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Caroline M. Elliott

Publications and source records attributed to Caroline M. Elliott.

34 records · Page 2Linked to original sources
USGS2014

Stream classification of the Apalachicola-Chattahoochee-Flint River System to support modeling of aquatic habitat response to climate change

A stream classification and associated datasets were developed for the Apalachicola-Chattahoochee-Flint River Basin to support biological modeling of species response to climate change in the southeastern United States. The U.S. Geological Survey and the Department of the Interior’s National Climate Change and Wildlife Science Center established the Southeast Regional Assessment Project (SERAP) which used downscaled general circulation models to develop landscape-scale assessments of climate change and subsequent effects on land cover, ecosystems, and priority species in the southeastern United States. The SERAP aquatic and hydrologic dynamics modeling efforts involve multiscale watershed hydrology, stream-temperature, and fish-occupancy models, which all are based on the same stream network. Models were developed for the Apalachicola-Chattahoochee-Flint River Basin and subbasins in Alabama, Florida, and Georgia, and for the Upper Roanoke River Basin in Virginia. The stream network was used as the spatial scheme through which information was shared across the various models within SERAP. Because these models operate at different scales, coordinated pair versions of the network were delineated, characterized, and parameterized for coarse- and fine-scale hydrologic and biologic modeling. The stream network used for the SERAP aquatic models was extracted from a 30-meter (m) scale digital elevation model (DEM) using standard topographic analysis of flow accumulation. At the finer scale, reaches were delineated to represent lengths of stream channel with fairly homogenous physical characteristics (mean reach length = 350 m). Every reach in the network is designated with geomorphic attributes including upstream drainage basin area, channel gradient, channel width, valley width, Strahler and Shreve stream order, stream power, and measures of stream confinement. The reach network was aggregated from tributary junction to tributary junction to define segments for the benefit of hydrological, soil erosion, and coarser ecological modeling. Reach attributes are summarized for each segment. In six subbasins segments are assigned additional attributes about barriers (usually impoundments) to fish migration and stream isolation. Segments in the six sub-basins are also attributed with percent urban area for the watershed upstream from the stream segment for each decade from 2010–2100 from models of urban growth. On a broader scale, for application in a coarse-scale species-response model, the stream-network information is aggregated and summarized by 256 drainage subbasins (Hydrologic Response Units) used for watershed hydrologic and stream-temperature models. A model of soil erodibility based on the Revised Universal Soil Loss Equation also was developed at this scale to parameterize a model to evaluate stream condition. The reach-scale network was classified using multivariate clustering based on modeled channel width, valley width, and mean reach gradient as variables. The resulting classification consists of a 6-cluster and a 12-cluster classification for every reach in the Apalachicola-Chattahoochee-Flint Basin. We present an example of the utility of the classification that was tested using the occurrence of two species of darters and two species of minnows in the Apalachicola-Chattahoochee-Flint River Basin, the blackbanded darter and Halloween darter, and the bluestripe shiner and blacktail shiner.

Alabama, Florida, Georgia, Virginia↗
USGS2013

Application of the Precipitation-Runoff Modeling System (PRMS) in the Apalachicola-Chattahoochee-Flint River Basin in the southeastern United States

