Mountain Scholar :: Browsing by Author "Kampf, Stephanie, committee member"

Browsing by Author "Kampf, Stephanie, committee member"

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Open Access
A geomorphic classification of ephemeral streams in arid regions
(Colorado State University. Libraries, 2013) Sutfin, Nicholas A., author; Wohl, Ellen, advisor; Bledsoe, Brian, committee member; Kampf, Stephanie, committee member
Current stream classifications do not adequately describe ephemeral streams in arid regions because these environments are characterized by high spatial and temporal variability of complex hydrologic interactions. To investigate the influence of channel form on riparian vegetation in the arid southwestern United States, I test a geomorphic classification for ephemeral streams based on the degree of confinement and the composition of confining material. I present five stream types: 1) bedrock channels entirely confined by exposed bedrock and void of persistent alluvium; 2) bedrock with alluvium channels at least partially confined by bedrock but containing enough alluvium to create bedforms that persist through time; 3) incised alluvium channels bound only by unconsolidated alluvial material into which they are incised; 4) braided washes that exhibit multi-thread, braided characteristics regardless of the degree and composition of confining material; and 5) piedmont headwater 0-2nd order streams confined only by unconsolidated alluvium and which initiate as secondary channels on piedmont surfaces. The objectives of this thesis were to i) validate distinct differences of channel geometry among the five stream types and ii) examine localized differences in geometry of the five stream types across watersheds with varying characteristics. Eighty-six study reaches were surveyed on the U.S. Yuma Army Proving Ground (YPG) and eighteen study reaches on Barry Goldwater Air Force Range (BMGR) in southwestern Arizona. Non-parametric permutational multivariate analysis of variance (PERMANOVA) for all 101 study reaches indicates significant differences (P<0.001) in channel geometry between the five stream types with regard to width-to-depth ratio, stream gradient, shear stress, and unit stream power. PERMANOVA results indicate no significant differences in channel geometry of individual stream types within watersheds of differing characteristics. A linear discriminant function of the four physical driving variables derived from 86 study reaches at YPG predict stream type with a 73% external hit rate for the 15 study reaches at BMGR. Classification and regression tree (CART) analysis identify thresholds for distinguishing stream types and indicates the relative importance of variables such that: width-to-depth ratio (W/D) correctly distinguishes 93.8% of braided channels (W/D > 91.2), shear stress (τ) correctly distinguishes 95.2% of bedrock channels (τ > 151.6 Pa), and unit stream power (ω) correctly distinguishes 68% of piedmont headwater channels (ω ≤ 35.63 W/m2). The resulting classification will provide a basis for examining relationships between channel characteristics, hydrologic process, riparian vegetation and ecosystem sensitivity of ephemeral streams in arid regions of the American Southwest.
Open Access
A method for assessing impacts of parameter uncertainty in sediment transport modeling applications
(Colorado State University. Libraries, 2009) Ruark, Morgan D., author; Niemann, Jeffrey D., advisor; Kampf, Stephanie, committee member; Griemann, Blair, committee member
Numerical sediment transport models are widely used to evaluate impacts of water management activities on endangered species, to identify appropriate strategies for dam removal, and many other applications. The SRH-1D (Sedimentation and River Hydraulics - One Dimension) numerical model, formerly known as GST ARS, is used by the U.S. Bureau of Reclamation for many such evaluations. The predictions from models such as SRH-1D include uncertainty due to assumptions embedded in the model 's mathematical structure, uncertainty in the values of parameters, and various other sources. In this paper, we aim to develop a method that quantifies the degree to which parameter values are constrained by calibration data and determines the impacts of the remaining parameter uncertainty on model forecasts. Ultimately, this method could be used to assess how well calibration exercises have constrained model behavior and to identify data collection strategies that improve parameter certainty. The method uses a new multi-objective version of Generalized Likelihood Uncertainty Estimation (GLUE). In this approach, the likelihoods of parameter values are assessed using a function that weights different output variables using their first order global sensitivities, which are obtained from the Fourier Amplitude Sensitivity Test (FAST). The method is applied to SRH-1D models of two flume experiments: an erosional case described by Ashida and Michiue (1971) and a depositional case described by Seal et al. (1997). Overall, the results suggest that the sensitivities of the model outputs to the parameters can be rather different for erosional and depositional cases and that the outputs in the depositional case can be sensitive to more parameters. The results also suggest that the form of the likelihood function can have a significant impact on the assessment of parameter uncertainty and its implications for the uncertainty of model forecasts.
Open Access
A multi-scale analysis of vegetation and irrigation heterogeneity effects on ecohydrological function and ecosystem services in a semi-arid urban area
(Colorado State University. Libraries, 2014) Gage, Edward A., author; Cooper, David, advisor; Ham, Jay, committee member; Kampf, Stephanie, committee member; Ryan, Michael, committee member
To view the abstract, please see the full text of the document.
