Understanding the Effects of Stormwater Management Practices on Water Quality and Flow

Science Center Objects

Urban development can have detrimental impacts on streams including altering hydrology, increasing nutrient, sediment, and pollutant loadings, and degrading biological integrity. Stormwater Best Management Practices (BMPs) can be used to mitigate the effects of urban development by retaining large volumes of stormwater runoff and treating runoff to remove pollutants. This project focuses on understanding how the presence, type, and spatial pattern of urban stormwater BMPs in a watershed impacts ecosystem processes and function.

Aerial view of development.

Aerial view of development. (Public domain.)

Research Objectives:

Location of study watersheds in Clarksburg, Maryland.

Location of study watersheds in Clarksburg, Maryland. (Public domain.)

Better understand the effects of stormwater BMPs on water quality, water quantity, groundwater recharge, geomorphology, denitrification potential, and benthic macroinvertebrate communities.

Study Area:

We are studying the use of stormwater BMPs in watersheds located within the Clarksburg Special Protection Area in Montgomery County, Maryland. Clarksburg is a suburb of Washington, DC, located approximately 30 miles northwest of Washington DC. We are monitoring a forested watershed, an urban control watershed, and three urban treatment watersheds that have housing developments with a high density of stormwater BMPs that were designed to retain and infiltrate stormwater.

The U.S Geological Survey, U.S. Environmental Protection Agency, and Montgomery County Department of Environmental Protection have monitored conditions in these watersheds since 2004. The project team is currently expanding this research to include urbanizing areas in the southeastern US.

Streamflow, Groundwater, and Water Quality Monitoring: 

We use streamgages and precipitation gages to assess hydrologic alterations by comparing the frequency, magnitude, timing, and rate of change of stormflow events in watersheds with different types and densities of BMPs.  We monitor groundwater levels in shallow wells to assess the impacts of infiltration-focused BMPs on groundwater recharge and water table fluctuations. We collect water quality samples during baseflow and stormflow conditions to monitor differences in sediment, nutrient, and bacteria concentrations in the study watersheds. Soil samples are collected to identify soil microbial community structure and function, with a focus on soil denitrifiers.

Images of how and why we monitor various water parameters.

Monitoring water quality, hydrology, and soils to understand the effects of stormwater management practices. (Public domain.)

Detecting Geomorphic Changes: 

Hillshade showing topographic changes before and after suburban develop

Hillshade showing topographic changes before and after suburban develop in Tributary 104 located in Clarksburg, MD. Left photo is from 2002 (pre-development) and right photo is from 2013 (post-development). (Public domain.)

Repeat lidar-derived digital elevation models and field surveys are being used to assess changes in topography and stream geomorphology in watersheds undergoing urban development. These datasets allow us to track changes to overland flow paths, hydrologic connectivity between impervious surface and the stream network, and stream channel geometry during and after watershed development. Tracking geomorphic change provides insight into the movement water and sediment through the landscape.