North-central Texas Research Articles

Two plant-fossil assemblages of early Permian age from north-central Texas and their comparison with other Permian deposits of the region

North-Central Texas preserves an early Permian record of floristic change from the Asselian through the Kungurian. The regional floras that occur during that time interval vary compositionally in systematic ways and indicate major periods of environmental change. Here we describe two such floras from the late Artinskian, found in close geographic and stratigraphic proximity, the latter collection (1991) initially was thought to be from the same site as an earlier collection (1974), but proved to be from a different layer in the same area. The two floras, “Farmer's Tank” and “Cattle Tank” were analyzed quantitatively. They are composed of the same basic mixture of taxa but with strikingly different dominance-diversity profiles; Farmer's Tank is dominated by walchian conifers with subdominant marattialean tree ferns and gigantopterids, and Cattle Tank by marattialean tree ferns with subdominant noeggerathialeans and callipterids with conifers fourth in rank. These floras are from the early phases of a change in regional floras from heavily dominated by conifers and other xeromorphic, drought-tolerant elements, to “mixed” floras rich in, even dominated by marattialean tree ferns, but retaining a major component of drought-tolerant elements. These quantitative differences may reflect differences in the environment of deposition, but also possibly in season of the year - the Farmer's Tank collection is rich in seeds of considerable variety (13 morphotypes), whereas the Cattle Tank collection contains few seeds. These floristic features strongly suggest a landscape under seasonal climatic conditions with a period of moisture deficit.

Comparing efficiencies of population control methods for responding to introductions of transboundary animal diseases in wild pigs

Introductions of transboundary animal diseases (TADs) into free-ranging wildlife can be difficult to control and devastating for domestic livestock trade. Combating a new TAD introduction in wildlife with an emergency response requires quickly limiting spread of the disease by intensely removing wild animals within a contiguous area. In the case of African swine fever virus (ASFv) in wild pigs (Sus scrofa), which has been spreading in many regions of the world, there is little information on the time- and cost-efficiency of methods for intensively and consistently culling wild pigs and recovering carcasses in an emergency response scenario. We compared the efficiencies of aerial operations, trapping, experimental toxic baiting, and ground shooting in northcentral Texas, USA during two months in 2023. Culling and recovering carcasses of wild pigs averaged a rate of 0.15 wild pigs/person hour and cost an average of $233.04/wild pig ($USD 2023) across all four methods. Aerial operations required the greatest initial investment but subsequently was the most time- and cost-efficient, costing an average of $7266 to reduce the population by a standard measure of 10 %, including recovering carcasses. Aerial operations required a ground crew of ∼7 people/helicopter to recover carcasses. Costs for reducing the population of wild pigs using trapping were similar, although took 13.5 times longer to accomplish. In cases where carcass recovery and disposal are needed (e.g., response to ASFv), a benefit of trapping was immediate carcass recovery. Toxic baiting was less efficient because both culling and carcass recovery required substantial time. We culled very few wild pigs with ground shooting in this landscape. Our results provide insight on the efficiencies of each removal method. Strategically combining removal methods may increase overall efficiency. Overall, our findings inform the preparation of resources, personnel needs, and deployment readiness for TAD responses involving wild pigs.

Improving urban flyways for bats: the importance of tree canopy structure

Urbanization can hinder movement and restrict landscape permeability for wildlife. However, there is the potential to improve landscape connectivity by establishing and maintaining movement corridors throughout urban areas. One way to achieve this is through the urban forest; the collection of trees in an urban area. Specifically, it is the characteristics of trees within this forest that can provide the structural and functional connectivity that enables wildlife to move effectively through urban areas. To investigate this, we explored the influence of four tree characteristics, alone and in combination, on bat commuting activity along 30 potential movement corridors in an urban setting in north central Texas. Along 10, 30, and 50 m corridor sections, we calculated percent canopy cover, maximum gap distance between canopies, and canopy rugosity using a 60 cm resolution tree canopy layer, while maximum tree height was determined in situ. We then conducted behavioral observations using thermal cameras and acoustic monitoring along the 10 m section of each site between March and September of 2022 and 2023 to determine the amount of time bats were observed commuting/h and species present. Our analysis revealed that increasing percent canopy cover and rugosity positively influenced commuting activity up to a certain threshold (> 60% and > 1.3, respectively), beyond which they may became detrimental. In contrast, the presence of gaps in the canopy lowered commuting, while tree heights > 11 m increased this activity. When considered together, bats in our study area showed a preference for commuting routes with tall trees and straighter, less cluttered canopies with no gaps. Additionally, sites with these features had a greater species diversity. These findings suggest that we can manage and plan the urban forest by establishing an interconnecting network of tree‐lines and forest edges to enhance landscape permeability for bats and subsequently aid urban bat conservation.

