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Collaborative Research: Streamflow, Urban Riparian Zones, BMPs, and Impervious Surfaces

EPA Lead: S. Taylor Jarnagin

Streamflow, Urban Riparian Zones, BMPs, and Impervious Surfaces (7pp, 1.25MB, About PDF)

EPA Landscape Ecology Branch, Environmental Sciences Division, USEPA/ORD National Exposure Research Laboratory
Mail Drop E243-05
109 T.W. Alexander Drive
Research Triangle Park, NC 27711
E-mail: jarnagin.taylor@epa.gov
Work Office Telephone: 919-541-1987
Work Fax: 919-541-0864

The U.S. EPA Landscape Ecology Branch (LEB) in Research Triangle Park, North Carolina is currently conducting collaborative urban development/landscape change/stream ecology research in the Clarksburg Special Protection Area (CSPA) in Montgomery County, Maryland.  Our primary research collaborators in this effort are the USGS Eastern Geographic Science Center, Reston Virginia and the Montgomery County, Maryland, Department of Environmental Protection, Rockville Maryland.  Our collaborative efforts are a part of the ongoing Clarksburg Monitoring Partnership (for more information on the Clarksburg Monitoring Partnership see the URL: http://www.montgomerycountymd.gov/dectmpl.asp?url=/content/dep/water/spaclarksburg.asp).Exit Disclaimer

The CSPA subwatersheds are on the outer edge of the exurban development shockwave expanding outward from the Washington DC metropolitan area and are outlined in yellow on the upper-left of Figure 1. The CSPA is an area of rapid development that we expect will be built out within the next five to ten years. The Montgomery County Department of Environmental Protection (DEP) has been monitoring stream biology and chemistry in the area streams for more than a decade and the CSPA involves the use of best management practices (BMPs) that are designed to limit the impact of development on water resources. For more information about the Montgomery County Special Protection Area programs, see the URL: http://www6.montgomerycountymd.gov/dectmpl.asp?url=/content/dep/water/whatarespas.asp.Exit Disclaimer

The first objective of the collaborative research is to correlate the impacts of ongoing development and the mitigating effect of local BMPs on the hydrological, biological, and chemical parameters of the CSPA water resources using a Before-After, Control-Impact (BACI) study design. This objective is focused on determining the effectiveness of BMP mitigation on streamflow disturbance, channel erosion and stream sedimentation due to impervious surfaces, sub-surface storm sewers and altered landform due to urbanization at the small watershed spatial scale.

Our primary research task in this objective is to map development and BMP placement as they occur; both the anthropogenic surface structures such as roads, buildings, parking lots, and changes in surface topography associated with urbanization and the subsurface storm sewer network; and to monitor the physical, chemical, and biological aspects of the associated water resources as development progresses. Changes in streamflow, surface water/groundwater relationships, and the biological and chemical parameters of the CSPA water resources are correlated with development patterns, anthropogenic alterations of the environment, and the BMPs designed to mitigate the impacts of development.  Montgomery County has obtained six high-resolution digital orthophotography overflights of the study area between (1998 and 2010) that form the basis for mapping the changes in land cover over this time period.  The USEPA and Montgomery County have obtained five Light Detection And Ranging (LiDAR) overflights of the study area that greatly increase the spatial resolution of the topographical analyses possible in the CSPA (Figure 2). These overflights and future LiDAR and other remote sensing (RS) collections are being used to determine if RS technology can be used to map changes in stream morphology associated with development as well as to assist in the hydrological modeling and surface mapping of that development. Our research at the watershed scale is intended to assess the effectiveness of BMPs by employing both positive and negative controls (stream gauges and monitoring in areas without development and areas developed without the CSPA BMPs) as well as pre- and post development data from areas gauged prior to development within the CSPA (Figure 3).

This research involves two primary components:

1) High resolution watershed mapping (i.e. urban growth, BMP placement, land use/land cover change, and topographic change) over time integrating various geospatial datasets including LiDAR, aerial photography, and satellite imagery, with all datasets collected for display and analysis in a Geographic Information System (GIS),  and

2) Coordinated monitoring of physical and biological parameters: chemical and biological stream monitoring, streamflow and precipitation gauging, and weather parameters.

To date, the USEPA has:

a) Funded the United States Geological Survey Water Resources Discipline (USGS WRD) for the placement of five stream gauges and a precipitation gauge in the CSPA to complement the existing Montgomery County DEP precipitation gauge and co-funded (along with Montgomery County) the continued operation of these stream gauges,

b) Collected repeat LiDAR data for analysis of stream channel and landform change (Figure 2), and

c) Collected multiple high-resolution satellite data for mapping land-cover change due to development.

