Treesearch

The migration of alluvial channels through the geologic landform is an outcome of the natural erosive processes. Mankind continually attempts to stabilize channel meandering processes, both vertically and horizontally, to reduce sediment discharge, provide boundary definition, and enable economic development along the river's edge. A critical component in the reduction of bank erosion and subsequent channel migration is to stabilize river bendways. The mitigation of erosion is addressed through the damping of the magnitude and orientation of the applied shear stresses developed by the...

Natural channels never stop changing their geomorphic characteristics. Natural alluvial streams are similar to living creatures because they generate water flow, develop point bars, alter bed profile, scour the bed, erode the bank, and cause other phenomena in the stream system. The geomorphic changes in a natural system lead to a wide array of research worldwide, because methods of predicting channel change are limited. Bank erosion due to meandering of the channel is a critical issue in modern river engineering. In the United States, the severity of the problem was recognized when...

As with every natural process, river morphology incorporates a complex and nuanced set of processes that combine to produce an infinite set of possible outcomes. Natural laws that govern natural systems cause rivers to react to changes in the environment in order to maintain equilibrium. Changes in hydraulics, sediment transport, and habitat help keep natural systems in balance. Natural reactions can be predictable, such as seasonal variations in weather patterns, or quite unpredictable, such as major flooding events or tectonic activity. Human impact to the environment is rarely subtle...

The Elephant Butte Reach spans about 30 miles, beginning from the South Boundary of the Bosque del Apache National Wildlife Refuge (River Mile 73.9) to the "narrows" of the Elephant Butte Reservoir (River Mile 44.65), in central New Mexico. Sediment plugs occasionally form along the Middle Rio Grande, completely blocking the main channel of the river. In 1991, 1995, and 2005, the Tiffany Plug was initiated at the upstream end of the Elephant Butte Reach. In 2008, the Bosque del Apache Plug formed just upstream of the Elephant Butte Reach. Sediment plugs occur at the location of a constricti...

The Middle Rio Grande is a 29-mi reach of the Rio Grande in central New Mexico extending from the downstream side of Cochiti Dam to Bernalillo, New Mexico. A map of the Middle Rio Grande reach is presented in Figure 1.1. In recent years, the Middle Rio Grande has been the focus of a variety of channel restoration techniques, including the use of native material and rock spur-dike structures in attempts to control bank erosion rates, channel migration rates, and habitat degradation (Darrow 2004).

Fluvial systems respond to changes in boundary conditions in order to sustain the flow and sediment supplied to the system. Local channel responses are typically difficult to predict due to possible affects from upstream, downstream, or local boundary conditions that cause changes in channel or planform geometry. Changes to the system can threaten riverside infrastructure and riparian zones, which may affect the local ecology. This research focuses on meandering channel patterns and the forces applied to their physical boundaries by the complex three-dimensional (3-D) flow found in...

Open space lands, national forests in particular, are usually treated as homogeneous entities in hedonic price studies. Failure to account for the heterogeneous nature of public open spaces may result in inappropriate inferences about the benefits of proximate location to such lands. In this study the hedonic price method is used to estimate the marginal values for proximity to the Pike National Forest. The results indicate that specifying the forest as homogeneous overstates the benefits for homes within two miles relative to specifying the forest based on land use characteristics,...

This article identifies and compares meanings of wildfire risk mitigation for stakeholders in the Front Range of Colorado, USA. We examine the case of a collaborative partnership sponsored by government agencies and directed to decrease hazardous fuels in interface areas. Data were collected by way of key informant interviews and focus groups. The analysis is guided by the Circuit of Culture model in communication research. We found both shared and differing meanings between members of this partnership (the "producers") and other stakeholders not formally in the partnership (the "consumers"...

Changes in land use and land cover have affected and will continue to affect biological diversity worldwide. Yet, understanding the spatially extensive effects of land-cover change has been challenging because data that are consistent over space and time are lacking. We used the U.S. National Land Cover Dataset Land Cover Change Retrofit Product and North American Breeding Bird Survey data to examine landcover change and its associations with diversity of birds with principally terrestrial life cycles (landbirds) in the conterminous United States. We used mixed-effects models and model...

Ecosystems are changing in response to observed changes in climate, extreme events, and disturbances such as fire and insects. We read not only that these changes are occurring but that we should expect them to continue - changes in temperature; more extreme events; and more disturbances such as fire and insects that are not like the past. Key point: these changes in climate and ecosystems are now part of the environment in which resource management occurs.