The first year of the study ( July 2020 – June 2021 ) served as the baseline assessment for the water budget , where we observed a two-inch deficit in groundwater levels . Water budget analysis from data gathered from June 2021 to August 2022 show there was a deficit of six inches , suggesting a decline in hydrologic conditions on the island . During the start of the growing season in 2022 , Charleston County exhibited moderate drought conditions for a period of 18 weeks ( NOAA NIDIS ). While the annual accumulated rainfall total for 2022 ( 44.68 inches ) would be considered average for the region , there was an increased intensity and reduced frequency of rainfall events which contributed to reduced groundwater storage . As a result , most of the accumulated rainfall resulted in stormwater runoff which did not recharge groundwater and likely contributed to drought conditions . Stormwater runoff is of particular concern because it introduces contaminants downstream which degrade water quality and serves as an indicator of the lack of groundwater recharge . Increased volumes of stormwater runoff are produced with increased coverage of impervious surface and the lack of a significant downhill gradient to move surface runoff more efficiently . This potentially affected vegetative productivity in the region through drought stress .
Time-series analysis of upland vegetation within the Watershed was conducted to show general trends in vegetative productivity from baseline data . Analysis was conducted separately on aerial imagery and satellite imagery to identify any changes in vegetation trends . Aerial imagery provided high resolution datasets to track smaller changes at the peak of the growing season , with baseline assessments occurring in 2015 where we exhibited little to no drought conditions . Satellite imagery is collected frequently every 10-16 days at lower resolutions , the baseline assessment conducted in 2019 . Each of these datasets were used to study the trends from the baseline datasets to the most currently available dataset . Vegetative trend analyses in subsequent habitat sections utilized the same imagery datasets with different methodologies . Aerial imagery suggested an increase in vegetative productivity , while satellite imagery over the short term shows mostly stable vegetative health throughout the watershed . Satellite and aerial imagery analysis shows high correlation in areas where there is decreasing vegetative health . The reduction in vegetative productivity from the satellite imagery is likely attributed to development pressure and drought stress in areas where decreases are shown .
Ecological Health of Kiawah Island 2022 18