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Full-Text Articles in Social and Behavioral Sciences
Downstream Changes In Stream Power In The Henry Mountains, Utah, William Graf
Downstream Changes In Stream Power In The Henry Mountains, Utah, William Graf
William L. Graf
Total stream power does not necessarily increase systematically in the downstream direction because of the conflicting influences of channel slope, width, and depth. Historical records and field data for arroyo systems of the northern Henry Mountains, south-central Utah, show that total stream power decreased in the downstream direction during a deposition period before 1896 and increased downstream during an erosion period thereafter. When total stream power declined in the downstream direction, channels were small and meandering, and the ten-year flood exceeded channel capacity, resulting in overbank deposition of sediment. After an especially erosive flood in 1896, total stream power increased …
Rivers, Dams, And Willow Flycatchers: A Summary Of Their Science And Policy Connections, William Graf, Julie Stromberg, Brad Valentine
Rivers, Dams, And Willow Flycatchers: A Summary Of Their Science And Policy Connections, William Graf, Julie Stromberg, Brad Valentine
William L. Graf
The southwestern willow flycatcher (Empidonax traillii extimus) is a riparian bird that spends winter months in Central and South America and summer breeding months in riparian zones of the American Southwest. Decline of the willow flycatcher population to less than 1000 breeding pairs prompted the Federal government to declare the species endangered, triggering a major recovery effort. The most important aspect of recovery is management and improvement of the riparian habitat of the bird population. Although the direct management of the species is primarily a biological issue, fluvial hydrology and geomorphology play an important role in understanding the dynamics of …
Downstream Hydrologic And Geomorphic Effects Of Large Dams On American Rivers, William Graf
Downstream Hydrologic And Geomorphic Effects Of Large Dams On American Rivers, William Graf
William L. Graf
The hydrology and geomorphology of large rivers in America reflect the pervasive influence of an extensive water control infrastructure including more than 75,000 dams. One hundred thirty-seven of the very large dams, each storing 1.2 km3 (106 acre feet) of water or more, alter the flows of every large river in the country. The hydrologic effects of these very large dams emerge from an analysis of the stream gage records of 72 river reaches organized into 36 pairs. One member of each pair is an unregulated reach above a dam, whereas the other is a regulated reach downstream from the …
Geomorphology And American Dams: The Scientific, Social, And Economic Context, William Graf
Geomorphology And American Dams: The Scientific, Social, And Economic Context, William Graf
William L. Graf
American geomorphologic research related to dams is embedded in a complicated context of science, policy, economics, and culture. Research into the downstream effects of large dams has progressed to the point of theory-building, but generalization and theory-building are from this research because (1) it is highly focused on a few locations, (2) it concerns mostly very large dams rather than a representative sample of sizes, (3) the available record of effects is too short to inform us on long-term changes, (4) the reversibility of changes imposed by dam installation and operation is unknown, and (5) coordinated funding for the needed …