The Green River canyons of the eastern Uinta Mountains have experienced a 5- year period of high debris flow activity. Catchment factors were studied in watersheds and on debris fans with recent debris flows, leading to the development of a conceptual framework of the hillslope and debris flow processes that deliver sediment to the Green River. Two recent fan deposits were monitored to determine the magnitude and processes of reworking that occur during mainstem floods of varying magnitude. The dominant debris flow initiation mechanism, termed the firehose effect, occurs when overland flow generated on bedrock slopes cascades down steep cliffs and saturates and impacts colluvium stored in bedrock hollows, causing failure. The dry climate and high strength of bedrock cause hillslopes to be weathering-limited, prohibiting the formation of extensive regolith and vegetative cover. This reduces the degree vegetation regulates geomorphic processes and causes wildfire to have little influence on debris flow initiation. The dry climate and strong rocks also lead to high runoff ratios and steep escarpments that result in debris flow initiation via the firehose effect. This initiation process also dominates in Grand Canyon, where geologic and topographic characteristics are similar, but differs from locations in the Rocky Mountains where fire has a strong influence on debris flow processes. Monitoring of two recently aggraded debris fans shows that mainstem floods with magnitudes as low as 75% of the pre-dam 2-year flood cause significant erosion of fan deposits, whereas floods with magnitudes less than 40% of the pre-dam 2-year flood do little reworking. Armoring of the debris fan surface limited the degree ofreworking done by successive floods. Eroded material was deposited directly downstream of the fan, not at the expansion gravel bar. This depositional location represents a change in the organization of the fan-eddy complex, potentially altering the location of recirculating eddies and associated backwater habitats. These results indicate that the firehose effect may be the dominant initiation processes in the steep canyons of the Colorado Plateau and that dam releases that significantly rework fan deposits are within the operational range of large dams in the Colorado River system.

Extensive research exists regarding invasive alien plant species including impacts to native ecosystems and efficacy of control methods on public lands and river corridors. Many studies have identified the need for more research regarding the social implications of invasive alien species management. More specifically, additional research is needed regarding the impacts of invasive alien plant management on the Colorado Plateau to river-based recreation experiences. It is important for public land management agencies like the National Park Service to understand recreation-based stakeholders’ knowledge, norms, and preferences toward managing prevalent alien plants like tamarisk. For this study, 330 river users were questioned about their knowledge of tamarisk and preferences for tamarisk management on the Green and Colorado River corridors of the Colorado Plateau. Results show that a majority of river users want tamarisk to be removed. The tamarisk control methods investigated in this thesis were also evaluated by respondents as acceptable. The methods evaluated to be the most acceptable were the cut-stump method and the use of tamarisk leaf beetle, while prescribed fire and the use of a machine to mulch tamarisk were found to be less acceptable. The use of chainsaws to perform the cut-stump method was found to be acceptable in both the Green and Colorado River corridors. This thesis concludes with a summary of findings and implications for land managers and future research.

Nursery habitat availability is considered a bottleneck to successful recruitment of Colorado squawfish (Ptychocheilus Lucius). Detailed geomorphic studies were conducted in a 1.5-km reach to examine channel response to flows and the geomorphic setting of nursery habitats during a 2-year period. Videography was used to extend relationships in the 1.5-km reach to a longer 10-km reach. Nursery habitat availability varied yearly with little persistence in location or geomorphic setting of individual habitats for the 2 years of this study. A small number of habitats provided most of the area of high-quality (i.e., deep) habitat, and most of the total area of habitat was formed by three geomorphic classes. Although the 1993 flood reduced the area of available habitat, area of deep habitat increased. The 1994 low-peak flood increased the area of habitat, but most habitats were shallow. The 1993 and 1994 multi-peaked habitat availability curves for the 1.5-km-reach bank-attached bar were the result of the superposition of curves from habitats in each geomorphic classification, and showed that the discharge that maximized habitat availability changed yearly. A complexity index was evaluated for the 10-km reach as surrogate for habitat availability. Total base-flow habitat availability was significantly correlated to the complexity index, but deep habitat availability was not. Measured channel topography was used as input to a flow and sediment transport model. Simulated hydrograph runs produced greater bank-attached bar aggradation and thalweg scour than steady flows, although some unrealistic patterns of scour occurred. New flow recommendations must include occasional high flows sufficient to rebuild channel topography. Flaming Gorge Dam releases should be used to augment the Yampa River flood peak, but not increase low flood-peak duration. The conceptual model for habitat availability developed here may be used to target the formation and availability of habitats. Base flow recommendations designed to maximize habitat availability should be evaluated annually. Winter flows should be reevaluated for their negative effects on habitat.

