Channel delineation datasets associated with "River channel response to invasive plant treatment across the American Southwest"

The dataset contains river channel delineations in the form of an ArcGIS PRO shapefile. The shapefile contains polygons that were generated for each study site. There are fifteen study sites. Each study site contains a treated and untreated reach, and each of these reaches has pre- and post-treatment delineations. One study site, Chinle Creek, contains four treated reaches and four untreated reaches.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

Field-based Learning in Surface and Groundwater Processes: Preparing Water Literate Citizens and Water Resource Professionals

Hydrologic field stations installed in the Cache La Poudre River basin will provide authentic field-based learning opportunities for non-majors and majors at Colorado State University to prepare a water literate citizenry and water resource professionals. Previous experience from a campus well field has demonstrated the effectiveness of local field-based instruction in water resources. Results from three semesters of perception surveys and pre- and post-knowledge tests show increased student satisfaction and knowledge gain in fundamental water concepts through the groundwater field exercise. The new hydrologic stations are designed to build upon these results to further improve undergraduate teaching and learning of water concepts in Warner College of Natural Resources (WCNR) using the Poudre watershed as the focus. Given the numerous relevant scientific and societal issues related to our hometown watershed, now is the time to develop high-impact watershed-based learning tools for undergraduates. The hydrologic field stations will span a gradient along the Poudre River and its tributaries from the mountains at CSU’s Pingree Park campus to the plains, providing a full spectrum of geologic, climatic, biologic, and land use characteristics in the watershed. The mid-canyon site at Gateway Natural Area will be the first location accessed either in the field, virtually, or both, by 1300 students in twelve courses in WCNR. Students will collect and analyze the water quantity and quality data that are relevant to the future use of the Cache La Poudre River watershed, and all student-collected data will be made available on the FLOW (Fostering Learning of Water) website. Key learning goals include mastering surface and groundwater flow measurement, flow calculation and interpretation, hydrologic and geomorphic mapping and spatial analysis, assessing physical-biotic interactions along riparian corridors, evaluating human impacts to river networks, assessing alluvial aquifer properties, and computer modeling, thus giving students the broad knowledge and scientific skills necessary to participate as water literate citizens, enter the environmental science workforce, or pursue graduate research

Ice loss from the East Antarctic Ice Sheet during late Pleistocene interglacials

Understanding ice sheet behaviour in the geological past is essential for evaluating the role of the cryosphere in the climate system and for projecting rates and magnitudes of sea level rise in future warming scenarios1,2,3,4. Although both geological data5,6,7 and ice sheet models3,8 indicate that marine-based sectors of the East Antarctic Ice Sheet were unstable during Pliocene warm intervals, the ice sheet dynamics during late Pleistocene interglacial intervals are highly uncertain3,9,10. Here we provide evidence from marine sedimentological and geochemical records for ice margin retreat or thinning in the vicinity of the Wilkes Subglacial Basin of East Antarctica during warm late Pleistocene interglacial intervals. The most extreme changes in sediment provenance, recording changes in the locus of glacial erosion, occurred during marine isotope stages 5, 9, and 11, when Antarctic air temperatures11 were at least two degrees Celsius warmer than pre-industrial temperatures for 2,500 years or more. Hence, our study indicates a close link between extended Antarctic warmth and ice loss from the Wilkes Subglacial Basin, providing ice-proximal data to support a contribution to sea level from a reduced East Antarctic Ice Sheet during warm interglacial intervals. While the behaviour of other regions of the East Antarctic Ice Sheet remains to be assessed, it appears that modest future warming may be sufficient to cause ice loss from the Wilkes Subglacial Basin

Comparative Composition, Diversity and Trophic Ecology of Sediment Macrofauna at Vents, Seeps and Organic Falls

Sediments associated with hydrothermal venting, methane seepage and large organic falls such as whale, wood and plant detritus create deep-sea networks of soft-sediment habitats fueled, at least in part, by the oxidation of reduced chemicals. Biological studies at deep-sea vents, seeps and organic falls have looked at macrofaunal taxa, but there has yet to be a systematic comparison of the community-level attributes of sediment macrobenthos in various reducing ecosystems. Here we review key similarities and differences in the sediment-dwelling assemblages of each system with the goals of (1) generating a predictive framework for the exploration and study of newly identified reducing habitats, and (2) identifying taxa and communities that overlap across ecosystems. We show that deep-sea seep, vent and organic-fall sediments are highly heterogeneous. They sustain different geochemical and microbial processes that are reflected in a complex mosaic of habitats inhabited by a mixture of specialist (heterotrophic and symbiont-associated) and background fauna. Community-level comparisons reveal that vent, seep and organic-fall macrofauna are very distinct in terms of composition at the family level, although they share many dominant taxa among these highly sulphidic habitats. Stress gradients are good predictors of macrofaunal diversity at some sites, but habitat heterogeneity and facilitation often modify community structure. The biogeochemical differences across ecosystems and within habitats result in wide differences in organic utilization (i.e., food sources) and in the prevalence of chemosynthesis-derived nutrition. In the Pacific, vents, seeps and organic-falls exhibit distinct macrofaunal assemblages at broad-scales contributing to ß diversity. This has important implications for the conservation of reducing ecosystems, which face growing threats from human activities

Holocene sea ice variability driven by wind and polynya efficiency in the Ross Sea

