Abstract
Waterways such as the Hudson River play an integral role in agriculture,
health, transportation, recreation, energy, and sustaining biodiversity.
Although water pollution in New York Harbor has been extensively
studied, the reduction of millions of commuters during the COVID-19
lockdown presents an unprecedented opportunity to study human impact on
water quality. We used remote sensing data to assess how the COVID-19
lockdown impacted water quality in New York Harbor, particularly in
areas near Combined Sewer Outfalls (CSOs). This technique has previously
been used to measure water quality in the Hudson River. We used ACOLITE
to process Landsat-8 and Sentinel-2 images from 2015-2020. The
algorithms “t_nechad”, “spm_nechad”, and “kdpar_qaasw” were
used to measure turbidity, and “chl_oc2”, “chl_oc3”,
“chl_re_moses3b”, “chl_re_moses740”, and “chl_re_mishra” to
measure chlorophyll concentration. After uploading processed images into
SeaDAS, we extracted values from pixels corresponding to Department of
Environmental Protection (DEP) field sites. At these sites, the DEP
measures Total Suspended Solids and Chlorophyll A Concentration using
optical turbidity sensors and fluorometers, respectively. By comparing
pixel values with DEP data we determined that the chlorophyll algorithms
did not produce accurate readings of chlorophyll concentration in New
York Harbor. We focused on analyzing turbidity at five DEP sites, four
of which were located around wastewater treatment plants, to assess any
CSO-induced changes in water quality. The frequency of usable satellite
data from 2020 was severely limited by cloudiness, so we combined
Landsat-8 and Sentinel-2 turbidity measurements (R = 0.8685) to form
time series for each site. We expected to see a decrease in turbidity
during the lockdown period, due to a decrease in sewage from office
buildings. However, turbidity strongly fluctuated throughout all years
with no discernable temporal pattern, and we could not distinguish
between 2020 measurements and seasonal patterns. Thus, preliminary
analysis shows that there was no significant variation in water
turbidity due to the COVID-19 lockdown.