A detailed study was made of the composition and distribution of modern and fossil animal and plant traces around saline, alkaline lakes in tectonically active, closed lake-basins. Modern and Pleistocene traces that were examined in lake basins of the Kenya Rift Valley (Lakes Bogoria, Magadi, and Nasikie Engida) were compared directly with fossil traces from the Eocene Lake Gosiute in the Green River Formation of Wyoming, U.S.A., which had a similar hydrochemistry. Analysis of lithofacies and the stratigraphic packaging of the sediments hosting biogenic structures was undertaken so that their vertical and lateral distribution could be used to interpret lake histories and to help to develop depositional models of enigmatic sedimentary successions. A focus was given to the application of the results for paleoecology and stratigraphy, and a model for predicting the position of different trace associations in vertical successions and in different parts of saline, alkaline lake basins has been developed. Evidence from the Kenyan lakes and Eocene Lake Gosiute shows that (1) sedimentary environments are diverse in underfilled basins, and frequent lake-level fluctuations strongly impact the distribution of sedimentary environments suitable for the production and preservation of biogenic structures; (2) the distribution of biogenic structures in underfilled basins is related to the geomorphological and structural setting, tectonic activity, catchment lithology, the basin margin or basin centre location, climate, and salinity and alkalinity, together with other finer-scale environmental and biological controls; (3) because saline environments are restrictive, sites of relatively dilute inflow (springs, rivers and deltas, ephemeral streams) provide oasis-like habitats for animals and plants, and contribute to the increased diversity and laterally variable distribution of saline-lake trace assemblages; and (4) the vertical distribution of trace fossils in a stratigraphic succession reflects changing environments through time; important stratigraphic surfaces, usually formed during periods of lake-level fall, can be recognized from the overprinting patterns of traces produced under different conditions.

A detailed study was made of the composition and distribution of modern and fossil animal and plant traces around saline, alkaline lakes in tectonically active, closed lake-basins. Modern and Pleistocene traces that were examined in lake basins of the Kenya Rift Valley (Lakes Bogoria, Magadi, and Nasikie Engida) were compared directly with fossil traces from the Eocene Lake Gosiute in the Green River Formation of Wyoming, U.S.A., which had a similar hydrochemistry. Analysis of lithofacies and the stratigraphic packaging of the sediments hosting biogenic structures was undertaken so that their vertical and lateral distribution could be used to interpret lake histories and to help to develop depositional models of enigmatic sedimentary successions. A focus was given to the application of the results for paleoecology and stratigraphy, and a model for predicting the position of different trace associations in vertical successions and in different parts of saline, alkaline lake basins has been developed. Evidence from the Kenyan lakes and Eocene Lake Gosiute shows that (1) sedimentary environments are diverse in underfilled basins, and frequent lake-level fluctuations strongly impact the distribution of sedimentary environments suitable for the production and preservation of biogenic structures; (2) the distribution of biogenic structures in underfilled basins is related to the geomorphological and structural setting, tectonic activity, catchment lithology, the basin margin or basin centre location, climate, and salinity and alkalinity, together with other finer-scale environmental and biological controls; (3) because saline environments are restrictive, sites of relatively dilute inflow (springs, rivers and deltas, ephemeral streams) provide oasis-like habitats for animals and plants, and contribute to the increased diversity and laterally variable distribution of saline-lake trace assemblages; and (4) the vertical distribution of trace fossils in a stratigraphic succession reflects changing environments through time; important stratigraphic surfaces, usually formed during periods of lake-level fall, can be recognized from the overprinting patterns of traces produced under different conditions.

