Houston-Galveston Region Research Articles

Land Subsidence Due to Creep of the Gulf Coast Aquifer System in the Houston-Galveston Region

ABSTRACT The compaction measurements of Quaternary and Tertiary Gulf Coast aquifer system sediments in the Houston-Galveston region (TX) show spatially variable compression of 0.08 to 8.49 mm/yr because of geohistorical overburden pressure when groundwater levels in the aquifer system were stable after about the year 2000. An aquifer-system creep equation is developed for evaluating this variable compression, with a thickness-weighted average creep coefficient based on Taylor's (1942) secondary consolidation theory. The temporal variation of aquifer system creep can be neglected in a short-term observation period (such as a decade) after a long-term creep period (such as over 1,000 years) in geohistory. The creep coefficient of the Gulf Coast aquifer system is found to be in a range of 8.74 × 10−5 to 3.94 × 10−3 (dimensionless), with an average of 1.38 × 10−3. Moreover, for silty clay or clay-dominant aquitards in the Gulf Coast aquifer system the creep coefficient value varies in the range of 2.21 × 10−4 to 3.94 × 10−3, which is consistent with values found by Mesri (1973) for most soils, which vary in the range of creep coefficient, 1 × 10−4 to 5 × 10−3. Land subsidence due to secondary consolidation of the Gulf Coast aquifer system is estimated to be 0.04 to 4.33 m in the 20th century and is projected to be 0.01 to 0.64 m in the 21st century at the 13 borehole extensometer locations in the Houston-Galveston region. The significant creep should be considered in the relative sea level rise, in addition to tectonic subsidence and primary consolidation.

Strategic Evacuation for Hurricanes and Regional Events with and without Autonomous Vehicles

A scheduling algorithm is developed for optimal planning of large-scale, complex evacuations to minimize total delay plus travel time across residents. The algorithm is applied to the eight-county Houston-Galveston region and land use setting under the 2017 Hurricane Harvey scenario with multiple destinations. Autonomous vehicle (AV) use under central guidance is also tested, to demonstrate the evacuation time benefits of AVs. Higher share of AVs delivers more efficient evacuation performance, thanks to greater reliability on evacuation order compliance, lower headways, and higher road capacity. Furthermore, 100% AV use delivers lower overall evacuation costs and network clearance times and less uncertainty in travel times (via lower standard deviation in). Based on evaluations of different evacuation schedules, a 50% compressed evacuation time span resulted in longer travel times and network congestion. A 50% longer evacuation time span reduced residents' total travel time and network congestion, but increased the evacuation cost. As expected, evacuation efficiency falls when evacuees do not comply with evaucation schedules. Large shares of AVs will not be possible in the near future, so methods to enhance evacuees' compliance behavior (e.g., enforced and prioritized evacuation orders) should be considered until a meaningful level of AV technical maturity and penetration rate is available. This paper demonstrates the benefits of scheduled departure times, AV use, and evacuation order compliance, which help balance conflicting objectives during emergencies.

The Secondary Consolidation (Creep) due to Geohistorical Overburden Pressure in the Houston-Galveston Region, Texas

