Browsing by Subject "Galveston County"

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Coastal Hazards Atlas of Texas: A Tool for Hurricane Preparedness and Coastal Management - Volume 1 Brazoria, Galveston, and Harris Counties
(1999) Gibeaut, James; White, William Allen, 1939-
This report accompanies the CD-ROM of the Texas Coastal Hazards AtlasVolume 1. The atlas is being developed in response to the need for technical information by coastal planners and to increase public awareness of coastal processes. The area covered in volume 1 is Galveston, Brazoria and southeast Harris Counties. This area includes the Gulf of Mexico shoreline from High Island to the Brazos River and the southern and western Galveston Bay system. The atlas consists of Geographic Information System files in Arc View format. The maps may be viewed and customized on a personal computer using Arc View or ArcExplorer software. Following is the database structure:
Dune and Beach Dynamics in Galveston County, Texas 1994-1998: Critical Information for Coastal Management
(1999) Gibeaut, James; Gutiérrez, Roberto, 1951-
Changes in beach and dune topography along the Gulf of Mexico shoreline in Galveston County, Texas were documented by comparing topographic transects oriented perpendicular to the shoreline (beach profiles) at 32 locations. All profiles were measured in September 1994 and again in November 1997. Subsets of the profiles were measured in 1995, 1996, and within weeks before and after Tropical Storm (TS) Frances in September 1998. Data on ocean level, waves, wind, and surface currents were compiled for the period to examine the response of the shoreline to certain conditions. In conjunction with this study, airborne laser terrain mapping (ALTM) surveys were conducted in November 1997, August 1998, and September 1998. The ALTM surveys were sponsored by the National Aeronautics and Space Administration (NASA) and have been evaluated for their usefulness in beach and dune studies.
Field Identification and Classification of Coastal Dunes, Galveston County, Texas
(1995) Morton, Robert A.; Gutierrez, Roberto, 1951-; Gibeaut, James
As part of the Texas Natural Resources Inventory (NRI), beach and dune profiles were surveyed at 33 transects spaced 7,000 to 10,000 ft apart along the Gulf shore of Galveston County. These surveys were conducted to establish the position of the dune protection line and the vegetation line. Geographic positions of the dune protection line and the vegetation line on each transect were obtained with geodetic quality Global Positioning System (GPS) receivers. The GPS positions were converted to state plane coordinates to facilitate entry into ARC/INFO, the NRI geographic information system. Dune characteristics such as height, continuity, density of vegetative cover, and location with respect to the Gulf shore were recorded to determine the occurrence and distribution of different dune types. The functional relationships and response of different dune types to storm conditions were reviewed, and an ordinal ranking of dunes was prepared. On one end of the spectrum are high, continuous well-vegetated foredune ridges, and on the other end are low, isolated, barren or sparsely vegetated coppice mounds.
Identification of Shoreline Erosion Features and 60 Year Projection of the Gulf Shoreline Position, Galveston and Brazoria Counties, Texas
(1996) Morton, Robert A.; Angle, Edward S.