Social and built environmental factors associated with adult asthma hospital admission in the North Central Texas

Asthma, one of the most common chronic diseases of adults and children, is an important public health concern. The cause of asthma is thought to be a combination of genetic and environmental factors, and a growing body of research has investigated the possible geographic and contextual factors that contribute to asthma prevalence. However, few studies have incorporated geographic and environmental variables into their designs, despite evidence that geography is associated with asthma exacerbation. Additionally, studies of asthma exacerbations among adults are limited. The situation regarding asthma is particularly concerning in North Central Texas (NCT) compared to the national context. In light of this, we analyzed the geographic variation of approximately 12,000 adult patients hospitalized for asthma in the North Central Texas Region, and their association with built environmental features such as land use types, dwelling characteristics, exposure to traffic parameters at the Census Block Group (CBG) level, and pollutant concentrations in the relevant counties for the year 2014. We applied the Hierarchical Linear Model (HLM), and our analysis indicates that there are significant health disparities in the region. We found that the adult asthma hospitalization rate is significantly higher in low-income, low-education neighborhoods with a significant Black population. Furthermore, factors such as increased travel distance to work and substandard dwelling conditions have been found to trigger an increase in hospital visits for asthma patients. Conversely, the presence of greenspace in the surrounding area has been found to help reduce the frequency of asthma-related hospital visits. It is worth noting that both indoor and outdoor environmental quality contribute to adult asthma hospitalizations. Overall, our study highlights the importance of considering geographic and environmental factors in understanding the prevalence and exacerbation of asthma. Our findings suggest that targeted interventions, such as improving indoor and outdoor environmental quality and increasing access to greenspace, may help reduce the burden of asthma in high-risk communities.

Including isolated aphasia improves sensitivity and negative predicative value for large vessel occlusion screening

BackgroundLarge Vessel Occlusion (LVO) screening tools provide objective assessments to guide diagnostic decisions during acute stroke activations. The Stroke VAN screening tool includes weakness, vision, aphasia, and neglect; however, only screens positive if weakness is present regardless of presence of other symptoms including isolated aphasia. The purpose of this project was to evaluate wAve, a modified Stroke VAN screening tool. WAve includes components of VAN with emphasis on isolated aphasia. MethodsWe conducted a retrospective cohort study on 376 persons who presented with stroke symptoms within 24 h of last known well (LKW) to the Emergency Department of an urban comprehensive stroke center in north central Texas between July 2019 and January 2020. Comparison of VAN and wAve predictive values was calculated using Chi square analysis. Sensitivity and specificity was checked by using MedCalc software. Data from the electronic medical record was obtained for analysis including a documented wAve score and a calculated VAN score. Results of CT angiogram diagnostic testing was used to determine congruence of screening results with evidence of LVO. Power analysis described by Hajian- Tilaki was used to estimate study size. ResultsResults included 192 positive wAve screens and 184 negative wAve screens compared to 152 positive VAN screens and 224 negative VAN screens. The sensitivities for wAve and VAN were 89 % and 80 % respectively. Negative predictive values for wAve and VAN were 97 % and 95 % respectively. In isolated aphasic person, one of eight presented with a LVO and received intervention. ConclusionThe team discovered more LVOs were identified with wAve than VAN in persons exhibiting isolated aphasia symptoms. Larger studies are needed to understand the role isolated aphasia plays in LVO detection.