Abstract. The combination of groundwater withdrawal, hydrocarbon extraction, salt-dome movement and faulting have caused widespread subsidence in the Houston-Galveston region (HGR). Subsidence results from primary consolidation consisting of inelastic (nonrecoverable) and elastic (recoverable) compaction caused by subsurface fluid withdrawal and secondary consolidation (creep) over time caused by overburden pressure. Subsidence in the HGR is monitored using borehole extensometers that were installed at 13 locations across Harris and Galveston counties between 1962 and 1980. By 1977, withdrawals from the Chicot and Evangeline aquifers resulted in groundwater-level declines of about 114 and 115 m relative to predevelopment water levels, respectively in parts of Harris County. By 1979, as much as 3 m of land subsidence was estimated to have occurred in localized areas of the HGR. Land subsidence can be hazardous in populated areas because it exacerbates the effects of storm surge and impedes storm-water runoff by decreasing land-surface elevations in areas where water accumulates. To assess aquifer compaction in response to changes in groundwater levels, a bulk land-surface subsidence rate is assumed to be the sum of the primary consolidation rate and the negligibly variable component of overburden pressure referred to as the “pseudo-constant secondary consolidation rate.” From 1931 to 1976, groundwater levels decreased as groundwater withdrawal rates increased from 0.57 to 4.3 million m3 d−1, causing pressure heads in aquitards the Chicot and Evangeline aquifers to continually decline. In response to reductions in groundwater withdrawal rates from 4.3 to 3.0 million m3 d−1 between 1976 and 2001, groundwater levels rebounded, decreasing inelastic compaction rates in some parts of the HGR from as much as about 40 mm yr−1 in the early 1980s to negligible amounts by 2000. Inelastic consolidation from about 1937 to 2000 contributed to land-surface subsidence and its associated effects. Land-surfaces have rebounded in localized areas of the HGR where groundwater levels rebounded significantly. Pseudo-constant secondary consolidation rates were computed at each of the 13 extensometers and ranged from 0.48 to 8.49 mm yr−1 in areas where groundwater levels in the two aquifers were stabilizing. This secondary consolidation subsidence is beyond the control of any groundwater-level management schemes because it is caused by geohistorical overburden pressure on the two aquifers.

Parameterized fragility models for multi-bridge classes subjected to hurricane loads

Past hurricanes in the United States have highlighted the structural vulnerability of bridges exposed to storm surge and wave loads, triggering the development of fragility models. These models are essential for estimating the likelihood of structural failures in bridges during extreme events to support risk mitigation and resilience enhancement. However, the literature still lacks fragility models that can accommodate the effects of spatial variability of surge and wave loads and bridge characteristics like superstructure type and span slope. In addition, the presence of different types of superstructure within the same bridge necessitates the development of fragility models which can handle such variations. In this light, first, this study develops fragility models for individual spans of different bridge classes (concrete girder, steel girder, slab, box girder) considering spatial variability of wave loads and variations in structural characteristics. Herein, nonlinear dynamic analyses are employed for calculating the structural response and stepwise logistic regression is used for deriving the predictive fragility models. Then, a bridge system fragility assessment framework is proposed for system reliability assessment of the entire bridge, which accounts for different types of superstructures within the bridge and partially correlated span failures. In order to demonstrate the application of the fragility models and the system fragility assessment framework for regional level risk mitigation, the performance of bridges in the Houston-Galveston region is evaluated for two storm scenarios. The results show that the system failure probability obtained using no correlated span failure assumption is close to the actual failure probability obtained using the proposed approach highlighting the effects of correlations (or the lack of) on the system fragility.

Uneven Neighborhood Recovery: Hurricane Damage and Neighborhood Change in the Houston–Galveston Region since 1970

Despite the growing number of natural disasters around the globe, limited research exists on post–disaster patterns of neighborhood change. In this paper, we test two theories of neighborhood change, the “recovery machine” and “rent gap,” which predict opposing effects for low socioeconomic status (SES) neighborhoods following damage from hurricanes, tropical storms, and other natural hazard events. The recovery machine theory posits that after natural hazard events, local communities experience patterns of recovery based on their pre–disaster SES and access to resources, suggesting that wealthier neighborhoods will recover robustly while lower status neighborhoods languish. In contrast, the rent gap theory suggests that developers will identify a profit opportunity in the depressed values created by damage from natural hazard events, and seek to redevelop low SES areas. We use fixed effects models with census data from 1970 to 2015 to test the impact of damage from natural hazards on neighborhood change. We find substantial recovery and change in low–income neighborhoods, but not in the high–income neighborhoods supporting the rent gap theory. We conclude that natural hazard events resulting in damage produce uneven recovery by socioeconomic status of neighborhoods, potentially leading to displacement of low SES groups.