A hydrologic model of the Apalachicola–Chattahoochee–Flint River Basin (ACFB) has been developed as part of a U.S. Geological Survey (USGS) National Climate Change and Wildlife Science Center effort to provide integrated science that helps resource managers understand the effect of climate change on a range of ecosystem responses. The hydrologic model was developed as part of the Southeast Regional Assessment Project using the Precipitation Runoff Modeling System (PRMS), a deterministic, distributed-parameter, process-based system that simulates the effects of precipitation, temperature, and land use on basin hydrology. The ACFB PRMS model simulates streamflow throughout the approximately 50,700 square-kilometer basin on a daily time step for the period 1950–99 using gridded climate forcings of air temperature and precipitation, and parameters derived from spatial data layers of altitude, land cover, soils, surficial geology, depression storage (small water bodies), and data from 56 USGS streamgages. Measured streamflow data from 35 of the 56 USGS streamgages were used to calibrate and evaluate simulated basin streamflow; the remaining gage locations were used for model delineation only. The model matched measured daily streamflow at 31 of the 35 calibration gages with Nash-Sutcliffe Model Efficiency Index (NS) greater than 0.6. Streamflow data for some calibration gages were augmented for regulation and water use effects to represent more natural flow volumes. Time-static parameters describing land cover limited the ability of the simulation to match historical runoff in the more developed subbasins. Overall, the PRMS simulation of the ACFB provides a good representation of basin hydrology on annual and monthly time steps. Calibration subbasins were analyzed by separating the 35 subbasins into five classes based on physiography, land use, and stream type (tributary or mainstem). The lowest NS values were rarely below 0.6, whereas the median NS for all five classes was within 0.74 to 0.96 for annual mean streamflow, 0.89 to 0.98 for mean monthly streamflow, and 0.82 to 0.98 for monthly mean streamflow. The median bias for all five classes was within –4.3 to 0.8 percent for annual mean streamflow, –6.3 to 0.5 percent for mean monthly streamflow, and –9.3 to 1.3 percent for monthly mean streamflow. The NS results combined with the percent bias results indicated a good to very good streamflow volume simulation for all subbasins. This simulation of the ACFB provides a foundation for future modeling and interpretive studies. Streamflow and other components of the hydrologic cycle simulated by PRMS can be used to inform other types of simulations; water-temperature, hydrodynamic, and ecosystem-dynamics simulations are three examples. In addition, possible future hydrologic conditions could be studied using this model in combination with land cover projections and downscaled general circulation model results.

Alabama, Florida, Georgia↗
USGS2011

Geomorphic Classification and Evaluation of Channel Width and Emergent Sandbar Habitat Relations on the Lower Platte River, Nebraska

This report presents a summary of geomorphic characteristics extracted from aerial imagery for three broad segments of the Lower Platte River. This report includes a summary of the longitudinal multivariate classification in Elliott and others (2009) and presents a new analysis of total channel width and habitat variables. Three segments on the lower 102.8 miles of the Lower Platte River are addressed in this report: the Loup River to the Elkhorn River (70 miles long), the Elkhorn River to Salt Creek (6.9 miles long), and Salt Creek to the Missouri River (25.9 miles long). The locations of these segments were determined by the locations of tributaries potentially significant to the hydrology or sediment supply of the Lower Platte River. This report summarizes channel characteristics as mapped from July 2006 aerial imagery including river width, valley width, channel curvature, and in-channel habitat features. In-channel habitat measurements were not made under consistent hydrologic conditions and must be considered general estimates of channel condition in late July 2006. Longitudinal patterns in these features are explored and are summarized in the context of the longitudinal multivariate classification in Elliott and others (2009) for the three Lower Platte River segments. Detailed descriptions of data collection and classification methods are described in Elliott and others (2009). Nesting data for the endangered interior least tern (Sternula antillarum) and threatened piping plover (Charadrius melodus) from 2006 through 2009 are examined within the context of the multivariate classification and Lower Platte River segments. The widest reaches of the Lower Platte River are located in the segment downstream from the Loup River to the Elkhorn River. This segment also has the widest valley and highest degree of braiding of the three segments and many large vegetated islands. The short segment of river between the Elkhorn River and Salt Creek has a fairly low valley width and high channel sinuosities at larger scales. The segment from Salt Creek to the Missouri River has narrow valleys and generally low channel sinuosity. Tern and plover nest sites from 2006 through 2009 in the multi-scale multivariate classification indicated relative nesting selection of cluster 2 reaches among the four-cluster classification and reaches containing clusters 2, 3, and 6 from the seven-cluster classification. These classes, with the exception of cluster 6 are common downstream from the Elkhorn River. Trends in total channel width indicated that reaches dominated by dark vegetation (islands) are the widest on the Lower Platte River. Reaches with high percentages of dry sand and dry sand plus light vegetation were the narrowest reaches. This suggests that narrow channel reaches have sufficient transport capacity to maintain sandbars under recent (2006) flow regimes and are likely to be most amenable to maintaining tern and plover habitat in the Lower Platte River. Further investigations into the dynamics of emergent sandbar habitat and the effects of bank stabilization on in-channel habitats will require the collection and analysis of new data, particularly detailed elevation information and an assessment of existing bank stabilization structures.

