What is GIS, and why do we use it?

A Geographic Information System, or GIS, is a computer-based application that allows us to view, analyze, and manipulate spatial data. More than just “map making”, GIS integrates geographic data with information about the geographic features. Using the GIS programs, not only can the location of something be shown on a map, but information about these features can also be seen and used for a variety of purposes.

The Delaware SWCD uses GIS for a wide variety of things across our entire scope of programs from Drainage Projects and Agricultural Services, to Drainage Maintenance, and to Conservation Education, and Watershed Planning.

 


GIS Data

The data we use for our GIS applications comes from a variety of sources including data created by the Delaware County Auditor, the Ohio Department of Administrative Services, the Ohio Department of Natural Resources, and “in-house” created data layers.

 

Delaware County Auditor

The Delaware County Auditor’s GIS office was established in 1994, and has been the recipient of numerous internation, national, and local awards for its exemplary and innovative use of GIS technology in property taxation as well as many other applications. The Auditor’s GIS office is the source of the majority of spatial data specific to Delaware County including Parcels, Roads, Municipal Boundaries, Township Boundaries, Flood Plains, School District Boundaries, Census Data, Topography, and other information. The Auditor’s GIS Office also has digital orthophotography (an aerial photograph that has been geometrically corrected so that it can be used to measure true distances) for 1997, 2002, 2006, 2008, and 2010. All of the Auditor’s GIS data can be viewed for free by accessing the Auditor’s Office GIS Website.

 

State of Ohio – Ohio Geographically Referenced Information Program (OGRIP)

OGRIP, which is part of the state’s Department of Administrative Services, Office of Information Technology, is made up primarily of volunteers from state agencies, local and regional governments, utilities, universities, private organizations, and other interested individuals. The goals of OGRIP are to encourage the creation of digital geographic data, foster the ability to easily determine what geographic data exists, and foster the ability to easily access this data. One of the major projects of OGRIP has been the publication of digital orthophotography for every county in the state. Additionally, OGRIP also has published LIDAR images for almost every county. LIDAR is a remote sensing technology that measures distance by using lasers. It allows for the creation of a “photo” with surface elevations embedded within it. We can use these LIDAR images to analyze surface topography and map watercourses and drainage areas among other things. Other data available through OGRIP includes state and county boundaries, census data, statewide road information, municipal boundaries, major streams and rivers, and water well log locations.

 

State of Ohio – Department of Natural Resources

The Department of Natural Resouces, ODNR, maintains a vast amount of GIS data primarily focused in the environmental area. This includes soils, land cover, watersheds, erosion potential, ground water resources, land use/land cover, the Ohio Wetlands Inventory, and farmland information.

 

Delaware SWCD Data

    • Drainage Maintenance Data
      The Drainage Maintenance program maintains drainage infrastructure in agricultural, suburban, and commercial areas. Our Drainage Maintenance GIS data consists of project boundaries, agricultural tile and waterways, storm tile, storm tile features such as catch basins, curb inlets, and manholes, retention and detention basins, and flood routing. These data layers are dynamic as new features are added as new projects are added to the program.

 

    • Historic County Drainage
      The process that allows for landowners to petition the County Commissioners for drainage improvements (ORC 6131) has been around since the late-1800s. The Drainage Maintenance provision of this law (ORC 6137) was enacted in 1957 and basically requires all projects done under the petition process to placed on the Drainage Maintenance program upon completion. As such, many of the projects done under the petition process are not included on the maintenance program, and thus not included in our Drainage Maintenance GIS data layers. This data layer specifically contains the location of those projects including open ditches and subsurface drainage tile. This data layer was not created by the SWCD; however, we do currently maintain it. In some instances, the data was created from historic hand-drawn records. Because of this, the locations of some features are approximate.

 

    • Technical Assistance
      Beginning in 2004, the Delaware SWCD began tracking all technical assistance contacts based on parcel location. This data layer allows us to track the type and location of assistance provided as well as tie assistance notes to the parcel itself. Using this system, our technicians can easily access information about previous contacts with a parcel allowing them to better assist the landowners.

 

    • Historic Conservation Practices
      The creation of a digital inventory of all conservation practices designed by the Delaware SWCD was originally begun in the Upper Big Walnut Creek Watershed as part of ongoing partnership with the USDA Agricultural Research Service (ARS) Soil Drainage Research Unit studying the effects of conservation practices on water quality improvement. Once the Upper Big Walnut Creek Watershed was completed, the project was expanded to the entire county. Every conservation practices designed by the SWCD since its inception in 1944 has been scanned and it’s location digitized based on photo and parcel data. Using this layer, we can not only see the locations of the practices, but also access the digital copies of the engineering plans directly from the GIS program.

 

    • Historic Stream Names
      This project was started as an effort to create a roster of historically accurate names for streams and channels in Delaware County. Names were researched using a variety of sources. Current aerial orthophotography was used for spatial accuracy. All known names have been recorded with preference given to the earliest known and/or most legally-binding name. Record sources used to create this layer include Historical Plat Records, USGS databases and topographic maps, 1866 Historical Township maps obtained from the Delaware County Historical Society, Delaware County Ditch Records, Delaware County Engineer’s Office Bridge Records, and USDA NRCS project watershed records.

 

  • Historic Aerial Photography
    In addition to the digital orthophotography available from the Delaware County Auditor, the SWCD has also digitized and georeferenced historic aerial photographs. Years available include 1939, 1951, 1957, 1964, 1971, 1980, and 1988 (color infrared).

 

For more information, contact:

Bret Bacon, Conservation Services Coordinator
(740) 368-1921
Email: bret-bacon@delawareswcd.org

 


GIS LINKS

Delaware County Auditor’s GIS Office

Ohio Geographically Referenced Information Program (OGRIP)

OGRIP Statewide Imagery Downloads

Ohio Dept. of Natural Resources Geographic Information Management Systems Statewide Data

USDA NRCS Web Soil Survey

Ohio NRCS GIS

United States Geologic Survey Digital Map Products

USGS National Hydrography Dataset (NHD)