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  • ItemOpen Access
    Channel delineation datasets associated with "River channel response to invasive plant treatment across the American Southwest"
    (Colorado State University. Libraries, 2022) Wieting, Celeste; Friedman, Jonathan; Rathburn, Sara L.
    Invasive riparian plants were introduced to the American Southwest in the early 19th century and contributed to regional trends of decreasing river channel width and migration rate in the 20th century. More recently efforts to remove invasive riparian vegetation (IRV) have been widespread, especially since 1990. To what extent has IRV treatment reversed the earlier trend of channel narrowing and reduced dynamism? In this study, paired treated and untreated reaches at 15 sites along 13 rivers were compared before and after IRV treatment using repeat aerial imagery to assess long-term (~10 year) channel change due to treatment on a regional scale across the Southwest U.S. We found that IRV treatment significantly increased channel width and floodplain destruction. Treated reaches had higher floodplain destruction than untreated reaches at 14 of 15 sites, and IRV treatment increased the rate of floodplain destruction by a median factor of 1.9. The effect of treatment increased with the stream power of the largest flow over the study period. Resolving observations of channel change into separate measures of floodplain destruction and formation provided more information on underlying processes than simple measurements of channel width and centerline migration rate. Restoration practitioners who perform IRV treatment projects often focus on wildlife or vegetation response; however, geomorphic processes should be considered in restoration planning because they drive aquatic habitat and vegetation dynamics, and because of the potential for damage to downstream infrastructure. Depending on the restoration goal, management practices can be used to enhance or minimize the increase in channel dynamism caused by IRV removal.
  • ItemOpen Access
    Dataset associated with "A First-Order Approximation of Floodplain Soil Organic Carbon Stocks in a River Network: the South Platte River, Colorado, USA"
    (Colorado State University. Libraries, 2022) Wohl, Ellen; Knox, Richard
    We use the hydrogeomorphic floodplain tool GFPLAIN to delineate the extent of 100-year floodplains in the South Platte River watershed of Colorado, USA. We distinguish elevation bands for the steppe, montane, subalpine, and alpine zones. We also differentiate bead (floodplain width/channel width > 5) and string (floodplain width/channel width < 5) reaches within the montane and subalpine zones. Drawing on prior, field-based measurements of organic carbon stock in downed, dead wood and soil in these floodplain types, we estimate total floodplain organic carbon storage, which includes organic carbon storage in lake and reservoir sediments in the watershed. Soil constitutes the greatest reservoir of floodplain carbon. The total estimated area of floodplain is 2916 km2, which is 4.3% of the total watershed area of the South Platte River. Our preferred estimate is 42.7 Tg C storage (likely range of 39.1-42.7 Tg). This equates to 11.1% of a previously estimated overall carbon stock (above and belowground biomass and soil organic carbon) in the entire watershed of 384 Tg C. Floodplains are thus disproportionately important, relative to their surface area, in storing organic carbon in this semiarid watershed. Field measurements of floodplain soil organic carbon storage from across the globe indicate that this finding is not unique to this watershed and this has implications for prioritizing floodplain management and restoration as a means of enhancing carbon sequestration.
  • ItemOpen Access
    Data Associated with "Logjam Characteristics as Drivers of Transient Storage in Headwater Streams"
    (Colorado State University. Libraries, 2022) Marshall, Anna; Zhang, Xiaolang; Sawyer, Audrey Hucks; Wohl, Ellen; Singha, Kamini
    Logjams in a stream create backwater conditions and locally force water to flow through the streambed, creating zones of transient storage within the surface and subsurface of a stream. We investigate the relative importance of logjam distribution density, logjam permeability, and discharge on transient storage in a simplified experimental channel. We use physical flume experiments in which we inject a salt tracer, monitor fluid conductivity breakthrough curves in surface water, and use breakthrough-curve skew to characterize transient storage. We then develop numerical models in HydroGeoSphere to reveal flow paths through the subsurface (or hyporheic zone) that contribute to some of the longest transient-storage timescales. In both the flume and numerical model, we observe an increase in backwater and hyporheic exchange at logjams. Observed complexities in transient storage behavior may depend largely on surface water flow in the backwater zone. As expected, multiple successive logjams provide more pervasive hyporheic exchange by distributing the head drop at each jam, leading to distributed but shallow flow paths. Decreasing the permeability of a logjam or increasing the discharge both facilitate more surface water storage and elevate the surface water level upstream of a logjam, thus increasing hyporheic exchange. Multiple logjams with low permeability result in the greatest magnitude of transient storage, suggesting that this configuration maximizes solute retention in backwater zones, while hyporheic exchange rates also increase. Understanding how logjam characteristics affect solute transport through both the channel and hyporheic zone has important management implications for rivers in forested, or historically forested, environments.
