" were regionally contemporaneous. Hereford (1984) analyzed the influence of climate on the geomorphology and alluvial stratigraphy of the Little Colorado River in narrow bedrock-canyon reaches from Tolchico to Cameron. A time-stratigraphic analysis showed synchronous deposition throughout his study area, which supports, as Hack (1942) posited, regional climatic control over sedimentation.…”

Section: Vegetationmentioning

confidence: 99%

“…Other researchers of contracting dryland ephemeral streams have likewise concluded that channel narrowing was not initiated by the arrival of tamarisk (for example, Everitt, 1998;Cadol and others, 2011). Hereford (1984) attributed 20 th -century channel narrowing of the Little Colorado River to hydrologic changes due to climate. Because of these changes, the width of channel is reduced, and therefore its flow capacity decreases.…”

Section: Vegetation and Channel Morphologymentioning

confidence: 99%

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Historical channel-planform change of the Little Colorado River near Winslow, Arizona

Block¹

2014

Scientific Investigations Report

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For more information on the USGS-the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment-visit http://www.usgs.gov or call 1-888-ASK-USGS For an overview of USGS information products, including maps, imagery, and publications, visit http://www.usgs.gov/pubprodTo order this and other USGS information products, visit http://store.usgs.gov Suggested citation: Block, Debra, 2014, Historical channel-planform change of the Little Colorado River near Winslow, Arizona: U.S. Geological Survey Scientific Investigations Report 2014-5112, 24 p., 2 plates, http://dx.doi.org/10.3133/ sir20145112. ISSN 2328-0328 (online) Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner. iii AcknowledgmentsThis study was conducted with the permission of the Navajo Nation Department of Minerals, the Navajo Nation Water Management Branch, and the Leupp and Birdsprings Chapters of the Navajo Nation. Access to the Winslow levee was granted by Trent Larson of Navajo County. The staff of Homolovi State Park graciously allowed access to the river channel adjacent to the park. Tammy Rittenour of the Utah State University's Luminescence Laboratory analyzed the optically stimulated luminescence signals from late Pleistocene terraces adjacent to the study area ( fig. 1) AbstractThis study evaluates channel-planform adjustment on an alluvial reach of the Little Colorado River and documents the geomorphic evolution of the channel through an analysis of aerial photographs and orthophotographs for the period 1936-2010. The Little Colorado River has adjusted to the effects of an extreme flood in 1923 and a subsequent decline in peak discharge and mean annual flow by channel narrowing: the channel width and area of the river have decreased by approximately 90 percent over the study period. Although deposition historically exceeds erosion, lateral migration exacerbates localized erosion, particularly near hydraulic controls. Despite repeated cutoff and avulsion, the Little Colorado River has steadily increased in length and sinuosity over a period of 74 years.Changes in temperature and precipitation are likely affecting the discharge of the Little Colorado River near and downstream of Winslow, Ariz. Nonparametric methods of trend detection determine whether the probability distribution of temperature, precipitation, and peak streamflow has changed over time. Time-series plots of temperature and precipitation show statistically significant trends at the 99-percent-confidence level when evaluated with a Mann-Kendall test. An increasing trend was indicated in mean daily minimum air temperature (T min ), whereas decreasing trends were indicated in both annual precipitation (P ann ) and monsoon-season...

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Section: Channel Response To Flow Eventsmentioning

confidence: 95%

Section: Vegetation and Channel Morphologymentioning

confidence: 99%

Section: Vegetation and Channel Morphologymentioning

confidence: 99%

Section: Vegetationmentioning

confidence: 99%

Section: Vegetation and Channel Morphologymentioning

confidence: 99%

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Historical channel-planform change of the Little Colorado River near Winslow, Arizona

Block¹

2014

Scientific Investigations Report

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Influence of the Linkage between Leaving Group and Nucleoside on Substrate Efficiency for Incorporation in DNA Catalyzed by Reverse Transcriptase

Giraut

Herdewijn

2010

ChemBioChem

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An amino acid deoxyadenosine phosphoramidate and the corresponding phosphodiester congener have been synthesized and tested for primer extension by HIV-1 reverse transcriptase. Replacement of the phosphoramidate linkage of L-histidine-dAMP by a phosphodiester linkage was found to have a beneficial influence on the affinity of this substrate towards HIV-1 reverse transcriptase and on the velocity of the nucleotide incorporation reaction. Modifications of the nature of the P--X bond can be useful to fine-tune the substrate properties of nucleoside triphosphate analogues. Our results also demonstrate that polymerization pausing observed during the incorporation of leaving group modified dNTPs is not caused by the nature of the linkage.

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Long‐term cottonwood establishment along the Green River, Utah, USA

Scott

Miller

2017

Ecohydrology

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Cottonwood (Populus spp.) riparian forest and woodlands provide valuable ecological goods and services, especially in arid and semiarid regions of North America. Successful establishment and survival for cottonwoods requires bare, moist alluvium that is relatively safe from fluvial disturbance. These are restrictive requirements in dry regions. Cottonwoods can survive for three to four centuries and thus may provide a long‐term record of specific fluvial and geomorphic events. We used C14 analysis and ring counts of cottonwood stems to document a long‐term record of cottonwood establishment. We related this record to the century‐long gage record at Green River, Utah along with historical photos and paleoflood records. Radiometric carbon dating and ring counts suggest some cottonwood stems established on high alluvial deposits following large floods as early as the late 1600s through the late 1800s. Cottonwoods also established on inset floodplain surfaces following sustained decreases in peak flows resulting from climatic drought and the closing of Flaming Gorge Dam. Finally, establishment occurred on both higher post‐dam flood deposits as well as low, active channel surfaces following floods and during a series of low flow years. With continued peak‐flow reduction, cottonwood recruitment will likely be restricted to spatially limited, lower elevation surfaces and subjected to competition from an array of herbaceous and woody riparian species.

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Climate and ephemeral-stream processes: Twentieth-century geomorphology and alluvial stratigraphy of the Little Colorado River, Arizona

Cited by 160 publications

References 0 publications

Historical channel-planform change of the Little Colorado River near Winslow, Arizona

Historical channel-planform change of the Little Colorado River near Winslow, Arizona

Influence of the Linkage between Leaving Group and Nucleoside on Substrate Efficiency for Incorporation in DNA Catalyzed by Reverse Transcriptase

Long‐term cottonwood establishment along the Green River, Utah, USA

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