Spatial and temporal patterns in streamflow, water chemistry, and aquatic macroinvertebrates of selected streams in Fairfax County, Virginia, 2007–18

Abstract

Ecologists with the Fairfax County Department of Public Works and Environmental Services, primarily Shannon Curtis and Joe Sanchirico, have contributed greatly to this effort through field work and program responsibilities. Their dedication to the success of this effort has been vital in the progress toward the achievement of program objectives. Staff at the Fairfax County Environmental Services Laboratory performed the nutrient analyses for the large number of samples collected. Their efforts to accommodate unpredictable sample collection schedules are greatly appreciated. This study was designed by Doug Moyer and Ken Hyer of the U.S. Geological Survey (USGS), who continue to contribute to the success of the effort by sharing expertise in water-resources monitoring and data analysis. Alyssa Thornton and numerous USGS hydrologic technicians have spent substantial amounts of time in the field maintaining instrumentation and collecting data, and their efforts are greatly appreciated. We would also like to thank Guoxiang Yang for his analysis of long-term trends in continuously collected specific conductance data.

Small forested watershed weathers effects of climate change better than a nearby urban watershed in Northern Virginia, USA

“…The results of this study provide insight about the effects of urbanization on watershed hydrology in the region. Trends in baseflow index, runoff ratio, and mean daily flow were reported for two nearby urban watersheds, Difficult Run (16 km northwest of 4MR) and Accotink Creek (13 km west of 4MR) over a similar period (Porter et al, 2020). Like 4MR, high flows and annual runoff ratios have increased in both watersheds since the late 1940s.…”

“…The trends in annual precipitation, intensity, and the recurrence of heavy rainfall events (Table 2) in the two watersheds for WY 1952 through 2022 were remarkably similar, indicating that the climate is changing and specifically that precipitation is increasing in this area. groundwater-surface-water exchange (Hardison et al, 2009;Nagy et al, 2012;Porter, 2022;Porter et al, 2020;Walsh et al, 2005).…”

“…These differences provide insight about how urbanization can alter watershed hydrology and stream hydraulics. Numerous studies have linked land development to increases in the magnitude and recurrence of streamflow generated by overland runoff and decreases in those flows sustained by groundwater‐surface‐water exchange (Hardison et al, 2009; Nagy et al, 2012; Porter, 2022; Porter et al, 2020; Walsh et al, 2005). Notably, the streamflow metrics revealed higher flows in 4MR than SFQ across all flows, not just high flows.…”

“…This study was not designed to establish a link between SCMs and streamflow metrics; however, the substantial amount of implementation over that period may be related to the lack of a trend in precipitation-adjusted annual peak flows since 1982.The results of this study provide insight about the effects of urbanization on watershed hydrology in the region. Trends in baseflow index, runoff ratio, and mean daily flow were reported for two nearby urban watersheds, Difficult Run (16 km northwest of 4MR) and Accotink Creek (13 km west of 4MR) over a similar period(Porter et al, 2020). Like 4MR, high flows and annual runoff ratios have increased in both watersheds since the late 1940s.…”

“…The stream supports a rich diversity of benthic macroinvertebrates, and riparian habitat is in excellent condition (Kwiatkowski, 2011). Various federal, state, and local entities use SFQ as a reference stream for stream and habitat assessments (Bhaskar et al, 2020; Fairfax County, 2022; Mangun, 1989; Maurakis, 2010; Mogollón et al, 2016; Porter et al, 2020).…”