The causes of the recent increase in Antarctic sea ice extent, characterised by large regional contrasts and decadal variations, remain unclear. In the Ross Sea, where such a sea ice increase is reported, 50% of the sea ice is produced within wind-sustained latent-heat polynyas. Combining information from marine diatom records and sea salt sodium and water isotope ice core records, we here document contrasting patterns in sea ice variations between coastal and open sea areas in Western Ross Sea over the current interglacial period. Since about 3600 years before present, an increase in the efficiency of regional latent-heat polynyas resulted in more coastal sea ice, while sea ice extent decreased overall. These past changes coincide with remarkable optima or minima in the abundances of penguins, silverfish and seal remains, confirming the high sensitivity of marine ecosystems to environmental and especially coastal sea ice conditions

Pleistocene glacial outburst flooding along the Big Lost River, east-central Idaho

Cataclysmic flood features including scabland topography, streamlined hills, a loess scarp, and flood transported boulders were mapped along Box Canyon, lower Big Lost River, eastern Snake River Plain. These features are similar to landforms within the Cheney-Palouse scabland tract, eastern Washington, formed by the great Missoula floods. Step-backwater hydraulic modeling of flow through the 11 km-long Box Canyon gorge indicates that a discharge of 60,000 m^3sec^-1 was required to produce the geologic paleostage evidence. Maximum stream power per unit area of bed locally attained values of 26,000 Wm^-2, which is comparable to the more extensive late Pleistocene Bonneville and Missoula flows. Flood power, estimated to exceed 1000 Wm^-2 , induced plucking of the jointed-basalt channel banks of Box Canyon. Tracts of scabland with networks of anastomosing channels migrated headward, driven by unit stream power values in the 600-1000 Win^-2 range. Deposition of the largest flood boulders occurred above a limiting unit stream power of 1400 Wm^-2. This ceiling on boulder deposition indicates that entrainment of these largest boulders probably took place under maximum unit stream power conditions (26,000 Wm^-2). The irregular volcanic rift topography along Box Canyon was the dominant control on removal and accumulation of flood boulders, however. Paleoflooding along Box Canyon may in part, although probably not solely, be attributed to outbursts from a glacial lake in the headwaters region located in the Pioneer Mountains.hydrology collectio

Modeling pool sediment dynamics in a mountain river

2001 Fall.Includes bibliographical references.An increasingly important source of sediment into river systems is sediment that accumulates within reservoirs and is subsequently released into the downstream ecosystem. In Colorado alone, five large-scale sediment releases from reservoirs within the last decade have resulted in a host of environmental hazards, particularly the loss of aquatic biota and their habitat. The most recent example occurred in September 1996 when approximately 7,000 m3 of clay- to gravel-sized sediment were released from Halligan Dam into the North Fork Cache la Poudre River in northern Colorado. The sediment caused extensive aggradation of the original cobble-boulder bed, primarily in pools, and complete fish mortality for 12 km downstream from the dam. Because of the thriving, pre-release wild trout fishery downstream from Halligan Reservoir, flushing of sediment from pools to recreate overwinter fish habitat was of prime concern. The purpose of this investigation was to evaluate the applicability of various hydraulic and sediment transport models as predictors of pool recovery along the steep gradient, bedrock-controlled North Fork River. Two modeling scenarios representing a low and high flushing discharge were modeled using one- and semi-two dimensional sediment transport models, HEC-6 and GSTARS2.0, respectively. The models were calibrated against quantitative measurements of pool bed elevation obtained during field surveys. HEC-6 results indicate that long-term, robust simulations yield the closest agreement between predicted and measured pool bed elevation change. Greater than 50 percent of the actual scour and deposition within three pools was modeled using HEC-6.Modeling accuracy using GSTARS2.0 was considerably more variable, and no pool-wide trends were obtained. A two-dimensional, finite element hydraulic model, RMA2, improved delineation of flow hydraulics in areas of flow separation and recirculation within a compound pool.RMA2 results of depth-averaged velocity magnitude and vectors broadly agree with timed photographs of surface flow patterns, and correspond with velocity measurements for low-velocity areas such as eddy pools. Patterns of boundary shear stress and a particle stability index accurately predict gross areas of scour and deposition, but fail to represent the simultaneous aggradation and degradation measured in pools. Estimates of bedload transport capacity from the two-dimensional modeling results are one order of magnitude greater than measured transport rates, and indicate that supply-limited conditions existed along the North Fork following a clear-water flushing release. Further correlations between observed and modeled sedimentation patterns are hindered by the disparity in resolution between the field data and modeled results; field-based cross sectional information is quickly outstripped by the finite element model RMA2. Finally, a conceptual model of pool sediment dynamics was developed for water resource specialists as an alternative to the time-intensive effort and expertise required of the numerical modeling. Predictable sites of channel aggradation and degradation resulting from a sediment pulse are identified on a reach-scale hierarchy. Processes of sediment delivery, storage, and transfer into and out of eddies that influence fish occur on the width scale, however. Sedimentation within laterally confined pools is dependent on pool geometry, distance downstream from the dam (a surrogate of sediment supply), and the duration and magnitude of flows following the release. At low flows, sediment deposition is restricted to small areas of recirculating flow. As discharge increases, migration of the separation point and development of a strong shear zone limits the transfer of sediment between the eddy and the main flow. The sediment release from Halligan induced persistent, long-term storage of fine sediment because of an elevated channel bed and loss of channel capacity. Recognition of the hazards associated with a large influx of sediment into a riverine ecosystem is critical for a greater understanding of the effects of sediment releases, and future management of sediment within reservoirs

Accept and support a multi-thread career path to keep women in the academic stream

We propose a call to action from those of us who have navigated the academic channel to help keep women afloat through the process of seeking, securing, and ascending the ranks of faculty positions