Birds are the most diverse extant group of terrestrial vertebrates, and relationships amongst major extant and extinct avian lineages remain hotly debated. A clade of Aves which has received limited attention is the extinct Zygodactylidae, a species-rich group of perching birds that possess a foot with a retroverted fourth toe, an elongate tarsometatarsus and a large intermetacarpal process in the wing. Specimens currently included within Zygodactylidae previously were thought to be sister taxa to songbirds (Passeriformes) or woodpeckers and allies (Piciformes). Zygodactylids were most abundant during the Eocene in North America and Europe and persisted to the Early Miocene. Five exceptionally preserved fossils from the Early Eocene Green River Formation of Wyoming are described, and provide insights into the interrelationships of zygodactylid taxa and the position of the clade within Aves. In an attempt to resolve systematic relationships within zygodactylids, and the position of the clade within Aves, I conducted two sets of phylogenetic analyses. The first focused on clarifying relationships within Zygodactylidae. Each taxon was evaluated for 37 morphological characters. Resulting strict consensus cladograms yield topologies in which two of the new Green River specimens are positioned in a clade within Zygodactylus, a taxon previously known only from the Early Oligocene and Early Miocene of Europe. The second set of analyses sought to assess which extant avian lineage is most closely allied with Zygodactylidae. Those analyses used a dataset of 135 characters evaluated for 57 species and a supraspecific terminal, Zygodactylidae. Scoring of Zygodactylidae was based on morphological observations from all described taxa within Zygodactylidae. The extant species sample was chosen to evaluate previously proposed hypotheses of relationships between Zygodactylidae and other avian clades and included songbirds, parrots and 43 species from the coraciiform-piciform clade (e.g., woodpeckers, galbulids, rollers and motmots). Outgroup species were iteratively swapped to determine if outgroup choice affected recovered estimates of zygodactylid relationships within Aves. Zygodactylidae is the sister taxon to songbirds in the resultant tree topologies. These results forward our understanding of the relationship between Zygodactylidae and Passeriformes within Aves. / text

In recent years, historians have displayed a growing interest in the cultural development of certain well-defined regions. Often a river valley inspired such a study, for example, R.E. Banta’s The Ohio, Thomas Clark’s The Kentucky and Harriette Arnow’s Seedtime on the Cumberland. These and many other river histories dealt less with the river itself than with its tendency to define and alter an area’s culture This thesis, dealing with the culture of Green River’s steamboat era, is less about the steamboat or Green River than it is about their effect on river people. It searches the area’s homes, schools, business establishments, churches, military and recreational activities from 1828 to 1931. This century is viewed through the records of four generations who know the steamboat intimately. It examines birth and death in Green River country and the sung that were sung in between.

