WorldCat Identities

Mitchell, Robert J. (Geologist)

Overview
Works: 29 works in 54 publications in 1 language and 63 library holdings
Genres: Academic theses  Case studies  Internet videos 
Classifications: LD5778.9, 551.49
Publication Timeline
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Most widely held works by Robert J Mitchell
The hydrogeology of north Lummi Island, Washington by William M Sullivan( )

2 editions published in 2005 in English and held by 4 WorldCat member libraries worldwide

Lummi Island is a 10.8 square mile island in the northern Puget Sound Region, west of Bellingham, Washington. The population of Lummi Island has grown steadily for decades to approximately 900 permanent and 1,500 seasonal residents. The increasing demand for groundwater resources on the island has caused some wells to experience seasonal shortages and seawater intrusion, prompting an assessment of the hydrogeology for growth-management purposes. My study focused on characterizing the hydrogeology of the north half of the island (3.9 square miles) where most residents live and where groundwater is the sole source of potable water. I examined data collected from up to 130 wells including well logs, seasonal water level measurements, water chemistry, and precise GPS well-head elevations and positions. From these data, I created a three-dimensional bedrock and unconsolidated stratigraphic model using Department of Defense Groundwater Modeling Software. A dramatically undulating bedrock surface is concealed nearly everywhere by mostly fine-grained unconsolidated Pleistocene deposits up to 300 feet thick. Bedrock in the study area is dominated by tightly-folded sandstone, shale, and conglomerate of the Tertiary Chuckanut Formation (sandstone) in the north. This is separated by a deep southeastnorthwest trending trough from metamorphosed volcanics of the pre-Tertiary Fidalgo opiolite sequence (greenstone) in the south. The stratigraphic model and potentiometric data were used to identify and define the extent, volume, and thickness of at least 12 distinct aquifers. The major aquifer is the Sandstone Aquifer, one of two separate bedrock aquifers that occupy the majority of the study area. Half of 130 wells examined are in sandstone and greenstone. Hydraulic properties including horizontal hydraulic conductivity, estimated from well log data, indicate the Sandstone Aquifer is in the upper range of textbook values for fractured sandstone. The Greenstone Aquifer is much smaller and has the lowest hydraulic properties of any in the study area. Seasonal water level fluctuations are greatest in the bedrock aquifers. Ten Pleistocene aquifers were identified as thin, largely discontinuous coarse-grained (mostly sand) lenses within less permeable, fine-grained silt-clay diamicton. These aquifers fill depressions in the bedrock surface. Seven Pleistocene aquifers lie below sea level and three are perched well above sea level. The Legoe Bay and Nugent aquifers are the largest and most utilized Pleistocene groundwater source, occupying most of the southern half of the study area. These aquifers have the highest hydraulic properties and mostly negligible seasonal water level fluctuations. Recharge areas identified through the stratigraphic model, potentiometric surfaces, and water chemistry occupy the inland and upper regions of the study area. Infiltration of water through overlying glacial drift into bedrock aquifers is the most important recharge mechanism because of their large areal extent and because many Pleistocene aquifers receive recharge, in part, from where they are in contact with saturated bedrock. The average recharge magnitude, estimated from a site-specific water-mass balance, is 8 inches/year or 24% of average annual precipitation. A chloride-mass balance, performed as a semi-independent estimate, establishes a lower bound for recharge of 4 inches/year or 11% of average annual precipitation. Water-chemistry data vary among aquifer media. Water chemistry in the Sandstone Aquifer is dominated by sodium ions while most Pleistocene aquifers are dominated by calcium ions. Despite that nearly 80% of all wells that are completed below sea level, wide-spread seawater intrusion is not evident. Only 5 wells were determined to be intruded and, 14 additional wells may be experiencing some degree of intrusion. Occurrences of seawater intrusion are localized and are most common in the Sandstone Aquifer where low storage and fracture flow combine to increase contamination susceptibility
An investigation of denitrification events along Pangborn Creek in the Abbotsford-Sumas aquifer, Washington by Leslie B McKee( )

2 editions published in 2004 in English and held by 3 WorldCat member libraries worldwide

The Abbotsford-Sumas aquifer is a shallow, unconfined aquifer located in the agricultural regions of southwestern British Columbia and northwestern Washington and has a history of nitrate contamination. I monitored nitrate distributions in a study area bisected by a wide- scale peat deposit within a portion of the Whatcom County component of the aquifer to assess the current nitrate distribution, evaluate ground and surface water interactions in the peat, and determine the affect of peat on denitrification. The water quality dataset and statistical analyses showed that nitrate contamination was heavily concentrated upgradient of the peatlands. In general, shallow wells (<10 m below the median water>table) north of the peatlands had higher nitrate concentrations than deeper wells (>10 m below the median water table). Some upgradient wells showed low nitrate concentrations and data suggest they received denitrified ground water from unmapped peat deposits. Nitrogen isotope data ([lower case delta]15N on nitrate) indicated that nitrate sources included manure and inorganic commercial fertilizers. The contamination south of the peatlands was significantly lower than the contamination to the north and the median nitrate levels within the peatlands were near the detection limit. Nitrogen gas measurements and a combination of nitrogen ([lower case delta]15N on nitrate) and oxygen ([lower case delta]180 on water) isotopes confirmed that denitrification occurred in the peatlands and in much of the ground water south of the peatlands. In addition, the gas measurements suggested that iron, manganese, sulfate, and methane occurred throughout the peatlands and may have contributed to redox reductions. The implication of these findings is that a natural means for nitrate reduction exists in this region. Hydrostratigraphic data suggest that peat deposits occur throughout Whatcom County at various unmapped depths. Identifying these peat deposits and quantifying the upgradient ground water nitrate contributions may help facilitate nutrient management in the region
Quantifying the glacial meltwater component of streamflow in the middle fork Nooksack River, Whatcom County, WA, using a distributed hydrology model by Carrie B Donnell( )

2 editions published in 2007 in English and held by 3 WorldCat member libraries worldwide