The second major research component of the EPA contribution to the ongoing Clarksburg Monitoring Partnership is place-based monitoring of specific BMPs and the green infrastructure in the stormwater drainage areas feeding into the BMPs.  The objective of this component is to find methods of urban development and stormwater best management practices (BMPs) that work at the neighborhood spatial scale.  These BMPs need to both protect homeowners and their personal property from water damage during precipitation events and also maintain good water quality and fishable, drinkable, and swimmable surface waters; both in the areas being developed and the downstream receiving waters.  We are working to identify neighborhood development patterns, Green Infrastructure (GI) techniques, and advanced stormwater management practices that are working well and use those areas as models to help plan future developments to better meet the needs of both homeowners and the environment.  We will be monitoring stormwater runoff during individual precipitation events during the spring and summer of 2012 in four different areas in the CSPA to learn what works in both open single family residential housing designs and more tightly spaced housing patterns in areas that employ GI and those that use more centralized BMPs.  We will compare inflow and outflow water volume and stormwater constituents of concern to assess both the effectiveness of GI on the landscape and the effectiveness of individual BMP components.

The Collaborative Streamflow, Urban Riparian Zones, BMPs, and Impervious Surfaces Research being done by the USEPA LEB in Research Triangle Park, North Carolina is a component of the EPA’s Safe and Sustainable Water Resources Research Program.  The data from this research will be used to inform advanced urban stormwater modeling being done at the USEPA Ecosystems Research Division in Athens, Georgia.

This EPA-USGS-DEP collaborative research effort is an example of a Federal-Local technology-transfer partnership where innovative technologies are researched at the Federal level and the results made available at a local level for neighborhood solutions.  This research effort is an example of former EPA Administrator Mike Leavitt's "Enlibra Principles", where the "principles of flexibility, innovation, partnership and collaboration ... and other common sense ideas that will accelerate environmental progress" guide the research effort. This research is a collaborative effort where local stakeholders are involved setting research goals and Federal agencies are involved offering expertise and capabilities not available at the local level.  Past and current partners in this research are EPA Landscape Ecology Branch, Research Triangle Park, North Carolina; Montgomery County Department of Environmental Protection (DEP), Rockville, Maryland; USGS Water Resources Discipline (WRD), Baltimore, Maryland and Eastern Geographic Science Center (EGSC), Reston, Virginia; University of Maryland, Baltimore County, Maryland (UMBC), Department of Geography and Environmental Systems, and The Center for Urban Environmental Research and Education (CUERE); University of Maryland, College Park, Maryland, Department of Civil & Environmental Engineering and the Behavior, Ecology, Evolution and Systematics (BEES) Program; College of Engineering, Virginia Polytechnic Institute and State University, Blacksburg Virginia; Environmental Systems Analysis, Inc., Annapolis Maryland; and the Maryland-National Capital Park and Planning Commission (M-NCPPC), Silver Spring Maryland.

This paper has been reviewed in accordance with the United States Environmental Protection Agency's peer and administrative review policies and approved for presentation and publication.

Click image or figure number to view larger size:

Link to Figure 1: Satellite classification of urban land cover 1970s - 2000.
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Figure 1: Satellite classification of urban land cover 1970s - 2000. The Clarksburg Special Protection Area (CSPA) subwatersheds (yellow outline) are at the northwest edge of the current development extent of the Washington DC metropolitan area.

   Image from EPA Science Forum 2003 poster: "Use of LIDAR to Monitor Stream Morphology Changes Due to Urbanization of a Suburban Watershed". S. Taylor Jarnagin and David B. Jennings, e-mail: jarnagin.taylor@epa.gov. US Environmental Protection Agency, ORD/NERL/ESD Landscape Ecology Branch, Mail Drop E243-05, 109 T.W. Alexander Drive, Research Triangle Park, NC 27711.

Link to Figure 2: Building a better Digital Elevation Model (DEM).
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Figure 2: Building a better Digital Elevation Model (DEM). The National Elevation Data (NED), 30-meter pixel spatial resolution at the outer edge of Figure two is compared with a sub-meter DEM derived from a Light Detection And Ranging (LiDAR) overflight of the Clarksburg Special Protection Area. Both images have been processed to the same color elevation scale to graphically illustrate how much more topographical detail is available from the LiDAR imagery and how the mapping of anthropogenic development structures can be assisted with LiDAR. .

   Image from EPA Science Forum 2003 poster: "Use of LIDAR to Monitor Stream Morphology Changes Due to Urbanization of a Suburban Watershed". S. Taylor Jarnagin and David B. Jennings, e-mail: jarnagin.taylor@epa.gov. US Environmental Protection Agency, ORD/NERL/ESD Landscape Ecology Branch, Mail Drop E243-05, 109 T.W. Alexander Drive, Research Triangle Park, NC 27711.


Link to Figure 3: Clarksburg Maryland Special Protection Area.
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Figure 3: Clarksburg Maryland Special Protection Area showing subwatersheds (in yellow), stream gauges (green circles) and precipitation gauge (pink crosses) locations, and water quality monitoring locations (red stars).

   Image by. S. Taylor Jarnagin, e-mail: jarnagin.taylor@epa.gov. US Environmental Protection Agency, ORD/NERL/ESD Landscape Ecology Branch, Mail Drop E243-05, 109 T.W. Alexander Drive, Research Triangle Park, NC 27711.

 

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