Instructional Note: North Central Texas College’s First-Year Composition Textbook Project

In the fall of 2018, the First-Year Composition program at North Central Texas College (NCTC) initiated what informally became known as the Textbook Project. Our goal was to provide our community college students with innovative, imaginative, and inspiring classroom experiences that paralleled the high-impact opportunities their peers were afforded at four-year universities. The Textbook Project encompassed five key features: an NCTC-specific textbook, a campus-wide common read, resources for faculty and students in our college’s LMS, a college-wide lecture series, and funding for faculty professional development. Five years later, the project’s emphasis on continuity through collaboration has revitalized the department through faculty engagement and increased student success.

Late Pennsylvanian fishes from the Finis Shales of North-Central Texas (USA)

Late Pennsylvanian fishes from the Finis Shales of North-Central Texas (USA)

Plant interactions with arthropods and pathogens at Sanzenbacher Ranch, early Permian of Texas, and implications for herbivory evolution in Southwestern Euramerica

IntroductionThe Sanzenbacher Ranch deposit represents an early Permian plant assemblage in north-central Texas predominantly composed of pteridosperms, of which callipterids are dominant. This study investigates the interactions of a taxonomically broad range of plant hosts with insects, mites, and pathogens to assess the richness and frequency of damage.MethodsWe used standard methods of the functional feeding group--damage type system and analyses graphically illustrated as nonmetric multidimensional scaling.ResultsOf the total surface area represented, we quantified the fraction of the area herbivorized, providing a comparative perspective with regard to several similar studies of herbivory at nearby plant assemblages from the late Paleozoic. To assess insect herbivory, 1,361 plant specimens were analyzed, including fronds, leaves, reproductive structures, axes, and wood impressions. A total of 205 specimens presented one or more instances of insect herbivory (11.17%). Callipterid-peltasperms exhibited the highest number of interactions, with Autunia conferta, Rhachiphyllum schenkii, cf. Lodevia sp., cf. Comia sp., and an unidentified callipterid accounting for 49.34% of all interactions. Medullosans represented 10.53%, followed by lyginopterids with 8.55%. Forty-eight damage types (DTs) were recognized and classified into the nine functional feeding groups of hole feeding, margin feeding, surface feeding, piercing and sucking, oviposition, galling, seed predation, borings, and pathogens.DiscussionWhen compared to analogous late Paleozoic plant assemblages in Texas, Sanzenbacher Ranch exhibited almost all herbivore functional feeding groups, high richness of DTs, and low herbivory index of 0.26. This record shows high plant diversity in a seasonally dry environment that supports a trend of an early Permian increase in DT diversity in southwestern Euramerica. Sanzenbacher Ranch, different from other early Permian plant assemblages, sheds light on the dynamic ecological interactions of these ancient ecosystems.

Seasonal efficacy and risks from a sodium nitrite toxic bait for wild pigs.

Wild pigs (Sus scrofa) are an invasive and destructive species throughout many regions of the world. A sodium nitrite (SN) toxic bait is currently used in Australia and being developed for use in the US and other countries to combat the increasing populations of wild pigs. In the US, efforts to modify the Australian SN-toxic bait and baiting strategy have focused on reducing issues with non-target animals accessing the SN-toxic bait spilled outside of bait stations by wild pigs. We tested and compared modifications for efficacy (with wild pigs) and hazards (with non-targets) in north-central Texas, US during summer (July 2021) and winter (March 2023) seasons. During both seasons we found that visitation to the bait sites declined 94-99% after deploying the SN-toxic bait, and we found a total of 106 dead wild pigs, indicating considerable lethality for the local population. Prior to deploying the SN-toxic bait, Global Positioning System (GPS)-collared wild pigs were more likely to cease visiting bait sites during summer when foraging resources were abundant. Farrowing decreased visitation to bait sites during the winter. We observed no dead non-targets during summer; winter results showed an average of 5.2 dead migrating birds per bait site (primarily Dark-eye juncos [Junco hyemalis]) from consuming SN-toxic bait spilled by wild pigs. The presence and winter-foraging behaviors of migrating birds appeared to increase hazards for those species. The current formulation of SN-toxic bait was effective at removing wild pigs during both seasons, however it is clear that different baiting strategies may be required in winter when migrating birds are present. Baiting wild pigs prior to farrowing during the winter, and during drier summers, may further improve efficacy of the bait. Reducing hazards to non-targets could be achieved by refining the SN-toxic bait or modifying bait stations to decrease the potential for spillage, decreasing environmental persistence if spilled, or decreasing attractiveness to migrating birds. © 2024 Society of Chemical Industry. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Reassessment of ‘Captorhinikos’ chozaensis, an early Permian (Cisuralian: Kungurian) captorhinid reptile from Oklahoma and north-central Texas

