Theses and Dissertations - Department of Geography

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Accessibility and university populations: local effects on non-motorized transportation in the Tuscaloosa-Northport area
(University of Alabama Libraries, 2012) Lundberg, Benjamin; Weber, Joe; University of Alabama Tuscaloosa
This research examined the local bicycle and pedestrian networks through Geographic Information Systems (GIS) and survey data, using the Tuscaloosa and Northport, Alabama, area as a case study. The local non-motorized travel networks were analyzed in GIS to measure the overall network connectivity and accessibility. Results of the measures of network connectivity and modeling of accessibility indicated that areas within one mile of the UA's campus have the highest levels of bicycle and pedestrian network connectivity and accessibility. As a travel distance increases from UA, connectivity and accessibility for the bicycle and pedestrian networks decreases. An on-line survey was administered to the University of Alabama (UA) students and employees, and the results of the survey were used to formulate an understanding of how UA's population views non-motorized travel and the respective networks. Survey results show that individuals within the sample population use non-motorized travel methods to commute to UA but their use is significantly lower than automobile use. In addition, the survey data was considered alongside evaluations of network connectivity and accessibility, thus providing a powerful tool for studying the local bicycle and pedestrian travel networks.
Accessibility of movement challenged persons to evacuation routes and their earthquake risk perception
(University of Alabama Libraries, 2021) Bhuiya, Md Musfiqur Rahman; Shao, Wanyun; University of Alabama Tuscaloosa
This study aims to evaluate the accessibility during earthquake evacuation for movement challenged persons (MCPs), a disable group highly vulnerable to earthquake, and explores their risk perception in the context of megacity Dhaka, Bangladesh. As there is no accessibility measure to determine accessibility of a network of MCPs integrating physical impedance faced by them in their movement, this study has modified Link to Node Ratio calculate the accessibility of MCPs with consideration of physical impedance and applied it determine the accessibility of MCPs to evacuation routes of 13 wards of Dhaka. Study of accessibility of MCPs during evacuation reveals that 6 wards have poor overall accessibilities while 3 wards have relatively satisfactory conditions of overall accessibility and 4 wards have relatively good accessibilities but fall short of satisfactory conditions. The study reveals that MCPs who are more aged and have more severe level of disability perceive accessibilities of evacuation network, indoor floor surface and entrance gate to be lower. Moreover, male and better educated MCPs is found to perceive accessibilities of indoor floor surface and entrance gate to be higher. Age, income, structure, having experienced an earthquake earlier, mass media as a source of information on earthquake training is found to contribute to perceiving higher level of earthquake risk (as a whole). MCPs who have participated in the training program is found to know what they should do in the advent of an earthquake irrespective of being outside or inside of the home. The study reveals lack of accessibility in training centers and lack of distribution of information of training programs as key reasons behind MCPs not participating in the training.
Acculturation in a community garden: the shifting role of a Hmong garden in eastern Wisconsin
(University of Alabama Libraries, 2019) Misfeldt, James Arthur; LaFevor, Matthew C.; University of Alabama Tuscaloosa
Sheboygan, Wisconsin is a small midwestern city that is home to a community garden that has been kept by a Hmong immigrant community for more than 30 years. This thesis uses a cultural geographic approach to present an ethnography of Sheboygan’s Hmong community garden. This ethnography addresses convergent knowledge gaps in the literature on immigration in the United States, Hmong studies, and the political ecology of urban commons. It is presented that the interrelated processes of acculturation and neoliberalization have shaped the garden and those who use it. Acculturation is an important determining factor in how members of Sheboygan’s Hmong community perceive the garden and the expansion of neoliberal policy in Sheboygan has been shaped by individuals’ relationships with it. These relationships, as well as power relationships in Sheboygan, are explored in the narrative of an event that led to the garden’s 2015 move.
