June 27, 2002 -- Since its inception in 1998, the Texas Strategic Mapping Program (StratMap) initiative has successfully resulted in a comprehensive digital base map for Texas by combining seven layers of digital geographic information for sharing by universities, governmental and private entities, as well as the general public.
With the completion of the original data layers during the summer of 2001, the StratMap team is focusing on better maintaining changing features, developing new ways to distribute data, evolving standards, and enhancing organization of the databases behind the spatial data.
The team has identified additional support for distribution and maintenance for three layers - digital orthophoto quads (DOQs), transportation, and boundaries - as the most pressing needs.
The funds provided by the 77th Texas Legislature for StratMap maintenance and distribution are managed by the Texas Natural Resources Information System (TNRIS) division of the Texas Water Development Board (TWDB). These funds will allow for the annual update of transportation and boundary data.
Due to the cost and lengthy production cycle of the data, the DOQs - digital high-resolution images combining the details of an aerial photograph with the properties of a map - will be regenerated across Texas over an eight-year cycle. Funds will also be used to further enhance the existing digital hydrography (surface water features) to place it within the new National Hydrography Dataset (NHD) model.
TNRIS has received numerous inquiries about creating new DOQs throughout Texas. They have entered into several agreements with outside groups to obtain existing DOQs and make them available to the public. The TWDB has formed partnerships with the Capital Area Planning Council, Houston-Galveston Area Council, City of San Antonio, North Central Texas Council of Governments, City of Abilene, and the Potter-Randall County Emergency Communication District. TWDB also entered into an agreement with the U.S. Geological Survey for new aerial photography in southern Texas that can be used in future DOQs (see Figure 1, above).
Transportation and boundary data are currently being maintained by numerous local, regional, and state agencies. TNRIS collects this information, merges it with other StratMap data, and makes it available to the public. The scope of transportation and boundary updates is expected to change markedly over time. Maintenance focuses on adding and adjusting these changing features.
There are many potential changes not only to the data content collected, but also in the way the data are submitted and distributed. For instance, many local groups collect transportation and boundary data for emergency communication (E-911) purposes. These datasets contain addresses that could be added to the StratMap data. In addition, there may be more efficient ways for local agencies to directly update their data in the StratMap database and have improved data access.
The new NHD hydrography data model was developed jointly by the U.S. Geological Survey and the Environmental Protection Agency. NHD is a process for indexing water features based on a standard unique identification code (reach code). Using NHD, governmental agencies will link their hydrologic data to a common base map.
Examples of stand-alone databases that can be linked using NHD include Water Quality Monitoring Sites, Drinking Water Intakes, Permitted Dischargers, Toxic Release Inventory (TRI) Sites, 303(d) TMDL Program Listed Waters, and 305(b) National Water Quality Inventory Waterbodies. NHD will be developed by hydrologic units - medium-sized standardized watersheds that typically cover some thirty 7.5-minute USGS quadrangles. Figure 2 shows a sample Texas hydrologic unit.
For more information on the latest developments in the StratMap program, contact Drew Decker at 512-936-7447 or by email at [email protected].
(All photos courtesy of the Texas Water Development Board)