Groundwater Level Change Management on Control of Land Subsidence Supported by Borehole Extensometer Compaction Measurements in the Houston-Galveston Region, Texas

As much as 3.05 m of land subsidence was observed in 1979 in the Houston-Galveston region as a result primarily of inelastic compaction of aquitards in the Chicot and Evangeline aquifers between 1937 and 1979. The preconsolidation pressure heads for aquitards within these two aquifers were continuously updated in response to lowering groundwater levels, which in turn was caused by continuously increasing groundwater withdrawal rates from 0.57 to 4.28 million m3/day. This land subsidence occurred without any management of changes in groundwater levels. However, the management of recovering groundwater levels from 1979 to 2000 successfully decreased inelastic compaction from about 40 mm/yr in the early 1980s to zero around 2000 through decreasing groundwater withdrawal rates from 4.3 to 3.0 million m3/day. The inelastic consolidation that had existed for about 63 years roughly from 1937 to 2000 caused a land subsidence hazard in this region. Some rebounding of the land surface was achieved from groundwater level recovering management. It is found in this paper that subsidence of 0.08 to 8.49 mm/yr owing to a pseudo-constant secondary consolidation rate emerged or tended to emerge at 13 borehole extensometer station locations while the groundwater levels in the two aquifers were being managed. It is considered to remain stable in trend since 2000. The subsidence due to the secondary consolidation is beyond the control of any groundwater level change management schemes because it is caused by geo-historical overburden pressure on the two aquifers. The compaction measurements collected from the 13 extensometers since 1971 not only successfully corroborate the need for groundwater level change management in controlling land subsidence but also yield the first empirical findings of the occurrence of secondary consolidation subsidence in the Quaternary and Tertiary aquifer systems in the Houston-Galveston region.

Estimating Residential Property Loss Reduction from a Proposed Coastal Barrier System in the Houston-Galveston Region

AbstractIn the wake of increasing development in coastal metropolitan areas, there are growing concerns about the impact of a potential storm surge event on residential properties. This study exami...

Effects of groundwater regulation on aquifer-system compaction and subsidence in the Houston-Galveston Region, Texas, USA

Abstract. Subsidence has been a primary concern in the Houston area for many years. Since 1906, about 4 m of subsidence has occurred in the coastal areas, with a broad area of about 2 m of subsidence existing today throughout most of the Houston Area. In 1975, as a result of area residents and local governments becoming increasingly alarmed by the continued impact of subsidence on economic growth and quality of life in the region, the Harris-Galveston Subsidence District was created by the 64th Texas Legislature as an underground water conservation district with the mission to provide for the regulation of the withdrawal of groundwater to control subsidence. Over its nearly 40 years of existence, the District has developed substantial data sets providing the foundation for its regulatory plan. The District's regulatory plan allows groundwater users an amount of annual groundwater based on a percentage of an individual permitee's total water demand. The management of the groundwater resources within the District has involved significant coordination with regional ground and surface water suppliers; ongoing interaction with other state and local regulatory bodies; analysis of accurate and up to date predictions on water usage; the enforcement of disincentives to those who rely too heavily on groundwater and a commitment to practicing and promoting water conservation. Areas nearest the Gulf of Mexico coast have completed the conversion to alternative (other than groundwater) water sources, consequently the effective stress on the aquifer has decreased and subsidence rates have been reduced. Areas within the District further inland are currently proceeding through the conversion process, and subsidence has continued in those areas as development of the groundwater resources has continued.