  • ItemOpen Access
    Dataset associated with “Aufeis as a Major Forcing Mechanism for Channel Avulsion and Implications of Warming Climate”
    (Colorado State University. Libraries, 2022) Wohl, Ellen; Scamardo, Julianne
    Prompted by field observation of an aufeis-induced channel avulsion along the Hula Hula River in June 2021, we use measurements of channel migration zone width along 15 rivers flowing north across the Arctic coastal plain in Alaska, USA. We differentiated sites with aufeis that covered > 1 km2 in early summer during the period 2017-2021 from sites without such aufeis formation. All but 4 of the 28 sites with aufeis have widths greater than the 95% confidence interval and 20 sites fall outside of the 95% prediction interval for channel width based on drainage area. Pairwise comparison indicates that the population of aufeis sites have significantly wider channel migration zones (p < 0.0001) than non-aufeis sites after accounting for drainage area. Seasonal aufeis facilitates lateral channel migration and associated heterogeneity. Loss of aufeis under warming climate may reduce habitat diversity in these river corridors.
  • ItemOpen Access
    Supplementary materials associated with “The Transience of Channel-Spanning Logjams in Mountain Streams”
    (Colorado State University. Libraries, 2022) Wohl, Ellen; Iskin, Emily
    We use 11 years of annual surveys in streams of the Southern Rockies of Colorado, USA to examine the persistence and geomorphic effects of logjams. Each year’s survey includes ~300 logjams along more than 21 km of 4 mountain streams in primarily old-growth subalpine forest. Streams alternate longitudinally between laterally confined reaches with a single channel and wider reaches with multithread channel planform. We distinguish logjam persistence and site persistence. Logjam persistence is the median timespan over which an individual jam is present. Site persistence describes the tendency for jams to disappear and then re-form at the same site. We hypothesize that (i) site persistence is greatest in multithread reaches; (ii) logjam persistence is greatest in multithread reaches; and (iii) average backwater storage at each jam is greater in multithread reaches. We find that spatial and temporal metrics of site persistence differ significantly between single and multithread reaches. Individual logjam persistence does not differ significantly. Backwater storage is significantly greater in multithread reaches. Varying combinations of riparian forest age and average logjams per channel length explain variation in jam and site persistence and backwater storage via multivariate linear regression analyses. Over the 11 years of survey, a total of 429 distinct logjams were observed. Only 2.1% of the population was present for all 11 annual surveys. Median jam persistence is 1-2.5 years; median site persistence is 6-10 years. Despite the transience of most channel-spanning logjams in the population, these jams create persistent effects in channel planform and backwater storage.
  • ItemOpen Access
    Cameron Pass, CO Spring 2019: Ground-penetrating radar surveys, snow depths, and snowpits
    (Colorado State University. Libraries, 2021) Bonnell, Randall; McGrath, Daniel
    This dataset contains snow depths, measurements from snowpits, ground-penetrating radar raw files, and derived liquid water content values collected at Cameron Pass, CO during Spring 2019. Snow depths were measured using a manual probe. Snowpit data includes density and temperature measurements, stratigraphy notes, and weather notes. Ground-penetrating radar was collected using a 1 GHz Sensors & Software ProEx unit coupled to the snow surface. Liquid water content was calculated using the picked two-way travel time from processed ground-penetrating radar, snow densities, and snow depths.
  • ItemOpen Access
    Datasets associated with ‘All Logjams Are Not Created Equal’
    (Colorado State University. Libraries, 2021) Livers, Bridget; Wohl, Ellen
    Logjams create diverse physical and ecological effects in stream channels, including at least temporary storage of water, sediment, and particulate organic matter. We hypothesize that logjams that span the entire bankfull channel width in channels < 25 m wide are more effective in storing these materials than non-channel spanning logjams. We test this hypothesis by systematically comparing characteristics of 183 logjams from 17 stream reaches in the Southern Rocky Mountains. Our dataset is novel in that it evaluates naturally occurring logjams in unaltered streams in a single study area specifically based on whether they span the stream channel. We find that channel-spanning logjams have a significantly larger number of wood pieces, longer & wider pieces, more ramp and bridge pieces, and greater logjam height and volume, both as raw data and when standardized by average channel width. Channel-spanning logjams also have significantly greater backwater pool volume and volume of particulate organic matter stored in backwater pools and in logjams. Restoration employing engineered logjams in relatively small channels currently focuses on non-spanning logjams, but could be expanded to include spanning logjams.