Open Access
A multi-scale, hierarchical approach to map the location and condition of riparian zones in the southern Rockies ecoregion
(Colorado State University. Libraries, 2014) Salo, Jessica Ann, author; Theobald, David, advisor; Bledsoe, Brian, committee member; Brown, Thomas, committee member; Kampf, Stephanie, committee member; Merritt, David, committee member
Riparian zones are important for their contribution to biodiversity and ecosystem services, especially in the western United States where riparian zones occupy a small proportion of the landscape but support a majority of the biodiversity. Riparian zones are currently threatened by multiple stressors, and will likely face further stresses associated with climate change and additional water withdrawals due to population growth particularly in the western United States and other arid regions. Consequently, it is imperative to understand the current location and extent of riparian zones. Although many agencies and organizations are concerned with the location, condition, and benefits of these ecosystems, few accurate datasets of riparian zone are available over broad spatial extents, and cost-effective methods to map riparian zones at fine spatial resolutions do not currently exist. My dissertation research develops a more comprehensive understanding of the location and condition riparian ecosystems in a semi-arid, mountainous region by developing methods that can be applied to other geographic regions. To do this, I took a three pronged approach to mapping riparian zone location and condition. First, I identify and evaluate existing GIS-based methods that have been previously used to map riparian zones in order to determine how accurately the methods are in a semi-arid, mountainous watershed. Second, I create a multi-scale, hierarchal method to map riparian zones by capturing the dominant physical processes to map the location of current and potential riparian zones using readily available, national datasets and demonstrate the approach for the Southern Rockies Ecoregion. Third, I estimate riparian condition using a straightforward, cost-effective approach at management relevant scales (i.e. reach) and evaluate the dominant ecological and physical processes and anthropogenic stressors that impact riparian ecosystems. Results from my dissertation indicate that existing methods to map potential riparian zones are not very accurate, having only a maximum accuracy of kappa coefficient of 0.38. The most appropriate existing method for mapping potential riparian zones in semi-arid mountainous regions incorporates upstream drainage area and valley topography. I develop a multi-scale, hierarchical, process guided model to map riparian zones and found that the Southern Rockies Ecoregion is composed of 3.2% (± 0.3%) potential and 2.5 (± 0.3%) current riparian zones, indicating that 20.3% (± 1.1%) of riparian zones have been removed by human activities. Based on field verification/validation, my new method has an overall accuracy of 92% for potential riparian zones and 91% in the current riparian zones. Finally, the method I developed to predict riparian condition indicated that riparian zones in the Southern Rockies Ecoregion are comprised of 7.2% low condition, 15.2% medium condition, and 77.7% high condition and that the most important variables in predicting riparian condition in the Southern Rockies Ecoregion are human modification in riparian zones, the number of upstream transportation crossings, human modification within the upstream watershed, and the proportion of the upstream watershed that is protected by GAP Status 1 management plans. The overall accuracy of my riparian condition model was 60.5%. The model could be improved though the use of higher resolution predictor variables. If fine grain (< 5 m) terrain data were available for the study area, additional geomorphic variables, such as valley width to channel width ratio, could be developed and should enhance model performance.
Open Access
Assessing the use of dual-drainage modeling to determine the effects of green stormwater infrastructure networks on events of roadway flooding
(Colorado State University. Libraries, 2020) Knight, Kathryn, author; Bhaskar, Aditi, advisor; Arabi, Mazdak, committee member; Kampf, Stephanie, committee member
Roadway flooding occurs when a stormwater network does not have the capacity to drain all runoff generated by precipitation. Roadway flooding causes damage to infrastructure and property, risks to human health and safety, and disruptions to transportation systems. Green stormwater infrastructure (GSI) has been increasingly used to reduce stormwater input to the subsurface stormwater network, stormwater draining to urban streams, and to improve water quality. It is unclear how GSI interacts with surface runoff and stormwater structures to affect the spatial extent and distribution of roadway flooding. This interaction was explored using a dual drainage model with individual stormwater structures represented, fine spatial resolution, and bidirectional flow between the subsurface stormwater network and surface runoff. The model was developed using the Stormwater Management Model for PC (PCSWMM) in the urban watershed Harvard Gulch in Denver, Colorado. We examined how dual drainage modeling could reveal the effect of converting between 1% and 5% of directly connected impervious area (DCIA) in the watershed to bioretention GSI on the extent, depth, and distribution of roadway flooding. Results of the surface flooding model were generally co-located with resident reports related to flooding within the study area. Results show that even for 1% of DCIA converted to GSI, the extent and mean depth of roadway flooding was reduced for the duration of the simulation, and increasing GSI conversion further reduced roadway flooding depth and extent. We found diminishing returns in the roadway flood extent reduction per additional percentage of DCIA converted to GSI beyond 2.5%, whereas diminishing returns occurred beyond 1% conversion to GSI for mean roadway flood depth reduction. This work also examined the limitations to the accurate representation of roadway flooding due to incomplete input data, a lack of observational data for urban floods, GSI placement methods, and high computational demands. With future work to reduce limitations, detailed dual drainage modeling has the potential to better predict what strategies will mitigate roadway flooding.
Open Access
Changes in taxonomic and functional diversity of aquatic macroinvertebrates along a gradient of stream size and flow stability in the northeastern Colorado Rocky Mountains
(Colorado State University. Libraries, 2018) Lafferty, M Holliday, author; Poff, N. LeRoy, advisor; Kondratieff, Boris, committee member; Kampf, Stephanie, committee member
While the pattern of aquatic macroinvertebrate communities along stream size gradients have been examined in past studies, it is usually in the context of the river continuum, moving along a stream network from the headwaters to large rivers. The effect of stream size among small headwater streams has received less attention. With increasing temperatures and decreasing snowfall predicted in the Colorado Rockies, streams in the area are likely to decrease in size and have an increased likelihood of flow cessation in especially dry years. To understand how these changes will affect aquatic macroinvertebrate communities, this study explored differences in species occurring in streams of differing size and flow stability. I examined the taxonomic and functional diversity of aquatic macroinvertebrates in 12 headwater streams in the Cache la Poudre watershed of northern Colorado. Each stream was assigned a stream “type” based on size (measured by discharge and drainage area) and the stability of the flow throughout the summer. My results show that size was positively correlated with both taxonomic and functional richness. I found that the large streams with intermediate stability and small streams with stable flow had greater taxa and functional richness than did the small streams with intermediate flow and small streams with unstable flow, illustrating that flow stability is also important in determining macroinvertebrate communities. Certain species functional traits, such as inhabiting erosional zones and filter-feeding were found to be associated with increasing stream size and stability. I calculated β-diversity across the size and stability gradient and found that replacement of taxa (turnover) better explained among-site differences than did addition of taxa (nestedness). The specific taxa that prefer smaller streams were identified with indicator species analysis. Overall, these results indicate that the hotter and drier summers predicted by climate change models may lead to decreases in overall macroinvertebrate taxa and functional richness and potentially cause displacement of taxa as the smallest headwater streams become less stable.
