Using cloud-based remote sensing to estimate Hurricane Impacts on Vegetative Cover in Carolina Bays in North Carolina

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2018-05

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Schager, Sara, Masters of Environmental Assessment, Using cloud-based remote sensing to estimate Hurricane Impacts on Vegetative Cover in Carolina Bays in North Carolina Carolina Bays are unique geographically isolated wetlands that provide critical habitat to several species of plants and animals in the southeastern United States. These areas, due to their inland location, unique vegetation, and shallow inundation of water, can experience strong effects from hurricanes. Hurricanes’ high winds, and large amounts of precipitation could affect these shallow, inland wetlands. Carolina Bays have not been well studied, and the impacts of hurricanes on them have been even less evaluated. I utilized a cloud-based remote sensing approach to examine the effects of hurricanes on the vegetative cover of Carolina Bays. Using Climate engine, I utilized the normalized difference vegetation index (NDVI) as a measure of vegetation status. I evaluated seven hurricanes and 32 sites to determine if hurricanes affected vegetative cover in Carolina Bays. Out of the 32 sites and seven hurricanes examined, five sites showed statistically significant effects to vegetation from hurricanes. Site 6 had a higher NDVI value (0.909) before the hurricane than it did during the same time period the year after the hurricane occurred (0.755). Additionally, Site 6 was 60% agricultural field. This site showed that Climate Engine is capable of detecting changes in NDVI values on Carolina Bay sites. Four sites affected by Hurricane Fran had a significantly lower NDVI the month after the hurricane occurred than they did the month before the hurricane. Hurricane Fran was a larger hurricane event and probably had bigger vegetative impacts than the smaller hurricane events. My research suggests that NDVI values obtained from Climate Engine are capable of determining vegetative impacts on Carolina Bays, especially changes to NDVI of Carolina Bays during bigger hurricanes. While Climate Engine makes large amounts of remote sensing data easily accessible, in our case the remote sensed data did not show very strong impacts of smaller hurricane events on Carolina Bays. This is probably due to the fact that the actual impacts on the ground are limited due to the dynamic nature of the Carolina Bays themselves, rather than limitations of Climate Engine. Limitations such as cloud cover during evaluation windows, resolution of satellite photography (30 x 30 m pixels), and the fact that NDVI cannot pick up on species composition changes or changes caused by fallen debris may have hindered evaluation. Future research on Carolina Bays should focus on changes in depth of water due to precipitation and fallen debris, which may uncover additional impacts to these ecosystems from hurricanes.

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Carolina Bays, hurricane impacts, climate engine, NDVI, wetland vegetation, LANDSAT

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