Characterizing the hydraulic interactions of hurricane storm surge and rainfall–runoff for the Houston–Galveston region

Planning of traditional coastal flood risk management strategies are largely predicated on storm surge protection against extreme hurricanes, i.e. storm surge. However, (1) hurricane storm surge and (2) hurricane rainfall–runoff are not mutually exclusive flood hazards. Little research has emphasized the need for quantifying and characterizing the joint hydraulic processes between hurricane storm surge and rainfall–runoff during real events for enhancing effective flood risk mitigation. In this regard, an improved hydrological and hydrodynamic modeling framework has been developed for the Houston Ship Channel (HSC) and Galveston Bay to serve as a quantitative testbed for evaluating coupled hurricane storm surge and rainfall–runoff. Modularity within the modeling framework allows for landfall shifting of historical hurricane tracks, wind fields, and corresponding rainfall patterns to serve as numerical model inputs, as well as providing an expanded dataset of storm events. Distributed hydrologic and unsteady hydraulic analyses of upstream rainfall–runoff and storm surge are conducted for hurricanes Katrina (2005), Ike (2008), and Isaac (2012) under three synthetically shifted landfall locations near the HSC and Galveston Bay regions. For the modeled scenarios, results show that peak flows from storm surge easily dominate those of rainfall–runoff, but that rainfall–runoff can constitute more than half of the total flood volume draining towards the HSC. Most modeled scenarios reveal less than 24h of separation between peak surge and peak rainfall–runoff. In the same way that storm surge is sensitive to hurricane landfall location and angle of approach, so are spatial rainfall distributions and associated inland runoff processes, due to wide topological variations in coastal watershed boundaries. Analysis of coastal flood mitigation is extended with the dynamic modeling of a proposed storm surge barrier system at the HSC, with its performance quantified under the given hurricanes. The surge barrier system is demonstrated to be hydraulically feasible for all scenarios, with maximum water surface elevation reductions ranging between 0.63m and 3.28m. However, accurate storm surge and riverine flood forecasting methods will be critical for achieving optimal gate and barrier operations.

Exploring the impacts of flood insurance reform on vulnerable communities

This paper identifies geographic areas whose real estate markets were potentially impacted by US flood insurance reform, and it explores concurrent vulnerabilities—by income and race—in the most impacted areas. Because of the geographic and demographic significance of the Gulf Coast in terms of flood risk, flood insurance, and vulnerability, the Houston-Galveston region was selected for analysis. Flood insurance reform under the Biggert–Waters Flood Insurance Reform Act of 2012 occurred unabated over a 21-month period from July 2012 to March 2014. This period represents a unique real-world intervention that can be analyzed using a quasi-experimental design. The period was characterized by numerous anecdotal reports of spiking flood insurance rates and market uncertainty. Market data were gathered for two years before and two years after Biggert–Waters in Harris and Galveston Counties. Paired z-tests were performed to examine before and after market differences. Findings showed 17 zip codes that experienced significant impacts (p<0.01 in 14 zip codes, p<0.05 in 3 zip codes). Among the significantly impacted zip codes, low-income households were overrepresented by 11% in Harris County and by 32% in Galveston County; and minorities were overrepresented by 43% in Galveston. These results support the hypothesis that flood insurance reform can have disproportionate impacts. The paper provides a straightforward approach for analyzing the real estate market impacts of flood insurance reform at a community scale. It also provides a basis for recommending that regulatory decisions involving flood insurance must be informed by an analysis of disproportionate impacts.

Options for improving evacuation: Investigating an unconventional strategy and expanding route options using TRansportation ANalysis and SIMulation System.

Various agencies including state departments of transportation, emergency management offices, a municipal works agency, or a highway patrol agency may prepare evacuation plans. Storm strength and landfall predictions determine procedures and strategies. Studies have been conducted that examined various methods considering evacuees' behaviors, traffic control, safety, and preferential routing. The occasions when a hurricane is imminent require residents to make a choice between sheltering-in-place or evacuating. Tremendous growth is anticipated in many US coastal communities and that will place greater pressure on evacuation strategies in future years. Given the inevitability of future hurricane evacuations and the intensive growth projections for US coastal areas, this research examines evacuation options with a focus on the Houston-Galveston region. The research examines two scenarios using the TRansportation ANalysis and SIMulation System simulation model which relies on a GIS base. Study results showed that both scenarios perform well as alternative options for inclusion in regional planning. It is recommended that these two scenarios be included in the array of responses available for decision makers depending on the myriad of variables-citizen response, congestion levels on the roadways and location, and prediction of an impending storm. The options may be applied independently or in concert with other strategies.