Open Access
Comparing multi-level and full spectrum detention design for urban stormwater detention facilities
(Colorado State University. Libraries, 2010) Zhang, Xiaoju, author; Roesner, Larry A., advisor; Willson, Bryan D., advisor; Grigg, Neil S., committee member; Kampf, Stephanie, committee member
Peak flow attenuation and water quality control are widely used in urban stormwater systems. Standard practice typically involves peak shaving of post-development flows to pre-development peak flow levels to control flood flows and best management practices (BMPs) for removing pollutants from runoff. Usually both practices are integrated by using Multi-level Detention ponds. Recently, Wulliman and Urbonas (2005 and 2007) have proposed the so-called Full Spectrum Detention approach to design detention facilities able to control runoff events. This method is based on the concept of capturing the Excess Urban Runoff Volume (EURV) that results from urbanization and releasing it over a period of 72 hours. This method has been tested successfully for the Denver region and excellent matching of post-development peak flows to pre-development peak flows has been achieved. However, these results have been obtained using discrete design storms and the model has not been studied using a continuous simulation approach. Continuous simulations are useful because they provide information about the long-term performance through peak flow exceedance frequency and flow duration curves. Moreover, these results can be used to define the stream erosion potential, a metric that characterizes the geomorphic stability of urban streams. Continuous simulation has been successfully used to characterize the performance of Multi-level Detention method, which uses combined peak shaving and extended detention practices, and protocols to reduce urbanization impacts in different locations have been demonstrated with it. This study compares the effectiveness and differences of the Multi-level Detention design approach with that of the Full Spectrum Detention approach through the use of design storms and 60-year continuous precipitation records in a conceptual watershed for two different climate regions in the United States. The US EPA Stormwater Management Model (SWMM) is used to simulate the response of a conceptual watershed using both design approaches. Sensitivity analysis of the land-use properties is performed in order to validate the assumptions of the Full Spectrum Detention method by using both Colorado Unit Hydrograph Procedure (CUHP) and SWMM models. The performances of these two design approaches are tested initially by comparing the post-development peak flows for different design storms with the pre-development conditions. Additionally, 60 years of hourly rainfall records are used to run continuous simulations and compute peak flow frequency exceedance curves, flow duration curves, the hydrologic metrics T0.5, and average boundary shear stress curves, which are used to compute the stream erosion potential. The differences of both design methods are assessed by comparing the post-development results with those obtained for the pre-development conditions.
Open Access
Controls on groundwater-surface water interaction in a glacial valley, northern Colorado
(Colorado State University. Libraries, 2022) Doebley, Valerie, author; Ronayne, Michael, advisor; McGrath, Daniel, committee member; Kampf, Stephanie, committee member
In the last few decades, scientists determined that groundwater discharge may supply a significant portion of streamflow in mountain watersheds. However, difficulties with access and drilling typically limit the use of monitoring wells to study groundwater in high-elevation, mountainous catchments. The recent installation of two 10-meter-deep monitoring wells plus several riparian wells along the South Fork of the Cache la Poudre River at the Colorado State University Mountain Campus provided an opportunity for a unique hydrogeological study at a mountainous site. Data from these wells combined with numerical groundwater modeling helped quantitively and qualitatively characterize groundwater-surface water exchange along a ~2.7-km study reach. Analyses reveal complex temporal and spatial variation of gaining and losing stream conditions within the study reach. First, well water level elevations and groundwater modeling results indicate that the South Fork is generally gaining in the upper portion of the valley and losing near the downstream end. We suggest that valley geometry and channel planform influence the spatial differences in groundwater-surface water exchange along the study reach. Second, streamflow differencing and modeling results suggest that the study reach changes between overall gaining and overall losing stream conditions multiple times between May and October. We suggest that these temporal variations in groundwater-surface water exchange are driven by seasonal changes in surface water contributions to streamflow and evapotranspiration. Third, stable isotope (δ2H, δ18O) analyses and groundwater modeling results suggest that localized recharge from moraine ponds and stream leakage are important sources of aquifer recharge. These results indicate that groundwater and surface water at the Mountain Campus are highly interdependent, and that any disturbances that impact surface water contributions to streamflow may ultimately impact the groundwater contributions as well.
Open Access
Crossing a threshold: the legacy of 19th century logging on log jams and carbon storage in Front Range headwater streams
(Colorado State University. Libraries, 2013) Beckman, Natalie, author; Wohl, Ellen, advisor; Kampf, Stephanie, committee member; Niemann, Jeffrey, committee member; Rathburn, Sara, committee member
Instream wood has an important effect on the geomorphic and ecological function of streams, but human impacts have altered both the forests that supply wood and the streams themselves. These changes may have pushed many stream systems over a threshold past which the stream morphology and ecology do not return to their pre-disturbance state, but instead settle into a "new normal." This dissertation addresses the question of whether logging which took place in the 19th century has had lasting and significant effects on the instream wood and carbon storage of headwater streams in Colorado's Front Range. The distribution of logs within the headwaters of the Big Thompson River, North Saint Vrain Creek and Cache la Poudre River in northern Colorado were assessed to quantify the ways in which logs and forest characteristics relate to carbon storage within a stream. Characteristics of jams (size, number per kilometer) and carbon storage correlate most closely with reach-scale variables, implying that management would be most effective at the reach scale. Increased total wood load and decreased spacing between key pieces are the most important changes that can be made to promote the formation of jams within a reach. Old growth forest creates significantly different total carbon storage and partitioning of carbon storage, which extends previous work on the effects of old growth forest on terrestrial carbon to riverine environments.
Open Access
Dam overtopping and flood routing with the TREX watershed model
(Colorado State University. Libraries, 2014) Steininger, Andrew, author; Julien, Pierre Y., advisor; Niemann, Jeffrey, committee member; Kampf, Stephanie, committee member
Modeling dam overtopping and flood routing downstream of reservoirs can provide basic information about the magnitudes of flood events that can be beneficial in dam engineering, emergency action planning, and floodplain management. In recent years there has been considerable progress in computer model code development, computing speed and capability, and available elevation, vegetation, soil type, and land use data which has led to much interest in multi-dimensional modeling of dam failure, overtopping, and flood routing at the watershed scale. The purpose of this study is to ascertain the capability of the Two-dimensional, Runoff, Erosion and Export (TREX) model to simulate flooding from dam overtopping as the result of large scale precipitation events. The model has previously been calibrated for the California Gulch watershed near Leadville Colorado and was used for all of the simulations preformed for this study. TREX can simulate the reservoir filling and overtopping process by inserting an artificial dam into the digital elevation model (DEM) of a watershed. To test the numerical stability of the model for large precipitation events, point source hydrographs were input to the model and the Courant-Friedrichs-Lewy (CFL) condition was used to determine the maximum numerically stable time steps. Point sources as large as 50,000 m3/s were stably routed utilizing a model time step as small as 0.004 seconds. Additionally the effects of large flows on the flood plain were analyzed using point source hydrographs. The areal extent of floodplain inundation was mapped and the total areal extent of flooding was quantified. The attenuation of watershed outlet discharge due to upstream dams was analyzed. Three probable maximum precipitation (PMP) events and three estimated global maximum precipitation (GMP) events (the 1 hour, 6 hour, and 24 hour duration events), were simulated. Larger duration rainstorms had lower rainfall intensities but larger runoff volumes. A series of artificial dams ranging from 5 to 29 meters high were inserted into the DEM in sequential simulations and the attenuation of the downstream flood wave was quantified. The maximum attenuation of the peak discharge at the outlet of the watershed was 63% for an 18 meter high rectangular dam for the 1 hour PMP event, 58 % for a 20 meter high dam for the 6 hour PMP event, and 46% for a 29 meter high dam for the 24 hour duration PMP event. The same analysis was done using estimated global maximum precipitation (GMP) events. The maximum attenuation of the peak discharge at the outlet of the watershed was 59% for a 23 meter high rectangular dam for the 1 hour GMP event, 21 % for a 29 meter high dam for the 6 hour GMP event, and 9% for a 29 meter high dam for the 24 hour duration GMP event.
