Empirical analysis of volunteer convergence following the 2011 tornado disaster in Tuscaloosa,Alabama     

Emmett J. Lodree  Lauren B. Davis 《Natural Hazards》2016,84(2):1109-1135

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Exploring the Digital Divide in an Australian Regional City: a case study of Albury     

John Atkinson  Rosemary Black  Allan Curtis 《The Australian geographer》2008,39(4):479-493

The ‘digital divide’ is generally considered to be the gap between people who have access to information and communication technologies (ICT) and those who do not, and an issue of significant social justice. This paper presents findings from research that explored the digital divide within the regional city of Albury. The study focused on assessing whether there was a digital divide; identifying strategies to address any divide; and developing a methodology that could be used to explore the digital divide in other contexts. Data were gathered using semi-structured interviews, focus groups, and a telephone survey of city residents. Findings demonstrated that a digital divide existed in that there were differences in computer access in relation to income and different locations within the city, and for access to the Internet by age, education and income levels. Overall, the patterns indicated that those with lower education and income and the elderly reported lower levels of access to ICT. Drawing on the research findings we suggest some practical ways of addressing the digital divide that could be applied to other similar locations where a digital divide exists, such as providing technical support and training, improved access to and awareness of ICT services, and facilitating access to ICT services such as the provision of appropriate hardware and software for disadvantaged groups. Our view is that the mixed-method approach we employed provided helpful, reliable information at reasonable cost and could be considered by other researchers and local governments.  相似文献   

Geophysical and Hydrochemical Identification of Flow Paths with Implications for Water Quality at an ARR Site     

Andrew D. Parsekian  Julia Regnery  Alex D. Wing  Rosemary Knight  Jörg E. Drewes 《Ground Water Monitoring & Remediation》2014,34(3):105-116

Two key challenges regarding the design and operation of aquifer recharge and recovery (ARR) systems are evaluating aquifer heterogeneity and understanding hydrochemical interactions. Uncertainty in this respect can impact the volume of recoverable water and the improvement in water quality. The objective of this research is to leverage the advantages of geophysical measurements and hydrochemical sampling to reveal the properties of an ARR site to inform current ARR system operations and future design decisions. Electrical resistivity tomography was used to image the subsurface below two key infiltration/extraction areas of an ARR site in Colorado, USA. Hydrochemical measurements on transects intersecting the geophysical measurements resolved bulk parameters (i.e., total organic carbon, nitrate, and major cations and anions) and trace organic chemicals (e.g., pharmaceuticals, personal care products). Conservative tracers were also used to estimate degrees of mixing and water travel times and to better assess the performance of the ARR site regarding water quality changes and water recovery. The electrical resistivity measurements suggest that certain areas of the infiltration basins have hydraulic connections to the extraction wells through preferential flow paths, compared with other infiltration basins that are separated by fine‐grained materials from their respective extraction wells. The hydrochemical results indicate that consistent improvements in water quality can be achieved in these preferential flow paths within relatively short travel times (<5 d) at this ARR site.  相似文献   

Effort changes around a marine reserve: The case of the California Rockfish Conservation Area     

Janet Mason  Rosemary Kosaka  Aaron Mamula  Cameron Speir 《Marine Policy》2012

This article is an analysis of observed changes in the level of fishing effort and the spatial distribution of fishing effort following implementation of a marine reserve off the California coast. The Rockfish Conservation Area (RCA) closes the area between depth contour based boundaries to commercial trawl fishing. In this analysis, commercial fishing vessels are grouped based on their level of fishing effort within the closed area prior to the closure in order to compare changes in effort levels between groups. The results suggest that the RCA may have had a small effect on the level of fishing effort in the California groundfish trawl fishery. Spatial distribution of fishing effort before and after implementation of the marine reserve is also compared. Some concentration of effort occurred along parts of the closed area boundaries. This pattern suggests the “fishing the line” behavior noted in the marine reserve literature, but other possible explanations exist including the effects of coincident changes in other regulations and changing bioeconomic conditions.  相似文献   

Altimetric Lagrangian advection to reconstruct Pacific Ocean fine-scale surface tracer fields     

Marine Rogé  Rosemary A. Morrow  Guillaume Dencausse 《Ocean Dynamics》2015,65(9-10):1249-1268

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Characterizing Heterogeneity in Infiltration Rates During Managed Aquifer Recharge   总被引：1，自引：0，他引：1       下载免费PDF全文

Chloe Mawer  Andrew Parsekian  Adam Pidlisecky  Rosemary Knight 《Ground water》2016,54(6):818-829

Infiltration rate is the key parameter that describes how water moves from the surface into a groundwater aquifer during managed aquifer recharge (MAR). Characterization of infiltration rate heterogeneity in space and time is valuable information for MAR system operation. In this study, we utilized fiber optic distributed temperature sensing (FO‐DTS) observations and the phase shift of the diurnal temperature signal between two vertically co‐located fiber optic cables to characterize infiltration rate spatially and temporally in a MAR basin. The FO‐DTS measurements revealed spatial heterogeneity of infiltration rate: approximately 78% of the recharge water infiltrated through 50% of the pond bottom on average. We also introduced a metric for quantifying how the infiltration rate in a recharge pond changes over time, which enables FO‐DTS to be used as a method for monitoring MAR and informing maintenance decisions. By monitoring this metric, we found high‐spatial variability in how rapidly infiltration rate changed during the test period. We attributed this variability to biological pore clogging and found a relationship between high initial infiltration rate and the most rapid pore clogging. We found a strong relationship (R² = 0.8) between observed maximum infiltration rates and electrical resistivity measurements from electrical resistivity tomography data taken in the same basin when dry. This result shows that the combined acquisition of DTS and ERT data can improve the design and operation of a MAR pond significantly by providing the critical information needed about spatial variability in parameters controlling infiltration rates.  相似文献   