Angler perceptions of changes in lateral connectivity: the case of the Black Warrior River
(University of Alabama Libraries, 2015) Van Allen, Shivon; Bryan, Colgen H.; University of Alabama Tuscaloosa
Due to current river management priorities for aging, altered, and sedimented river systems, access to off-channel areas on the Black Warrior River system in West Alabama has diminished. As a result, satisfaction of river recreation stakeholders is lowered, ecological services provided by these areas are reduced, and the interests of recreationists, such as anglers, are neglected by dominant main river channel management practices. An understanding of the extent to which anglers perceive changes and the importance they place on off-channel area access is under-researched. The objectives of this study are to determine the extent to which anglers perceive changes in access to off-channel resources, the influence of off-channel areas on river recreation activities and behaviors, and management and policy implications. A two survey strategy, one delivered in-person and another via the Internet, assessed how anglers observe and experience changes in lateral connectivity. Angler perceptions of changes resulting from decreased lateral connectivity in altered waterways were documented, using the Black Warrior River in Alabama as a case study. The research reveals the recreational impacts of diminishing lateral connectivity, develops a framework for understanding perceptions of lateral connectivity changes, and aids in informing and influencing future river management plans and policy.
Application of Deep Learning to Estimate Mean River Cross-Sectional Depth
(University of Alabama Libraries, 2021) Raney, Arthur Austin; Cohen, Sagy; University of Alabama Tuscaloosa
Estimates of riverine channel geometry play a vital role in the physical representation of stream networks in models used to predict flood and drought conditions, manage water resources, and increase our knowledge of fluvial conditions under a changing climate. A well established body of literature exists that explains the relationship between channel geometry parameters width, depth, and velocity to instantaneous river discharge using a log-log linear power-law regression. In this study, a state-of-the-art deep learning regression model is presented and compared against the power-law method to evaluate their abilities to estimate cross-sectional mean river depth. Results reveal three key findings, the neural network: (1) decreases RMSE by 22% verse a CONUS scale power-law equation, (2) reduces prediction variance across Strahler stream orders, and (3) generally outperforms regional power-law equations with an average decrease in RMSE of 8.7%. Lastly, a reach-level CONUS dataset of estimated mean river depth is delivered.
Applications of Landsat-5 TM imagery in assessing and mapping water quality in Bankhead Reservoir of the Black Warrior River
(University of Alabama Libraries, 2012) Forrer, Dorothy Colleen; Han, Luoheng; University of Alabama Tuscaloosa
Bankhead Reservoir of the Black Warrior River is designated for swimming, fish and wildlife, and to be used as a public water source. The water quality of Bankhead Reservoir is impacted by both point and nonpoint source pollution. Only a limited number of intensive studies have been conducted on Bankhead due to the cost and resources necessary to sample areas distributed throughout the entire system. This research uses remote sensing technologies coupled with a limited number of in situ water samples to estimate and map the concentrations of total suspended solids and chlorophyll-a in Bankhead Reservoir using Landsat TM data. The principle behind the technique used implements spectral reflectance to predict water quality variables via different regression models. The results from this study serve as baseline water quality maps that can be used for comparison in future monitoring. A land use/land cover map was created of the study area to briefly investigate potential land use related causes of water quality variation. The use of remote sensing allows for a more synoptic view of total suspended solids and chlorophyll-a concentrations in Bankhead Reservoir for both spring and summer conditions.
Assessing the influence of climate change on flooding hazards following tropical cyclone events in the southeast United States
(University of Alabama Libraries, 2016) Stone, Monica Helen; Cohen, Sagy; University of Alabama Tuscaloosa
Recent tropical cyclones, like Hurricane Katrina, have been some of the worst the United States has experienced. Tropical cyclones are expected to intensify, bringing about 20% more precipitation, in the near future in response to global climate warming. Further, global climate warming may extend the hurricane season. This study focuses on four major river basins (Neches, Pearl, Mobile, and Roanoke) in the Southeast United States that are frequently impacted by tropical cyclones. The Soil and Water Assessment Tool (SWAT) was used to model flow along these rivers from 1998-2014 with 20% more precipitation during tropical cyclones. The results of this study show that an increase in tropical cyclone precipitation due to future climate change may increase peak flows at the mouths of these Southeast rivers by ~7-18%. Most tropical cyclones that impact these river basins occur during the low discharge season, and thus rarely produce flooding conditions at their mouths. An extension of the current hurricane season of June-November, due to global climate warming, could encroach upon the wet season in these basins and lead to increased flooding. On average, this analysis shows that an extension of the hurricane season to May-December increased flooding susceptibility by 63% for the rivers analyzed in this study. That is, 4-6 more days per year likely would have been above bankfull discharge if an average tropical cyclone had occurred any day (based on 1998-2014 data) in the months May-December than in the current hurricane season months of June-November. More research is needed on the mechanisms and processes involved in the water balance of the four rivers analyzed in this study, and others in the Southeast United States, and how this is likely to change in the near future with global climate warming.