Abstract‘Captorhinikos’ chozaensis Olson, 1954 is a captorhinid eureptile with multiple tooth rows from the lower Permian (Cisuralian: Kungurian) Clear Fork Group of north-central Texas and the Hennessey Formation of Oklahoma. It has five maxillary and four dentary tooth rows. We re-examined the available specimens referred to ‘Captorhinikos’ chozaensis to elucidate aspects of its skeletal structure and assess its phylogenetic relationships. Our parsimony analysis confirmed previous suggestions that this taxon is not referable to the same taxon as Captorhinikos valensis Olson, 1954 (type species of the genus) and ‘Captorhinikos’ parvus Olson, 1970 and thus is placed in its own new genus, Sumidadectes. It also recovered Sumidadectes chozaensis n. comb. as the earliest-diverging moradisaurine captorhinid.UUID: http://zoobank.org/0f89869a-1889-4d90-b721-a89ba5f40c4b

Evaluation of statistical downscaling techniques and projection of climate extremes in central Texas, USA

This study evaluates statistical downscaling techniques using different metrics and compares climate change signals and extreme precipitation and temperature changes under future climate change scenarios in the Bosque watershed, North-Central Texas. The study utilizes observed gridded Daymet data to assess the effectiveness of statistical downscaling techniques. It involves comparing the mean, the 90th percentile, 10th percentile, wet day frequency, and Cumulative Distribution Function (CDF) of climate model simulations before and after downscaling and the Daymet data during the historical period (1981–2005). Furthermore, the study analyzes changes in climate change signals, extreme precipitation, and temperature values under both near-future (2031–2060) and far-future (2070–2099) climate scenarios. The Ratio Delta method (DeltaSD) and Equi-Distant Quantile Mapping (EDQM) statistical downscaling techniques adjust the mean annual, the wet days frequency, the 90th and 10th percentiles, and the CDF of Global Climate Models (GCMs) simulations of historical precipitation and temperature. The downscaling techniques influenced the climate change signal and changes in extreme values in the future climate. When examining future climate projections produced using the DeltaSD method, we observe a more pronounced reduction in precipitation, while simulations generated through EDQM exhibit a higher frequency of heavy precipitation events (R10mm, R20mm) and consecutive dry days (CDD). It's worth noting that the uncertainties associated with the statistical downscaling techniques are relatively small and not statistically significant (≤0.05). In contrast, substantial and significant uncertainties arise from the choice of emission scenarios and the selection of driving GCMs. Across most climate change scenarios, there is a consistent trend towards increased temperatures and extreme temperature indices. The trend of extreme temperature indices shows variation following the choice of emission scenarios where a significant change in temperature extremes was detected under the RCP8.5 emission scenario.

Wing phalanges of a ?thalassodromine pterosaur from the Aptian–Albian Antlers Formation of Texas, USA

Fragmentary pterosaurian wing phalanges from the Aptian-Albian Antlers Formation of north-central Texas, USA are described. Wing phalanges 1 and 2 have suboval shafts with thickened bone at the leading and trailing edges, whereas the third wing phalanx has a flattened airfoil-like cross-section with greatly thickened bone at the leading and trailing edges and a small subrectangular medullary cavity. The cortical bone exhibits an unusual coarse surface texture, and bone thin sections reveal extensive Haversian remodeling and endosteal lamellar bone. The morphology of the wing phalanges differs from that of dsungaripterids, pteranodontoids, and azhdarchids, so the specimen is not a North American record of the Dsungaripteridae as some have stated; whereas based on comparisons to a roughly contemporaneous indeterminate thalassodromine pterosaur specimen from the Romualdo Formation of Brazil, the specimen is tentatively interpreted as an indeterminate thalassodromine with an estimated wingspan of ∼3.5 m.