Open Access
Demand management' and injustice in rural agricultural irrigation in western Colorado: an anatomy of ambivalence
(Colorado State University. Libraries, 2022) MacIlroy, Kelsea E., author; Hempel, Lynn, advisor; Carolan, Michael, committee member; Malin, Stephanie, committee member; Kampf, Stephanie, committee member
The Colorado River is overdrawn. Decisions made a century ago created an institutional framework allowing overuse while climate change has exacerbated it with increasing temperatures and reduced natural flows. 'Demand management', a key component of the 2019 Upper Basin Drought Contingency Plans, would utilize water conserved from consumptive use to create a 500,000 acre-foot storage pool, only used to protect the Upper Basin of the Colorado River in the event they were unable to meet water delivery obligation to the Lower Basin. Rural irrigators on Colorado's West Slope would be the prime contributors to such a program, but largely responded with ambivalence. Increasingly, collaborative water governance is cited as the best way to create change in water distribution. However, if rural irrigators respond with ambivalence, why would they participate voluntarily in such a program? Using a grounded theory approach, interviews and focus groups with 45 participants, and participant observation, I explore why rural irrigators were ambivalent towards a program that would, ostensibly, protect them in times of water shortage. Drawing from the concept of sociological ambivalence and the literatures of water justice, hydrosocial analysis, and rurality, I describe the symbolic and material landscape that shapes perceptions of 'demand management'. I argue irrigators were ambivalent because they understood the need for water conservation, but they also perceived injustice in terms of distribution, recognition, and representation. Since rural irrigators are the linchpin in any water conservation program that would address overuse in the Colorado River Basin, their perceptions of injustice must be addressed. Findings provide key insight into water governance as it relates to crafting effective water policy.
Open Access
Effects of conjunctive use on streamflow at the Tamarack State Wildlife Area, northeastern Colorado
(Colorado State University. Libraries, 2012) Donnelly, Erin, author; Stednick, John, advisor; Ronayne, Michael, committee member; Sale, Thomas, committee member; Kampf, Stephanie, committee member
The Tamarack Recharge Project in northeastern Colorado is intended to augment the streamflow of the South Platte River by 10,000 acre-feet between April and September to increase aquatic habitat for four federally threatened or endangered bird and fish species in Nebraska. The project goal is to retime surface water flows by pumping unappropriated alluvial groundwater into a recharge pond where it infiltrates and returns to the river at critical low flow periods. Retimed surface water flow will help maintain critical habitat for native aquatic species by increasing streamflow without harming water rights holders. To evaluate the effects of this managed groundwater recharge on streamflow in the South Platte River, the hydrologic environment was characterized and quantified through streamflow monitoring, water table elevation mapping, and a groundwater tracer study. Stream discharge measurements were taken at 4 cross sections on the South Platte River. Two cross sections were considered upgradient of the recharge pond and two were downgradient of the recharge pond. The mean flow of the upstream cross sections was 2.64 cubic meters per second (cms) compared to 2.66 cms at the downstream cross sections, which was not a significant difference. A fluorescein tracer study was used to estimate groundwater travel times and hydraulic conductivity. Based on the arrival time of the breakthrough curve at different piezometers, the mean hydraulic conductivity was estimated to be 331 m/d. Using this value, the estimated return time to the South Platte River at 4 cross sections ranged from 92 to 534 days. Measurements of discharge and water table elevations suggesting that Tamarack Project did not produce a measureable increase in streamflow in the South Platte River during the target period are not indicative of project functionality. The annual volume of water pumped into the recharge pond was less than 1% of the annual yield of the South Platte River. While the volume of return flows did not produce measureable results in the river, data from the tracer study and in-stream vertical hydraulic gradient data indicate a gaining stream condition during the fall and a losing stream during the winter and early spring. Potential source(s) of groundwater discharging to the stream include the recharge pond and irrigation return flows and warrant further study.
Open Access
Estimating changes in streamflow attributable to wildfire in multiple watersheds using a semi-distributed watershed model
(Colorado State University. Libraries, 2023) Wells, Ryan, author; Niemann, Jeffrey D., advisor; Kampf, Stephanie, committee member; Nelson, Peter, committee member
Over half of western U.S. water supply is sourced from forested lands that are increasingly under wildfire risk. Studies have begun to isolate the effects of wildfire on streamflow, but they have used coarse temporal resolutions that cannot account for the numerous, interconnected watershed processes that control the responses to rainfall events. To address these concerns, we developed a method to isolate fine-scale (daily) effects of fire from climate. Wildfire effects were represented by the difference between measured post-fire daily streamflow and simulated unburned post-fire daily streamflow from a hydrologic model calibrated to pre-fire conditions. The method was applied to track hydrologic recovery after wildfires in six burned watersheds across the western U.S.: North Eagle Creek, NM (2012 Little Bear Fire), Lopez Creek, CA (1985 Las Pilitas Fire), and City Creek, Devil Canyon Creek, East Twin Creek, and Plunge Creek, CA (2003 Old Fire). All six watersheds experienced prolonged increases of post-fire streamflow, with the most consistent changes occurring during periods of low streamflow. Following 6 years of increased streamflow, Lopez Creek experienced 6 years of reduced streamflow, before returning to pre-fire streamflow behavior 12 years after the fire. North Eagle Creek and the four watersheds affected by the Old Fire continued to demonstrate elevated streamflow 9 and 18 years post-fire, respectively. This study demonstrates the utility of examining post-fire streamflow at daily resolution over multiple years. In particular, these results captured the variability of change across flow frequencies during recovery periods that would not be quantifiable otherwise.