Glacial meltwater is a vital component of rivers and streams in glaciated regions such as the Pacific Northwest, and can be critical for municipal water supplies, power generation, and habitat issues. The Middle Fork of the Nooksack River is fed by meltwater from Deming Glacier on Mount Baker, WA. The City of Bellingham has been diverting water from the Middle Fork since 1962 to supplement the water supply, and to maintain water quality in Lake Whatcom, the water source for the city. Because of regulations, water is only diverted when the Middle Fork exceeds minimum acceptable streamflow. A concern for water resource managers in Whatcom County, WA, is that Deming Glacier is retreating. In this study, the Distributed Hydrology Soils Vegetation Model (DHSVM) is used to perform a detailed assessment of the hydrology in the Middle Fork basin, to quantify future meltwater contributions to the Middle Fork Nooksack River as Deming Glacier continues to retreat, and to evaluate streamflow contributions based on predicted climate change. DHSVM is a physically based, spatially distributed hydrology model that simulates a water and energy balance at the pixel scale of a digital elevation model (DEM). DHSVM requires multiple GIS input grids to characterize the watershed including a DEM, soil type, soil thickness, vegetation, stream network, and watershed boundary. Required meteorological input includes an hourly time series of air temperature, relative humidity, incoming shortwave and longwave radiation, and wind speed. Meteorological data were compiled from historical records of lower-altitude weather stations. The model was calibrated to measured snow-water equivalent at the Middle Fork SNOTEL station and stream discharge at the USGS stream gauge on the Middle Fork using a 1-hour time step and 50 m GIS grid resolution. Once calibrated, the model was applied to examine the effects of glacier size on streamflow. The model was also applied to simulate future streamflow based on predicted future climate change scenarios. The estimated glacial meltwater component of late-summer streamflow as defined by the 2002 glacier coverage and present climate conditions was between 8.4% and 26.1%, depending on the climate of a given year (wet year vs. dry year). The late-summer glacial meltwater component was greater for drought simulations and predicted climate simulations, but less for increased precipitation simulations. DHSVM consistently simulated a smaller glacial meltwater component for progressively smaller glaciers. Simulation results suggest that late-summer streamflow in the Middle Fork could be reduced by as much as 8.6% as the direct result of glacier shrinkage predicted in the next fifty years, or by as much as 15.7% as the result of glacier shrinkage and predicted climate change for the same time period. Glacier shrinkage could have significant implications for salmon habitat and migration during the late-summer, and may in turn compromise the feasibility of the Middle Fork Nooksack diversion. Further research is necessary to evaluate the effects of glacier shrinkage on the entire Nooksack watershed, particularly the North Fork
Application of a nitrate fate and transport model to the Abbotsford-Sumas aquifer, Whatcom County, Washington by Margo A Burton( )

2 editions published in 2007 in English and held by 3 WorldCat member libraries worldwide

The Abbotsford-Sumas aquifer is a shallow, unconfined aquifer located in an agriculturally intensive area in northwestern Washington and southwestern British Columbia. Due to aquifer characteristics and surface land use, the Abbotsford-Sumas aquifer has had a history of nitrate contamination from non-point sources. As such, nutrient managers are interested in predictive tools to evaluate management strategies. I assessed the effectiveness of a GIS based nitrate fate and transport model developed specifically for the Abbotsford-Sumas aquifer by Almasri and Kaluarachchi (2004) as a predictive tool for nutrient management. This model couples four sub-models that collectively estimate nutrient loading, predict soil-nitrogen dynamics (NLEAP), calculate groundwater velocity (MODFLOW), and nitrate fate and transport in groundwater (MT3D). The model was used to validate measured nitrate concentrations in the aquifer, and to assess the impact of land use changes and irrigation on nitrate concentrations. Validating nitrate concentrations was difficult due to the model's design as a single layer aquifer. For those well sites with similar modeled and measured depths, the model was fairly effective at predicting nitrate concentration. Previous work has shown that nitrate is stratified in the Abbotsford-Sumas aquifer, but this fate and transport model estimates the same nitrate concentration for an entire water column. The model was sensitive to land use changes; however, the scale of the model is too coarse to capture local changes and seasonal variation. Changes in irrigation rate and concentration showed little change in resulting nitrate leaching. This lack of response is contrary to previous work, and indicates that the model underestimates irrigation's impact on groundwater nitrate concentrations
Applicability of the nlos model for predictions of soil water movement and nitrogen transport in an agricultural soil, Agassiz, BC by Heather R Hirsch( )

2 editions published in 2007 in English and held by 3 WorldCat member libraries worldwide

The Abbotsford-Sumas aquifer is a shallow, unconfined aquifer in northern Whatcom County, WA and southern British Columbia, Canada that is contaminated with nitrates due to agricultural land use. Currently, conservation managers rely on Post-Harvest Soil Nitrate Tests (PHSNTs) to predict nitrate leaching potential to the aquifer. However, these tests have limitations as an assessment tool because of their inaccuracy. Therefore, US and Canadian government agencies are considering the NLEAP on STELLA (NLOS) leaching model as an additional tool for assessing nutrient management strategies. NLOS is an adaptation of the Nitrogen Leaching and Economic Analysis Package (NLEAP) model. I examined the applicability of the model by calibrating it to an agricultural field plot in southern British Columbia. NLOS was calibrated to an agricultural field in Agassiz, BC for this study, but I expect it will perform similarly in the Abbotsford-Sumas aquifer due to similar soil types and climatic conditions. NLOS incorporates fertilizer application events, climatic data, and soil properties, to simulate one-dimensional water flow and nitrogen fate and transport. Field data from a trial of silage corn located at the Pacific Agri-Foods Research Centre in Agassiz, BC (PARC Agassiz) was used to calibrate the model. Monthly sampling included soil, soil pore water, nitrous oxide emissions, and groundwater chemistry parameters. The field soil (a silt loam) was subjected to a nutrient loading and crop management scenario comparable to regional farming practices. The ability of NLOS to predict water and nitrate transport during seasonal precipitation events was examined by comparing simulations to monthly field data. NLOS was found to be useful for predictions of soil nitrate and ammonium in the upper 12 inches of the soil profile, and nitrate leaching from the 36-inch depth. Model predictions accounted for 84% of the observed variability in nitrate leached from 24 to 36 inches deep. Simulated soil nitrate and ammonium in the upper 12 inches of the soil profile accounted for 84% and 87%, respectively, of the variability in the observed values. NLOS also produced adequate predictions of nitrate leaching from 12 to 24 inches deep (R2 = 0.63), and soil water from 0 to 36 inches deep (average R2 for all layers = 0.52). Field observations and model simulations indicate that nutrients in the soil and soil pore water fluctuated in direct response to fertilizer applications, crop events, and precipitation. Although the model performed reasonably well, more frequent field data collection is recommended for further model calibration and validation. The calibrated model was also used to assess various nutrient-loading scenarios and to recommend the timing of the PHSNT. Hypothetical scenarios suggest that timing fertilizer application to rainfall events is the most effective way to reduce nitrate leaching. Field observations and model simulations also indicate that conducting the PHSNT concurrent with crop harvesting would provide the most accurate assessment of nitrate leaching potential
Streamflow calibration of two sub-basins in the Lake Whatcom Watershed, Washington using a distributed hydrology model by Katherine D Kelleher( )

