THE ROUTINE DISASTER: A CASE STUDY IN EL SALVADOR

A 2010 report by the UN Disaster Assessment and Coordination ranked El Salvador as the most vulnerable country in the world to natural disasters, with roughly 95% of the population at risk. The combination of recurring natural disasters and high vulnerability in a relatively small country has led to repeated exposure of local residents to significant natural phenomena of all sorts, including earthquakes, flooding, landslides, volcanic eruptions, and hurricanes. The effect of disaster assistance can be multi-faceted and this report examines the case of flooding hazards of a small town in the south-eastern San Miguel region of the country, called El Borbollón, in which assistance seems to have become a natural part of the local economy. . This community sits at the base of a large watershed. Wet season flooding events raise the lake levels by 1 to 3 meters almost every year, completely submerging the town’s main road. Occasional 4 to 6 meter flooding events cause the evacuation of 1000+ community members; this occurred most recently during Tropical Depression 12-E in the 2011 wet season. I argue that a purely hydrological approach to assessing the local flood hazard is insufficient. First, I evaluate the magnitude of the Tropical Depression 12-E flooding event via HEC-HMS computer modeling and GIS, coupled with an analysis of ASTER satellite imagery. Parallel hazard and vulnerability analyses were conducted, and I describe my findings from a social research perspective. I find that locals have largely decided to co-exist with this recurring flood event, because they have much to gain by living in a perpetually at-risk condition, through the benevolence of aid organizations. This exposes a fundamental question: is it still a disaster if it is routine? By examining the role that large-scale flooding events play on the lives of local inhabitants, we present examine a scenario that more closely represents the multifaceted reality in which we live. Similar situations likely exist elsewhere, and lessons learned here may be more broadly applicable. The existence of a routine disaster means revisions might be necessary to government, scientist, and aid organization strategies

Quantification of Flow Unit and Bounding Element Properties and Geometries, Ferron Sandstone, Utah: Implications for Heterogeneity in Gulf Coast Tertiary Deltaic Reservoirs

Outcrop exposures are being studied to quantify the internal permeability distribution of fluvial-deltaic sandstones, which results in reservoir compartments bounded by baffles or barriers to gas flow. This information will be used to develop reservoir models that can guide infill drilling to optimize incremental gas reserve growth from sandstone reservoirs. The objectives are being accomplished through integration of (1) outcrop characterization, (2) petrophysical measurements, and (3) pore-level modeling. Projected long-term benefits of the study are two-fold. First, increased understanding of internal architecture and improved methods for quantification of heterogeneity will facilitate development of strategies to minimize risk in the extended development of fluvial-dominated deltaic gas reservoirs. Second, targeting of incremental gas resources in mature reservoirs will lead to extended recovery of a low-cost, low-risk resource. Results of the first year of studies show that the architecture, geometry, and internal permeability distribution of fluvial-deltaic sandstones are generally predictable and that a four-order hierarchy of bounding surfaces exists. Initial tests have been completed, and reliable measurements of petrophysical properties of flow units, flow baffles, and flow barriers are being performed on outcrop samples. Development of a pore-level simulator has been essentially completed. Results, in general, indicate that the field approach is sound and that information gained on outcrop can be used to produce realistic reservoir models.Bureau of Economic Geolog

Quantifying Reservoir Heterogeneity Through Outcrop Characterization: 1. Architecture, Lithology, and Permeability Distribution of a Seaward-Stepping Fluvial-Deltaic Sequence, Ferron Sandstone (Cretaceous), Central Utah

The internal architecture of natural gas reservoirs fundamentally controls production efficiency and the volume of gas unrecovered at abandonment. To better understand reservoir complexity, we investigated relations between sandstone architecture and permeability structure of landward-stepping (wave-modified) Ferron deltaic sandstones exposed in central Utah. Deltaic sandstones extend 4 mi along sediment-transport direction in the landward-stepping Ferron genetic sequence GS 5. Most sand was deposited in transgressive, delta-front, and distributary-channel facies. Distributary channels constitute the principal reservoir facies because mean permeability in distributary-channel sandstones is approximately twice that of delta-front and transgressive sandstones, and because distributary-channel sandstones are well developed. Channel architecture, bounding-surface character, and permeability distribution change systematically from landward to seaward position in the system. Near the landward limit, mean permeability is 300 md, mud occurs as clasts along channel-flank bounding surfaces, and permeability systematically decreases upward. Near the seaward extent of the system, mean permeability is 750 md, mud is segregated into discrete strata-bounding sand bodies, and vertical permeability trends are uniformly high. Statistical analysis shows that lithofacies are the fundamental sandstone architectural units. Similar lithofacies have similar permeability character, regardless of position in the facies tract. Variable preservation of lithofacies controls permeability distribution throughout the channel system. Semivariogram analysis shows that vertical and horizontal permeability correlation distances correspond to distances between bounding surfaces and to sand-body dimensions. Diagenetic overprint is minor, owing to low burial temperatures.Bureau of Economic Geolog