Open Access
Estimation of catchment-scale soil moisture patterns from topography and reconstruction of a preserved ash-flow paleotopography
(Colorado State University. Libraries, 2012) Coleman, Michael Lee, author; Niemann, Jeffrey D., advisor; Salas, Jose D., committee member; Green, Timothy R., committee member; Kampf, Stephanie, committee member
This dissertation consists of three parts, two of which examine methods for estimating spatial soil moisture patterns while the third investigates the reconstruction of a fluvially-eroded paleotopography. Part I of the dissertation evaluates unsupervised machine-learning techniques' effectiveness for estimating soil moisture patterns and compares them with linear regression. Physical processes that impact soil moisture are typically expressed as nonlinear functions, but most previous research on the estimation of soil moisture has relied on linear techniques. In the present work, two machine learning techniques, a spatial artificial neural network (SANN) and a mixture model (MM), that can infer nonlinear relationships are compared with multiple linear regression (MLR) for estimating soil moisture patterns using topographic attributes as predictor variables. The methods are applied to time-domain reflectometry (TDR) soil moisture data collected at three catchments with varying characteristics (Tarrawarra, Satellite Station, and Cache la Poudre) under different wetness conditions. The methods' performances with respect to the number of predictor attributes, the quantity of training data, and the attributes employed are compared using the Nash-Sutcliffe Coefficient of Efficiency (NSCE) as the performance measure. The performances of the methods are dependent on the site studied, the average soil moisture and the quantity of training data provided. Although the methods often perform similarly, the best performing method overall is the SANN, which incorporates additional predictor variables more effectively than the other methods. Next, Part II of the dissertation presents the development and testing of a new conceptually-based model for estimating soil moisture patterns and describes the investigation of the climatic, vegetation and soil characteristics that affect pattern organization and temporal stability with the model. Soil moisture is a key hydrologic state variable for the Earth's surface affecting both energy and precipitation partitioning. Additionally, the nonlinear dependence of hydrologic processes on soil moisture means that not only is the average moisture condition important for many applications, but the spatial patterns of soil moisture are also important. At the catchment scale, soil moisture patterns have been observed to exhibit different types of dependence on topography. Some catchments have their wettest locations in the valley bottoms, while others have their wettest locations on hillslopes that are oriented away from the sun. Additionally, some catchments have moisture patterns that maintain a similar organization at all times (time stability), while other catchments have soil moisture patterns that change through time (time instability). Although these tendencies are well known, the reasons for their occurrence at a particular catchment are not well understood. In this paper, we investigate the conditions under which the different types of topographic dependence and different degrees of time instability occur through the use of a new conceptual model. The type of topographic dependence and the degree of instability are quantified by two metrics that are also introduced in the paper, and the effects of soil, vegetation, and climatic parameters on these metrics are then evaluated. The evaluations indicate that saturated horizontal hydraulic conductivity, pore disconnectedness, vegetation evapotranspiration efficiency, and an exponent relating the horizontal hydraulic gradient to the topographic slope have the strongest effects on the organization and instability of the soil moisture patterns. In contrast, annual potential evapotranspiration alone does not strongly impact the organization or its stability. Finally, Part III of the dissertation describes the modification of a previously-developed interpolation scheme for fluvial topography and the reconstruction of a paleotopography that may be potentially important to groundwater movement by the modified method. Many applications in geology require estimation of the depth and thickness of lithologic layers based on limited observations. The boundaries of such layers are typically estimated using Kriging or other estimation methods that produce smooth surfaces. In some cases, however, smooth surfaces may be inappropriate. A boundary that is formed by a preserved hillslope and valley paleotopography, in particular, is expected to exhibit drainage characteristics and inherent roughness that are not consistent with standard estimation methods. This paper discusses the generalization of a technique originally designed to interpolate fluvially-eroded topography. The method incorporates a simple river basin evolution model to generate realistic topography and adjusts an erodability parameter in space to match observed elevations. The method is generalized to allow flow to enter from outside the interpolation region, which is a likely scenario when reconstructing paleotopography. The method is then applied to the lower boundary of the Tshirege Member of the Bandelier Tuff, which underlies Los Alamos National Laboratory and Bandelier National Monument in north-central New Mexico. The method produces surfaces with major valleys that are consistent with previous observations. The method is also applied in a framework that estimates the likelihood that any particular point within the interpolation region drains through a specified boundary. Although the surfaces vary between simulations, most portions of the interpolation domain drain through consistent boundaries.
Open Access
Evaluating L-band radar for the future of snow remote sensing
(Colorado State University. Libraries, 2024) Bonnell, Randall, author; McGrath, Daniel, advisor; Fassnacht, Steven, committee member; Kampf, Stephanie, committee member; Marshall, Hans-Peter, committee member; Ronayne, Michael, committee member
Snowpack monitoring is essential because seasonal snowpacks provide water for billions of people, support streamflow and ecosystems, and are a fundamental component of the Earth's energy system. However, no current snowpack monitoring system is capable of measuring snow water equivalent (SWE), the most important snowpack hydrologic variable, accurately and at high spatiotemporal (<500 m, 20 km of nearly continuous relative permittivity estimates, and thereby bulk density, from combined near-coincident measurements of GPR two-way travel times and lidar snow depths at three different field sites and in both dry and wet snow conditions. Variogram analyses were conducted and revealed a 19 m median correlation length for relative permittivity and density in dry snow. For wet snow, the correlation length increased to >30 m. I then leveraged the derived densities to evaluate six snow density models to better understand the limitations of these models within lidar and radar remote sensing methods. Two models yielded densities that estimated SWE within ±10% when SWE exceeded 400 mm, but model uncertainty increased to >20% when SWE was less than 300 mm. Thus, the refinement of these density models and the development of future density models is a high priority to fully realize the potential of SWE remote sensing methods. The L-band (1–2 GHz) InSAR technique for measuring changes in SWE (ΔSWE) is a promising method for SWE retrievals because the longer wavelength (~0.25 m) has minimal interaction with the snowpack microstructure and has increased canopy penetrative capabilities. In Chapter 3, I evaluated 10 L-band InSAR pairs collected by NASA UAVSAR near Cameron Pass, Colorado with GPR and terrestrial lidar measurements of ΔSWE in open meadows and burned forests. For single InSAR pairs, UAVSAR ΔSWE retrievals yielded an overall Pearson's correlation coefficient of 0.72–0.79, with a RMSE of 19–22 mm. I expanded the analysis beyond the locations of GPR and lidar surveys to evaluate the time series of UAVSAR SWE retrievals by including measurements of SWE from seven automated stations and found a RMSE of 42 mm. These findings support the use of this technique in unforested areas with dry snow conditions for the upcoming L-band NISAR satellite mission Given the findings of Chapter 3 and the canopy penetration capabilities of L-band radar, I designed Chapter 4 to evaluate the influence of forest cover on the UAVSAR signal. In Chapter 4, I evaluated eight L-band InSAR pairs collected by UAVSAR over the montane forests of Fraser Experimental Forest, Colorado with manually surveyed snow depths and snow pits and a pair of airborne lidar surveys. Compared with in situ measurements, I found that forest cover fractions <40% yielded RMSEs of ~15 mm, whereas RMSE more than doubled for forest cover fractions >50%. Further, normalized cumulative UAVSAR SWE and normalized lidar snow depths yielded identical statistical distributions for forest cover fractions <50% across the full study area, but these distributions diverged as forest cover fraction increased. Thus, forest cover fraction is a significant source of uncertainty for L-band InSAR retrievals of SWE, but this technique may be the first space-borne technique capable of retrieving SWE below non-dense forest canopy without any a priori information.
