Landsat-Based Evaluation of Vegetation and Snow Around Hoh Glacier, Olympic National Park, Washington Between 1987 and 2022

Abstract

Glaciers within the Olympic Mountains, Washington, occupy a significant role in local ecosystems by providing cold meltwater to feed rivers and forests downstream. Atop Mount Olympus, glaciers are fed by storm clouds inundated with moisture from the Pacific Ocean during the autumn, winter, and spring seasons. The Hoh Glacier, alongside the Blue and White Glaciers, provides cool meltwater during rain-starved summers to the Hoh Watershed, allowing keystone salmon and bull-trout populations to flourish. However, due to anthropogenic climate change, glaciers worldwide have receded or outright disappeared. The glaciers atop Mount Olympus are no exception to this global trend and are estimated to disappear by 2070. This project uses remote sensing to quantify how vegetation and snow cover around the Hoh Glacier have changed across 35-years in 5-year intervals starting in 1987 and concluding in 2022. Multispectral Landsat imagery of the watershed surrounding Hoh Glacier will be quantified and classified from the normalized difference vegetation index (NDVI) and the normalized difference snow index (NDSI). Land cover classified by NDVI revealed that barren, rocky, snowy terrain decreased over time while sparse vegetation increased. Through NDSI, land designated as possessing snow fell, while terrain which lacked snow increased between 1987 and 2022.