Long-term and seasonal geomorphological changes at Padre Island, Texas are identified and linked with potential external drivers. Aerial and satellite images from 1950 to 2018, monthly images from 2019 to 2020, and a 2018 LiDAR data set are used to assess long-term and seasonal geomorphological changes within a 50 km2 area of Padre Island near Port Mansfield, Texas. Trends in landcover are evaluated by mapping and comparing the relative areal coverage of each facies. Vegetated dunes, absent initially, emerged in the fore-island and expanded into the back-barrier to cover 14% of the study area. The active vegetation-free back-barrier dune field steadily decreased in areal extent from 12% to 6% as vegetation spread. Nebkha dune coverage fluctuated between 4% and 7%. Expansive microbial mats colonized the wind tidal and deflation flats surrounding the vegetated dunes and back-barrier dune field giving rise to a remarkably different landscape over the 50-year period studied. An assessment of external forcing factors identifies increased rates of relative sea level rise and decreased sediment influx as the most likely primary factors driving the geomorphological changes. These changes have induced a widespread shift toward stabilization of island sediments by vegetation and microbial mats, which in turn has starved the back-barrier of sediments resulting in low rates of accretion and increased flooding. These findings highlight the sensitivity of the back-barrier and, in particular, the dune facies to changes in sea level and sediment supply, and show that microbial mats are effective at stabilizing island sediments and may be harbingers to barrier island response to rising sea level. As shown in this study, long-term monitoring of geomorphic facies changes and topography can detect important shifts in the island state that can be used to inform decision making for these sensitive coastal landscapes. 相似文献
This paper investigates use of inventories, or checklists of activities, as an emergency management tool to motivate preparedness action in individuals. It develops the inventory concept to provide the foundation for a more targeted approach to storm preparation communication and community engagement. It also examines the potential efficacy of alternatives to paper-based checklists, such as web or smartphone applications. Academic and grey literature was reviewed to collect activities for a storm inventory for emergency agencies to measure individual preparedness and for individuals to measure their preparation progress. The resulting master list was refined for application and tested for useability in a pilot study of semi-structured interviews in a storm-susceptible community in Queensland, Australia. Also, clustering items by type of preparedness activity reveal where strengths and weaknesses exist in individual preparedness. For instance, preparation for leaving and safety planning were shown to be the areas of weakest activity in the pilot sample, while preparation of the house for a storm was the strongest area. In addition, behaviour change literature shows potential for effective use of an inventory-based smartphone application in motivating preparation activity. Data collected by a storm preparedness smartphone application could show where a communication or engagement program for targeted communities should be focused. It is supported by health literature that identifies preferences of individuals to make progress on complex tasks in stages, the value of lists to achievement of goals and demonstrated increase in uptake of activities prompted by smartphone applications over web or paper-based diaries.
The intensity of global groundwater use rose from 124 m3 per capita in 1950 to 152 m3 in 2021, for a 22.6% rise in the annual per capita use. This rise in global per capita water use reflects rising consumption patterns. The global use of groundwater, which provides between 21% and 30% of the total freshwater annual consumption, will continue to expand due to the sustained population growth projected through most of the 21st century and the important role that groundwater plays in the water-food-energy nexus. The rise in groundwater use, on the other hand, has inflicted adverse impacts in many aquifers, such as land subsidence, sea water intrusion, stream depletion, and deterioration of groundwater-dependent ecosystems, groundwater-quality degradation, and aridification. This paper projects global groundwater use between 2025 and 2050. The projected global annual groundwater withdrawal in 2050 is 1535 km3 (1 km3 = 109 m3 = 810,713 acre-feet). The projected global groundwater depletion, that is, the excess of withdrawal over recharge, in 2050 equals 887 km3, which is about 61% larger than in 2021. This projection signals probable exacerbation of adverse groundwater-withdrawal impacts, which are worsened by climatic trends and the environmental requirement of groundwater flow unless concerted national and international efforts achieve groundwater sustainability. 相似文献
In hydrological modelling of catchments, wherein streams are groundwater-fed, an accurate representation of groundwater processes and their interaction with surface water is crucial. With this purpose, a coupled model was recently developed linking SWAT (Soil and Water Assessment Tool) with the fully-distributed groundwater model MODFLOW (Modular Groundwater Flow). In this study, SWAT and SWAT-MODFLOW were applied to a Danish groundwater-dominant catchment, simulating groundwater abstraction scenarios and assessing the benefits and drawbacks of SWAT-MODFLOW. Both models demonstrated good performance. However, SWAT-MODFLOW provided more realistic outputs when simulating abstraction: the decrease in streamflow was similar to the volume of water abstracted, while in SWAT the impact was negligible. SWAT also showed impacts on streamflow only when abstractions were taken from the shallow aquifer, not from the deep aquifer. Overall, SWAT-MODFLOW demonstrated wider possibilities for groundwater analysis, providing more insights than SWAT in supporting decision making in relation to environmental assessment. 相似文献