2 editions published in 2006 in English and held by 3 WorldCat member libraries worldwide

Lake Whatcom provides drinking water to the City of Bellingham and portions of Whatcom County. Therefore, quantifying streamflow into the lake is important to establish the contribution of ground water and surface water runoff in the Lake Whatcom water budget. Runoff is nearly 74% of the total inputs to the lake, thus the runoff provides the most water and nutrients to the lake. The primary goal of this study was to determine the ability of the Distributed Hydrology-Soils-Vegetation Model (DHSVM) to simulate the hydrologic processes in two sub-basins of the Lake Whatcom watershed. DHSVM is a physically based model that simulates a water and energy balance at the scale of a digital elevation model (DEM). GIS maps of topography (DEM), the watershed boundary, soil texture, soil thickness, vegetation, and a flow network define the characteristics of a watershed. The input meteorological requirements for DHSVM include time-series data representing air temperature, humidity, wind speed, incoming shortwave radiation, incoming longwave radiation and precipitation. Meteorologic data were compiled from recent records of a local weather station, except for longwave radiation, which was estimated. I calibrated and validated DHSVM for water years 2002 -- 2003, using streamflow records from Austin and Smith Creeks within the Lake Whatcom watershed. Simulations were performed using one-hour time steps and a 30- meter pixel size. Sensitivity analyses were performed with the model to determine the model's sensitivities and ability to capture hydrologic processes within the watershed by altering soils, vegetation types, and precipitation inputs. The calibration simulations for WY 2002 had a calibration error of 1% for Austin Creek and -3% for Smith Creek. Both simulation errors are less than the recommended maximum error of +/-5%. The validation was more problematic because of gaps within the recorded streamflow data. However, for the time frame where the simulated flow and recorded flow did overlap, the validation simulation error was -5% for Austin Creek and 3% for Smith Creek. The sensitivity analyses provided insight into parameter influences. The soil sensitivity simulations in Smith Creek have high mass balance errors indicating that model calculations were not performing adequately. The high mass balance error suggests that the model is over-estimating either the storage or the output. The vegetation sensitivity simulations did not affect streamflow other than slightly increasing storm peaks. More realistic simulations that capture vegetation removal through deforestation and urbanization would require the use of a road and storm sewer networks within the model to appropriately simulate decreased infiltration and rerouting of storm water runoff. Additional precipitation gage data added to the model, illustrated an increase in peaks in Austin Creek. Smith Creek did not have the increase in peaks, primarily due to the distance from the precipitation gage at Brannian Hatchery. The overall streamflow in Austin Creek did not increase with the addition of three precipitation gages to the input file, although the volume of storm event peaks did increase. I also simulated streamflow for Austin Creek and Smith Creek with two other interpolation methods (INVDIST and VARCRESS) using the additional precipitation gages. The INVDIST interpolation method provided the greatest increase in both Austin Creek and Smith Creek, again primarily increasing peak volumes with little change in base flow. Future efforts should focus on modeling the individual subbasins, rather than attempting to model the entire Lake Whatcom watershed. The heterogeneities between the individual sub-basins are captured by DHSVM which increase the difficulty in modeling the entire watershed
Modeling relative effects of riparian cover and groundwater inflow on stream temperature in lowland Whatcom County, Washington by Sarah Harper-Smith( )

2 editions published in 2008 in English and held by 3 WorldCat member libraries worldwide

Many Pacific Northwest streams have water temperatures that exceed thermal thresholds for salmonids. Supporting and maintaining streams with temperatures below these thermal thresholds requires an understanding of the relationships between the main factors influencing stream temperatures. This study examined the relative effects of two of these factors, riparian canopy cover and groundwater inflow, on stream temperatures at the reach scale. I measured stream temperature, net groundwater exchange, and riparian canopy cover levels in 10 different study reaches designed to comprise a factorial combination of reaches with vegetated and unvegetated riparian buffers, as well as gaining and not-gaining groundwater. I then modeled stream temperatures in each reach with the SSTEMP stream temperature model, and compared model-predicted temperatures to measured stream temperatures during the warmest part of the summer. Finally, I manipulated the model to examine the relative impacts of riparian canopy cover (0-100%) and groundwater inflow (0-50%) on predicted stream temperatures. SSTEMP predicted daily mean reach temperatures well across the range of conditions studied here, although it overpredicted daily maximum temperatures. Model manipulations of groundwater inflow and canopy cover levels showed consistent trends in affecting stream temperatures. Under peak summer conditions and "base" groundwater (0%) and canopy cover (0%) conditions, predicted mean stream v temperatures warmed by an average of ~ 4°C across all streams. Full canopy cover and 50% groundwater inflow each reduced this predicted warming by ~ 2.5°C when manipulated independently. However, only the combination of both high canopy cover and groundwater inflow actually reduced predicted mean stream temperatures within the study reaches. In contrast, canopy cover had much stronger effects on modeled maximum stream temperatures than did groundwater inflow. Under peak summer conditions, 100% canopy cover reduced predicted downstream warming of daily maxima by ~ 10°C, while 50% groundwater inflow did so by only ~ 2°C compared to base conditions. The results of this study affirm that both canopy cover and groundwater inflow play significant roles in minimizing stream temperatures in summer, and both should be considered when making restoration, land use, and other management decisions
Modeling the contributions of glacial meltwater to streamflow in Thunder Creek, North Cascades National Park, Washington by Jay W Chennault( )