Open Access
Evaluating post-fire geomorphic change on paired mulched and unmulched catchments using repeat drone surveys
(Colorado State University. Libraries, 2023) Hayter, Lindsey, author; Nelson, Peter, advisor; Kampf, Stephanie, committee member; Morrison, Ryan, committee member
Sediment redistribution after wildfire can dramatically alter a catchment and pose risks to local infrastructure and water quality. Mulch application is increasingly being used to mitigate post-fire hillslope runoff and erosion, although relatively little is known about its effects at the catchment scale. In this study we used repeat drone surveys to measure erosion and deposition across 6 small (0.5-1.5 km2) catchments, 3 mulched and 3 unmulched, in the 2020 Colorado Cameron Peak Fire burn scar. The objectives were to (1) quantify sediment volumes and spatial patterns of erosion and deposition on a catchment and channel scale, (2) compare geomorphic change to mulch coverage, vegetation cover, precipitation intensity, burn severity, and morphologic metrics, and (3) identify conditions in which mulch may be most appropriate based on findings. Initial drone surveys were gathered in the spring of 2022 shortly after mulching and were differenced to surveys collected in fall of 2022, capturing the erosional effects of a Colorado monsoon season within a 6.4 cm horizontal resolution DEM of Difference (DoD). Structure from motion (SfM) errors were thresholded out of the DoD to yield maximum and mean levels of detection at 14 cm and 5 cm respectively. Vegetation was filtered from the DoD by supervised classification of vegetation in the drone imagery. We found hillslope erosion dominated the sediment budget, with the mulched catchments eroding 141% more per area than the unmulched. A regression model suggested erosion to be most influenced by vegetation, hillslope length, and maximum 60-minute rainfall intensity. Channels were overall net depositional, and patterns of erosion and deposition in channels were controlled by changes in slope and stream power as well as local morphologic metrics. Our analysis does not find a significant impact of mulch at the catchment scale especially when coverage is low (~22%) and highlights the importance of understanding catchment attributes and processes when making post-fire treatment decisions.
Open Access
Evaluation of sampling techniques to characterize topographically-dependent variability for soil moisture downscaling
(Colorado State University. Libraries, 2013) Werbylo, Kevin, author; Niemann, Jeff, advisor; Green, Tim, committee member; Kampf, Stephanie, committee member
Soil moisture patterns are an important consideration in many catchment-scale hydrologic applications. Unfortunately, estimating soil moisture patterns at resolutions that are appropriate for these applications (e.g., grid cells with a linear dimension of 10 to 50 m) is difficult. Downscaling methods can be used to estimate catchment-scale soil moisture patterns from coarser resolution estimates or spatial average soil moisture values. These methods usually infer the fine-scale variability in soil moisture using variations in ancillary variables like topographic attributes that have relationships to soil moisture. Previously, such relationships have been observed in catchments using soil moisture observations taken on uniform grids at hundreds of locations on multiple dates, but collecting data in this manner limits the applicability of this approach. The objective of this paper is to evaluate the effectiveness of two strategic sampling techniques for characterizing the relationships between topographic attributes and soil moisture for the purpose of constraining downscaling methods. The strategic sampling methods considered are conditioned Latin hypercube sampling (cLHS) and stratified random sampling (SRS). Each sampling method is used to select a limited number of locations and/or dates for soil moisture monitoring at three catchments with detailed soil moisture datasets (Tarrawarra, Satellite Station, and Cache la Poudre). These samples are then used to calibrate two available downscaling methods, and the effectiveness of the sampling methods is evaluated by the ability of the downscaling methods to reproduce the known soil moisture patterns at the catchments. The results show that cLHS and SRS can characterize the relationships between soil moisture and ancillary topographic variables with many fewer locations and dates than previously used. For example, when the number of locations for soil moisture monitoring is reduced by 82-90% and these locations are only monitored on 3 dates, the explanatory power of the downscaling methods frequently only reduces by less than 50%. Furthermore, both strategic sampling methods can substantially outperform random sampling when the number of samples is limited.