Characterizing hurricane storm surge behavior in Galveston Bay using the SWAN + ADCIRC model

The SWAN+ADCIRC shallow-water circulation model, validated for Hurricane Ike (2008), was used to develop five synthetic storm surge scenarios for the upper Texas coast in which wind speed was increased and landfall location was shifted 40km westward. The Hurricane Ike simulation and the synthetic storms were used to study the maximum water elevations in Galveston Bay, as well as the timing and behavior of surge relative to the hurricane track. Sixteen locations indicative of surge behavior in and around Galveston Bay were chosen to for analysis in this paper. Results show that water surface elevations present in Galveston Bay are dominated by the counterclockwise hurricane winds and that increasing wind speeds by 15% results in approximately 23% (+/−3%) higher surge. Furthermore, shifting the storm westward causes higher levels of surge in the more populated areas due to more intense, higher shore-normal winds. This research helps to highlight the vulnerability of the upper Texas Gulf Coast to hurricane storm surge and lends insight to storm surge and flood mitigation studies in the Houston–Galveston region.

Capturing Latent Household Preferences in Daily-Activity Pattern Choices

One fundamental feature of most operational activity-based models (ABMs) developed in the United States is the concept of a day activity pattern, which, in its broadest sense, is a way of characterizing all the activities undertaken in a day at the individual level. This pattern often includes a sequence of models that generate activities of different types for each individual. In many cases, these models treat all individuals in a household independently, while in other cases, specialized techniques capture intrahousehold relationships. This paper presents a new technique for capturing some of these intrahousehold relationships in a daily-activity pattern (DAP) model via terms for latent household preferences while also allowing for other specific relationships to emerge in more standard ways. The model is estimated on data from the Houston–Galveston region and serves as an extension to the DAP model framework being used in the ABM system under development for that region. The results suggest that strong household level preferences exist. For many activity pattern types, these household preferences are more important than the preferences of the individual. In addition, the modeling framework is concise, can easily accommodate households of any size, and can predict the exact number and type of mandatory tours (i.e., work, school, and university activities) for individuals in a single model.

Dynamic Traffic Assignment Evaluation of Hurricane Evacuation Strategies for the Houston–Galveston, Texas, Region

The Houston–Galveston, Texas, region has experienced several major hurricanes in recent years. During the evacuation for Hurricane Rita in 2005, the Texas Department of Transportation (DOT) decided to implement contraflow operations on I-45 to relieve massive evacuee congestion departing Houston to the north. The decision to implement contraflow was a difficult one because it involved multiple jurisdictions and required extensive coordination of manpower and resources from various entities. After the Hurricane Rita experience, the Texas DOT implemented a new strategy, referred to as “evaculane,” in which evacuation traffic could use the outside paved shoulder as a traveling lane when an evacuation was under way and evaculane signing beacons were activated. The objective is to increase capacity along key evacuation routes while avoiding the need for full-scale contraflow operation whenever possible. The evaculane on I-10 was successfully put into use during the Hurricane Ike evacuation in 2008. With the widening and completion of evaculanes on I-10 and US-290 as well as a partial contraflow plan for the I-45 corridor, the Texas DOT sponsored a study to develop a decision support tool to help determine whether these strategies would adequately handle the evacuation demand for various Houston–Galveston region evacuation scenarios. This paper describes the quantitative assessment of the performance of alternative evacuation strategies using a dynamic traffic assignment model, DynusT. The evaluation results indicated the evaculanes on I-10 and US-290 can sufficiently handle high evacuation demand on both routes without contraflow operation. In addition, a partial contraflow plan for I-45 was shown to provide sufficient capacity to handle high evacuation demand in lieu of full-scale contraflow operation.