  • ItemOpen Access
    Dataset for Geomorphology and climate interact to control organic carbon stock and age in mountain river valley bottoms
    (Colorado State University. Libraries, 2018) Scott, Daniel; Wohl, Ellen
    Organic carbon (OC) stored in dead vegetation and soil represents a massive and relatively sensitive pool of carbon whose distribution and residence time affects global climate. Mountain river basins can store large OC stocks. However, the distribution, magnitude, and residence time of OC stored in mountain river valley bottoms remain unquantified on broad scales, hampering understanding of how these regions contribute to terrestrial OC cycling. We compare four disparate mountain river basins to show that mountain river valley bottoms store substantial OC stocks in floodplain soil and downed wood that vary with valley bottom form and geomorphic processes. We quantify soil OC radiocarbon age to show that soil burial is essential to preserving old OC. Valley bottom morphology, soil retention, and vegetation dynamics determine partitioning of valley bottom OC between soil and wood, implying that modern biogeomorphic process and the legacy of past erosion regulate the modern distribution of OC in river networks. The age of the floodplain soil OC pool and the distribution of OC between wood and soil imply that mountain rivers are highly sensitive to alterations in soil and wood retention, which may have both short- and long-term feedbacks with the distribution of OC between the land and atmosphere.
  • ItemOpen Access
    Dataset for Geomorphic regulation of floodplain soil organic carbon concentration in watersheds of the Rocky and Cascade mountains, USA
    (Colorado State University. Libraries, 2018) Scott, Daniel; Wohl, Ellen
    Mountain rivers have shown the potential for high organic carbon (OC) storage in terms of retaining OC-rich soil. We characterize valley bottom morphology, floodplain soil, and vegetation in two disparate mountain river basins: the Middle Fork Snoqualmie, in the Cascade Mountains, and the Big Sandy, in the Wind River Range of the Rocky Mountains. We use this dataset to examine variability in OC concentration between these basins as well as within them, at multiple spatial scales. We find that although there are some differences between basins, much of the variability in OC concentration is due to local factors, such as soil moisture and valley bottom geometry. From this, we conclude that local factors likely play a dominant role in regulating OC concentration in valley bottoms, and that inter-basin trends in climate or vegetation characteristics may not translate directly to trends in OC storage. We also use analysis of OC concentration and soil texture by depth to infer that OC is input to floodplain soils mainly by decaying vegetation, not overbank deposition of fine, OC-bearing sediment. Geomorphology and hydrology play strong roles in determining the spatial distribution of soil OC in mountain river corridors.
  • ItemOpen Access
    Dataset for Natural and anthropogenic controls on wood loads in river corridors of the Rocky, Cascade, and Olympic mountains, USA
    (Colorado State University. Libraries, 2018) Scott, Daniel; Wohl, Ellen
    This dataset describes wood loads in four mountain river basins of the Western United States. In addition to wood load, this dataset includes valley bottom, topographic, and forest characteristics. Please see the accompanying article (DOI listed upon publication) for a full explanation of methods used to collect this data and resulting analysis.
  • ItemOpen Access
    Data associated with Geomorphic controls on floodplain soil organic carbon in the Yukon Flats, interior Alaska, from reach to river basin scales
    (Colorado State University. Libraries, 2018) Lininger, K. B.; Wohl, E.; Rose, J. R.
    Floodplains accumulate and store organic carbon (OC) and release OC to rivers, but studies of floodplain soil OC come from small rivers or small spatial extents on larger rivers in temperate latitudes. Warming climate is causing substantial change in geomorphic process and OC fluxes in high latitude rivers. We investigate geomorphic controls on floodplain soil OC concentrations in active-layer mineral sediment in the Yukon Flats, interior Alaska. We characterize OC along the Yukon River and four tributaries in relation to geomorphic controls at the river basin, segment, and reach scales. Average OC concentration within floodplain soil is 2.8% (median = 2.2%). Statistical analyses indicate that OC varies among river basins, among planform types along a river depending on the geomorphic unit, and among geomorphic units. OC decreases with sample depth, suggesting that most OC accumulates via autochthonous inputs from floodplain vegetation. Floodplain and river characteristics, such as grain size, soil moisture, planform, migration rate, and riverine DOC concentrations, likely influence differences among rivers. Grain size, soil moisture, and age of surface likely influence differences among geomorphic units. Mean OC concentrations vary more among geomorphic units (wetlands = 5.1% vs. bars = 2.0%) than among study rivers (Dall River = 3.8% vs. Teedrinjik River = 2.3%), suggesting that reach-scale geomorphic processes more strongly control the spatial distribution of OC than basin-scale processes. Investigating differences at the basin and reach scale is necessary to accurately assess the amount and distribution of floodplain soil OC, as well as the geomorphic controls on OC.