Scientific Investigations Report↗
USGS2010

Bathymetric and Velocimetric Survey and Assessment of Habitat for Pallid Sturgeon on the Mississippi River in the Vicinity of the Proposed Interstate 70 Bridge at St. Louis, Missouri

A bathymetric and velocimetry survey was conducted on the Mississippi River in the vicinity of a proposed new bridge for Interstate 70 at St. Louis, Missouri. A multibeam echo sounder mapping system and an acoustic Doppler current profiler were used to obtain channel-bed elevations and vertically averaged and near-bed velocities for a 3,545-foot (1,080-meter) long reach of the Mississippi River approximately 1,935 feet (590 meters) wide from the Illinois to Missouri banks. Data from the 2009 survey were used to determine the conditions of the benthic habitat in the vicinity of the proposed Interstate 70 bridge. The channel-bed elevations ranged from approximately 346 feet (105.46 meters) to 370 feet (112.78 meters) above the North American Vertical Datum of 1988 in a majority of the channel except for the channel banks. Large dune features up to 12.5 feet (3.81 meters) high were present in the middle of the channel, and numerous smaller dunes and many ripples as smaller features were superimposed on the larger dunes. However, it is uncertain if the large dune features present in mid-channel are long-term features or an artifact of the seasonal flooding on the Mississippi River. A substantial scour depression was present on the right descending bank (Missouri side) near the downstream end of the study area, as well as other smaller scour holes near the instream barge mooring structures on the Missouri bank. The vertically averaged velocities acquired with the acoustic Doppler current profiler ranged from approximately 2 feet per second (0.61 meters per second) along the channel margins to approximately 7.0 feet per second (2.13 meters per second) in the main channel, with an average velocity of 5.5 feet per second (1.68 meters per second) in mid-channel. The orientation of the vertically averaged velocity vectors showed flow crossing from the Illinois bank to the Missouri bank from upstream to downstream in the study area, which was confirmed by the orientation of the large dune features in mid-channel and a shift in the channel thalweg from the Illinois bank to the Missouri bank. The near-bottom velocities acquired with the acoustic Doppler current profiler ranged from 0.3 to 7.0 feet per second (0.09 to 2.13 meters per second), and the effects of the large dune features were apparent in the more random scattering of the velocity vectors, the low velocities downstream from the dunes, and higher velocities near the crests of the dunes. Despite the considerable physical complexity of this site because of the arrangement of large sand dunes in the middle of the channel, existing studies do not document persistent use of these deep, fast, main-channel habitats by pallid sturgeon. Narrow channel-margin areas on both banks having relatively low velocity, high depth slope, and high velocity gradients are similar to adult migration habitats as documented on the Missouri River downstream from Kansas City, Missouri. Although the reach generally lacks features associated with sturgeon habitat selection on the Middle Mississippi River, the barge mooring areas on the right descending bank have topographic complexity and contain large woody debris and small patches of probable gravel-cobble substrate that may have positive habitat value for sturgeon or other species. Furthermore, telemetry studies have documented sturgeon migrating upstream and downstream through this reach as adults, and they probably drift downstream through this reach as free-embryo larvae. Successful upstream migration may depend on availability of areas with hydraulic complexity and relatively low velocities, as presently exist on the margins of the site. Additionally, complexity at the channel margin may provide areas where larvae settle out from drifting in the main current or may act to slow bulk drift rates. Construction of bridge piers close to the banks will likely alter hydraulics and sediment transport on the channel margins and may result in substanti