A Foundation for Developing a Coastal Sustainability Program in the Houston-Galveston Region

Sustainability: The Journal of RecordVol. 4, No. 6 Research and SolutionsA Foundation for Developing a Coastal Sustainability Program in the Houston-Galveston RegionGarrett DolanGarrett DolanSearch for more papers by this authorPublished Online:23 Dec 2011https://doi.org/10.1089/SUS.2011.9647AboutSectionsPDF/EPUB Permissions & CitationsPermissionsDownload CitationsTrack CitationsAdd to favorites Back To Publication ShareShare onFacebookTwitterLinked InRedditEmail FiguresReferencesRelatedDetailsCited byUnderstanding the Coastal Ecosystem-Based Management Approach in the Gulf of MexicoJournal of Coastal Research, Vol. 63Electronic Governance for Sustainable Development — Conceptual framework and state of researchGovernment Information Quarterly, Vol. 30 Volume 4Issue 6Dec 2011 Information©2011 by Mary Ann Liebert, Inc.To cite this article:Garrett Dolan.A Foundation for Developing a Coastal Sustainability Program in the Houston-Galveston Region.Sustainability.Dec 2011.293-296.http://doi.org/10.1089/SUS.2011.9647Published in Volume: 4 Issue 6: December 23, 2011PDF download

A study of VOC reactivity in the Houston-Galveston air mixture utilizing an extended version of SAPRC-99 chemical mechanism

The Houston-Galveston area is the region where National Ambient Air Quality Standard (NAAQS) for ozone is often violated. Emissions from industrial sources contribute significantly to elevated ozone concentrations and make air composition quite unique in comparison to typical urban composition. In this study, source-oriented reactivity of individual organic compounds, released in urban and industrial areas inside Houston-Galveston region, with regard to ozone formation is determined. The CMAQ model and an extended version of SAPRC-99 mechanism, representing 26 additional individual compounds explicitly, is employed for the model simulations. The incremental volatile organic compound (VOC) reactivities calculated for the Houston-Galveston conditions show variations with respect to the differences in the air compositions between urban and industrial areas as well as meteorological conditions. The compounds with the highest reactivities, such as 2-methyl-2-butene, trans-2-butene and cis-2-butene, were found to be most sensitive to the environment in which they were released. According to the reactivities weighted by VOC mixing ratios, ethene, propene and formaldehyde show the highest impact on ozone formation. Reactivities of most investigated compounds estimated for the Houston-Galveston air conditions are in good agreement with the ‘reference’ maximum incremental reactivity (MIR) scale.

Episodic Performance and Sensitivity of the Urbanized MM5 (uMM5) to Perturbations in Surface Properties in Houston Texas

We present an application of a fine-resolution, meso-urban meteorological model (urbanized MM5; uMM5) to a multi-day episode in August 2000 in the Houston-Galveston Texas, USA region. The model's episodic performance and its response to small changes in land-cover and surface physical properties in the area, e.g., scenarios of urban heat island mitigation, are evaluated. The model formulation is reviewed along with its parameterizations, data needs, and fine-resolution geometrical input. Development of scenarios of increased urban albedo and vegetative cover is also discussed. This initial application of the uMM5 to the Houston-Galveston region serves as a basis for future model improvements, evaluation of newer data and parameterization applications, testing more aggressive surface modification scenarios, and performing fine-resolution photochemical modelling. It also provides data for comparison of model results with those from previous studies of this region.

Cardiac troponin T and C-reactive protein for predicting prognosis, coronary atherosclerosis, and cardiomyopathy in patients undergoing long-term hemodialysis.