1 edition published in 2004 in English and held by 2 WorldCat member libraries worldwide

In regions where glaciers occur, like the North Cascades, glacial meltwater is a vital component of rivers and streams. Glacial meltwater can also be critical for hydroelectric and municipal purposes. A concern for water resources managers is that glaciers in the North Cascades have been shrinking. The glacier ice coverage of Thunder Creek watershed, the most heavily glaciated basin in the North Cascades, has dropped from approximately 22.5 % to 12.8 % since the Little Ice Age (LIA) maximum (ca. 1850). Glacial meltwater contributions to Thunder Creek are of interest because the creek serves as a tributary to Diablo Reservoir, which is one of three reservoirs on the Skagit River maintained by Seattle City Light for hydroelectric power production. In this study, I use the Distributed Hydrology Soils Vegetation Model (DHSVM) to evaluate the effects of glacial retreat on summer stream discharge in Thunder Creek. DHSVM is a physically based model that simulates a water and energy balance at the scale of a digital elevation model (DEM). GIS maps of topography (DEM), the watershed boundary, soil type, soil thickness, vegetation, and a flow network define the characteristics of a watershed. The input meteorological requirements for DHSVM include time-series data representing air temperature, humidity, wind speed, incoming shortwave radiation, incoming longwave radiation and precipitation. These data were compiled from recent historical records of local weather stations, except for longwave radiation, which was estimated. I calibrated and validated DHSVM for water years 1998-2002 to seasonal snow accumulation and melt at Thunder Basin SNOTEL and North Klawatti Glacier using two-hour time steps and a 50-meter pixel size. I also calibrated and validated the model to hydrographs measured at the U.S. Geological Survey (USGS) gauging station at Thunder Creek. DHSVM was then used to assess the influence that modern glaciers have on streamflow in Thunder Creek. The model was also used to estimate streamflow with LIA and 1958 glacial conditions as well as glacial conditions at 50, 100, 150, 300 and 500 years in the future based on current rates of glacial retreat. Results of the modeling indicate the percentage of late summer streamflow in Thunder Creek from glacial meltwater varied annually from 0.6% to 56.6% in water years 1998 through 2002. The timing of the initiation of glacial meltwater in the simulated Thunder Creek hydrograph varied from June 13 to July 26. Glacier melt also had a greater effect on streamflow during warm and dry years rather than cool and wet years. LIA glacial meltwater simulations produced between 6.1% and 63.4% more total late summer runoff than from the 1998 glaciers due to an increase in glacier area. In contrast, future glacier meltwater simulations produced systematically less runoff as the watershed was deglaciated. Simulation results suggested that within 100 years, total August and September streamflow in Thunder Creek could decrease more than 30% due to shrinking glaciers
A Holocene glaciolacustrine record of the Lyman Glacier and implications for glacier fluctuations in the North Cascades, Washington by Harold N Wershow( )

2 editions published in 2016 in English and held by 2 WorldCat member libraries worldwide

The Holocene glacial history of the North Cascades is poorly understood, in part because most existing records rely on moraine remnants and are therefore discontinuous. To develop a more complete record of Holocene fluctuations of North Cascades glaciers, we collected and analyzed glaciolacustrine sediments (i.e., rock flour) deposited over the past ~7800 years in Lyman Lake by the upstream Lyman Glacier. We combined these results with equilibrium-line altitude (ELA) reconstructions and glacier-climate modeling to quantify the climatic conditions that drove these fluctuations. Finally, we compared the Lyman Glacier's continuous fluctuation record to existing glacier and climate records of the North Cascades. Our results indicate that the Lyman Glacier was absent in the early Holocene, from before 7.8 ka until ~4.9 ka, when it experienced an early Neoglacial advance that persisted until at least ~3.8 ka. Following an extended non-glacial interval, the glacier experienced significant advances between ~2.6 - 2.25 ka, ~1.8 - 1.3 ka and ~1.1 - 0.9 ka. An advance starting ~ 0.8 ka (1150 CE) culminated at the glacier's maximum Holocene extent between ~0.6-0.5 ka (~1350 - 1450 CE), from which it retreated and disappeared entirely by ~0.35 ka (~1600 CE). After ~200 years with no significant glacier presence in the cirque, the glacier reformed and rapidly advanced to its maximum Holocene extent (~1800 - 1900 CE). Following this event, the glacier retreated steadily throughout the 20th and early 21st centuries and as of 2014, has approached its minimum viable extent. Paleo-ELA reconstructions of the glacier's maximum Holocene extents suggest that summers were ~2.6 °C cooler than modern (l981 - 2010 CE); alternatively, glacier-climate modeling indicates that annual temperatures ~1.5 °C cooler than modern would result in maximum glacier extents. Combining these new results with existing North Cascades glacial records indicates that: 1) the earliest Neoglacial advances in the region (starting ~6 ka) occurred asynchronously, with higher latitude and more maritime sites experiencing earlier advances; 2) Neoglacial advances remained small, infrequent and asynchronous until the last millennium; 3) Beginning at ~1.0 ka, glaciers throughout the North Cascades advanced synchronously, signaling the onset of the Little Ice Age (LIA); 4) North Cascades glaciers reached their maximum Holocene extents during the 15th and early 16th centuries (~0.55 - 0.45 ka), followed by apparent regional retreat and a final smaller 19th century (~0.15 - 0.05 ka) re-advance. The asynchronous early-to-mid Neoglacial fluctuations followed by synchronous LIA behavior suggests that local climate factors drove glacier fluctuations until the regional climate signal became strong enough to induce synchrony ca. 1.0 ka. Although the inferred regional retreat remains uncertain, the disappearance of the Lyman Glacier in the mid-LIA (~0.45 - 0.15 ka) is consistent with the precipitation record at Castor Lake (~100 km to the east), which indicates unusually dry winter conditions between ~1450 - 1850 CE (~0.5 - 0.1 ka)
Irregular tessellated surface model map algebras to define flow directions and delineate catchments using LiDAR bare earth sample points by Gerald B Gabrisch( )