Scientific Investigations Report↗
USGS2010

Development of a channel classification to evaluate potential for cottonwood restoration, lower segments of the Middle Missouri River, South Dakota and Nebraska

This report documents development of a spatially explicit river and flood-plain classification to evaluate potential for cottonwood restoration along the Sharpe and Fort Randall segments of the Middle Missouri River. This project involved evaluating existing topographic, water-surface elevation, and soils data to determine if they were sufficient to create a classification similar to the Land Capability Potential Index (LCPI) developed by Jacobson and others (U.S. Geological Survey Scientific Investigations Report 2007–5256) and developing a geomorphically based classification to apply to evaluating restoration potential. Existing topographic, water-surface elevation, and soils data for the Middle Missouri River were not sufficient to replicate the LCPI. The 1/3-arc-second National Elevation Dataset delineated most of the topographic complexity and produced cumulative frequency distributions similar to a high-resolution 5-meter topographic dataset developed for the Lower Missouri River. However, lack of bathymetry in the National Elevation Dataset produces a potentially critical bias in evaluation of frequently flooded surfaces close to the river. High-resolution soils data alone were insufficient to replace the information content of the LCPI. In test reaches in the Lower Missouri River, soil drainage classes from the Soil Survey Geographic Database database correctly classified 0.8–98.9 percent of the flood-plain area at or below the 5-year return interval flood stage depending on state of channel incision; on average for river miles 423–811, soil drainage class correctly classified only 30.2 percent of the flood-plain area at or below the 5-year return interval flood stage. Lack of congruence between soil characteristics and present-day hydrology results from relatively rapid incision and aggradation of segments of the Missouri River resulting from impoundments and engineering. The most sparsely available data in the Middle Missouri River were water-surface elevations. Whereas hydraulically modeled water-surface elevations were available at 1.6-kilometer intervals in the Lower Missouri River, water-surface elevations in the Middle Missouri River had to be interpolated between streamflow-gaging stations spaced 3–116 kilometers. Lack of high-resolution water-surface elevation data precludes development of LCPI-like classification maps. An hierarchical river classification framework is proposed to provide structure for a multiscale river classification. The segment-scale classification presented in this report is deductive and based on presumed effects of dams, significant tributaries, and geological (and engineered) channel constraints. An inductive reach-scale classification, nested within the segment scale, is based on multivariate statistical clustering of geomorphic data collected at 500-meter intervals along the river. Cluster-based classifications delineate reaches of the river with similar channel and flood-plain geomorphology, and presumably, similar geomorphic and hydrologic processes. The dominant variables in the clustering process were channel width (Fort Randall) and valley width (Sharpe), followed by braiding index (both segments). Clusters with multithread and highly sinuous channels are likely to be associated with dynamic channel migration and deposition of fresh, bare sediment conducive to natural cottonwood germination. However, restoration potential within these reaches is likely to be mitigated by interaction of cottonwood life stages with the highly altered flow regime.

