Papers by Nathan McKinney
Remote Sensing
Terrestrial LiDAR (light detection and ranging) has been used to quantify micro-topographic chang... more Terrestrial LiDAR (light detection and ranging) has been used to quantify micro-topographic changes using high-density 3D point clouds in which extracting the ground surface is susceptible to off-terrain (OT) points. Various filtering algorithms are available in classifying ground and OT points, but additional research is needed to choose and implement a suitable algorithm for a given surface. This paper assesses the performance of three filtering algorithms in classifying terrestrial LiDAR point clouds: a cloth simulation filter (CSF), a modified slope-based filter (MSBF), and a random forest (RF) classifier, based on a typical use-case in quantifying soil erosion and surface denudation. A hillslope plot was scanned before and after removing vegetation to generate a test dataset of ground and OT points. Each algorithm was then tested against this dataset with various parameters/settings to obtain the highest performance. CSF produced the best classification with a Kappa value of 0....
Geotechnologies and the environment, 2022
Remote Sensing, 2022
The advances of remote sensing techniques allow for the generation of dense point clouds to detec... more The advances of remote sensing techniques allow for the generation of dense point clouds to detect detailed surface changes up to centimeter/millimeter levels. However, there is still a need for an easy method to derive such surface changes based on digital elevation models generated from dense point clouds while taking into consideration spatial varied uncertainty. We present a straightforward method, Las2DoD, to quantify surface change directly from point clouds with spatially varied uncertainty. This method uses a cell-based Welch’s t-test to determine whether each cell of a surface experienced a significant elevation change based on the points measured within the cell. Las2DoD is coded in Python with a simple graphic user interface. It was applied in a case study to quantify hillslope erosion on two plots: one dominated by rill erosion, and the other by sheet erosion, in southeastern United States. The results from the rilled plot indicate that Las2DoD can estimate 90% of the to...
Water Supply, 2017
Geographic Information Systems (GIS) software is used to analyze rainwater harvesting potential i... more Geographic Information Systems (GIS) software is used to analyze rainwater harvesting potential in Escambia County, Florida, USA. The approach presented can be replicated using LiDAR data, and the infrared spectrum of National Agriculture Imagery Program (NAIP) imagery. GIS surface maps are analyzed in combination with local utility consumption data to determine potential reductions in potable water consumption for households. The results indicate an extensive urban catchment of rooftop surfaces, and commensurate potential for rainwater harvesting and stormwater attenuation. Sixty two percent of the households analyzed consumed less water than could be potentially harvested. The remaining 38% consumed more water than could be potentially harvested. There are noted and significant differences between the two sample populations, including differences in water consumed and roof size. A comparison of lot size between the two sample populations did not yield any significant difference. T...
Journal of Coastal Research, 2017
Coastal erosion is a global issue, putting increasing physical and socioeconomic stresses on coas... more Coastal erosion is a global issue, putting increasing physical and socioeconomic stresses on coastal communities. While shoreline protection structures are typically seen as potential solutions, negative environmental impacts often result. Groins, a shore-normal type of structure, can successfully impound sediment; however, improper design can lead to downdrift erosion and create hazardous rip currents. Widespread construction of groins on the northern coast of the Yucatán Peninsula is thought to have caused significant morphologic change to the shoreline, raising questions as to their effectiveness. The objective of this regional survey was to collect geodata on shoreline position and existing shoreline protection structures. Methods included (1) GPS mapping of the shoreline and groin structures along a 13-km stretch of coastline; (2) developing a classification for groin construction, condition, and attachment to the present shoreline; and (3) analyzing surface area difference 5 m immediately updrift and downdrift from each structure. Results showed that (1) since 1994, 127 additional structures were built, perhaps in response to the 128 structures detached from the shoreline that were observed in this study; (2) the 305 surveyed groins, classed into various types, had largely lost their effectiveness; and (3) greater surface area difference precedes an area of chronic erosion referenced by previous researchers. This survey provided a greater understanding of structure usage and impact on the regional scale and showed that coastal management approaches must rely upon more than groins to maintain a sustainable coastal environment.
International Journal of Biometeorology, 2010
Previous studies have shown that natural disasters, and hurricanes in particular, have led to mor... more Previous studies have shown that natural disasters, and hurricanes in particular, have led to more deaths than those usually documented in short post-storm surveys. Such indirect deaths, thought to be related to dietary, stress or pre-existing medical conditions, can exceed the number of direct deaths and may persist for weeks or even months beyond the event itself. In the present study, cumulative sum of deviations plots are used to quantify the number of direct and indirect deaths resulting from Hurricanes Charley, Frances, Ivan and Jeanne that made landfall in Florida in 2004. Results suggest that there was an elevated mortality for up to 2 months following each storm, resulting in a total of 624 direct and indirect deaths attributable to the storm. Trauma-related deaths that can be associated directly with the storm account for only ∼4% of the total stormrelated mortality, while indirect mortality accounts for most storm-related deaths. Specifically, a large percentage of the elevated mortality was associated with heart (34%) and cancer-related deaths (19%), while diabetes (5%) and accident-related deaths (9%) account for a smaller but still significant percentage of the elevated mortality. The results further suggest that the elevated mortality was the result of additional deaths that would not have otherwise occurred within that 5 month period, and not simply a clustering of deaths that were inevitable between 1 August and 31 December 2004. The elevated mortality identified in this study is significantly greater than the official count of 31 direct and 113 indirect deaths resulting from the four hurricanes combined. This suggests a need for improved mortality counts and surveillance in order to better evaluate and identify effective prevention policies, and to identify preventable deaths.
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Papers by Nathan McKinney