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To support an investigation of the effectiveness of a large-scale river restoration project, several types of field data were collected from two gravel-bed reaches of the regulated lower Merced River in California's Central Valley, primarily in the fall of 2016. These data sets were intended to characterize salmon spawning habitat and identify factors influencing spawning site selection. This parent data release includes links to child pages for the following data sets: 1) Bulk samples of streambed sediment used to characterize the subsurface grain size distribution. 2) Pebble counts used to characterize the sediment grain size distribution of the bed surface. 3) Force gage measurements used to parameterize a...
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Surveys of channel and floodplain topography were used to characterize the morphology of two reaches of the lower Merced River in California's Central Valley and to parameterize a hydraulic model. These data were collected to support research intended to evaluate the extent to which large-scale restoration projects provided improved salmon spawning habitat. A related goal of this study was to improve our understanding of the geomorphic factors influencing spawning site selection by salmon. At the Merced River Ranch field site, river channel and floodplain topography was measured using a combination of real-time kinematic (RTK) GPS for wadable parts of the channel, an echo sounder for deep pools, and photogrammetry...
In the past two decades, major flood events have occurred on the lower Colorado River, a dramatic shift from the low flows and moderate floods associated with prior decades of river regulation. This study uses repeat aerial photography and Geographic Information System analysis to examine the planform channel response of the upper Colorado River delta (limitrophe reach) to this recently altered hydrology. Results indicate that channel contraction has been the dominant planform process in recent decades, but periodic floods resulted in channel expansion (1981–1988; 1997–2000) or likely reduced the channel contraction measured between successive aerial photographs (1976–1981; 1988–1994). Sinuosity adjustments...
Small-bodied, riverine minnows that historically characterized fish assemblages of Great Plains rivers in North America have declined because of river fragmentation, dewatering, river channel degradation, river salinization and nonnative species introductions. The Pecos bluntnose shiner Notropis simus pecosensis, a member of this guild, persists in one segment of the Pecos River, New Mexico, USA. We characterized habitat associations for the species at two spatial scales. In general, N. s. pecosensis associated with fluvial habitats, but velocity association depended on body size, with larger individuals using swifter habitats. All N. s. pecosensis associated with relatively low depths (3–51 cm), which were most...
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Note: This item is being used in a data pipeline that supports the Dam Removal Information Portal. We recommend users directly access the American River's Dam Removal Database from Figshare: https://doi.org/10.6084/m9.figshare.5234068. In the last century, the U.S. led the world in dam building for many purposes, including hydropower, irrigation, flood control and water storage. While dams can benefit society, they also cause considerable harm to rivers. Dams have depleted fisheries, degraded river ecosystems, and altered recreational opportunities on nearly all of our nation’s rivers. Today, many dams that were once at the epicenter of a community’s livelihood are now old, unsafe or no longer serving their intended...
Although ?70 dams have been decommissioned in Wisconsin over the past 30 y, little is known about the physical and ecological effects of dam removal on riverine ecosystems. The purpose of our study was to document changes in channel form and macroinvertebrate assemblages following the removal of a low-head, run-of-river dam from the Baraboo River,Wisconsin, in January 2000. We surveyed cross sections and collected benthic macroinvertebrate samples in 6 reaches (an upstream reference reach, reaches immediately above and below the dam that was to be removed, and sequential unimpounded and impounded reaches further downstream) in a multiple-dam sys- tem. Surveys were conducted in December 1999, before dam removal,...
Alteration of natural flow regimes by river regulation affects fish distribution and assemblage structure, but causative pathways are not always direct and may go unrecognized. The Colorado River population of the endangered Colorado pikeminnow, Ptychocheilus lucius, suffers from low rates of recruitment and reduced carrying capacity. We hypothesized that availability of prey fish for this large-bodied native piscivore may, in part, be limited by reduced standing crops of periphyton and macroinvertebrates resulting from accumulation of fine sediment in the riverbed. We stratified the 373-km-long study area into 11 strata and sampled various physical and biological parameters in runs and riffles of three randomly...
Kentchurch Weir, a low-head weir on the river Monnow, Wales, was demolished in August 2011, releasing a sediment wave that had formed behind the structure for at least a century. We surveyed channel topography and bed-material composition through a 1.5-km long reach prior to weir removal and then periodically over a 2-year period. The fill material was finer than the ambient bed material with all particles mobilized by bankfull flows. Rapid degradation of the 1460-m3 sediment fill in the previously impounded reach occurred as bed material appeared to disperse downstream, consistent with other studies of sediment waves in gravel-bed rivers. The riverbed profile was gradually smoothed through the study reach by degrading...
In the late 1970s, the construction of weirs in Norwegian regulated river systems for aesthetic reasons was common. However, today, the focus of river restoration has shifted towards improving biological functionality and biodiversity. In the present study, two weirs, originally built to create a stable water level, were removed on a residual flow reach in a Norwegian regulated river as a measure to restore river connectivity and to re-establish the local population of Atlantic salmon. The removal design was based on hydraulic modelling, and biological monitoring was implemented before and after the weir removal to evaluate the biological response to weir removal. The results demonstrated that salmon spawning sites...
A slow draining reservoir on the U.S. East Coast was monitored to identify the processes governing channel evolution upstream of a dam removal. Channel evolution was documented through cross section surveys, sediment size analysis, discharge measurements, and visual assessments of vegetative growth. The reservoir drained slowly, allowing for an analysis of channel evolution and identification of the morphometric parameters defining the path and time required for a channel to reach dynamic equilibrium. Channel evolution was a multidirectional process, and evolving channel reaches actively migrated laterally while alternating between aggradation and degradation. Channel formation was dominated primarily by the hydrologic...
Straightened channels and altered and drained adjacent riparian wetlands have adversely impacted streams and rivers throughout the US Midwest. This research investigated the biological connection and water quality of a 0.07 ha diversion wetland and adjacent stream at the Olentangy River Wetland Research Park in central Ohio. Before the flowthrough conditions were established, we demonstrated with mark and recapture techniques that the wetland already was a biorefuge for fish under extreme conditions; two species (Centrarchidae) captured in the stream before a total drawdown of the stream were found in the wetland a year later. In addition, water at the bottom remained at around 4 °C over the winter likely due to...
Billions of dollars are being spent in the United States to restore rivers to a desired, yet often unknown, reference condition. In lieu of a known reference, practitioners typically assume the paradigm of a connected watercourse. Geological and ecological processes, however, create patchy and discontinuous fluvial systems. One of these processes, dam building by North American beavers (Castor canadensis), generated discontinuities throughout precolonial river systems of northern North America. Under modern conditions, beaver dams create dynamic sequences of ponds and wet meadows among free-flowing segments. One beaver impoundment alone can exceed 1000 meters along the river, flood the valley laterally, and fundamentally...
***This data product has been SUPERSEDED by Duda, J.J., Johnson, R.C., Wieferich, D.J., Wagner, W.J., and Bellmore, J.R., 2020, USGS Dam Removal Science Database v3.0 (ver. 3.0, January 2020): U.S. Geological Survey data release, https://doi.org/10.5066/P9IGEC9G.​***
    map background search result map search result map American Rivers Dam Removal Database Field measurements for characterizing salmon spawning habitat in two restored reaches of the lower Merced River, California Surveys of channel bed topography from two restored reaches of the lower Merced River, California Surveys of channel bed topography from two restored reaches of the lower Merced River, California Field measurements for characterizing salmon spawning habitat in two restored reaches of the lower Merced River, California American Rivers Dam Removal Database