Scientific Investigations Report↗
USGS2009

Channel morphodynamics in four reaches of the Lower Missouri River, 2006-07

Channel morphodynamics in response to flow modifications from Gavins Point Dam are examined in four reaches of the Lower Missouri River. Measures include changes in channel morphology and indicators of sediment transport in four 6 kilometer long reaches located downstream from Gavins Point Dam, near Yankton, South Dakota, Kenslers Bend, Nebraska, Little Sioux, Iowa, and Miami, Missouri. Each of the four reaches was divided into 300 transects with a 20-meter spacing and surveyed during the summer in 2006 and 2007. A subset of 30 transects was randomly selected and surveyed 7-10 times in 2006-07 over a wide range of discharges including managed and natural flow events. Hydroacoustic mapping used a survey-grade echosounder and a Real Time Kinematic Global Positioning System to evaluate channel change. Acoustic Doppler current profiler measurements were used to evaluate bed-sediment velocity. Results indicate varying amounts of deposition, erosion, net change, and sediment transport in the four Lower Missouri River reaches. The Yankton reach was the most stable over monthly and annual time-frames. The Kenslers Bend and Little Sioux reaches exhibited substantial amounts of deposition and erosion, although net change was generally low in both reaches. Total, or gross geomorphic change was greatest in the Kenslers Bend reach. The Miami reach exhibited varying rates of deposition and erosion, and low net change. The Yankton, Kenslers Bend, and Miami reaches experienced net erosion during the time period that bracketed the managed May 2006 spring rise event from Gavins Point Dam.

Scientific Investigations Report↗
USGS2009

Assessment of Lower Missouri River physical aquatic habitat and its use by adult sturgeon ( Genus Scaphirhynchus ), 2005-07

This report presents an exploratory analysis of habitat availability and use by adult Scaphirhynchus sturgeon on the Lower Missouri River from Gavins Point Dam, South Dakota, to the junction with the Mississippi River. The analysis is based on two main data sources collected from 2005 to 2007: (1) a compilation of 153 reach-scale habitat maps (mean reach length, 2.4 kilometers) derived from boat-collected hydroacoustic data and (2) a sturgeon location dataset from which 378 sturgeon telemetry locations are associated with the maps (within 7 days of the mapping and within 10 percent of the discharge). The report focuses on: (1) longitudinal patterns of geomorphic and hydraulic characteristics revealed by the collection of reach maps; (2) assessment of environmental characteristics at sturgeon locations in the context of the mapped reaches; and (3) consideration of spatial distribution of habitat conditions that sturgeon appear to select. Longitudinal patterns of geomorphology, hydraulics, and associated habitats relate strongly to the engineered state of the river. Reaches within each of the following river sections tended to share similar geomorphic, hydrologic, and hydraulic characteristics: the Minimally Engineered section (Gavins Point Dam to Sioux City, Iowa), the Upstream Channelized section (Sioux City, Iowa, to the junction with the Kansas River), and the Downstream Channelized section (Kansas River to the junction with the Mississippi River). Adult sturgeon occupy nearly the full range of available values for each continuous variable assessed: depth, depth slope, depth-averaged velocity, velocity gradient, and Froude number (a dimensionless number relating velocity to depth). However, in the context of habitat available in a reach, sturgeon tend to select some areas over others. Reproductive female shovelnose sturgeon (Scaphirhynchus platorynchus), in particular, were often found in parts of the reach with one or more of the following characteristics: high velocity gradient, high depth slope, low Froude number, and low (though not necessarily the lowest) depth-averaged velocity. Depths used by sturgeon varied considerably. We explored spatial patterns representing the variable ranges that reproductive female shovelnose sturgeon most strongly and consistently selected by mapping areas within reaches meeting the following criteria: greater than the 80th percentile of depth slope, greater than the 80th percentile of velocity gradient, and less than the 20th percentile of Froude number. Our data exploration indicates that areas meeting these criteria have some predictive value regarding sturgeon habitat selection. Of all sturgeon locations that fall on maps from the same year (sample size = 2,013), about 63 percent fall within about 35 percent of the area where at least one variable meets the above criteria and 18 percent of locations fall within 4 percent of the area where all three variables meet the above criteria. The spatial patterns of these mapped areas show distinct differences among the sections of the Lower Missouri River. For example, the areas of predicted selection exhibit a relatively complex mosaic with multiple interconnected pathways in reaches of the Minimally Engineered section. In contrast, areas of predicted selection are concentrated along the channel margins in reaches of the Upstream Channelized section. Because the patterns described in this report represent habitat use in the context of the available habitat in a highly altered river system, selection may not necessarily indicate preferred habitats or habitats sufficient for reproduction and survival of sturgeon species.