Concentrations of Sulfur Dioxide in Urban Air Space Above North Central Texas, United States

Hourly average sulfur dioxide concentrations in February and August 2022 were compiled, graphed, and evaluated for five air monitoring stations in north central Texas. The stations occupy the urban core and periphery of the Dallas-Fort Worth metropolitan area. Concentration time series were evaluated relative to stationary sources of sulfur dioxide, the urban core, and shifting wind patterns. Nine large sources emitting more than 100 tons of sulfur dioxide per year were identified in the study area, as were sixty additional facilities emitting between one and ninety-nine tons per year. The highest emitter, an electric power station, produced 4,921 tons of sulfur dioxide per year in 2021. Overall, sulfur dioxide concentrations were low, but periodically breached design standards downwind of large emitters. Hourly average sulfur dioxide concentrations ranged from a minimum of less than 0.1 parts per billion (ppb) at all monitoring stations to a maximum of 170.5 ppb at a station located approximately 1 km away from a mineral processing facility. However, monitoring stations located 2 km to 3 km away from, and periodically downwind of, other large emitters had much lower concentration spikes. This study (1) shows the importance of stationary sources, as opposed to lengthy transport and extensive regional mixing, on sulfur dioxide concentrations in urban complexes; and (2) a need for source-oriented monitors to effectively document sulfur dioxide concentrations in urban air space.

Tillage, Manure, and Biochar Short-Term Effects on Soil Characteristics in Forage Systems

Manure, a globally used soil amendment, can contribute to excessive N and P runoff, leading to water pollution. Biochar (BC) shows promise in mitigating nutrient loss by retaining soil nutrients. However, there is limited research exploring the combined effects of tillage practices, biochar, manure, forage crops, and soil types on soil nutrient characteristics in a single field study. Our objectives are to determine if, in North Central Texas, differing soil types, soil amendments, forage crops, and tillage practices affect soil nutrients when applied short term, and whether correlations exist among soil nutrient characteristics as affected by soil amendments, tillage practices, and the presence of forage crops. The study encompasses three field sites with five factors, including soil types, manure rates, biochar rates, tillage practices, and forage crop types. Soil samples were assayed for pH, electrical conductivity (EC), macronutrients, and micronutrients. Data analyses involved variance analysis, Fisher’s tests, and Pearson’s correlations using R in Rstudio (the IDE). Microplots treated with manure (average 2.16 ppm) retained 60% greater average nitrate levels at the end of the growing season than those treated with a synthetic fertilizer (average 1.35 ppm) (p ≤ 0.05). Moderate and strong correlations were observed between EC and S (r (106) = 0.43, p < 0.001 in loamy sand soil; r (106) = 0.80, p < 0.001 in clay loam soil) and between nitrate and Zn, (r (106) = 0.36, p < 0.001 in loamy sand soil; r (106) = 0.44, p < 0.001 in sandy loam soil) across different soil types. Soil type (texture) emerged as the primary influencing factor on plant-available soil nutrients and characteristics, followed by manure application and tillage practices. The impact of BC and forage crop type varied depending on other experimental factors. Understanding the influence of soil type, amendment application, and tillage on soil nutrient characteristics can guide sustainable forage production practices and soil nutrient management strategies.

