Description: Contours depicting land topography were constructed for the Texas coastal region. The underlying dataset was the U. S. Geological Survey National Elevation Dataset (NED), a raster dataset having a one arc-second grid resolution; it was imported into GMT (Generic Mapping Tools), where digital vector contours were derived. The raster data were smoothed and filtered prior to contouring. Editing of contours was carried out in the Adobe Illustrator software package, and exported in an image file. The vector contours were imported into Arc-GIS, where a shapefile containing the contours was created. The National Elevation Dataset (NED) is a new raster product assembled by the U.S. Geological Survey (USGS). Data corrections were made in the NED assembly process to minimize artifacts, permit edge matching, and fill sliver areas of missing data. The NED has a resolution of 1 arc-second (approximately 30 meters) for the conterminous United States, Hawaii, and Puerto Rico and a resolution of 2 arc-seconds for Alaska. National Elevation Dataset data sources have a variety of elevation units, horizontal datums, and map projections.
For information on NED, refer to http://erg.usgs.gov/isb/pubs/factsheets/fs14899.html
For information on GMT, refer to http://gmt.soest.hawaii.edu/
Note: Support of the Texas Parks and Wildlife Department in preparation of these datasets is gratefully acknowledged.
Description: Data from the CD mentioned below had been clipped by the state boundaries of Texas.
This CD-ROM contains vector and polygon coverages of average monthly and annual precipitation for the climatological period 1961-90. Parameter-elevation Regressions on Independent Slopes Model (PRISM) derived raster data is the underlying data set from which the polygons and vectors were created. PRISM is an analytical model that uses point data and a digital elevation model (DEM) to generate gridded estimates of annual, monthly and event-based climatic parameters. Detailed descriptions of the PRISM raster data can be found with the accompanying raster data sets. For further information, the online PRISM homepage can be found at .
This data was accessed from the Texas General Land Office and clipped by HRRC for the dispaly in Texas Coastal Planning Atlas.
Description: Ecoregions denote areas of general similarity in ecosystems and in the type, quality, and quantity of environmental resources. They are designed to serve as a spatial framework for the research, assessment, management, and monitoring of ecosystems and ecosystem components. By recognizing the spatial differences in the capacities and potentials of ecosystems, ecoregions stratify the environment by its probable response to disturbance (Bryce and others, 1999). These general purpose regions are critical for structuring and implementing ecosystem management strategies across federal agencies, state agencies, and nongovernment organizations that are responsible for different types of resources within the same geographical areas (Omernik and others, 2000). The approach used to compile this map is based on the premise that ecological regions are hierarchical and can be identified through the analysis of the spatial patterns and the composition of biotic and abiotic phenomena that affect or reflect differences in ecosystem quality and integrity (Wiken 1986; Omernik 1987, 1995). These phenomena include geology, physiography, vegetation, climate, soils, land use, wildlife, and hydrology. The relative importance of each characteristic varies from one ecological region to another regardless of the hierarchical level. A Roman numeral hierarchical scheme has been adopted for different levels of ecological regions. Level I is the coarsest level, dividing North America into 15 ecological regions. Level II divides the continent into 52 regions (Commission for Environmental Cooperation Working Group 1997). At level III, the continental United States contains 104 ecoregions and the conterminous United States has 84 ecoregions (United States Environmental Protection Agency [USEPA] 2003). Level IV is a further subdivision of level III ecoregions. Explanations of the methods used to define the USEPA's ecoregions are given in Omernik (1995), Omernik and others (2000), and Gallant and others (1989). Ecological and biological diversity of Texas is enormous. The state contains barrier islands and coastal lowlands, large river floodplain forests, rolling plains and plateaus, forested hills, deserts, and a variety of aquatic habitats. There are 12 level III ecoregions and 56 level IV ecoregions in Texas and most continue into ecologically similar parts of adjacent states in the U.S. or Mexico. The level III and IV ecoregions on this poster were compiled at a scale of 1:250,000 and depict revisions and subdivisions of earlier level III ecoregions that were originally compiled at a smaller scale (USEPA 2003; Omernik 1987). This poster is part of a collaborative project primarily between USEPA Region VI, USEPA National Health and Environmental Effects Research Laboratory (Corvallis, Oregon), Texas Commission on Environmental Quality (TCEQ), and the United States Department of Agriculture-Natural Resources Conservation Service (NRCS). Collaboration and consultation also occurred with the United States Department of the Interior-Geological Survey (USGS)-Earth Resources Observation Systems Data Center, and with other State of Texas agencies and universities.
The project is associated with an interagency effort to develop a common framework of ecological regions (McMahon and others, 2001). Reaching that objective requires recognition of the differences in the conceptual approaches and mapping methodologies applied to develop the most common ecoregion-type frameworks, including those developed by the United States Forest Service (Bailey and others, 1994), the USEPA (Omernik 1987, 1995), and the NRCS (U.S. Department of Agriculture-Soil Conservation Service, 1981). As each of these frameworks is further refined, their differences are becoming less discernible. Regional collaborative projects such as this one in Texas, where some agreement has been reached among multiple resource management agencies, are a step toward attaining consensus and consistency in ecoregion frameworks for the entire nation.
Comments and questions regarding this Level III and IV Ecoregions of Texas map should be addressed to Glenn Griffith, Dynamac, Inc., 200 SW 35th Street, Corvallis, OR 97333, (541) 754-4465, FAX: (541) 754-4716, email: griffith.glenn@epa.gov, or to James Omernik, USGS, c/o US EPA - NHEERL, 200 SW 35th Street, Corvallis, OR 97333, (541) 754-4458, email: omernik.james@epa.gov.
The origional data was accessed from the Texas General Land Office and clipped by HRRC for the display in Texas Coastal Planning Atlas.
Description: Vegetation types of Texas - including cropland as delineated from Landsat MSS satellite imagery and ground survey. The data was accessed from the Texas General Land Office and clipped by HRRC for the display in Texas Coastal Planning Atlas.
Description: Wetland areas mapped by the U.S. Fish and Wildlife Service's National Wetlands Inventory based on 1992-93 photography within the areas of certain U.S. Geological Survey 1:24,000 quads in coastal counties of Texas. Digital line graph files containing these quad areas were converted to ARC/INFO and appended into a single coverage by Texas General Land Office.
Description: Wetland areas mapped by the U.S. Fish and Wildlife Service's National Wetlands Inventory based on 1992-93 photography within the areas of certain U.S. Geological Survey 1:24,000 quads in coastal counties of Texas. Digital line graph files containing these quad areas were converted to ARC/INFO and appended into a single coverage by Texas General Land Office.
Description: The origioal data layer portrays major dams of the United States, including Puerto Rico and the U.S. Virgin Islands. The map layer was created by extracting dams 50 feet or more in height, or with a normal storage capacity of 5,000 acre-feet or more, or with a maximum storage capacity of 25,000 acre-feet or more, from the 79,777 dams in the U.S. Army Corps of Engineers National Inventory of Dams. This is a replacement for the April 1994 map layer. The data was modifies by HRRC for the display in Texas Coastal Planning Atlas.