LB 26-272 - Climate Change Disaster Risks: Land Use Changes in Riparian Ecosystems and Water Quality Impact. Broad Run Watershed, Prince William County, Virginia.

Background/Question/Methods:

Background: Prince William County is Virginia's second most populous county and the 10th most diverse county in the nation (United States Census, 2020). Degrading water quality due to pollution and diminishing aquatic life have been a major concern in the Chesapeake Bay watershed (DEQ, 2017). The United Nation's Sustainable Development Goals (SDGs) call for actions to be taken in areas with such critical importance to humans and the planet (UN, 2015).

The Broad Run is an impaired stream in Prince William County. It covers an area of over 73 square miles and has 185 miles of streams made up of 50 sub watersheds.

Question: What is the impact of increasing human interactions and land use changes on forested riparian zones and water quality with changing climate in Prince William County?

Method: This work is a geospatial analysis of supervised classification of land cover/use changes using Geographic Information Systems (GIS). Data from the United States Geological Survey (USGS) Landsat 7 and 8, Trends Earth, National Land Cover, Aquaduct Water Stress, MODIS/Terra Land Surface temperature/Emissivity, NOAA Land Cover, Normalized Difference Vegetation Index (NDVI), Greenhouse Gases and water quality in situ data are used followed by a flood model relating to climate change.

Results/Conclusions:

Results: Analyzes of Landsat data from three different years, show an increase in land use and impervious surfaces. Increase in buildup areas have also created larger and more storm water ponds with significant loss in forested and riparian areas. The presence of chemical elements and heavy metals (copper) is significant. These impact water quality with potential increase in water stress in the future. Flood model results also show future increase in flooding with changing climate.

Conclusion: Increase in buildup areas with impervious surfaces due to increasing development in Prince William County has an impact on water quality. The presence of chemical elements and heavy metals like copper in waterways may have degradable impact to humans and other aquatic organisms in the Chesapeake Bay watershed in general.

The Broad Run flows into the Occoquan River which also constitutes the Occoquan Reservoir, a major drinking water source for most parts of Prince William and Fairfax Counties. The Occoquan River flows into the Potomac River which is a major tributary of the Chesapeake Bay.

This work has a profound implication for more data and studies on water quality and riparian buffers in the Chesapeake Bay and how they are affected by climate change.