Browsing by Subject "urbanization"
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Item Impervious Areas: Examining the Undermining Effects on Surface Water Quality(2012-02-14) Young, De'Etra JenraThis study explored the relationship between increased proportions of imperviousness in a watershed on surface water quality and examined the effectiveness of using remote sensing to systematically and accurately determine impervious surfaces. A supervised maximum likelihood algorithm was used to classify the 2008 high resolution National Agriculture Imagery Program (NAIP) imagery into six classifications. A stratified random sampling scheme was conducted to complete an accuracy assessment of the classification. The overall accuracy was 85%, and the kappa coefficient was 0.80. Additionally, field sampling and chemical analysis techniques were used to examine the relationship between impervious surfaces and water quality in a rainfall simulation parking lot study. Results indicated that day since last rain event had the most significant effect on surface water quality. Furthermore, concrete produced higher dissolved organic carbon (DOC), dissolved organic nitrogen (DON), potassium and calcium in runoff concentrations than did asphalt. Finally, a pollutant loading application model was used to estimate pollutant loadings for three watersheds using two scenarios. Results indicated that national data may overestimate annual pollutant loads by approximately 700%. This study employed original techniques and methodology to combine the extraction of impervious surfaces, utilization of local rainfall runoff data and hydrological modeling to increase planners' and scientists' awareness of using local data and remote sensing data to employ predictive hydrological modeling.Item Nesting ecology of mourning doves in changing urban landscapes(Texas A&M University, 2005-02-17) Munoz, Anna MariaTexas A&M University (TAMU) supports a substantial breeding population of mourning doves (Zenaida macroura) with one of the highest nest densities in Texas. There has been a long history of mourning dove research on the TAMU Campus, with initial population studies conducted in the 1950?s, and the most recent studies occurring in the 1980?s. The TAMU Campus and surrounding areas have experienced substantial changes associated with urbanization and expansion over the last 50 years, altering mourning dove habitat on and around campus. The objective of this study was to examine mourning dove nesting and production in an urban setting and determine how microhabitat and landscape features affect nest-site selection and nest success. Specifically, I (1) examined trends in mourning dove nesting density and nest success on the TAMU Campus, and (2) identified important microhabitat and landscape features associated with nest-site selection and nesting success. Mourning dove nests were located by systematically searching potential nest sites on a weekly basis from the late-March through mid-September. Nests were monitored until they either failed or successfully fledged at least 1 young. A total of 778 nests was located and monitored on campus. All nest locations were entered into ArcView GIS. An equal number of nests were randomly generated in ArcView and assigned to non-nest trees to evaluate habitat variables associated with nest-site selection for mourning doves. Binary logistic regression was used to evaluate the significance of microhabitat and landscape variables to nest-site selection and nest success. Comparisons with data collected in 1950, 1978, and 1979 showed relatively similar nesting densities, but a significant decrease in nest success over time. A comparison of microhabitat features between actual nest trees and random locations (non-nest trees) indicated increasing values of tree diameter at breast height and tree species were important predictors of mourning dove nest-site selection. Landscape features found important in dove nest-site selection were proximity to open fields, roads, and buildings. Proximity to roads and buildings also were significant predictors of nest success. Combining significant microhabitat and landscape variables for nest-site selection increased the predictability of the model indicating a possible hierarchical nest-site selection strategy.Item Rethinking the nonmetropolitan turnaround: renewed rural growth or extended urbanization?(Texas A&M University, 2007-04-25) Wang, XiaodongThis dissertation proposes a new, synthesized perspective for explaining the ??????Nonmetropolitan Turnaround?????? in the 1970s and 1990s. By studying the definition of urbanization carefully, using the human ecological perspective, many processes happening during the ??????Nonmetropolitan Turnaround?????? in the 1970s and 1990s, such as suburbanization, deconcentration, and counterurbanization, can be understood as different forms of the urbanization processes. When the majority of the population was rural, the dominant pattern of urbanization was rural-urban migration. When the majority of the population became urban, the dominant urbanization pattern reversed to urbanrural migration because urban centers had reached beyond their optimal density and processes operated to reduce their density. This paper hypothesizes that the two ??????turnarounds?????? were simply the result of different aspects of urbanization complicated by