ABSTRACT

The Environmental Geologic Atlas of the Texas Coastal Zone, which required 25 man-years of research, was initiated in 1969 to meet a growing need for basic land resource information about one of the most rapidly developing regions of Texas. The Coastal Zone, covering about 20,000 square miles, is not only an area of accelerating, competitive, and, sometimes, conflicting land use, but is also a region of dynamic natural processes and delicately balanced environments. The Coastal Zone is underlain by a wide variety of Pleistocene and Holocene/Modern facies with differing physical properties and land use capabilities. Large-scale mapping (1:24,000) of first-order units, including substrates, biology, processes, and man-made features, resulted in the principal environmental resource document--an Environmental Geology Map. This map, at a scale of 1:125,000, displays the distribution of some 130 units, which comprise both Pleistocene and Holocene/Modern fluvial, deltaic, barrier-strandplain-chenier, offshore, bay-lagoon-estuary, marsh-swamp, eolian, and man-made coastal systems.

A series of 8 Special-Use Environmental Maps at a scale of 1:125,000 were, in part, derived from the Environmental Geology Map, and, in part, compiled from other extensive data sources. The special-use map series includes: Physical Properties; Environments and Biologic Assemblages; Current Land Use; Mineral and Energy Resources; Active Processes; Man-Made Features and Water Systems; Rainfall, Stream Discharge and Surface Salinity; and Topography and Bathymetry. These maps, which contain about 150 units, were designed for the special requirements of various users; essentially an unlimited number of such special-use and thematic maps can be generated from the basic map data.

A further step toward application of environmental geologic information in land use planning was derivation of fundamental planning units based on carrying capacity. These units have been alternately termed resource capability units and land resource units. Each land resource unit is an areally defined entity that exhibits a unique set of properties, which limits or sustains its use for the wide variety of human activities. The properties of land resource or resource capability units, which can be quantified and digitized, may serve as principal input into land use inventory and planning systems being devised to support future land use decisions. A land use planning system that is based realistically upon the nature and variability of natural systems and coastal substrates can provide a common-sense, flexible, and fair approach to land use planning. Such a system provides potential users with options long before development becomes a reality, enabling users to plan for necessary engineering improvements and/or economic trade-offs. Fundamental geology is a critical element in such a land use decision system.