2 editions published in 2011 in English and held by 2 WorldCat member libraries worldwide

Flow directions and catchment algorithms have historically utilized raster-based data models. A significant body of literature focuses on raster-based interpolation errors, and the subsequent surface reconditioning to compensate for those errors, that together degrade the accuracy of the derived flow directions and catchments. This research seeks to improve upon the raster-based approach by developing and evaluating a vector-based approach to generating flow directions and delineating catchments that preserves the accuracy of the input point data through the use of irregular tessellated surface models. Specifically, the Python computer programming language was used in conjunction with a geographic information system (GIS) to develop ITSMHydro, a custom toolset that creates a Delaunay triangulated irregular network (TIN) from LiDAR bare-earth sample point data, and subsequently generates flow directions, delineates basins, and processes spurious sink catchments. Surface model accuracy, and area, shape, and overlap of the resulting catchments were compared with catchments delineated using industry-standard raster-based digital terrain models. The vector-based approach implemented through ITSMHydro was limited to file sizes less than approximately 120,000 LiDAR strikes that processed in approximately 30 hours, whereas the industry-standard raster-based approach transformed 111,000,000 LiDAR strikes across the study area into a 3-feet pixel surface model and generated catchment boundaries in approximately 36 hours. A root mean square analysis of surface models indicates that surface model quality is more heavily degraded when LiDAR sample points are interpolated to raster grids as opposed to surface models relying on Delaunay TIN interpolation, suggesting that the vector-based approach maintains the quality and precision of the LiDAR input data. For the four test areas in which the two approaches were compared, ITSMHydro generated catchments that were generally smaller (percent difference in areas ranged from -83.97% to 9.39%) and with more complex boundaries (i.e. lower isoperimetric quotient in 3 out of 4 test areas) than the associated raster-based catchments. Coefficient of areal correspondence (CAC), a measure of overlap between catchments generated by the two methods where a value of 1 indicates perfect overlap, ranged from 0.28 to 0.80 in the four test areas. Given the lower relative accuracy of raster-based surface models evident in the study area, these differences suggest use of the raster-based approach may compromise accuracy in area, shape, and location of the resulting catchments. A vector-based approach that preserves the accuracy of the input data is preferred, especially in areas of low topographic relief. The file size constraints limit application of the approach developed herein, however, at least until technological advances and/or code revisions improve computer processing speed and file size capacity
Naturally occurring aqueous arsenic and seawater intrusion on Lummi Island, WA by Erica Martell( )

2 editions published in 2010 in English and held by 2 WorldCat member libraries worldwide

Two different types of groundwater contamination may be present in the aquifers on northern Lummi Island, Washington: naturally occurring arsenic and seawater intrusion. Freshwater on northern Lummi Island is stored in bedrock and unconsolidated glacial sediments. The naturally occurring arsenic, sourced from an undetermined stratigraphic layer, varies spatially throughout the island. Additionally, seawater may be intruding into the groundwater supply, which is the primary source of drinking water for the residents of the island. The process of mobilization of the naturally occurring arsenic and the extent of the seawater intrusion has not been fully explored. The purpose of my study was to determine the geochemical, physical, and seasonal influences on concentrations of arsenic and major ions on Lummi Island. I collected water samples and made in situ measurements from wells distributed throughout Lummi Island for geochemical analysis. Statistical analysis was used to test for a relationship between arsenic concentrations and geochemical factors or season. The speciation of arsenic in the groundwater was determined by plotting pH and redox potential measurements on an arsenic species stability diagram. Whole-rock chemical analysis was used to investigate the bedrock source of the arsenic. The extent of the seawater intrusion was determined using major ion analysis, and the source of the ions was interpreted using Piper diagrams. The relationship between aquifers, major ions, and seasonality was explored using multivariate statistical analysis. Whole rock analysis indicated that the highest arsenic concentration was in the sample taken from the Chuckanut conglomerate. When Eh and pH field measurements were plotted on an arsenic stability diagram, arsenate was revealed as the dominant species in the groundwater. Speciation calculations in PHREEQC supported the conclusion that arsenate was the dominant species in most water samples. No wells indicated seawater intrusion and some plotted in the freshening region of the Piper diagram. Wells that plotted in the freshening area of the Piper diagram were more likely to have higher arsenic concentrations. Bivariate analysis, principal component analysis, non-metric clustering and Piper plots failed to show a difference in the measured variables between the April and August samples. A positive correlation was found between specific conductance, Na+, Cl- and total alkalinity and dissolved arsenic, and a negative correlation was found between Ca2+ and Mg2+ and dissolved arsenic. No correlation was observed between dissolved arsenic and Fe or Mn. Multivariate statistics indicated a correlation between the presence of major ions and the dissolved arsenic concentrations. The positive correlation between alkalinity and dissolved arsenic, negative correlations between Ca2+ and Mg2+ and dissolved arsenic, and no correlations with Fe or Mn is consistent with an arsenic release through a desorption process. The presence of dissolved carbonate and bicarbonate is indicative of a chemical weathering process, which could lead to arsenic desorption, and the charge on Ca2+ and Mg2+ ions can facilitate the adsorption and desorption of dissolved arsenic. Since the Chuckanut sandstone had the highest dissolved arsenic concentrations, a chemical weathering process is most likely occurring within this stratigraphic layer. No wells in this study exceeded the SMCL (Secondary Maximum Contaminant Level), nor did any wells experience a statistically significant fluctuation in chlorides between the April and August sampling seasons. When the major ions were plotted on a Piper diagram, all of the wells plotted in either the "fresh" or the "freshening" part of the diagram; none of the samples plotted in the "intruding" or "intruded" area. Because there was no evidence that the wells in my study were experiencing seawater intrusion, the salts must be released from another source. This relationship between major ions and dissolved arsenic was supported by the multivariate statistical tests principal component analysis and linear discriminant analysis. The principal component analysis successfully classified arsenic into high and low groups, and once trained with a subset of the data, the linear discriminant analysis divided arsenic into high or low categories. The relationship between the major ions and dissolved arsenic can be interpreted from a Piper diagram when the high dissolved arsenic concentrations ([As]>0.07 mg/L) is color coded. These water samples all plotted in the freshening region of the Piper diagram. Because chlorides and dissolved arsenic were positively related, specific conductance, used as a proxy for chlorides, could be used as a rough indicator for arsenic
Thermal and hydrological conditions of the Goethe rock glacier, Central Sierra Nevada, California by Jezra Beaulieu( )