Sodium D2 line profiles: clues to the temperature structure of Mercury’s exosphere     

Rosemary M. Killen  Andrew Potter  Alan Fitzsimmons  Thomas H. Morgan 《Planetary and Space Science》1999,47(12):463-1458

The velocity distribution of atoms in an exosphere can be used to constrain source and loss processes. The velocity distribution itself can be constrained by observing the line profile of an atmospheric emission line. The only atomic species known to exist in the Hermean exosphere that has a strong enough resonance transition in the visible spectrum that its line profile can be observed from the ground with existing instruments is sodium. Line profiles of the sodium D2 emission (5889 A) were obtained at two facilities. On 29 and 30 May 1997, we obtained line profiles with the 107 inch telescope at The McDonald Observatory at coude focus. On 6 January 1998, we obtained line profiles at the Anglo–Australian telescope. The line profiles show that the sodium in Mercury’s atmosphere is at least 700 K hotter than the surface temperature throughout the atmosphere. This implies that the interaction of the Na atoms with the surface is governed by energetic processes.  相似文献   

Global surface currents: a high-resolution product for investigating ocean dynamics   总被引：3，自引：0，他引：3  

Joel Sudre  Rosemary A. Morrow 《Ocean Dynamics》2008,58(2):101-118

A global 1/4° resolution product of surface currents has been developed by the Centre de Topographie des Océans et de l’Hydrosphère. The surface current is calculated from a combination of Ekman currents derived from wind estimates from QuikSCAT satellite, geostrophic current anomalies derived from altimetry, and a mean geostrophic current derived from climatology. In the equatorial band, the currents are adjusted following the methodology proposed by Lagerloef et al. (J Geophys Res, 104(C10):22313–22326, 1999). These satellite-derived currents have been compared to different types of in situ current observations. A global validation is performed using Lagrangian surface drifting buoys and acoustic Doppler current profiler current observations along ship tracks. The comparison shows a very good agreement in the subtropical and mid-latitude bands. The correlation between the satellite-derived currents and the drifter currents in zonal mean bands is around 0.7 for most of the world oceans, both for the zonal and the meridional components. This correlation rises up to 0.8 in the regions of strong boundary currents. In the equatorial band, the correlation with the surface drifting buoys is reduced. A direct comparison with the TOGA/TAO moored current meter data at the equator shows that the low frequency currents are captured by the satellite current product, but there is a substantial high-frequency signal (<20 days), which is not reproduced. This is especially the case for the meridional component and is mainly related to the tropical instability waves. We also show that using daily QuikSCAT wind forcing improves the satellite current product, particularly in the high-latitude westerly wind belt and in the tropical Indian Ocean.  相似文献   

Research Note: A unifying framework for the widely used stabilization of potential field inverse problems     

Saeed Vatankhah  Rosemary Anne Renaut  Shuang Liu 《Geophysical Prospecting》2020,68(4):1416-1421

We present a brief review of the widely used and well-known stabilizers in the inversion of potential field data. These include stabilizers that use L₂, L₁ and L₀ norms of the model parameters and the gradients of the model parameters. These stabilizers may all be realized in a common setting using two general forms with different weighting functions. Moreover, we show that this unifying framework encompasses the use of additional stabilizations which are not common for potential field inversion.  相似文献   

Changes in event-based streamflow magnitude and timing after suburban development with infiltration-based stormwater management     

Kristina G. Hopkins  Aditi S. Bhaskar  Sean A. Woznicki  Rosemary M. Fanelli 《水文研究》2020,34(2):387-403

Green stormwater infrastructure implementation in urban watersheds has outpaced our understanding of practice effectiveness on streamflow response to precipitation events. Long-term monitoring of experimental suburban watersheds in Clarksburg, Maryland, USA, provided an opportunity to examine changes in event-based streamflow metrics in two treatment watersheds that transitioned from agriculture to suburban development with a high density of infiltration-focused stormwater control measures (SCMs). Urban Treatment 1 has predominantly single family detached housing with 33% impervious cover and 126 SCMs. Urban Treatment 2 has a mix of single family detached and attached housing with 44% impervious cover and 219 SCMs. Differences in streamflow-event magnitude and timing were assessed using a before-after-control-reference-impact design to compare urban treatment watersheds with a forested control and an urban control with detention-focused SCMs. Streamflow and precipitation events were identified from 14 years of sub-daily monitoring data with an automated approach to characterize peak streamflow, runoff yield, runoff ratio, streamflow duration, time to peak, rise rate, and precipitation depth for each event. Results indicated that streamflow magnitude and timing were altered by urbanization in the urban treatment watersheds, even with SCMs treating 100% of the impervious area. The largest hydrologic changes were observed in streamflow magnitude metrics, with greater hydrologic change in Urban Treatment 2 compared with Urban Treatment 1. Although streamflow changes were observed in both urban treatment watersheds, SCMs were able to mitigate peak flows and runoff volumes compared with the urban control. The urban control had similar impervious cover to Urban Treatment 2, but Urban Treatment 2 had more than twice the precipitation depth needed to initiate a flow response and lower median peak flow and runoff yield for events less than 20 mm. Differences in impervious cover between the Urban Treatment watersheds appeared to be a large driver of differences in streamflow response, rather than SCM density. Overall, use of infiltration-focused SCMs implemented at a watershed-scale did provide enhanced attenuation of peak flow and runoff volumes compared to centralized-detention SCMs.  相似文献