I applied empirical mode decomposition (EMD) and the Hilbert-Herbert transforms, as tools to analyze streamflow data. I used the EMD method to extract and analyze periodic processes and trends in several environmental datasets including daily stream flow, daily precipitation, and daily temperature on data from the watersheds of two rivers in the Upper Colorado River Basin, the Yampa and the Upper-Green rivers. I used these data to identify forcing functions governing streamflow. Forcing functions include environmental factors such as temperature and precipitation and anthropogenic factors such as dams or diversions. The Green and Yampa Rivers have similar headwaters, but the Yampa has minimal diversions or controls while Flaming George Dam on the Green river significantly affects flow. This provides two different flow regimes with similar large watersheds. In addition to flow data, I analyzed several time series data sets, including temperature and precipitation from Northeast Utah, North Western Colorado, and Southern Wyoming. These data are from the area that defines the Yampa River and Green River watersheds, which stretch from Flaming Gorge Dam to Ouray Colorado. The EMD method is a relatively new technique that allows any time series data set, including non-linear and non-stationary datasets that are common in earth observation data, to be decomposed into a small quantity of composite finite data series, called intrinsic mode functions (IMFs). The EMD method can decompose any complicated data into several IMFs that represent independent signals in the original data. These IMFs may represent periodic forcing functions, such as environmental conditions or dam operations, or they may be artifacts of the decomposition method and not have an associated physical meaning. This study attempts to assign physical meaning to some IMFs resulting from the decomposition of the Green and Yampa flows where possible. To assign physical meaning to the IMFs, I analyzed frequencies of each IMF using the Hilbert-Hung transform, part of the Empirical Mode Decomposition method, and then compared frequencies of the IMFs with the known frequencies of physical processes. I performed these calculations on both flow, temperature, and precipitation. I found significant correlation between IMF components of flow, precipitation, and temperature data with El Niño Southern Oscillation (ENSO) events. The EMD process also extracts the long-term trend in non-linear data sets that can provide insights into the effects of climate change on the flow system. Though in preliminary stages of research, these analysis methods may lead to further understanding the availability of water within the upper Yampa and Green River Watersheds.

Previous scientific research has documented channel narrowing on the Green River near Green River, Utah, but the exact timing, rates, and causal mechanisms of that narrowing have been the source of disagreement in the scientific literature. This thesis demonstrates that the Green River has narrowed in two separate periods during the last 100 years. The narrowing is driven primarily by changes in the hydrologic regime and not by the invasion of saltcedar. The channel narrowed between 1930 and 1938, when a shift from wetter than normal conditions to a period of draught led to a reduction in river discharge. Channel width then remained relatively stable until construction of Flaming Gorge Dam in 1962, despite the presence of saltcedar. Narrowing has occurred since dam construction. Detailed analysis of the formation of an inset floodplain deposit indicates that it formed by a process of vertical accretion, during incremental events. Inset bank deposits within the study area are composed primarily of particles smaller than 0.125 mm. Measurement of suspended sand distribution within the water column shows that particles of this size are carried in suspension by the 2-yr flood. Continued vertical accretion over time elevated the floodplain surface until inundation rarely occurs.

Currently, a variety of methods are available to monitor anurans, and little standardization of methods exists. New methods to monitor anurans have become available over the past twenty years, including PVC pipe arrays used for tree frog capture and Automated Digital Recording Systems (ADRS) used to remotely monitor calling activity. In addition to ADRS, machine-learning computer software, automated vocalization recognition software (AVRS), has been developed to automatically detect vocalizations within digital sound recordings. The use of a combination of ADRS and AVRS shows the promise to reduce the number of people, time, and resources needed for an effective call survey program. However, little research exists that uses the described tools for wildlife monitoring, especially for anuran monitoring. In the study, there were two problems addressed relating to AVRS. The first was the poorly understood relationship between auditory survey methods and physical survey methods. I tested this problem by using current auditory monitoring methods, ADRS and the AVRS Song Scope© (v.3.1), alongside more traditional physical monitoring methods that included drift fences, a PVC pipe array, and visual encounter transects. No significant relationship between physical and auditory community population measures was found. Auditory methods were also effective in the detection of call characteristic differences between urban and rural locations, further suggesting an influence of noise pollution. The second problem addressed was the call identification errors found in auditory survey methods. I examined the influence of treatments including the ADRS location, listener group, species, and season on the error rates of the AVRS Song Scope© (v.3.1) and groups of human listeners. Computer error rates were higher than human listeners, yet less affected by the treatments. Both studies suggested that AVRS was a viable method to monitor anuran populations, but the choice of methods should be dependent upon the species of interest and the objectives of the study.