Scientific Investigations Report↗
USGS2009

Geomorphic classification of the Lower Platte River, Nebraska

Geomorphic attributes were collected from natural color aerial orthophotography to develop a multiscale classification for the downstream-most 220 kilometers of the Platte River in eastern Nebraska. The intent of this classification is to define discrete reaches that have geomorphic characteristics favorable to endangered interior least terns ( Sternula antillarum ) and threatened piping plovers ( Charadrius melodus ) who use riverine sandbars for nesting habitat. Annual to daily fluctuations in discharge present a challenge to characterizing emergent sandbar habitat directly from existing aerial orthophotography for the Platte River. Therefore, this classification is based on geomorphic measures that are relatively insensitive to prevailing river discharge but may be physically related to emergent sandbar locations. Such features include valley width, channel width, and sinuosity. The results provide four-cluster and seven-cluster classifications for the Lower Platte River based on naturally occurring, statistically determined clusters of features. The classification was validated using tern and plover nest data for 2006–08. Forty-nine percent of the nest locations fell within the same class type in the four-cluster classification, which represented 18 percent of the study area. This class is found primarily in the Eastern Platte River Gorge, downstream from Salt Creek and upstream from the junction of the Platte River with the Missouri River.

Nebraska↗
USGS2008

Hydraulic and substrate maps of reaches used by sturgeon ( Genus Scaphirhynchus ) in the Lower Missouri River, 2005-07

This report is a repository of reach-scale maps of hydraulic and substrate characteristics generated for the habitat-use portion of an interdisciplinary sturgeon research project on the Lower Missouri River (from Gavins Point Dam to the junction with the Mississippi River). The maps were derived from hydroacoustic data sets that were collected for the purpose of assessing physical aquatic habitat in the vicinity of locations of adult shovelnose sturgeon ( Scaphirhynchus platorynchus ) and pallid sturgeon ( S. albus ). Hydroacoustic data sets were collected at the reach scale (mean reach length, 2.4 kilometers) in order to include the immediate vicinity of a targeted sturgeon location as well as the full range of habitat available at the bend and crossover scale. Reaches typically were surveyed on the day following the relocation of a telemetered sturgeon and at a discharge within 10 percent of the discharge on the sturgeon relocation date in order to characterize as closely as possible the channel morphology and flow-field conditions at the time that the sturgeon was present. One hundred fifty-three reaches were mapped during April–September in the years 2005 through 2007, with the majority of data collection occurring in the months of May and June (coinciding with the period of sturgeon migration and spawning in the Lower Missouri River). Interpolated maps (grid cell size, 5 meters) depict depth, generalized substrate, and depth-averaged velocity. Side-scan sonar imagery is also available for a subset of reaches. Collectively, the maps represent more than 20 percent of the length of the Lower Missouri River.

Data Series↗
USGS2007

The roles of physical habitat in reproduction and survival of pallid sturgeon and shovelnose sturgeon in the Lower Missouri River, progress 2005–06: Chapter D in Factors affecting the reproduction, recruitment, habitat, and population dynamics of pallid sturgeon and shovelnose sturgeon in the Missouri River

