Physical and Environmental Geography Commons^™

Timing And Formation Of Linear Dunes South Of The Niobrara River Valley, North-Central Nebraska Sand Hills, Ashley K. Larsen

Department of Geography: Dissertations, Theses, and Student Research

The Nebraska Sand Hills is a vast (7500 square kilometer) area of grass-stabilized sand dunes. Larger dunes in the Nebraska Sand Hills formed primarily during the Late Pleistocene, but many underwent widespread reactivation during the Holocene. Recent Optically Stimulated Luminescence (OSL) dating indicates that the last major phase of reactivation in the Sand Hills was during the Medieval Warm Period, approximately 800 years ago. Nevertheless, many questions about the evolution of the dunes remain unanswered, particularly regarding the formation of linear dunes in portions of the Sand Hills.

This study seeks to understand more about the formation of linear dunes …

Utilizing A Consumer-Grade Camera System To Quantify Surface Reflectance, Joseph J. Lehnert

Department of Geography: Dissertations, Theses, and Student Research

Consumer-grade camera systems are often employed in aerial remote sensing to provide insight into patterns and processes of interest to science and industry, a trend that has largely been encouraged by the rapid growth of the small unmanned aircraft system (sUAS) industry. However, little research exists on the ability of these systems to accurately measure surface reflectance in specific wavebands, a crucial consideration for many remote sensing applications. This research was conducted on the premise that with proper equipment and calibration techniques consumer-grade cameras would be capable of accurately measuring surface reflectance in user-defined wavebands of interest. A stereo-pair, Fujifilm …

Assessing Landslide Susceptibility With Gis Using Qualitative & Quantitative Methods In Knox County, Nebraska, Christian J. Cruz

Department of Geography: Dissertations, Theses, and Student Research

This thesis assesses landslide susceptibility using data from LiDAR DEMs, land cover, and soil surveys. Data were assessed quantitatively through Bayesian logistic regression within a geographic information system (GIS) and statistical software to produce a landslide susceptibility map. The study area exhibits moderate relief where bluffs along the Missouri River valley gradually recede into rolling loess-mantled hills further to the south and southeast in Knox County. The six factors used to determine susceptibility to landslides are: land cover, parent material, slope aspect, slope curvature slope degree, and soil series. My findings show an increase in slope is the most significant …

Dating Late Quaternary Alluvial Fills In The Platte River Valley Using Optically Stimulated Luminescence Dating, Jacob C. Bruihler

Department of Geography: Dissertations, Theses, and Student Research

Alluvial fills underlying the Platte River Valley in Nebraska record the geologic history of the Platte River in the late Quaternary. This study investigated the alluvium underlying the valley near the cities of North Platte and Kearney, Nebraska. Data obtained from sediment cores drilled in the alluvial deposits was used to investigate the changes in Platte River dynamics on a glacial – interglacial timescale. Optically Stimulated Luminescence (OSL) dating was used to determine burial ages of recovered sediments and to quantify the thicknesses of the late Pleistocene and Holocene alluvial fills at each study area. Our geochronology depicts considerable differences …

Proximal Sensing As A Means Of Characterizing Phragmites Australis, Travis Yeik

Department of Geography: Dissertations, Theses, and Student Research

Phragmites australis is an invasive wetland weed found throughout much of the United States. Documenting and mapping the growth and spread of this emergent macrophyte can be an important step in developing and implementing successful management strategies. Characterizing the phenology of a vegetation species with a sensor capable of hyperspectral resolution, positioned at close proximity to the canopy of interest, is often a first step necessary for understanding the basic species-specific reflectance patterns, and for quantifying the manner in which light interacts with the plants comprising particular communities. Spectral data over a P. australis canopy were collected during 22 field …

Multi-Temporal Analysis Of Crop Biomass Using Selected Environmental Variables And Remote Sensing Derived Indices, Nwakaku M. Ajaere

Department of Geography: Dissertations, Theses, and Student Research

Measuring biomass in crops is important for yield prediction, nutrient management and analysis of carbon sequestration. Studying crop phenology via biomass can also provide insight into not only the state of the ecosystem but also environmental factors which may affect crop growth. Remote sensing techniques, as an alternative to traditional in-situ sampling methods for biomass assessment, provide potentially more efficient data acquisition and cost-effective procedures. Numerous vegetation indices (VI) have been developed which use spectral reflectance data to measure plant biophysical characteristics. The first objective of this research was to examine the correlation between crop biomass and selected environmental variables …

Assessing Seasonal Features Of Tropical Forests Using Remote Sensing, Roberto Bonifaz-Alfonzo

Department of Geography: Dissertations, Theses, and Student Research

Tropical forests are key components of the biogeochemical cycles, complex in structure, diversity and dynamics, also, tropical regions have been deforested and modified by human activities particularly for agriculture. Understanding the inter-annual and intra-annual variation dynamics of tropical regions could give valuable information on temporal characteristics of ecosystems behavior which is important for mapping and monitoring. This dissertation assesses seasonal and inter-annual changes in the tropical land cover that may be related to changes in the natural environment and/or human activities. Research was focused on the Mayan forest located in southern Mexico and Northwest Guatemala, one of the northern-most important …