Challenges and Adaptations Experienced by Intimate Partner Violence Service Providers During COVID-19 Pandemic

Purpose: COVID-19 is an unprecedented pandemic that has caused an increase in the intimate partner violence (IPV) victims rate, and social service-providing agencies shifted to emergency online and distance service-providing systems. In our study, we aimed to explore the experiences of IPV service providers during this pandemic.Method: We used a cross-sectional qualitative method containing some quantitative questions. Data were collected by conducting 15 in-depth interviews and a survey with the service providers (22–65 years old) from six IPV service-providing agencies that are located in the Dallas-Forth Worth metroplex in North Central Texas. We used a phenomenological hermeneutical method to capture the service providers’ experiences.Results: Four key themes highlight the essence of the experiences of the IPV service providers while providing the services during COVID-19. The four major themes are (a) experiences with telehealth, (b) barriers to social and legal services, (c) altered relationships, and (d) mental health impacts. In addition, a few subthemes are explored under the first three major themes. The service providers we interviewed provided details and vital information regarding challenges, adaptations, and resilience they experienced to assist the most disadvantaged group of the population.Conclusion: This study will contribute to making attention to improving facilities, accessibility, and resources for both service providers and their clients. Findings highlight the need for agency owners and policymakers to consider more multimodal and creative solutions for such a vulnerable population and their service providers.

Assessing North Texas Regional Trauma Handoffs: A Multicenter Mixed-Methods Needs Assessment

IntroductionTrauma video review of Emergency Medical Services (EMS) handoffs demonstrates frequent problems including interruptions and incomplete information transfer. This study aimed to perform a regional needs assessment of handoff perceptions and expectations to guide future standardization efforts. MethodsA multidisciplinary team of trauma providers through consensus building created an anonymous survey which was then distributed through the North Central Texas Trauma Regional Advisory Council and four regional level-1 trauma institutions. Qualitative data underwent content analysis; quantitative data are presented with descriptive statistics. ResultsSurvey responses (n = 249) were submitted by trauma nurses (38%), EMS (24%), emergency physicians (14%), and trauma physicians (13%). Median overall handoff quality was rated well (4, scale 1-5) despite some variability between hospitals (3, scale 1-5). The top five most important handoff details were the same for both stable and unstable patients: primary mechanism, blood pressure, heart rate, Glasgow Coma Scale, and location of injuries. While providers felt neutral about the data order, the vast majority supported immediate bed transfer and primary survey in unstable patients. The majority of receiving providers report interrupting handoff at least once (78%); and 66% of EMS clinicians found interruptions disruptive. Content analysis revealed top priority categories for improvement: environment, communication, information relayed, team dynamics, and flow of care. ConclusionAlthough our data demonstrated satisfaction and concordance with respect to the EMS handoff, 84% of EMS clinicians reported some to high amounts of variability across institutions. Gaps in the development of standardized handoffs identified include exposure, education, and enforcement of these protocols.

Simultaneous seismic inversion study for channel sandstone identification, northern part of the Eastern Shelf, King County, North-Central Texas

This paper documents the results of a prestack simultaneous seismic inversion conducted to investigate the Wolfcampian lower Tannehill sandstone channels within a mixed carbonate siliciclastic system in the northern Eastern Shelf in King County, North Central Texas. Previous exploration methods for the Tannehill sandstone were based largely on well-log correlation which, because of their widely spaced sample points, are not optimal for channel delineation. We have generated crossplots of P- and S-wave velocity ratios ([Formula: see text]/[Formula: see text] ratios) versus P-impedance to determine lithologic types. We then used 3D seismic data and wireline logs to implement a prestack simultaneous seismic inversion procedure to generate P- and S-impedances, density, and [Formula: see text]/[Formula: see text] ratio volumes to identify the valley-fill Tannehill lowstand systems. Our results find that (1) based on impedance and density, the sandstone-rich channels can be easily separated from the carbonate-rich zones but are difficult to distinguish using [Formula: see text]/[Formula: see text]. (2) Although there appeared to be several channel systems in the area of investigation, two of these, hereby referred to as channel A and channel B, are recognized to be the key contributors of sandstone sediments to the shelf edge, slope, and basin areas. (3) Of these two channels, channel A is the larger and highly sinuous; it is associated with a meander loop, a point bar, and an abandoned channel. At the point-bar location, channel A has a width of 890 m (2920 ft) and a depth of 29 m (94 ft). The point bar is structurally anticlinal and thus constitutes a potential exploration target. In contrast, channel B is less sinuous, without any associated point bar. It has a maximum depth and width of 23 m (75 ft) and 270 m (886 ft), respectively. Finally, the inversion results suggest that other potential Tannehill sandstone reservoirs may still be present elsewhere within King County.