A database of 1267 quality-screened major- and trace-element analyses of chromites (s.l.) from kimberlites, lamproites, ultramafic lamprophyres (UMLs) and crustal sources (‘greenstones’, including ophiolites, gabbros, basalts and komatiites) has been subjected to statistical analysis, in order to derive discriminants for use in diamond exploration. The techniques used included nearest-neighbour analysis, CART (classification and regression trees) and MARS (multivariate adaptive regression splines). The results show that both CART and MARS approaches can correctly discriminate kimberlite/lamproite chromites from UML/‘greenstone’ chromites at levels near 90%. Discrimination into the four classes separately is achieved at levels of ca. 80% by MARS and > 70% by CART; much of the misclassification is between the kimberlite and lamproite classes. These results probably represent the maximum probable level of discrimination on chemical criteria, given that ascending magmas may sample both mantle and crustal rocks. The CART approach produces a classification tree that requires no further computation to classify a given grain; the MARS approach requires the use of a simple software package. Tests on known samples illustrate the high level of accuracy of the methods in an exploration context, as well as the useful petrogenetic conclusions that can be drawn from some ‘misclassifications’. 相似文献
Global sea level rise (SLR) will significantly alter coastal landscapes through inundation and erosion of low-lying areas. Animals that display area fidelity and rely on fringing coastal habitats during multiple life stages, such as diamondback terrapins (Malaclemys terrapin Schoepff 1793), are likely to be particularly vulnerable to SLR-induced changes. We used a combination of empirical nest survey data and results from a regional SLR model to explore the long-term availability of known nesting locations and the modeled availability of fringing coastal habitats under multiple SLR scenarios for diamondback terrapin in the MD portion of Chesapeake Bay and the MD coastal bays. All SLR scenarios projected the rapid inundation of historically used nesting locations of diamondback terrapins with 25%–55% loss within the next 10 years and over 80% loss by the end of the century. Model trajectories of habitat losses or gains depended on habitat type and location. A key foraging habitat, brackish marsh, was projected to decline 6%–94%, with projections varying spatially and among scenarios. Despite predicted losses of extant beach habitats, future gains in beach habitat due to erosion and overwash were projected to reach 40%–600%. These results demonstrate the potential vulnerability of diamondback terrapins to SLR in Chesapeake Bay and underscore the possibility of compounding negative effects of SLR on animals whose habitat requirements differ among life stages. More broadly, this study highlights the vulnerability of species dependent on fringing coastal habitats and emphasizes the need for a long-term perspective for coastal development in the face of SLR. 相似文献
Groundwater plays an important role in New Zealand water supplies and hence monitoring activities are conducted regularly. Most monitoring programmes aim to evaluate groundwater chemistry and almost completely overlook the microbial component in this ecosystem. In our present study, the bacterial community structure of groundwater in the Wairarapa Valley was examined using the terminal restriction fragment length polymorphism (T-RFLP), and relationships between bacterial community structure and groundwater chemistry, aquifer confinement and groundwater usage were explored. In addition, the results from this study were compared with a previous T-RFLP survey of the same area in an attempt to detect changes in bacterial community structure over time. The data obtained suggested that bacterial community structure was related to groundwater chemistry, especially to redox conditions. Species composition showed minimal variation over time if groundwater chemistry remained unchanged. These findings reflect the potential of using bacterial communities as biological indicators to evaluate the health of groundwater ecosystems. We suggest that it is important to include this type of broad bacterial diversity assessment criteria into regular groundwater monitoring activities. 相似文献
Discussion points raised by Rose ( 2016 ) concentrate on late Albian stratigraphic relationships between formations of the East Texas Basin and the San Marcos Arch of the Comanche Platform in the northern Gulf of Mexico. Criticisms of Phelps et al. (2014) regarding stratigraphic nomenclature, palaeogeography and regional lithostratigraphic correlations generally focus on interpretive aspects of the study or do not account for the full scope of published information. Revisions to the top Aptian–Albian Supersequence boundary by Rose are incompatible with the relative location of a subaerial unconformity, as well as deepening lithofacies trends and retrogradational stratigraphic patterns below the interpreted boundary. Rose's placement of the top Aptian–Albian Supersequence boundary precisely at the Albian–Cenomanian stage boundary also implies ca 1·4 Ma of diachroneity in second order sea‐level patterns between the northern Gulf of Mexico and other documented global sedimentary basins. 相似文献
The Neo-Tethyan subduction in Iran is characterized by the Urumieh–Dokhtar magmatic arc (UDMA), formed by northeast-ward subduction of the oceanic crust beneath the central Iran. This belt coincides with the porphyry copper metallogenic belt that comprises several metallogenic zones, including Ahar–Jolfa in northwest Iran. The Ahar–Jolfa metallogenic zone encompasses two main batholiths of Qaradagh and Sheyvardagh and numerous intrusive bodies of Cenozoic, which have produced many base and precious metal deposits and prospects. The former is considered as continuation of the Meghri–Ordubad pluton in South Armenian Block (SAB), which also hosts porphyry copper deposits (PCDs). The Sungun PCD is the largest occurrence in northwest Iran. Rhenium-Osmium ages of Sungun molybdenites are early Miocene and range between 22.9 ± 0.2 and 21.7 ± 0.2 Ma. Comparison of the ages obtained here with published ages for mineralization across the region suggests the following sequence. The earliest porphyry Cu–Mo mineralization event in northwest Iran is represented by Saheb Divan PCD of late Eocene age, which is followed by the second epoch of middle Oligocene, including the Cu–Mo–Au mineralization at Qarachilar and the Haftcheshmeh PCD. Mineralization in Sungun, Masjed Daghi, Kighal and Niaz deposits corresponds to the third mineralization event in northwest Iran. The first epoch in northwest Iran postdates all Eocene mineralizations in SAB, while the second epoch is coeval with Paragachay and the first-stage of Kadjaran PCDs. Its third epoch is younger than all mineralizations in SAB, except the second stage in Kadjaran PCD. Finally, the Cu mineralization epochs in northwest Iran are older than nearly all PCDs and prospects in Central Iran (except the Bondar Hanza PCD), altogether revealing an old to young trend along the UDMA and the porphyry Cu belt towards southeast, resulted from diachronous, later closure of the Neo-Tethyan oceanic basin in central and SE Iran. 相似文献