2 editions published in 2013 in English and held by 2 WorldCat member libraries worldwide

The potential of rock glaciers in the Sierra Nevada to provide critical hydrological reservoirs and ecological habitats in a changing climate remains largely untested. In an effort to constrain the microclimatic contributions of buried ice, continuous temperatures were recorded in the near-surface debris of a variety of ice-cored and associated landforms in the Goethe cirque from August 2011 and July 2012 (Goethe rock glacier=GRG, valley-wall rock glaciers=VRG, Recess Peak debris=RPD, talus=TAL, ranging from most ice to least ice). In addition, continuous meteorological conditions on the rock glacier and stage of the main meltwater outwash stream were recorded to assess temporal and spatial responses of hydrologic inputs and outputs to the rock glacier. The mean annual surface temperature (MAST) of the GRG is -2°C and the mean annual temperature at depth (MADT) is -2.5°C. The GRG has the steepest average annual temperature gradient of all the landforms with 0.44°C/m, indicating the presence of a large ice core. The MAST for RPD, VRG, and TAL are -0.5°C, -2°C, and -2.5°C, respectively, and their MADTs are -1°C, -3°C, and -3°C respectively. The mean annual air temperature (MAAT) from the on-site weather station in the cirque was -1.5°C, and the total cumulative precipitation was 552 mm. The modeled discharge varies from 0-1.6 cms, averaging 0.35 cms, and the stream temperatures vary from 0-3.85°C, averaging 0.53°C. According to Tritium signatures of stream water samples, the percent of ice-core melt versus snowmelt in the stream was 0% for the mid-summer of 2011, 5% for fall of 2011, and 13% for the early summer of 2012. The thermal and hydrological conditions in the Goethe cirque indicate a large sensitivity to meteorological conditions that is seasonally moderated by cold internal temperatures within the ice and debris of the landforms. The two contrasting summers during the yearlong study period exhibited different characteristics, particularly in discharge, stream temperature, and relative contribution of runoff source. The summer of 2011 was largely affected by exceptional snowpack from the previous winter, which was expressed by lower mean debris matrix temperatures, strong correlations between discharge and air temperature, and tritium signals that indicate a nearly pure snow-melt source for the outlet stream. The summer of 2012 was characterized by an exceptionally low snowpack compared to the winter of 2010-2011, which was expressed by higher mean matrix temperatures, strong correlations between stream temperature and matrix temperatures, and a tritium signal that indicated a modest amount of ice melt contribution to discharge in the outlet stream. Projected decreases in snow-cover and earlier onset of spring snowmelt for the region will likely change the timing of peak runoff in alpine basins, as well as increase the duration that rock glacier debris matrix is open to warm air temperatures, thereby inducing more melt of internal ice and greater contribution of ice melt to stream runoff. With continued warming, even these insulated ice bodies will degrade unless the climate returns to cooler and wetter conditions
Modeling slope failure in the Jones Creek Watershed, Acme, Washington by Brandon M Brayfield( )

2 editions published in 2013 in English and held by 2 WorldCat member libraries worldwide

Mountain watersheds in the Pacific Northwest are particularly susceptible to shallow landslides and debris flows during periods of intense precipitation. The Jones Creek watershed near Acme, WA, is a 6.7 km2 basin that hosts several active landslides. Shallow mass wasting on the unvegetated landslide toes, and deep-seated rotational slide movement can lead to landslide dam outburst floods and debris flows. There are approximately 100 buildings constructed on a 0.75 km2 alluvial fan deposited by debris flows sourced in the watershed. Predicting the occurrence of mass wasting and deep-seated movement events as they relate to the duration and intensity of antecedent precipitation conditions is important for land-use planning and emergency preparedness in the surrounding Acme community. The Distributed-Hydrology-Soil-Vegetation Model (DSHVM) simulates a water and energy balance at the pixel scale of a digital elevation model (DEM). I use DHSVM hydrology simulations, coupled with an infinite-slope failure model, to determine the probability of shallow mass-wasting events for a variety of historical precipitation scenarios. The infinite slope model uses a stochastic approach to predict the probability of slope failure on a cell-by-cell basis. Following the methods of Godt (2004), I use the simulated failure probabilities, paired with antecedent precipitation and intensity, to define a series of predictive antecedent precipitation thresholds for slope failure probability in the Jones Creek watershed. Although basin hydrology is not well-constrained in this study, the failure probability thresholds compare favorably with similar, more rigorous studies performed in the Pacific Northwest. Timber harvest can increase the rate of slope failure in steep basins due to reduced evapotranspiration and root strength loss. In order to supplement current logging prescriptions in the Jones Creek basin, I use DHSVM to model slope failure probability for a design storm event under a number of hypothetical harvest scenarios. DHSVM simulations suggest that root strength is the most important factor for the stabilization of slopes in the Jones Creek basin, and that a total basin harvest would significantly increase the susceptibility to slope failure. Based on the results of this study, I recommend expansion of the current logging prescriptions to include more harvest-restricted area. I also use RocScience SLIDE© version 6.0 software to model the influence of groundwater and soil mechanical properties on deep-seated slope stability for four deep-seated landslides in the Jones Creek watershed. Slide uses a comprehensive suite of tools for probabilistic modeling of complex failures, and incorporates a standalone finite element model for groundwater flow. SLIDE results indicate that the transition from unconsolidated material to weak bedrock on the toes of the deep seated landslides is likely to occur at a depth of less than two meters, which agrees with observed conditions in the basin
Science and strategy : how scientific and technical information are used in disputes over landslide regulations in Seattle, WA by Ana Miscolta-Cameron( )

