Abstract
The Center for Agricultural, Resource and Environmental Systems (CARES), has contracted with the Missouri Department of Natural Resources (MDNR) to conduct the Water Quality Data Enhancement Project. The objective of this project is to dynamically link water quality data to the National Hydrography Dataset (NHD) through a decision support system (DSS) tool to address environmental priorities within the state of Missouri. Using the DSS as a tool for both graphic representation and analysis, the project will be designed to support whole basin water quality planning, assessment, and enforcement activities of both the Department of Natural Resources and the public. The four phase project will begin with RF3 File Enhancement. This will be done in cooperation with the U.S. Environmental Protection Agency (USEPA) and U.S. Geological Survey (USGS) using the recently developed Hydrographic Visual Pass process (VP). In the creation of the NHD, USEPA RF3 attribute data will be conflated to the USGS DLG dataset. Phase two will be the accumulation of spatial data sets for the southeastern region of Missouri including concentrated animal feeding operations (CAFOs), Special Area Land Treatment (SALT) and EARTH projects and priority watersheds. Phase three will be the development of the DSS with accessibility of the data through the Internet of foremost concern. Phase four will be the production of presentation materials and a procedure manual for the DSS.
In 1994 a Memorandum of Understanding formalized the commitment of USGS and USEPA to merge RF3 and DLG as a response to their own needs and those of other users. This merger of complementary systems also coincided with the Federal Geographic Data Committee (FGDC) led efforts to develop the National Spatial Data Infrastructure (NSDI). As a result, the National Hydrography Dataset incorporates NSDI framework criteria set out by the FGDC. The NHD is the culmination of these recent cooperative efforts between USEPA and USGS. It combines the best of the USEPA RF3 and USGS DLG hydrography files: hydrologic ordering, navigation for modeling applications, the unique reach code for water features from RF3; and the spatial accuracy and fullness of DLG hydrography.
The NHD will supersede RF3 and DLG by incorporating them, and not by replacing them. Current users of these datasets will find the same data in a new, more flexible format. The NHD will be both familiar, greatly expanded and refined. The NHD is designed to provide comprehensive coverage of hydrologic data for the United States. While it is based on 1:100,000-scale data, the National Hydrography Dataset is designed to make it accommodate higher-resolution data required by many users, thereby encouraging its development.
The National Hydrography Dataset combines the extensive previous work of USGS, USEPA, and others. By integrating these databases, the NHD is immediately more inclusive, powerful and useful than any of its components. It is designed for continual expansion and improvement by end-users. The move towards 1:24,000-scale data is already underway in many states, for example, a pilot program in the State of Florida is scheduled to be completed on September 30th, 1997.
The NHD will be housed at the National Spatial Data Infrastructure (NSDI) Clearinghouse at the USGS Eros Data Center, and be available initially at the cataloging unit (CU) level. Accessible through the Internet via FTP and the World Wide Web, the data will be served in ASCII and/or SDTS formats, and perhaps also on CD-ROM or tape media.
Visual Pass processing will occur at both the 30 x 60 minute, 1:100,000-scale quadrangle and CU levels. For each quadrangle assigned to a site, participants will first perform conflation, centerline correction and navigation quality assurance/quality control (QA/QC). Once this quad-level QA/QC is completed, VP sites will then perform CU-level QA/QC for all CUs completely within the assigned set of quadrangles. After the initial processing by the VP site the quadrangles are returned to the USGS National Mapping Division. The NMD will perform QA/QC for all CUs that fall between participating sites and then perform the final central processing. This is to ensure that the data has been processed consistently across the country. The follow-on quality checking work will involve both an automated (blind) screening of all data, as well as a visual review of the data.
The initial or "blind pass" processing by USGS mainframe computers is expected to process 93%-95% of the conflation correctly. The remaining 5%-7% will have to be done using the VP tools. These AML tools are being developed by jointly by the USGS, USEPA and private contractors.
Three primary checks of the data will be made. The first will be the correcting of any conflation errors or omissions. RF3 reaches which did not conflate or conflated incorrectly to the DLG linework will be conflated manually using the VP menus. The tools allow the operator to correct reach IDs, fix flow direction, add missing reaches or delete extraneous linework. The second major goal will be to fix centerlines which failed to integrate into the DLG, add them where necessary or assign reach IDs. While the third check will be verifying and correcting navigation errors.
It is estimated the VP process will require six to eight hours for each 1:100,000-scale quadrangle. With nearly 1,850 quadrangles to process, the twenty-four sites doing the VP will share in approximately 14,000 hours of Visual Pass processing. The VP is expected to begin after a final training session for the participants in May, 1997. The goal for completion of the VP and making the NHD available is September 30th, 1997.
National Hydrography Dataset Home Page - nhd.fgdc.gov/index.html
USGS - EROS Data Center - http://edcwww.cr.usgs.gov/
And many thanks to Ann Peton, GIS Coordinator, Missouri Department of Natural Resources - Division of Environmental Quality, the Project Manager.