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This study explores how the relationship between flow and riparian vegetation varies along a montane river. We mapped occurrence of woody riparian plant communities along 58 km of the San Miguel River in southwest- ern Colorado. We determined the recurrence interval of inundation for each plant community by combining step-back- water hydraulic modeling at 4 representative reaches with Log-Pearson analysis of 4 stream gaging stations. Finally, we mapped bottomland surficial geology and used a Geographic Information System to overlay the coverages of geology and vegetation. Plant communities were distinctly arrayed along the hydrologic gradient. The Salix exigua Nuttall (sand- bar willow) community occurred mostly...
The impacts of the United States drought of 2007 to both society and ecosystems were substantive and included multi-billion dollar agricultural losses and the second worst wildfire season on record. The purpose of this paper is to place the 2007 drought in historical perspective relative to the climate record from 1895?2007 to increase our understanding of this hazard and contribute to improvements of drought mitigation plans. We compared the 2007 drought historically against the climatic record (1895?2007) using the Palmer Drought Severity Index (PDSI). We then examined the temporal progression of the 2007 drought and placed the peak month of drought severity (November) in historical perspective using rankings...
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The Quaternary Fault and Fold Database contains the results of thousands of scientific assessments of faults and associated folds in the United States that demonstrate geologic evidence for coseismic surface deformation in the Quaternary (the past 1,600,000 years). The Quaternary Fault and Fold Database includes information on the age of the most recent coseismic surface deformation, relative rates of activity, fault geometry, sense of movement, and citations of pertinent literature. Much of the information in the database is based on paleoseismology, which is the geologic study of prehistoric earthquakes. Paleoseismology combines well-established geologic practices such as trenching with archeological-style analysis...
A kinematic flood routing procedure has been devised for a small dendritic headwater gully network on the Western slope of Colorado. the program is spatially-distributed, incorporating lateral inflows from 103 field sites on the network for which channel geometry variables are known. This model, in which a lateral inflow algorithm for the sideslopes between each channel site is convoluted into a Freeze-type (1978) numerical scheme, is fully developed in this paper. Although the field basis of the lateral inflow algorithm has been tested elsewhere (Faulkner, 1990), sensitivity tests were needed for the roughness and hillslope velocity estimates used in the routing procedure. After these successful tests, a suitably...
This study explores how the relationship between flow and riparian vegetation varies along a montane river. We mapped occurrence of woody riparian plant communities along 58 km of the San Miguel River in southwest- ern Colorado. We determined the recurrence interval of inundation for each plant community by combining step-back- water hydraulic modeling at 4 representative reaches with Log-Pearson analysis of 4 stream gaging stations. Finally, we mapped bottomland surficial geology and used a Geographic Information System to overlay the coverages of geology and vegetation. Plant communities were distinctly arrayed along the hydrologic gradient. The Salix exigua Nuttall (sand- bar willow) community occurred mostly...
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