This report documents progress on three related components of habitat assessments in the Lower Missouri River during 2005–06. The habitat-use component links this research directly to sturgeon ecology research described in other chapters. The habitat availability and habitat dynamics assessments provide physical context for the ecological research. Results from 2005 to 2006 indicate that the methods developed to assess habitat use, quality, quantity, and dynamics are appropriate and sufficiently accurate to address critical questions about sturgeon habitat on the Lower Missouri River. Preliminary analysis of habitats occupied by adult female shovelnose sturgeon indicates that migrating sturgeon do not select for depth but seem to select for lower than reach-averaged velocities and higher than reach-averaged velocity gradients. Data collected to compile, calibrate, and validate multidimensional hydraulic models in probable spawning reaches appear to be sufficient to support the modeling objectives. Monitoring of selected channel cross sections and long profiles multiple times during the year showed little change at the upstreammost reach over the range of flows measured during 2006, likely because of channel stability associated with an armored bed. Geomorphic changes documented at monitoring cross sections increased with distance downstream. Hydroacoustic substrate-class parameters documented systematic changes with discharge and with hydraulic environment across the channel. Similarly, bed velocity varied predictably with discharge and hydraulic environment, indicating its potential as an indicator of bedload sediment transport. Longitudinal profiles showed substantial downstream movement of dunes over the monitored discharges, as well as substantial within-year variability in dune size. Observations of geomorphic change during the moderate flow range of 2006 support the hypothesis that the magnitude of flow modifications under consideration on the Lower Missouri River will be sufficient to transport sediment and potentially modify spawning habitats.

Lower Missouri River↗
USGS2006

Hydroacoustic mapping to define sedimentation rates and characterize lentic habitats in DeSoto Lake, DeSoto National Wildlife Refuge

Hydroacoustic tools were used to map depth, elevation, and substrate on DeSoto Lake in March 2006. DeSoto Lake, located on the DeSoto National Wildlife Refuge in Iowa and Nebraska, is one of the largest oxbow lakes of the Missouri River system. It is used by over 500,000 migratory birds each fall and spring and is also an important aquatic resource for anglers. Management concerns at the lake include the effects of erosion and sedimentation, aquatic vegetation establishment, shorebird habitat availability at different lake levels, and fish habitat structure. DeSoto Lake was cut off from the Missouri River in 1960, and the current mapping updates previous lower-resolution bathymetric maps created from lake surveys in 1967 and 1979. The new maps provide managers tools to assess aquatic habitats and provide a baseline for future monitoring of lake sedimentation and erosion.

Open-File Report↗
USGS2006

Geomorphic Classification and Assessment of Channel Dynamics in the Missouri National Recreational River, South Dakota and Nebraska

A multiscale geomorphic classification was established for the 39-mile, 59-mile, and adjacent segments of the Missouri National Recreational River administered by the National Park Service in South Dakota and Nebraska. The objective of the classification was to define naturally occurring clusters of geomorphic characteristics that would be indicative of discrete sets of geomorphic processes, with the intent that such a classification would be useful in river-management and rehabilitation decisions. The statistical classification was based on geomorphic characteristics of the river collected from 1999 orthophotography and the persistence of classified units was evaluated by comparison with similar datasets for 2003 and 2004 and by evaluating variation of bank erosion rates by geomorphic class. Changes in channel location and form were also explored using imagery and maps from 1993-2004, 1941 and 1894. The multivariate classification identified a hierarchy of naturally occurring clusters of reach-scale geomorphic characteristics. The simplest level of the hierarchy divides the river from segments into discrete reaches characterized by single and multithread channels and additional hierarchical levels established 4-part and 10-part classifications. The classification system presents a physical framework that can be applied to prioritization and design of bank stabilization projects, design of habitat rehabilitation projects, and stratification of monitoring and assessment sampling programs.

Scientific Investigations Report↗
USGS2005

Assessment of shallow-water habitat availability in modified dike structures, Lower Missouri River, 2004

This study documented the effects of wing-dike notching on the availability of shallow water habitat in the Lower Missouri River. Five wing dikes were surveyed in late May 2004 after they were notched in early May as part of shallow-water habitat (SWH) rehabilitation activities undertaken by the U.S. Army Corps of Engineers. Surveys included high-resolution hydroacoustic depth, velocity, and substrate mapping. Relations of bottom elevations within the wing dike fields to index discharges and water-surface elevations indicate that little habitat meeting the SWH definition was created immediately following notching. This result is not unexpected, as significant geomorphic adjustment may require large flow events. Depth, velocity, and substrate measurements in the post-rehabilitation time period provide baseline data for monitoring ongoing changes. Differences in elevation and substrate were noted at all sites. Most dike fields showed substantial aggradation and replacement of mud substrate with sandier sediment, although the changes did not result in increased availability of SWH at the index discharge. It is not known how much of the elevation and substrate changes can be attributed directly to notching and how much would result from normal sediment transport variation.

