2007 Annual Report
1a.Objectives (from AD-416)
Develop and validate methods to identify critical source areas of soil and nutrient loss in agricultural catchments of the Chesapeake Bay drainage basin using remote sensing techniques, particularly LiDAR-developed topographic maps.
A. Develop technology for detection of runoff and erosion prone critical source areas in steeply sloped landscapes of the Chesapeake Bay drainage area.
B. Develop technology for detection of runoff and nutrient loss critical source areas in nearly-level landscapes of the Chesapeake Bay drainage area.
1b.Approach (from AD-416)
This collaborative research will involve USDA-ARS and Canaan Valley Institute (CVI) scientists, in the context of ongoing research initiatives, particularly the Conservation Effects Assessment Project. Research will be conducted at sties representative of landscapes and agricultural practices within the Chesapeake Bay drainage basin, including the Mid-Atlantic Highlands of Appalachia, Allegheny Plateau, Valley and Ridge, and Atlantic Coastal Plain. Research in steeply sloping landscapes will center on identification of areas of high frequency runoff generation and erosion and on improving site assessment index application using high resolution elevation models. Research in nearly level landscapes will focus on characterization of overland flow and subsurface recharge areas, drainage ditch networks and critical control points favorable to different management practices. Testing of remote sensing applications will take advantage of ongoing USDA-ARS watershed studies (Choptank, Manokin, Mahantango, Town Brook) to assess the potential to remotely identify critical source areas of nutrient loss. Research in the Choptank watershed will involve direct collaboration with scientists at the Hydrology and Remote Sensing Laboratory in Beltsville, MD. Existing soil and water quality monitoring data from these established experimental watersheds, as well as direct sampling and new experimentation, will be used to support testing. CVI scientist will acquire and process remotely sensed data (e.g., LiDAR and hyperspectral). With these data, USDA-ARS and CVI will collaboratively develop of novel inference techniques to identify areas of flow favorable to nutrient transport. Critical flow areas will be used to target areas where investment in additional conservation practices can be expected to achieve maximum water quality benefit and to evaluate the effectiveness of existing conservation practices. USDA-ARS and CVI will evaluate the potential for widespread application of newly identified inference techniques and participate in the development of strategies for their use in watershed management.
This project has been in place for nine months. This report serves to document research conducted under an Assistance Type Cooperative Agreement between Canaan Valley Institute and ARS. Additional details of research can be found in the report for the associated project 1902-13000-011-00D, "Integrated Management of Land and Water Resources for Environmental and economic Sustainability in the Northeast U.S." The objectives of this research conducted under this agreement directly address related in-house CRIS project Objective 2: Evaluate landscape-scale controls on nutrient transfers to quantify aggregate N and P losses from farming systems and watersheds typical of the Northeast, and Objective 4: Determine effectiveness of conservation practices (BMPs) in the Cannonsville/Town Brook Watershed and other appropriate watersheds (CEAP-related).
A Postdoctoral Research Associate was hired in January 2007 to manage and co-ordinate project related research activities. Various project related activities and procedures were discussed, finalized and implemented in part using conference calls (September 2006) and one-to-one meetings (June, August, and September 2006, and in February and May 2007). In addition there were several trips made to the different research sites in PA and MD.
Research projects to address the objectives mentioned below have been initiated in the Mahantango watershed located in east-central Pennsylvania and the Choptank river watershed which feeds directly into the main stem of the Chesapeake Bay and is the only tidal watershed under study in the CEAP program.
• Relate topography to nitrogen (N) fertilizer recommendations: Corn yield response to N fertilizer applications was observed to co-vary with soil moisture as related to topographic position. LiDAR may be used to generate detailed topographic maps for the purpose of refining N fertilizer recommendations.
• Determine N availability for corn along a transect from drier to wetter landscape positions in a Delmarva Bay agricultural landscape.
• Detect Rill Erosion: Test the maximum vertical resolution of LiDAR for use in mapping rill erosion as an indication of variable source area runoff following a major rainfall event.
• Accurately delineate watershed boundaries. The watershed boundaries will then be used to define contributing areas for water quality sample analysis and landscape and water quality models.
• Locate areas of potential and actual water accumulation (flooding). This information will be used to estimate wetland services (e.g. pollutant removal, habitat, and flood mitigation).
• Delineate overland flow pathways which will be used to better define the linkage between agricultural fields and adjacent wetlands.
LiDAR and color-infrared imagery data were collected for the WE-38 (March 26, 2007) watershed in the Mahantango watershed and the Choptank area (March 28, 2007) using an aircraft-mounted Optech ALTM 3100 sensor, which can fire up to 100,000 laser pulses per second. The ALTM 3100 system records four hits from each of the laser pulses, meaning that elevation information will be gathered not only for the ground but for surface features as well.