metropolitan status reclassifications. The perspectives of suburbanization, counterurbanization and deconcentration are integrated into the urbanization perspective. Using migration flow data compiled by the Census Bureau from 1975 to 1980 and from 1995 to 2000, the summary analyses confirmed that the net migration due to the three forms of urbanization largely accounted for all of the net migrant flows. This dissertation further tested the validity of optimal density theory with net migration data and confirmed the utility of this perspective in predicting the direction of net migration.Item The impacts of urbanization on endangered florida key deer(Texas A&M University, 2006-04-12) Harveson, Patricia MoodyConservation of native wildlife is becoming increasingly difficult due to continued human population growth and expansion. As the human population continues to increase, so does the rate of consumption of our natural resources. As competition for resources between man and wildlife continues, it is important to understand the effects of urbanization on species. Endangered Key deer (Odocoileus virginianus clavium) are endemic to the Florida Keys archipelago stretching southwest off the southern tip of peninsular Florida. Key deer range is restricted to the Lower Florida Keys with approximately 60% residing on Big Pine Key and 15% residing on No Name Key which have undergone rapid human population growth and development over the past 30 years. Urban development and its associated risk factors (i.e., habitat loss and fragmentation, deer domestication, and deer??vehicle collisions) have been cited as the greatest threat to the Key deer population. For my dissertation research, I evaluated the impacts of 30 years of development on the Key deer population. My results suggest that increased habitat fragmentation and increased road traffic have created areas of varying habitat quality and mortality risk and have resulted in a source-sink system for Key deer on Big Pine Key. In my examination of Key deer metapopulation dynamics, I found a low probability of deer colonizing 2 target outer islands (Sugarloaf and Cudjoe) through dispersal alone in the next 20 years. Further, I examined the impacts of urbanization on changes in Key deer population dynamics, behavior, and morphology. Collectively, my results suggest that over the past 30 years Key deer have become more urbanized, which in turn has influenced Key deer behavior and population viability. Behavioral adaptations due to deer plasticity appear to have provided Key deer with mechanisms to persist in a changing environment due to urbanization. However, the future ability of Key deer to persist in a continuously urbanizing environment cannot be predicted. At some threshold, urban development would become unsustainable, and, unlike other forms of habitat change or environmental disturbances, urban development is in most cases irreversible, requiring careful planning in habitat conservation strategies.Item The influence of the growth of the Dallas/Fort Worth (DFW) Metroplex on regional precipitation patterns(2009-05-15) Nordfelt, Anna MarieDue to the effects urbanization has on land-use and land cover change (LULC), urban areas have a major influence on the environment. The strong coupling between the land and atmosphere can alter the microclimatology of cities and their surrounding regions. Previous research has shown that cities can influence regional precipitation patterns. This is a result of many factors such as: increased heating and lifting caused by the urban heat island effect (UHI), increased pollution and aerosols, alteration of land use/land cover (which includes surface albedo, presence or lack of vegetation, and surface roughness changes), and urban design (which leads to increased friction and convergence). This study analyzes temporal and regional changes in the precipitation patterns of the Dallas/Fort Worth Metroplex as it has grown over the past century, and provides a methodology for testing urban influences on precipitation in other metropolitan areas. Precipitation from 1930 ? 2007 was analyzed for the following three study regions: DFW (urban area), CRA (upwind control region), and CRB (downwind control region). By comparing early (1930 ? 1950) and late period (1987 ? 2007) precipitation within each region, it was found that there were no statistically significant differences between the two periods. Entire period precipitation (1930 ? 2007) at CRB was statistically significantly different from both DFW and CRA although early and late period precipitation was not. While precipitation was similar between the two periods in all regions, comparing precipitation between the regions using the entire period shows potential anthropogenic influences. Land cover change between 1976 and 2001 was analyzed and it was found that water in the DFW Metroplex study region increased by 54.75%, vegetation decreased by 20.34%, and urban land cover increased by 176.14%. This may increase atmospheric moisture, surface temperature, friction and lifting over the urban center, and decrease the amount of heat released from the ground. While natural climate variability is the most important factor influencing precipitation in this region, it is possible that urbanization is also changing local and regional precipitation patterns, it may not be the only factor influencing change.