Assessing the relationship between high lightning events and storm mode in Northern and Central Alabama
(University of Alabama Libraries, 2014) Willis, Morgan Terry; Senkbeil, Jason Carl; University of Alabama Tuscaloosa
Lightning is a dangerous and deadly hazard, yet it is often underestimated by the public and excluded from severe weather watches and warnings used by the National Weather Service. Previous studies have analyzed the relationship of lightning and storm intensity in relation to severe weather, but none have analyzed this relationship across all storm modes in an area including Northern and Central Alabama. This study attempts to assess the relationship between cloud-to-ground (CG) lightning and storm mode in storm events which occurred on lightning hazard days in Northern and Central Alabama during the years of 2007 to 2011. Storm variables for analysis included lightning flash rate, aspect ratio, total convective area above 20 dBZ, maximum convective area above 40 dBZ, and percent maximum convective area. Results show that lightning flash rates vary by season and storm mode. PCA and Cluster Analysis identified a total of 5 clusters of varying lightning flash rate and convective intensity. The storm mode events include non-summer linear, an anomalous MCS associated with a triple point frontal outflow boundary, summer airmass, non-seasonal weak, and summer MCS/MCC. Information obtained during this thesis has the potential to aid forecasters and emergency managers in Northern and Central Alabama by associating lightning flash rates with storm mode characteristics observed on lightning hazard days.
Assessing the role of bikesharing in transit-oriented development: a case study of Birmingham
(University of Alabama Libraries, 2016) Glass, Caroline Day; Appiah-Opoku, Seth; University of Alabama Tuscaloosa
Transit-oriented development (TOD) is a community development strategy that has increasingly gained exposure in urban areas across the United States as a method for reducing sprawl and increasing community vitality. Specifically, bikesharing is seen to play a major role in the success of transit-oriented development across urban communities as it increases travel possibilities, encourages public transit connections, and provides opportunities for recreation. This research employed a case study of Zyp BikeShare, a point-to-point bike rental program that began in Birmingham, Alabama, in 2015. Here, we analyzed the bikesharing program in terms of implementation and development, user catchment, transit paths, and usage trends. In doing so, we were able to create a methodology for analyzing specific bikeshare programs. Similar methodology can be applied to other bikesharing programs as the transit-oriented development technique continues to grow and develop in American cities.
Assessing the weekend accessibility of Rutgers University libraries
(University of Alabama Libraries, 2015) Hoffman, Amanda Jane; Weber, Joe; University of Alabama Tuscaloosa
Rutgers University- New Brunswick is a public four-year institution located within the limits of New Brunswick and Piscataway, New Jersey. Separated into four sub-campuses, Rutgers University – New Brunswick has developed an intricate campus transit system. Rutgers is one of many institutions who have sought to become more sustainable entities, in order to continue to provide exceptional services to students for the foreseeable future. In order to do so, universities are beginning to look towards alternative methods of transportation for their students to limit the use of private vehicles. This thesis research highlights the weekend accessibility of the four major campus libraries on the New Brunswick campus of Rutgers, comparing the usage of the campus transit system and one’s private vehicle. Using the potential interaction model of accessibility, this research measures the accessibility of each sub-campus to the library on the other 3 sub-campuses and each library to students coming from the other sub-campuses. The results of this research show which campus library is the most accessible to students from the other sub-campuses and which sub-campus is the most accessible to the 3 other libraries. This research also highlights the accessibility gap between students who take the campus transit system and those who make use of their private vehicle.
Barchan morphometry: examples from Earth and Mars
(University of Alabama Libraries, 2019) Butler, Robert Jack; Sherman, Douglas J.; University of Alabama Tuscaloosa
Barchans are a common sand dune type found on both terrestrial and Martian surfaces. The morphometry of individual barchans and barchan groups has been measured extensively in past studies. Within each dune field, similar sized barchans are observed to be abundant, but previous morphometric studies typically do not compare their results with those from many other dune fields. This study includes diverse dune fields on both Earth and Mars concentrating mostly on the dimensionless geometric variabilities of their barchan populations. The geometries show a degree of similarity between barchan populations despite the different environmental characteristics from one dune field to another. This project made use of NASA’s public photos, Mars Reconnaissance Orbiter CTX Imagery, Google Earth, and Digital Globe’s free, high-resolution imagery. The key dimensions of more than 1500 barchans, representing dunes from 14 terrestrial and 5 Martian dune fields, were measured using the Google Earth ruler tool and Photoshop CC software. Determining the variation of barchan geometry provides evidence of similar barchan characteristics on a large scale and creates a foundation for future research. Documenting these barchan geometries provides a better understanding of the geomorphic time-space sequences, evolutions, geospatial distributions of barchan populations, and may provide a robust basis for the classification of barchan morphologies according to dimensionless geometry.