Open Access
From the Colorado Front Range to global topography: evaluating the roles of tectonics and climate on long term landscape evolution
(Colorado State University. Libraries, 2022) Marder, Eyal, author; Gallen, Sean, advisor; Pazzaglia, Frank, committee member; Wohl, Ellen, committee member; Schutt, Derek, committee member; Kampf, Stephanie, committee member
Landscapes are primarily shaped by the interactions between tectonics and climate, and their interplay and relative roles in landscape evolution over thousands to millions of years have a significant impact on global erosion and nutrient and sediment productions. Thus, understanding and quantifying the impact of tectonics and climate on short- to long-term landscape evolution has large implications on natural global cycles (e.g., climate change, atmospheric and terrestrial carbon circulations), biodiversity and ecological sustainability, hazard management (e.g., earthquakes, landslides), infrastructure planning, and decision making. In the last decades, significant progress has been made in the field of tectonic geomorphology to try and resolve the relative roles of tectonics and climate in landscape evolution. Yet, many questions remained unresolved, for instance: - What drives landscape evolution in post-orogenic settings? - What is the relative role of climate in landscape evolution at the global scale? In my PhD, I address these questions by investigating the impact of tectonics and climate on fluvial topography and geomorphology at different spatiotemporal scales. In my first chapter, I present a local study in the southern Colorado Front Range to explore the relative roles of tectonics and climate on observed landscape unsteadiness that affected the area during the late Cenozoic. In the second chapter, I extend this study and address this question to the scale of the entire Colorado Front Range. In my third chapter, I explore the impact of climate on fluvial topography at the global scale. For all these studies, I integrate field data, digital topographic analysis, geochronology, and modeling to compare new and existing predictions for the roles of tectonics and climate at the local (chapter I), regional (chapter II), and global (chapter III) scales to empirical observations. Results from these studies shed light on some ongoing controversies (e.g., what drives topographic rejuvenation in the Colorado Front Range) and resolve misunderstood concepts (e.g., how climate is recorded in fluvially-dominated landscapes). The first and third chapters in this dissertation were submitted to peer-reviewed journals and are under review, while the second chapter is in its final stage as a third manuscript for a peer-reviewed journal. FIRST CHAPTER: LATE CENOZOIC DEFORMATION IN THE SOUTHERN COLORADO FRONT RANGE REVEALED BY RIVER PROFILE ANALYSIS AND FLUVIAL TERRACES Post-orogenic landscapes are important sources of sediment and nutrients relevant to many natural global cycles and ecological sustainability. Many of these settings exhibit evidence of recent landscape unsteadiness, but their driving mechanisms are poorly understood. The Colorado Front Range (FR), a post-orogenic setting that maintains high relief, elevated topography, and evidence of ongoing unsteadiness, is a good example of this enigma. Two prevailing hypotheses have been proposed to explain the geologically-recent landscape unsteadiness in the FR: (1) mantle dynamics and active tectonics during the late Cenozoic; (2) enhanced erosional efficiency associated with a Quaternary climate change. Here we evaluate these end-member hypotheses through a case study of tectonic geomorphology of the Upper Arkansas River basin in southern Colorado. We perform river profile analysis on bedrock channels in the eastern Rockies and map and analyze fluvial terraces in the western High Plains. We find that knickpoints in the eastern Rockies record a one- to two-stage increase in base level fall rate downstream of the FR mountain front and an eastward increase in the magnitude of incision. Similarly, terraces in the western High Plains record an eastward increase in the magnitude of incision. Collectively, and supported by flexural and supplemental geomorphic analyses, these results suggest a previously undetected regional-scale, west-directed back tilting signal associated with differential rock uplift. Based on existing geodynamic models, we interpret these deformation patterns and related landscape response as a result of a migrating dynamic topography that swept the southern FR from west to east during the late Cenozoic. SECOND CHAPTER: TECTONIC AND GEODYNAMIC CONTROL ON REJUVENATION IN THE COLORADO ROCKY MOUNTAINS The Colorado Rocky Mountains (CRM) ancient foreland basin, currently known as the High Plains, shows a steeper long-wavelength tilt away from its hinterland relative to other active mountain range foreland basins worldwide. Further, studies showed that the High Plains experienced a transition from a system of net deposition to one characterized by net erosion at ~5 Ma. However, the mechanisms proposed to explain these observations are the center of ongoing debate. Some argue that the tilting and the transition from deposition to erosion were facilitated by tectonically- or geodynamically-driven changes in rock uplift rate, while others argue that these records are simply the result of an increase in erosional efficiency driving river incision and relaxation with some amount of isostatic rebound. One of the main reasons this controversy continues is that empirical studies trying to address this question were conducted mostly in the High Plains, where landscape geomorphic signatures used to distinguish between these two hypotheses are ambiguous. Here, we conduct a geomorphic analysis of the Colorado Rockies, which lies upstream of the High Plains province and is characterized by a harder crystalline basement, where bedrock rivers might still achieve a record of the transient landscape of the CRM and help clarify potential drivers. We combine river profile analysis with a compilation of new and existing basin average erosion rates from cosmogenic 10Be and channel incision rates from luminescence dating on fluvial terraces to differentiate two geomorphic zones in the Colorado Rockies: 1. an upper, relict topography upstream of convex upward knickpoints that is consistent with lower long-term background erosion rates of ~0.03 mm/yr and lower channel steepness of ~80-100 m0.9; 2. a transient landscape downstream of these knickpoints that is consistent with higher channel incision rates of ~0.3 mm/yr and higher channel steepness that increases systematically from ~150 m0.9 in the northern CRM to 300 m0.9 in the southern CRM. These results and their spatial patterns across the CRM are inconsistent with existing predictions from a climate-induced increased erosional efficacy during the last Cenozoic. Rather, they imply a long-wavelength deformation and a sustained tectonic uplift rate associated with active tectonics and geodynamics that impacted the CRM in the last 5 Ma. THIRD CHAPTER: CLIMATE CONTROLS ON FLUVIAL TOPOGRAPHY Conceptual and theoretical models for landscape evolution suggest that fluvial topography is sensitive to climate. However, it has remained challenging to demonstrate a compelling link between fluvial topography and climate state in natural landscapes. One possible reason is that many studies compare erosion rates to climate data, although theoretical studies note that, at steady-state, climate is encoded in topography rather than in erosion rates. Here, we use an existing global compilation of 10Be basin average erosion rates to isolate the climate signal in topography for fluvially-dominated catchments underlain by crystalline bedrock that appear to be in morphological steady state. Our results show that the nonlinearity between erosion rates and the normalized river channel steepness index, which is a proxy for fluvial relief, systematically increases with increasing mean annual precipitation and decreasing aridity. When interpreted in the context of detachment-limited bedrock incision models that account for incision thresholds and stochastic distribution of floods, this systematic pattern can be explained by a decrease in discharge variability in landscapes that are wetter and less arid, assuming incision thresholds are important. Our results imply a climate control on topography at a global scale and highlight new research directions that can improve understanding of climate’s impact on landscape evolution.