2 editions published in 2016 in English and held by 2 WorldCat member libraries worldwide

This thesis investigates the ways in which scientific and technical information are used to challenge policies regarding development in landslide-prone areas in Seattle, Washington. It examines the values that underlie actor arguments within those challenges, using the theoretical lens of Science, Technology, and Society. Twelve case studies are selected from a set of 90 permitting appeals, court cases, and growth management hearings board appeals between the years of 1990 and 2015, and analyzed to identify the complex ways in which scientific information is used to further actor positions. A narrative analysis approach is used to analyze the case studies, archived news coverage, and interviews with geologists and planners in order to identify actor values and narratives. The results of this project suggest that, despite the science-centered arguments of developers and government, actor decisions are highly influenced by values. Neighbors who oppose development draw their arguments from aesthetic values; developers draw their arguments from values that center on property rights and right to accept risk; and all actors, including government, base arguments on potential economic gains or losses. What can be concluded is that despite hillside development policy being based upon science and technical knowledge, actor arguments and concerns are often based upon values, which cannot be articulated through science and technical information. Though well-resourced actors can influence policy through the leveraging of science and technical information, the prominence of values in debates about landslide regulation indicate that science-based policy approaches that do not consider values may encounter more challenges from the public
Estimating sediment yield from the Swift Creek landslide, Whatcom County, Washington State by Curtis R Clement( )

2 editions published in 2014 in English and held by 2 WorldCat member libraries worldwide

The amount of suspended sediment carried by streams in mountainous watersheds is an important factor in environmental and engineering planning, especially when the material happens to be of toxic nature. The Swift Creek watershed contains a deep-seated landslide composed of weathered serpentinite, which includes chrysotile (capable of asbestiform morphology), chlorite, illite, and hydrotalcite. The United States Environmental Protection Agency has determined that the asbestiform material contains particles of sufficient size and quantity that could be hazardous to human health. The suspended sediment load from Swift Creek is primarily influence by the steep, disturbed and unvegetated toe of the landslide which provides a large surface for overland flow directly into the stream creating temperamental conditions, as well as an effectively endless supply of sediment. The remainder of the watershed is heavily forested and consequently supplies relatively little sediment to the stream. I attempted to develop a means to estimate sediment yield from the landslide, and provide a consistent method to monitor the stream in spite of the flashy conditions. I used the Distributed Hydrology-Soil-Vegetation Model to create a continuous discharge dataset from point discharge measurements. I also used the Turbidity Threshold Sampling method to collect physical water samples drawn during specific changes in turbidity and used the turbidity data as a proxy for suspended sediment. I developed linear models based on discharge and turbidity to estimate an annual yield. Pacific Surveying and Engineering conducted a similar study three years after my data collection period and estimated a sediment yield that did not support my sediment yield estimates. The methods were slightly different as necessitated by the difference in quality of the various data types. As a result, I evaluated the differences between the methods in an effort to determine if the disparity between my estimate and Pacific Surveying and Engineering's estimate was caused by procedural differences. I included an analysis of timing between peak turbidity and precipitation and between peak turbidity and discharge. I found that the time between storms was important to the suspended sediment magnitudes. Future modeling efforts will need to incorporate this discharge-sediment hysteresis over the linear models in this research and by Pacific Surveying and Engineering. The United States Geological Survey collected turbidity and discharge data on the Sumas River for several seasons. Monitoring here in the future will likely be more effective than monitoring Swift Creek directly because of the rivers discharge stability. If direct monitoring of the Swift Creek is to be continued, the relationship between discharge and suspended sediment should be further developed rather than turbidity and suspended sediment due to measurement stability
The effects of forecasted climate change on mass wasting susceptibility in the Nooksack River Basin by Kevin Knapp( )

2 editions published in 2018 in English and held by 2 WorldCat member libraries worldwide

The Nooksack River in Whatcom County, Washington is an essential fresh water resource for industry, agriculture, municipalities and serves as vital fish habitat. Like many mountainous watersheds in the western Cascades, the Nooksack Basin is susceptible to shallow mass wasting and debris flows because of its steep slopes, young glaciated terrain, and storms with high intensity precipitation. Understanding how projected reductions in snowpack and increased winter rainfall will affect mass - wasting susceptibility in the Nooksack basin is important, because sediment produced mass wasting will jeopardize valuable aquatic and fish habitat, increase flooding risk in the Nooksack River, and affect estuarine and coastal dynamics. With a projected 60% decrease in snow pack and increase in the snowline elevation by the 2075 climate normal, there will be an increase in exposed forest roads, harvestable forest areas, and previously mapped landslides, which are all documented to increase sediment delivery to streams. Retreating glaciers will produce at least 2 km 2 of exposed moraines, which have the potential to erode, fail and provide additional sediment to streams, especially during large storm events coinciding with minimum snowpack during the fall and early spring seasons . I applied a static infinite - slope ArcGIS model and a dynamic, probabilistic mass - wasting model integrated into the Distributed Hydrology Soil Vegetation Model (DHSVM) to the Nooksack River watershed to determine areas susceptible to mass wasting into the 21 st century. Susceptibility maps produced by the models indicate an increase in regions susceptible to slope failure during the winter months in snow free areas at higher elevations later in the 21 st century. Slope failure susceptibility increased with soil saturation, which is anticipated with higher intense winter rainfall events. Slopes greater than about 30° with thick regolith deposits and lower soil mechanical strength, e.g., sand, loamy sand, sandy loam, silt, moraines, glacial outwash and former landslide deposits were correlated with higher mass - wasting susceptibility. The simpler static ArcGIS infinite - slope model yielded comparable results to the more complex probabilistic method integrated into the DHSVM for identifying areas susceptible to mass wasting
Geologic development and ongoing activity of the Van Zandt landslide complex, northwest WA, USA by Geoffrey Malick( )

2 editions published in 2017 in English and held by 2 WorldCat member libraries worldwide