Biogenic modification of sediments by unionid mussels and their implications for sediment transport in the Sipsey River of Alabama
(University of Alabama Libraries, 2018) Koerner, Matthew Ryan; Davis, Lisa; University of Alabama Tuscaloosa
Few studies have tested the influence of freshwater mussels on sediment properties and their potential influence on geomorphic processes outside of lab-based flume studies. Freshwater mussels have historically constituted a great proportion of the benthic biomass in many rivers in the southeastern United States and may maintain or transform the physical stability of river bed sediment indirectly by their biogenic structure or directly through processes including biodeposition and bioturbation. We tested the effects of freshwater mussels on sediment properties (D50 median grain size and sorting), sediment scour and reach scale bedload transport by deploying 36 mussel enclosures in the Sipsey River, Alabama, for a 9-week period. We employed a randomized design consisting of 4 replicates of the following treatments: 3 diversity treatments (Cyclonaias asperata; Fusconaia flava; Cyclonaias asperata and Fusconaia flava), 2 abundance treatments (24 indiv/m2, 48 indiv/m2), a sediment only control, and 2 sham mussel controls (24 indiv/m2, 48 indiv/m2). Sliding-bead monitors were installed in the center of each mussel enclosure to measure the amount of scour over the 9-week period, and biomodifications to surface layer D50 particle sizes and Folk and Ward sorting coefficients were measured using ImageJ photo analysis software. Hypothetical differences of bedload transport rates between reaches containing mussels (24 indiv/m2; 48 indiv/m2) and no mussels were computed using BAGS (Bedload Assessment in Gravel-bed Streams, Version 2008.11) bedload transport model. The results of this experiment suggest freshwater mussels contribute to bed scour, and increase surface layer D50 particle sizes and the degree of surface layer sorting. BAGS predicted that bedload transports rates in a reach with high abundances of freshwater mussels were lower than a reach containing no mussels (88.6% lower under baseflow conditions and 55.3% lower under bankfull flow conditions), based on biomodifications to surface layer D50 particle sizes and sorting by freshwater mussels. These results suggest that alterations to sediment properties by freshwater mussels are quantifiable in non-flume based settings, and that freshwater mussels may play a significant role as ecogeomorphic agents in the Sipsey River, AL, and other rivers that contain dense, long-lived communities of freshwater mussels.
Biogeomorphic Impacts of Freshwater Mussels on Reach-Scale Geomorphology in the Sipsey River of Alabama
(University of Alabama Libraries, 2020) Shafer, Gregory Wayne; Davis, Lisa; University of Alabama Tuscaloosa
Freshwater mussels are burrowing, filter feeding organisms that were once widespread prior to river regulation but now face extinction or extirpation in many rivers of North America. The lifespan of some species can exceed a century and population densities have the potential to reach one hundred individuals per square meter in some rivers of Alabama. The functional traits of mussels, combined with their long lifespan and ability to occur in high-densities, suggest that they could impact reach-scale sediment processes, involving sediment transport and bank erosion, potentially leading to changes in channel morphology. Few studies, however, have examined ecosystem engineering by mussels and their potential effects on spatio-temporal changes in river morphology. We tested whether four, high-density mussel aggregations (> 14 ind/m2) influenced lateral river migration and bank erosion rates in a 48-km segment located in the Sipsey River of Alabama (USA). We digitized and compared riverbank positions of the study reach on georeferenced historical aerial images from 1965 and images from 2018. Above average rates of lateral migration (>0.2 cm per year) and bank erosion (>33 cm3 per year) occurred at all observed high-density mussel reaches. We observed the presence of mid-channel bars persisting for the duration of the 53-year study period immediately downstream of each high-density mussel location. Additionally, we tested whether mussel population densities can be used to predict locations of reach-scale riverbank erosion. We quantified bank erosion, mussel density, median particle size distribution, and determined bank erosion hazard index (BEHI) scores at 44 transects located within three reaches. We created a stepwise, linear regression model to determine the effect of mussel population density on bank erosion. Mussel density was a stronger predictor (r2= 0.25) of riverbank erosion than most BEHI metrics, including root depth (r2= 0.06) and bank height/bank full (r2= 0.01). The results of this study provide a critical step toward understanding reciprocal relationships between abiotic and biotic systems and new insights into the evolution of channel morphology not previously considered. Future river restoration projects should consider that many organisms, not just abiotic factors, can create biogeomorphic change of river geomorphology.