Open Access
Geospatial analysis of specific degradation in South Korea
(Colorado State University. Libraries, 2019) Kang, Woochul, author; Julien, Pierre Y., advisor; Grigg, Neil S., committee member; Morrison, Ryan, committee member; Kampf, Stephanie, committee member
South Korea experienced many local and concentrated sediment problems such as landslides, upland erosion, rills and valleys, aggradation/degradation, and flood plain sediment deposition. These problems vary in space and time, therefore a reliable and consistent approach to model sediment processes is desirable. In contrast to sediment yield at the basin scale, Specific Degradation (SD) is defined as the ratio of the sediment yield divided by the watershed area. Field measurements of discharge and sediment concentration are analyzed at 70 stations in South Korea. Half of the sampled river basins (35 stations) represent streams in mountain regions and the other half represent rivers. The Modified Einstein Procedure (MEP) was used to determine the total sediment load at all stations. The Flow Duration – Sediment Rating Curve (FD-SRC) method was used to determine the sediment yield and specific degradation for all gauging stations. The annual sediment yield of 70 rivers and streams in South Korea ranged from 10 to 1,000 tons/km2▪yr. The application of three existing models from the literature showed Root Mean Square Errors (RMSE) in excess of 1,400 tons/km2▪yr and gave negative values of the Nash-Sutcliffe Efficiency coefficient (NSE) for existing models, which indicates that the observed mean is a better predictor than the model. The main characteristics of each watershed were analyzed using GIS tools such as ArcGIS version 10.3.1. The data used for the analysis included: (1) daily precipitation data at 60 stations from the Korea Meteorological Administration (KMA); (2) a detailed soil map from the National Institute of Agriculture Sciences; (3) a 5m by 5m resolution Digital Elevation Model (DEM); and (4) land cover raster data at a 10 m resolution from the Ministry of Environment (ME). Seven regression models based on these watershed characteristics are proposed to estimate the mean annual sediment yield and specific degradation. In decreasing order of importance, the meaningful parameters are: (1) drainage area; (2) mean annual precipitation; (3) percentage of urbanized area; (4) percentage of sand of the surface soil (upper 50cm); (5) percentage of wetland and water; and (6) morphometric parameters such as watershed average slope and two parameters of the hypsometric curve. The RMSE for the newly developed models decreased to 90 tons/km2▪yr and the NSE increased from -50 to 0.5, which shows good agreement between the model and the measured sediment yield on these watersheds. The calculated specific degradation and mean annual soil loss of mountain streams were larger than alluvial rivers. Erosion loss mapping at 5m, 30m and 90m was also developed from the Revised Universal Soil Loss Equation (RUSLE). Satellite images and aerial photos were used to better represent geospatial features affecting erosion and sedimentation. Long-term reservoir sedimentation measurements were available to determine the Sediment Delivery Ratio (SDR). An important finding from this analysis is that the percentage of the area covered with wetland and water is well-correlated with the estimated sediment delivery ratios. It suggests that the transfer of sediment to the rivers is affected by wetlands located near alluvial rivers. The erosion maps at 5m resolution could clearly show unique erosion features (i.e. hill slopes, croplands, and construction sites) and locate areas for sediment deposition (i.e. wetlands and agricultural reservoirs). In comparison, the gross erosion rates at 90 m resolution were highly distorted and could not delineate the areas with high upland erosion rates. Sustainable sediment management with these methodologies could be helpful to solve various erosion and sedimentation problems.
Open Access
Great river wood dynamics in northern Canada
(Colorado State University. Libraries, 2016) Kramer, Natalie, author; Wohl, Ellen, advisor; Rathburn, Sara, committee member; Kampf, Stephanie, committee member; Leisz, Stephen, committee member
Downed wood is a resource easily utilized by plants and animals from the forests to the sea and is essential for many ecosystems. The diverse benefits that wood brings to streams and riparian corridors are well documented by river scientists and wood re-introduction is commonly used as a river restoration tool. However, much of the existing work investigates the short-term impact of wood rather than its variability through time and legacy on the landscape. In this dissertation, I use the Slave River (water discharge=2-7 x103 m3 s −1 , channel widths=300-2000 m, drainage area=6x105 km2 ), and its receiving sedimentary basin, the Great Slave Lake (surface area=273 km2 , depths 20-600 m, volume 1000-2000 km3 ), in northern Canada to better understand wood transport dynamics of a major river basin across varied timescales from minutes to centuries and the influence of driftwood on shoreline landscape evolution. The four primary contributions of this work are: a comprehensive literature review and synthesis of wood transport in rivers worldwide (Chapter 1), new methods for monitoring and quantifying wood flux with timelapse cameras (Chapter 2), description of processes among driftwood, sediment, and vegetation that result in shoreline features that I have coined "driftcretions" (Chapter 3), and expansion of wood transport research into multiple timescales with a focus on how flow history impacts magnitude of wood flux (Chapter 4). In Chapter 1, I: qualitatively summarize existing transport research around flow, wood and reach characteristics, quantitatively consolidate and analyze wood mobility field data in relation to increasing channel size, identify disconnects between driving processes and how mobility is measured, and constrain and conceptualize thresholds between wood dynamic ii regimes. In Chapter 2, I introduce a cheap, useful and fast way to monitor and estimate wood flux with timelapse photography through the use of the metric p, the probability of seeing wood within a timeframe, and I provide statistical methods to estimate appropriate sampling intervals to minimize bias and variance. In Chapter 3, I describe processes and rates by which pulsed driftwood export are delivered and accreted to shorelines and I discuss how these processes influence rates of carbon sequestration, sediment storage and habitat formation. In Chapter 4, I use a variety of methods centered around repeat photography and anecdotes to assess temporal variability of pulsed driftwood flux through the Slave River in the past century. Findings in this dissertation provide useful information for understanding pulsed wood flux, shoreline dynamics and landforms in marine and terrestrial water bodies before widespread historical deforestation, damming of rivers, and wood removal along major waterways. I not only synthesize and link existing work on wood mobilization, transport and deposition to an intriguing case study, but challenge existing wood transport premises, provide new conceptual models describing processes of wood transport through drainage networks, and present new approaches and methods for quantifying and analyzing the variability in wood flux and influence of wood deposits on landforms. My descriptions of wood transport and shoreline processes prior to development of river corridors will be an invaluable resource to groups who seek to identify environmental impacts of dams and to scientists who are investigating the impact that past and future development of river corridors has had or will have on ecosystems.