Changes in shoreline position along the southeastern Texas Gulf coast between 1974 and 1996 were documented by conducting a kinematic real-time differential global positioning system (GPS) field survey in 1996 and comparing that shoreline with other shorelines archived in a geographic information system. Results of the investigation show that (1) beach morphology, shoreline movement, and the regional geologic framework are closely interrelated, (2) Gulf beaches are generally retreating, and (3) the rates of retreat have accelerated locally. Gulf beaches between High Island and Rollover Pass have been retreating for centuries, and they continue to retreat. On Bolivar Peninsula, beaches between Rollover Pass and Caplen are retreating rapidly, whereas those farther southwest are either slowly retreating or are relatively stable; at the southern end of the Peninsula, beaches are stable or advancing from the sand supplied by updrift erosion. The shoreline on East Beach of Galveston Island undergoes minor fluctuations, but the beach position is relatively stable. West Beach of Galveston Island continues to retreat, but rates of retreat vary depending on location. The beach segment between the Indian Beach and Sea Isle subdivisions has the lowest long-term average retreat rate, whereas retreat rates generally increase to the northeast toward the seawall and to the southwest toward San Luis Pass. These three segments with different beach morphologies and retreat rates were also identified in prior studies. Beaches from San Luis Pass to the mouth of the Brazos River also are generally retreating, and rates of retreat near Surfside, Quintana, and Bryan Beach are influenced by the jetties at Freeport Harbor and the diversion of the mouth of the Brazos River. The long-term average annual erosion rate of beaches in Galveston and Brazoria Counties was determined using the database of digital shoreline positions and a framework of shore-normal transects spaced 150 ft apart along the shore. The linear regression statistical function of the Shoreline Shape and Projection Program (SSAPP) was used to calculate the average annual erosion rate and to estimate the position of the shoreline erosion feature in 60 years. The possible long-term effects of engineering projects such as shoreline protection structures and beach nourishment projects also were analyzed to assist in evaluating the validity of the projected shoreline position. The field surveys and statistical analyses demonstrated that the high water line mapped on aerial photographs undergoes large seasonal fluctuations and therefore is a less reliable indicator of shoreline position than the vegetation line, berm crest, or backbeach erosional scarp. The study also showed that GPS field surveys are a rapid, relatively low-cost method of acquiring accurate shoreline positions, and they have many advantages compared to aerial photographs.
Structure, Facies, and Internal Properties of the Frio 'A' Reservoir, Hitchcock N. E. Field, Galveston County, Texas
(1985) Light, M. P. R.
The N.E. Hitchcock field, which produces from the Frio 'A' or 9,100 ft sandstone, is defined by a northwest plunging anticline of moderate relief. It is truncated on its southeast flank by a major fault downthrown several hundred feet to the south. Several minor faults displace the original pay zone and may influence enhanced gas recovery efforts in the reservoir. The Frio 'A' sandstone, which occurs at the top of the Frio Formation in the Chocolate Bayou area, forms part of a constructive delta lobe in the N.E. Hitchcock field. It consists of a stacked sequence of distributary-mouth-bar sandstones which grade into a thin delta destructional unit and are overlain by the transgressive shallow-marine Anahuac shale. Marine reworking of the Frio 'A' sandstone has resulted in its broad lateral extent and internal continuity although thin shale breaks vertically partition the reservoir. Much of the preserved excellent porosity (≥ 30%) and permeability (≥ 1,000 md, 0.99 μm²) in the Frio 'A' sandstone is due to its distributary-mouth-bar origin. The porosity and permeability were subsequently modified by diagenetic reactions. The Frio 'A' aquifer extends some eight miles southwest of the N.E. Hitchcock field to the Alta Loma and Sarah White fields. It is confined on its northern and southern flanks by major growth faults. The continuity of the Frio 'A' sandstone has bearing on any plans to control water influx by drilling additional guard wells below the gas-water contact. However, reservoir modeling suggests that the faults are not sealing during co-production pressure drawdown. Variable areas of indurated authigenic kaolinite zones developed in the Frio 'A' sandstone adjacent to thin shale units probably result from fluids emitted from the shales which have a consistent illite-smectite composition. Slight reductions in salinity during production at the Prets No. 1 well may be evidence for contemporaneous dewatering of shales. Shale pyrolysis data indicate that the Anahuac and Frio shales are of too poor a quality and are too immature to have generated appreciable hydrocarbons. Furthermore, isotope data for the Prets No. 1 condensates imply a marine organic source for these fluids. Thermal and hydrocarbon maturity data indicate that the Upper Frio was subjected to an extended period of hot, extremely saline, basinal-fluid flow. This fluid flow appears to have introduced the hydrocarbons and caused albitization of feldspars and formation of carbonate cements.