Catastrophic wind and salvage harvesting effects on woodland communities
(University of Alabama Libraries, 2017) Kleinman, Jonathan Samuel; Hart, Justin L.; University of Alabama Tuscaloosa
Compound disturbances may result in novel forest successional and developmental patterns. This study investigated effects of post-wind disturbance salvage harvesting, a unique compound disturbance of which the ecological consequences are unresolved, in fire-restored longleaf pine woodlands of the Alabama Fall Line Hills, a characteristically biodiverse and rare ecosystem. Floristic inventories were developed and plot-level data were collected in areas undisturbed, wind-disturbed, and compound-disturbed (wind + salvage) to compare disturbance-mediated differences in (1) physical site conditions, (2) woody plant composition and structure, and (3) ground vegetation (herbaceous and woody plants ≤ 1 m in height). Multivariate analyses revealed distinct differences in ground vegetation across disturbance categories. Biophysical drivers most correlated with differences in species assemblages included volume of coarse woody debris, sapling density, percent canopy cover, and basal area. Wind-disturbed plots had the greatest species richness and diversity of saplings and ground vegetation, and had indicator species with unique habitat requirements (specialists). Indicator species of compound-disturbed plots were mostly generalists with broad habitat requirements. Reduced species diversity on compound-disturbed plots was attributed to salvage harvest-mediated reductions in habitat heterogeneity. Thus, leaving patches unharvested within salvaged stands is recommended to promote stand-scale plant diversity. Interestingly, regeneration of longleaf pine, the most desirable species in the system, increased with collective disturbance severity. Nonetheless, longleaf pine saplings and seedlings were markedly outnumbered by other species in all disturbance categories, indicating that these woodlands need prescribed fire or other competition reduction measures for recovery toward longleaf pine dominance.
Characteristics of recreational boat wakes
(University of Alabama Libraries, 2017) Shuster, Robert Lewis; Sherman, Douglas; University of Alabama Tuscaloosa
The applicability of using a boat’s size and speed to predict remotely the energy in its wake was studied. A portion of the Georgiana slough, a tributary of the Sacramento River, was instrumented with a data logger, camera, and KPSI 720t pressure transducer to record boat passages and the resulting wake. The camera was set to record only when triggered by a motion sensor and the data logger to save data only during daylight hours. The instruments were left in place for roughly the month of September 2009. The data gathered were then grouped into wake categories based on size, speed, and boat type. Distance from shore for each boat track creating a wake was assumed to be the same for all boats in the relatively narrow channel. A low statistically significant correlation (linear regression) was found between boat speed, size and type with measures of shoreline wake heights. Turned out to not correlate well. This surprising result may have been caused by several factors to be discussed but mainly due to boat length not actually capturing boat displacement which when combined with speed creates disturbance we see in the form of a boat wake. Using a double reciprocal regression model 〖boat size〗^3 was found to have the strongest correlation to index wave energy with an r^2 value of 87, and a p < 0.0001. Boat size was raised to the third power as a surrogate measurement of boat length, width, and hull depth to better capture a metric more closely associated with disturbance force. These results suggest that a boat’s size, which can be obtained remotely from cameras, can be used to help predict the energy content of the wake it can produce. This could be used to monitor remotely areas to help assess possible erosion impacts due to boat wakes and possibly help to establish no wake zones for sensitive water bodies.