Geomorphic mapping based on high-resolution lidar data indicates that the Van Zandt Landslide Complex (VZLC) has multiple crosscutting debris lobes (up to 51.4 x 106 m3) with long runouts (H/L= 0.14; 0.21) typical of catastrophic rock avalanches. AMS 14C dates from in situ logs and lake sediment cores yield overlapping ages for emplacement of Debris Lobe 2 (1330-1285 cal. yrs. B.P) and Debris Lobe 3 (1300-1285 cal. yrs. B.P.) Although Debris Lobe 3 overlies a portion of Debris Lobe 2, it is possible that emplacement of the two deposits was nearly synchronous or in rapid succession. The debris lobes are not contemporaneous with any known paleoseismic events from local shallow-crustal faults but do overlap with a known Cascadia megaquake (event T4). Abundant transverse surface fractures, a distal "splash zone," as well as debris exposures showing basal mixing, soft-sediment deformation, and substrate injection features provide evidence for significant rock avalanche-substrate interaction and mobility-enhancing liquefaction. To evaluate ongoing retrogressive block sliding in the headwall region, we installed wire extensometers in three prominent tension gaps and tracked their movement over an 18-month period between 10/15 and 4/17; all three sites experienced measurable displacement (up to 5.7 cm total), with progressive movement largely accelerating and decelerating in response to short- and long-term precipitation conditions. Although recorded strain rates were relatively slow during this period, incipient detachment scarps across the headwall involve slabs with a total volume of ~35.2 x 106 m3, the potential release of which could pose a serious hazard to people and property in the valley below
Sediment and phosphorus inputs from perennial streams to Lake Whatcom, northwestern Washington State by Katherine Beeler( )

2 editions published in 2014 in English and held by 2 WorldCat member libraries worldwide

Nutrient enrichment presents a common problem in lakes and streams by promoting algae growth and the depletion of dissolved oxygen. Lake Whatcom in northwestern Washington State is subject to a Total Maximum Daily Load (TMDL) to limit phosphorus input. The 20-km2 lake is supported by runoff from numerous perennial streams in a steep, 125-km2, moderately developed, forested watershed. Much of the phosphorus entering the lake is adsorbed to suspended sediment in streams and is transported to the lake during storm events. Understanding sediment and phosphorus transport to the lake is important for managing the TMDL and for maintaining water quality in general because the lake serves as the drinking water source for about 100,000 people. My objectives were to calculate sediment and phosphorus fluxes into Lake Whatcom and examine relationships among precipitation, discharge, sediment concentrations, and phosphorus concentrations. I collected a series of water samples near the mouth of Smith Creek in the Lake Whatcom watershed during 22 storm events between February 2013 and January 2014. The samples were analyzed for total suspended solids and total phosphorus. I used data from Smith Creek and four other streams to examine the effects of varying basin features on loading and to develop sediment-discharge and phosphorus-discharge models to estimate loading to the lake during the 2013 water year. Relationships among sediment, phosphorus, and discharge varied temporally and spatially in the watershed. During most storm events, the sediment peak preceded the discharge peak, indicating that transport was limited by sediment availability. In Smith Creek, the magnitude of hydrograph rise was the best predictor of the maximum sediment concentration during the event. Among the five streams studied, sediment yields ranged from 11.5 to 143 tonnes/km2/year. The steep, forested Smith Creek basin yielded the most sediment per area. Phosphorus yields ranged from 25.7 to 68.5 kg/km2/year, with the highest phosphorus yield coming from a small, low-relief basin containing 29% residential development. My sediment and phosphorous yields were comparable to estimates from similar streams in the Puget Sound region. Total suspended solids and total phosphorus were significantly correlated to discharge in most streams in the watershed, but variability within and among storm events resulted in uncertainty when calculating fluxes based on discharge. Continuous turbidity monitoring could allow for improved models and flux estimates
Creating a culture of writing( Visual )

2 editions published in 2008 in English and held by 2 WorldCat member libraries worldwide

This year's Showcase theme, "Creating a Culture of Writing," honors three Western Washington University faculty members who embed the writing process into their coursework and engage students with quality writing assignments
Modeling the effects of climate change on stream temperature in the Nooksack River Basin by Stephanie E Truitt( )

2 editions published in 2018 in English and held by 2 WorldCat member libraries worldwide

Stream temperatures in mountain streams in the western Cascade Mountains are heavily influenced by factors such as discharge, air temperature, and as in the case of the Nooksack River Basin in northwest Washington State; snow and glacial melt. The Nooksack basin is sensitive to warming climates due to the regions moderate Pacific maritime climate. Previous modeling studies in the upper Nooksack basins indicate a reduction in snowpack and spring runoff, and a recession of glaciers into the 21st century due to global climate change. How stream temperatures will respond to these changes is unknown. We use the Distributed Hydrology Soil Vegetation Model (DHSVM) coupled with a glacier dynamics model to simulate hydrology and the River Basin Model (RBM) to model stream temperature from present to the year 2090 in the North, Middle, and South forks of the Nooksack River basin. We simulate forecasted climate change effects on hydrology and stream temperature using gridded daily statically downscaled data from 10 global climate models (GCMs) of the Coupled Model Intercomparison Project Phase Five (CMIP5) with two different representative concentration pathways (RCP) RCP4.5 and RCP8.5. Simulation results project a trending increase in stream temperature into the 21st century in all three forks of the Nooksack. There is a strong correlation between rising stream temperatures and warming air temperatures, decreasing stream discharge; and snow and glacial meltwater. We find that the highest stream temperatures and the greatest monthly mean 7-day average of the daily maximum stream temperature (7-DADMax) values are predicted in the lower relief, unglaciated South Fork basin. For the 30 years surrounding the 2075 time period, the mouth of the South Fork is forecasted to have a mean of 115 days above the 16 °C 7-day average of the daily maximum stream temperature threshold. Streams in the Middle and North fork basins with higher elevations that sustain more snow and glacier ice are slower to respond to warming climates due to meltwater contributions, especially in the next 50 years. Towards the end of this century, when snowpack and glacial volume is greatly decreased, the buffering effect of meltwater declines, and the North and Middle forks experience larger increases in mean daily stream temperature. For the 30 years surrounding the 2075 time period, the mouths of the Middle and North forks are forecasted to have means of 35 and 23 days, respectively, above the 16 °C 7-DADMax threshold
 
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