Updated distribution of the Texas kangaroo rat (Dipodomys elator) and patterns of rodent species associations from county road surveys in Texas

The Texas kangaroo rat (Dipodomys elator) is a rare species of conservation interest at both the state and federal level. Therefore, an updated understanding of distribution and abundance of D. elator is critical for initiating informed decisions about its conservation status and subsequent management strategies. We surveyed more than 850 locations along unpaved county roads across the historical range of this species in north-central Texas to identify sites of D. elator presence and examine patterns of rodent species associations. We determined that D. elator presently occurs in five counties in Texas within its historical range and was the eighth most abundant species of the 14 species that we captured. Moreover, we found that the majority of pairwise species associations, including those involving D. elator, were random and there was no strong evidence that pairs of rodents were aggregating or segregating with respect to each other. We did observe negative associations between D. elator and both Dipodomys ordii (Ord’s kangaroo rat) and Sigmodon hispidus (hispid cotton rat). Nonetheless, these patterns indicate that interspecific interactions do not play a strong role in influencing the distribution of D. elator. However, the restricted and temporally dynamic distribution of this species suggests that a metapopulation perspective should be considered when making future conservation considerations.

Hydrology and hydrological extremes under climate change scenarios in the Bosque watershed, North-Central Texas, USA

This study evaluates hydrology and hydrological extremes under future climate change scenarios. The climate change scenarios were developed from multiple Global Circulation Models (GCMs), Representative Concentration Pathway (RCP) scenarios, and statistical downscaling techniques. To ensure hydrological model robustness, the Soil Water Assessment Tool (SWAT) was calibrated and validated using the Differential Split Sample Test (DSST) approach. The model was also calibrated and validated at the multi-gauges of the watershed. Future climate change scenarios revealed a reduction in precipitation (in the order of −9.1% to 4.9%) and a consistent increase in maximum temperature (0.34°C to 4.10°C) and minimum temperature (−0.15 °C to 3.7°C) in different climate model simulations. The climate change scenarios triggered a reduction of surface runoff and streamflow and a moderate increase in evapotranspiration. Future climate change scenarios projected a decrease in high flow (Q5) and low flow (Q95). A higher reduction of Q5 and annual minimum flow is also simulated in future climate scenarios, whereas an increase in annual maximum flow is simulated in climate change scenarios developed from the RCP8.5 emission scenario. The study suggests optimal water management structures which can reduce the effect of change in high and low flows.

Investigation of Infiltration Loss in North Central Texas by Retrieving Initial Abstraction and Constant Loss from Observed Rainfall and Runoff Events

Accurate modeling of infiltration losses is vital for runoff estimation and thus the development of flood design/protection criteria and water management schemes, etc. In design flood practices, the initial abstraction and constant loss (IACL) method has been widely applied due to its simplicity. However, due to a lack of physical equivalent properties, the IACL method is often subject to issues in parametrization and has large dependency on calibration efforts for storm events. Despite the wide range/variability of IACL values, a single set of IA and CL values is normally adopted for specific flood frequency, which may introduce uncertainty and bias in resulting peak streamflow. In this study, we identified a total of 2,036 rainfall-runoff events for 18 watersheds in North Central Texas to estimate the total losses with their IA and CL components based on time-series of mean areal precipitation (MAP) and streamflow data. Threshold behavior is found for all studied subbasins between the summation of gross rainfall and antecedent soil moisture versus runoff depth: below the threshold, runoff depth is minimal; whereas above it, runoff is largely linearly correlated with the summation of rainfall and antecedent soil moisture. This finding provides a convenient way to estimate/predict total loss or runoff depth given MAP and antecedent soil moisture. In addition, this study shows that the IA and CL values can be approximated by the gamma and Weibull distributions, respectively. The fitted distributions of IA and CL values can be applied in a Monte Carlo simulation framework to stochastically simulate numerous rainfall-runoff events for a flood frequency analysis.