Characteristics of tornadoes associated with land-falling Gulf Coast tropical cyclones
(University of Alabama Libraries, 2012) Rhodes, Cory Lynn; Senkbeil, Jason Carl; University of Alabama Tuscaloosa
Tropical cyclone tornadoes are brief and often unpredictable events that can produce fatalities and create considerable economic loss. Given these uncertainties, it is important to understand the characteristics and factors that contribute to tornado formation within tropical cyclones. This thesis analyzes this hazardous phenomenon, examining the relationships among tropical cyclone intensity, size, and tornado output. Furthermore, the influences of synoptic and dynamic parameters on tornado output near the time of tornado formation were assessed among two phases of a tropical cyclone's life cycle; those among hurricanes and tropical storms, termed tropical cyclone tornadoes (TCT), and those among tropical depressions and remnant lows, termed tropical low tornadoes (TLT). Results show that tornado output is affected by tropical cyclone intensity, and to a lesser extent size, with those classified as large in size and `major' in intensity producing a greater amount of tornadoes. Increased values of storm relative helicity are dominant for the TCT environment while CAPE remains the driving force for TLT storms.
Characterizing alluvial benches and incipient floodplains in a piedmont stream and investigating biogeomorphic feedbacks as a possible mechanism for their occurrence
(University of Alabama Libraries, 2012) Zimmermann, Bryce Thomas; Davis, Lisa; University of Alabama Tuscaloosa
In-channel benches are bank-attached, planar and narrow, fine-grained sediment deposits occurring between the river bed and the floodplain. Benches are often vegetated and sometimes paired and are formed predominately by suspended load deposition. These unique in-channel features are referred to are referred to by several different terms, such as berms, inner berms, shelfs, inset floodplains, and incipient floodplains which raises questions as to their formative processes and functionality within the fluvial system. As indicated by the broad terminology used to label benches, these features have considerable variation in characteristics. Two main classification systems have been developed for benches, one based on the elevation of the bench surface above the channel and the other based on the position of the bench along the channel. Several theories exist as to the formation and persistence of in-channel benches that are related to several different overarching controls, including: hydrologic variability related to drought and river regulation, accelerated sedimentation caused by anthropogenic disturbance, and rapid vegetation establishment under low-flow conditions. The geomorphic function of benches is a matter of some debate. In some cases, benches appear to function as incipient floodplains. In other locations benches are means of bank reconstruction in overwidened channels, and in some cases, benches are short-lived in-channel sediment storage feature This research aimed to better understand bench stratigraphy in order to interpret the instances in which benches act as incipient floodplains and to investigate what information about benches can be obtained by applying rudimentary dendroecological techniques. The research was conducted at several locations within Talladega Creek, Alabama. Five benches and their adjacent floodplains were cored to allow comparison of bench/floodplain stratigraphic and organic matter composition that would facilitate identification of incipient floodplains. In addition to sediment cores, tree cores were obtained for a minimum age analysis of bench surfaces and used to investigate historic hydroclimatic conditions that might be conducive to bench development. A tree species inventory of the benches was also recorded to compare to a theoretical model of riparian vegetation recently proposed by Corenbilt et al. (2007) that seeks to characterize biogeomorphic feedbacks. Stratigraphic interpretations based on particle size analyses indicate some differences exist between benches and floodplains. The benches were generally finer than the floodplains. Both benches and floodplains showed general fining upward, with some exceptions. Variations, however, are site specific, with both benches and floodplains exhibiting differences in organic matter content and median particle size by site. Tree cores revealed that in all cases, the establishment date of the oldest tree sampled at each site coincided with a drought period. The species inventory suggests some differences with the riparian vegetation model proposed by Corenbilt et al. (2007). The main conclusions that resulted from this research are that bench stratigraphy and organic matter content is determined by site-specific hydrogeomorphic and vegetation conditions rather than by broader influences. Based on the dendroecological analyses, it would appear that hydrologic variability associated with drought dominated hydroclimate is a factor in the formation of in-channel benches in Talladega Creek, Alabama. This is supported by the tree establishment dates and climatological data. The tree species inventory was not consistent with the Corenbilt et al. (2007) model, the species compositions indicating that as an environment for vegetation, in-channel benches function more like floodplains than in-channel features such as bars.