Quantification of Flow Unit and Bounding Element Properties and Geometries, Ferron Sandstone, Utah: Implications for Heterogeneity in Gulf Coast Tertiary Deltaic Reservoirs

Outcrop mapping, field permeability measurements, petrographic analyses, petrophysical measurements, and pore-level modeling studies are being conducted on exposures of the Ferron Sandstone, east-central Utah, to develop a better understanding of the dimensions and internal arrangement of flow units, baffles, and barriers in sandstone gas reservoirs. The ultimate goals of this work are to establish methods for applying outcrop studies to reservoir characterization and to develop reservoir models that will guide infill drilling to maximize incremental gas reserve growth from fluvial-deltaic sandstone reservoirs. Activities during the second year of this 3-year project focused on data collection and preliminary interpretations. Mapping and field permeability measurements were initiated on the seaward-stepping Ferron unit 2 sandstone. These results will provide a comparison with data collected during the 1990 field season when landward-stepping sandstones of Ferron unit 3 were examined. Framework grain and cement mineralogy and the composition of intergranular material were quantified for selected samples from unit 3. Petrophysical measurements were completed on 24 specimens from units 2, 4, and 3. Sections of the pore-level modeling code were rewritten to improve accuracy and efficiency, and scenarios were developed to model the effects of grain size, cementation, and compaction on porosity, single-phase permeability, and formation factor. Preliminary results indicate that important differences exist in the internal geometry of landward- and seaward-stepping fluvial-deltaic sandstones. It was also found that closer-spaced permeability measurements improved the resolution of permeability structure. Petrographic studies documented differences in composition between fluvial, transgressive, delta-front, and distributary-channel sandstones; these differences in rock composition are reflected by differences in the mean permeability of these facies as measured on outcrop. Initial comparisons of pore-level model results with measured petrophysical properties are encouraging and suggest that refinements based on examination of the analyzed samples will lead to a close match between observed and modeled behavior.Bureau of Economic Geolog

Memorandum of Understanding Between the United States Department of Energy and the State of Texas - Characterization of Oil and Gas Reservoir Heterogeneity

Ultimate recovery from Texas oil reservoirs at current technological and development levels is projected to be 36 percent of the oil in place. Thus, of the 165 billion barrels (Bbbl) of oil discovered statewide, 106 Bbbl will remain in existing reservoirs after recovery of proved reserves. This remaining resource is composed of residual oil (71 Bbbl) and mobile oil (35 Bbbl). The remaining mobile oil is conventionally recoverable but is prevented from migrating to the wellbore by intrareservoir seals or bounding surfaces. Reservoir architecture, the internal fabric or structure of reservoirs, governs paths of fluid migration during oil and gas production. Reservoir architecture is, in turn, the product of the depositional and diagenetic processes responsible for the origin of the reservoir. If an understanding of the origin of the reservoir is developed, reservoir architecture, and therefore the paths of fluid migration, become predictable. Thus, with a greater understanding of the fabric of the reservoir and its inherent control on the paths of fluid flow, we can more efficiently design and implement advanced recovery strategies.Bureau of Economic Geolog

Quantifying Reservoir Heterogeneity Through Outcrop Characterization: 2. Architecture, Lithology, and Permeability Distribution of a Seaward-Stepping Fluvial-Deltaic Sequence, Ferron Sandstone (Cretaceous), Central Utah