Missouri↗
USGS2004

Physical aquatic habitat assessment, Fort Randall segment of the Missouri River, Nebraska and South Dakota

This study addressed habitat availability and use by endangered pallid sturgeon (Scaphirhynchus albus) in the Fort Randall segment of the Missouri River. Physical aquatic habitat - depth, velocity, and substrate - was mapped in 15 sites in Augsust and October of 2002. Habitat assessments were compared with fish locations using radio telemetry. Results indicate that pallid sturgeon preferentially use locations in the Fort Randall segment deeper than the average available habitat, with prominent usage peaks aat 3.5-4.0 m and 6-6.5 m, compared to the modal availability at 3-3.5 m. The fish use habitats with a modal velocity of 80 cm/s; the used velocities appear to be in proportion to their availability. Fish located preferentially over sand substrate and seemed to avoid mud and submerged vegetation.

Open-File Report↗
USGS2003

Physical stream habitat dynamics in Lower Bear Creek, northern Arkansas

We evaluated the roles of geomorphic and hydrologic dynamics in determining physical stream habitat in Bear Creek, a stream with a 239 km2 drainage basin in the Ozark Plateaus (Ozarks) in northern Arkansas. During a relatively wet 12-month monitoring period, the geomorphology of Bear Creek was altered by a series of floods, including at least four floods with peak discharges exceeding a 1-year recurrence interval and another flood with an estimated 2- to 4-year recurrence interval. These floods resulted in a net erosion of sediment from the study reach at Crane Bottom at rates far in excess of other sites previously studied in the Ozarks. The riffle-pool framework of the study reach at Crane Bottom was not substantially altered by these floods, but volumes of habitat in riffles and pools changed. The 2- to 4-year flood scoured gravel from pools and deposited it in riffles, increasing the diversity of available stream habitat. In contract, the smaller floods eroded gravel from the riffles and deposited it in pools, possibly flushing fine sediment from the substrate but also decreasing habitat diversity. Channel geometry measured at the beginning of the study was use to develop a two-dimensional, finite-element hydraulic model at assess how habitat varies with hydrologic dynamics. Distributions of depth and velocity simulated over the range of discharges observed during the study (0.1 to 556 cubic meters per second, cms) were classified into habitat units based on limiting depths and Froude number criteria. The results indicate that the areas of habitats are especially sensitive to change to low to medium flows. Races (areas of swift, relatively deep water downstream from riffles) disappear completely at the lowest flows, and riffles (areas of swift, relatively shallow water) contract substantially in area. Pools also contract in area during low flow, but deep scours associated with bedrock outcrops sustain some pool area even at the lowest modeled flows. Modeled boundary shear stresses were used to evaluate which flows are responsible for the most mobilization of the bed, and therefore, habitat maintenance. Evaluation of the magnitude and frequency of bed-sediment entrainment shows that most of the habitat maintenance results from flows that occur on average about 4 to 7 days a year. Our analysis documents the geomorphic and hydrologic dynamics that form and maintain habitats in a warmwater stream in the Ozarks. The range of flows that occurs on this stream can be partitioned into those that sustain habitat by providing the combinations of depth and velocity that stream organisms live with most of the time, and those flows that surpass sediment entrainment thresholds, alter stream geomorphology, and therefore maintain habitat. The quantitative relations show sensitivity of habitats to flow variation, but do not address how flow may vary in the future, or the extent to which stream geomorphology may be affected by variations in sediment supply.

Arkansas↗