A classification scheme for landfalling tropical cyclones based on precipitation variables derived from GIS and ground radar analysis
(University of Alabama Libraries, 2011) Comstock, Ian Jacob; Senkbeil, Jason C.; University of Alabama Tuscaloosa
Landfalling tropical cyclones present a multitude of hazards that threaten life and property to coastal and inland communities. These hazards are most commonly categorized by the Saffir-Simpson Hurricane Potential Disaster Scale. Currently, there is not a system or scale that categorizes tropical cyclones by precipitation and flooding, which is the primary cause of fatalities and property damage from landfalling tropical cyclones. This research compiles ground based radar data (Nexrad Level-III) in the U.S. and analyzes tropical cyclone precipitation data in a GIS platform. Twenty-six landfalling tropical cyclones from 1995 to 2008 are included in this research where they were classified using Cluster Analysis. Precipitation and storm variables used in classification include: rain shield area, convective precipitation area, rain shield decay, and storm forward speed. Results indicate six distinct groups of tropical cyclones based on these variables.
Classifying land use/land cover change over time within the watershed boundary of keenjhar lake using supervised, unsupervised, and hybrid classification methods
(University of Alabama Libraries, 2021) Henry, Katherine Rae; Han, Luoheng; University of Alabama Tuscaloosa
This study determined the change of land use/land cover over time within the watershed boundary of Keenjhar Lake through the usage of remote sensing thematic classification methods, and, assessed if the changes occurring related to statements made in other studies about wetland and biodiversity decline. The three thematic classification methods utilized and compared in this study were the supervised, unsupervised, and hybrid classifications. Due to its higher overall accuracy, the supervised classification method was chosen to classify the March 07, 2020 Landsat 8 image and for post classifications from 1997 to 2002, 2002 to 2008, and 2002 to 2020. The results of this study did not support the hypotheses that there was a decline in wetland percent cover over time and that the hybrid classification was more accurate in comparison to other algorithms. The results did support the hypothesis that there was an increase in urban/agricultural land over time. The utilization of remote sensing in this study to assess land use/land cover did not indicate there was a decline in wetland size due to the 1998-2002 drought and other more recent droughts. For future studies, finer spatial resolution imagery is needed to further break down the land use/land cover classes and to determine minor changes that were not recognized in this study.
Climate-induced trends in global riverine water discharge and suspended sediment dynamics in the 21st century
(University of Alabama Libraries, 2019) Moragoda, Nishani Poorna; Cohen, Sagy; University of Alabama Tuscaloosa
Anthropogenic climate change, particularly through increased greenhouse gas (GHG) emissions, is projected to considerably impact 21st century precipitation distribution, altering fluvial processes such as sediment dynamics and riverine water discharge, worldwide. Changes in the magnitude of fluvial water and sediment fluxes can have profound impacts on the functioning and connectivity of earth’s natural systems. This study is focused on isolating the impacts of GHG-induced future climate change on riverine water discharge and suspended sediment fluxes in the 21st century at a global scale. A global-scale hydro-geomorphic model (WBMsed) was forced with precipitation and temperature projections generated from five General Circulation Models (GCMs), each driven by four Representative Concentration Pathways (RCPs). The results, based on an ensemble of model outputs, revealed that global river discharge and sediment dynamics are considerably impacted by anthropogenic climate change in the 21st century. Despite substantial regional heterogeneity, a global net increase is projected for both river discharge and sediment flux in the 21st century under all RCP scenarios. Increases are larger and more variable with increasing levels of GHG concentrations in the atmosphere. At the end of this century, climate change under RCP 2.6 is projected to cause approximately 1% increase in global river discharge and 5% increase in global suspended sediment flux. Under RCP 4.5 emission scenario, climate change will lead to a 5.6% increase in river discharge and 7% increase in sediment flux at a global scale. Approximately 5% and 9% increases are projected under RCP 6.0 in global river discharge and sediment flux respectively. Climate changes projected under RCP 8.5 will lead to the largest increases in river discharge and sediment flux (7.3% and 14.7% respectively) at the end of the 21st century. With increased warming, more extreme changes (increasing or decreasing) can be expected in both discharge and sediment flux. Also, the number of rivers with statistically significant trends in either direction increases with warming. In addition to magnitudes, inter-annual variability in both global river discharge and sediment fluxes also increase with increasing RCPs. Changes in sediment flux closely follow the patterns predicted for discharge, and are mostly driven by climate warming induced spatial and temporal variation in precipitation. However, the relationship between discharge and sediment flux was found to be non-linear both in space and time, demonstrating the utility of explicit modeling of both hydrology and geomorphology.

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