The internal architecture of natural gas reservoirs fundamentally determines gas migration, production efficiency, and the volume of gas unrecovered at abandonment. To determine the style and scale of reservoir complexity in fluvially dominated (seaward-stepping) deltaic reservoirs, we investigated relations between sandstone architecture and permeability distribution in seaward-stepping deltaic Ferron genetic sequence (GS) 2 sandstone outcrops in central Utah. Distributary-channel, mouth-bar, and delta-front deposits are the volumetrically important sand repositories in the Ferron GS 2. Mouth-bar facies are laterally extensive and relatively simple sand bodies with moderate mean permeabilities. Distributary channels also have good permeability but are narrow, sinuous, and separated from mouth-bar sandstones by low-permeability bounding surfaces, making them difficult targets for development. Statistical analyses of permeability data show that lithofacies are the fundamental sandstone architectural elements. Therefore, lithofacies are the basic units that should be used to construct reservoir models. The variable preservation of lithofacies controls permeability throughout the system. Vertical and horizontal permeability correlation distances correspond to distances between bounding surfaces and to macroform dimensions. Estimates based on field-scale mapping show that 91 percent of the reservoir area could be contacted at 320-acre well spacing. Sandstone architecture and permeability relations of the Ferron GS 2 are similar to those in Lake Creek (Wilcox Group, Texas Gulf Coast) reservoirs. This outcrop-reservoir comparison confirms that outcrop data are transferable to reservoirs.Bureau of Economic Geolog

Sequential Manipulation of Deformable Linear Object Networks with Endpoint Pose Measurements using Adaptive Model Predictive Control

Robotic manipulation of deformable linear objects (DLOs) is an active area of research, though emerging applications, like automotive wire harness installation, introduce constraints that have not been considered in prior work. Confined workspaces and limited visibility complicate prior assumptions of multi-robot manipulation and direct measurement of DLO configuration (state). This work focuses on single-arm manipulation of stiff DLOs (StDLOs) connected to form a DLO network (DLON), for which the measurements (output) are the endpoint poses of the DLON, which are subject to unknown dynamics during manipulation. To demonstrate feasibility of output-based control without state estimation, direct input-output dynamics are shown to exist by training neural network models on simulated trajectories. Output dynamics are then approximated with polynomials and found to contain well-known rigid body dynamics terms. A composite model consisting of a rigid body model and an online data-driven residual is developed, which predicts output dynamics more accurately than either model alone, and without prior experience with the system. An adaptive model predictive controller is developed with the composite model for DLON manipulation, which completes DLON installation tasks, both in simulation and with a physical automotive wire harness.Comment: Accepted to IEEE International Conference on Robotics and Automation - ICRA 2024. 7 pages. 4 figure

Avian blood parasites in an endangered columbid: Leucocytozoon marchouxi in the Mauritian Pink Pigeon Columba mayeri

There is increasing evidence that pathogens can play a significant role in species decline. This study of a complete free-living species reveals a cost of blood parasitism to an endangered host, the Pink Pigeon Columba mayeri, endemic to Mauritius. We investigated the prevalence and effect of infection of the blood parasite, Leucocytozoon marchouxi, in the free-living Pink Pigeon population. Overall, L. marchouxi infection prevalence detected was 18·3%. Juveniles were more likely to be infected than older birds and there was geographical variation in infection prevalence. Survival of birds infected with L. marchouxi was lower than that of uninfected birds to 90 days post-sampling. This study suggests that while common haematozoa are well tolerated in healthy adults, these parasites may have greater pathogenic potential in susceptible juveniles. The study is unusual given its completeness of species sampling (96%) within a short time-period, the accurate host age data, and its focus on blood parasites in a threatened bird species. Species for which long-term life-history data are available for every individual serve as valuable models for dissecting the contribution of particular pathogens to species decline

\u3cem\u3ePhytophthora cinnamomi\u3c/em\u3e Colonized Reclaimed Surface Mined Sites in Eastern Kentucky: Implications for the Restoration of Susceptible Species

Appalachian forests are threatened by a number of factors, especially introduced pests and pathogens. Among these is Phytophthora cinnamomi, a soil-borne oomycete pathogen known to cause root rot in American chestnut, shortleaf pine, and other native tree species. This study was initiated to characterize the incidence of P. cinnamomi on surface mined lands in eastern Kentucky, USA, representing a range of time since reclamation (10, 12, 15, and 20 years since reclamation). Incidence of P. cinnamomi was correlated to soil properties including overall soil development, as indicated by a variety of measured soil physical and chemical parameters, especially the accumulation of soil organic carbon. P. cinnamomi was detected in only two of the four sites studied, aged 15 and 20 years since reclamation. These sites were generally characterized by higher organic matter accumulation than the younger sites in which P. cinnamomi was not detected. These results demonstrate that P. cinnamomi is capable of colonizing reclaimed mine sites in Appalachia; additional research is necessary to determine the impact of P. cinnamomi on susceptible tree species at these sites