Cardiac troponin T (cTnT) and C-reactive protein (CRP) are prognostic markers in acute coronary syndromes. However, for patients with end-stage renal disease (ESRD) the ability of combinations of these markers to predict outcomes, and their association with cardiac pathology, are unclear. To investigate the association between levels of cTnT and CRP and long-term risk of cardiac pathology and death in patients with ESRD. A prospective cohort study initiated February through June 1998 and enrolling 224 patients with ESRD from 5 hemodialysis centers in the Houston-Galveston region of Texas. Levels of cTnT and CRP were analyzed at study entry in patients without ischemic symptoms. All-cause mortality during a mean follow-up of 827 (range, 29-1327) days. Secondary outcomes in predefined substudies were coronary artery disease (CAD), decreased (< or =40%) left ventricular ejection fraction (LVEF), and presence of left ventricular hypertrophy (LVH). One hundred seventeen (52%) patients died during follow-up. For levels of cTnT and CRP, progressively higher levels predicted increased risk of death compared with the lowest quartile (for cTnT quartile 2: unadjusted hazard ratio [HR], 2.2; 95% confidence interval [CI], 1.2-4.1; quartile 3: HR, 2.7; 95% CI, 1.5-4.9; quartile 4: HR, 3.0; 95% CI, 1.6-5.3. For CRP quartile 2: HR, 0.9; 95% CI, 0.5-1.6; quartile 3: HR, 1.8; 95% CI, 1.1-3.1; quartile 4: HR, 1.8; 95% CI, 1.1-3.2). Both cTnT and CRP remained independent predictors of death after adjusting for a number of potential confounders. The combination of cTnT and CRP results provided prognostic information when patients were divided into groups at or above and below the biomarker medians (high cTnT/high CRP levels vs low cTnT/low CRP levels for risk of death: HR, 2.5; 95% CI, 1.5-4.0). Elevated levels of cTnT, but not CRP, were strongly associated with diffuse CAD (n = 67; 0%, 25%, 50%, and 62% prevalence of multivessel CAD across progressive cTnT quartiles, P<.001). An LVEF of 40% or less was identified in 4 (9%), 3 (8%), 10 (27%), and 7 (19%) of patients across cTnT quartiles (P =.07). No trend for cTnT levels was found among patients with LVH (P =.45); similarly, no trend for CRP was found among patients with LVH (P =.65) or an LVEF of 40% or less (P =.75). Among stable patients with ESRD, increasing levels of cTnT and CRP are associated with increased risk of death. Furthermore, higher levels of cTnT may identify patients with severe angiographic coronary disease.

LAND SUBSIDENCE ALONG THE TEXAS GULF COAST DUE TO OIL AND GAS WITHDRAWAL

Land subsidence caused by groundwater withdrawal in the Houston–Galveston region is a well-documented phenomenon. Subsidence of up to 3 m has been calculated in the region since 1905. Subsidence caused by hydrocarbon withdrawal is also a plausible cause of subsidence, where groundwater withdrawal has diminished and significant petroleum production has occurred for> 95 years. Sixteen fields were investigated by acquiring reservoir depressurization data near bore-hole extensometers set up by the Houston–Galveston Coastal Subsidence District. All reservoirs were found to be well below hydrostatic pressure; a few of them were underpressured even before production began. Four oil and gas fields (the Mykawa, Satsuma, Dyersdale, and South Gillock) and three production zones (the Miocene, Frio, and Yegua) were used in a reservoir model and a boundary clay reservoir model to calculate subsidence. Subsidence under these fields is predicted to be as high as 0.44 m in a 19-year period at the Satsuma field and as low as 0.02 m in a 22-year period at the Dyersdale field. Implications of this study are (1) hydrocarbon production, although not the major contributor to most land surface subsidence in this area, does play a role; and (2) depressurization and, subsequently, subsidence from oil and gas fields may be regional and connected with other fields which is inferred from the fact that some fields were already underpressured before production began.

081020 (M10) Groundwater to surface water conversion in the Houston-Galveston region: Impact of mandates on water quality, subsidence, and water rates: Larson J.R., Dziuk L.J.,Risk Analysis, Vol. 15, Number 5, 1995, pp. 545–554

081020 (M10) Groundwater to surface water conversion in the Houston-Galveston region: Impact of mandates on water quality, subsidence, and water rates: Larson J.R., Dziuk L.J.,Risk Analysis, Vol. 15, Number 5, 1995, pp. 545–554