scholarly journals Bedrock depth influences spatial patterns of summer baseflow, temperature, and flow disconnection for mountainous headwater streams

2022 ◽  
Author(s):  
Martin A. Briggs ◽  
Phillip Goodling ◽  
Zachary C. Johnson ◽  
Karli M. Rogers ◽  
Nathaniel P. Hitt ◽  
...  
Keyword(s):  
Large Scale ◽  
Cold Water ◽  
Headwater Streams ◽  
Empirical Support ◽  
Stream Temperature ◽  
Thickness Variation ◽  
Stream Channel ◽  
Sediment Thickness ◽  
Groundwater Supply ◽  
Bedrock Depth

Abstract. In mountain headwater streams the quality and resilience of cold-water habitat is regulated by surface stream channel connectivity and groundwater exchange. These critical hydrologic processes are thought to be influenced by the stream corridor bedrock contact depth (sediment thickness), which is often inferred from sparse hillslope borehole information, piezometer refusal, and remotely sensed data. To investigate how local bedrock depth might control summer stream temperature and channel disconnection (dewatering) patterns, we measured stream corridor bedrock depth by collecting and interpreting 191 passive seismic datasets along eight headwater streams in Shenandoah National Park (Virginia USA). In addition, we used multiyear stream temperature and streamflow records to calculate summer baseflow metrics along and among the study streams. Finally, comprehensive visual surveys of stream channel dewatering were conducted in 2016, 2019, and 2021 during summer baseflow conditions (124 total km of stream length). We found that measured bedrock depths were not well-characterized by soils maps or an existing global-scale geologic dataset, where the latter overpredicted measured depths by 12.2 m (mean), or approximately four times the average bedrock depth of 2.9 m. Half of the eight study stream corridors had an average bedrock depth of less than 2 m. Of the eight study streams, Staunton River had the deepest average bedrock depth (3.4 m), the coldest summer temperature profiles, and substantially higher summer baseflow indices compared to the other study steams. Staunton River also exhibited paired air and water annual temperature signals suggesting deeper groundwater influence, and the stream channel did not dewater in lower sections during any baseflow survey. In contrast, streams Paine Run and Piney River did show pronounced, patchy channel dewatering, with Paine Run having dozens of discrete dry channel sections ranging 1 to greater than 300 m in length. Stream dewatering patterns were apparently influenced by a combination of discrete deep bedrock (20 m+) features and more subtle sediment thickness variation (1–4 m), depending on local stream valley hydrogeology. In combination these unique datasets show the first large-scale empirical support for existing conceptual models of headwater stream disconnection based on underflow capacity and shallow groundwater supply.

scholarly journals Morphology and Physicochemical Properties of Alluvial Soils in Riparian Forests after River Regulation

Forests ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 329
Author(s):  
Dorota Kawalko ◽  
Paweł Jezierski ◽  
Cezary Kabala
Keyword(s):  
Large Scale ◽  
Soil Classification ◽  
River Regulation ◽  
Riparian Forests ◽  
Deep Penetration ◽  
Alluvial Soils ◽  
Soil Morphology ◽  
Groundwater Supply ◽  
Quantitative Alteration ◽  
Favorable Conditions

The elimination of flooding and lowering of the groundwater table after large-scale river regulation allow deep penetration of soils by plant roots, soil fauna, and microorganisms, thus creating favorable conditions for advanced pedogenesis. Although the changes of the morphology and properties of agriculturally used drained alluvial soils in Central Europe have been well characterized, studies in riparian forests remain insufficient. An analysis of 21 profiles of forest soils located on the Holocene river terrace (a floodplain before river regulation and embankment) in SW Poland confirmed a noticeable pedogenic transformation of soil morphology and properties resulting from river regulation. Gleyic properties were in most profiles replaced with stagnic properties, testifying to a transition from dominant groundwater supply to precipitation-water supply. The development of a diagnostic mollic and cambic horizons, correlated with the shift in soil classification from Fluvisols to Phaeozems, and in the majority, to Cambisols, demonstrated a substantial change in habitat conditions. The transformation of alluvial soils may result in an inevitable modification of forest management in the river valley, including quantitative alteration in species composition of primarily riparian forests.

scholarly journals Ethnic Discrimination in the Dutch Labor Market: Differences Between Ethnic Minority Groups and the Role of Personal Information About Job Applicants—Evidence from a Field Experiment

2020 ◽  
Author(s):  
Lex Thijssen ◽  
Marcel Coenders ◽  
Bram Lancee
Keyword(s):  
Labor Market ◽  
Field Experiment ◽  
Ethnic Minority ◽  
Large Scale ◽  
Minority Groups ◽  
Personal Information ◽  
Empirical Support ◽  
Ethnic Discrimination ◽  
Ethnic Minority Groups ◽  
Large Scale Field

AbstractIn this study, we present the results of a large-scale field experiment on ethnic discrimination in the Dutch labor market. We sent fictitious job applications (N = 4211) to vacancies for jobs in ten different occupations in the Netherlands. By examining 35 different ethnic minority groups, we detect considerable differences in discrimination rates, predominantly between Western and non-Western minorities. Furthermore, we find little systematic variation in discrimination patterns with regard to gender, regions, and occupations, pointing to the existence of an ethnic hierarchy that is widely shared among employers. Finally, we do not find empirical support for the hypothesis that adding personal information in job applications reduces discrimination.

scholarly journals Using autonomous video to estimate the bottom-contact area of longline trap gear and presence–absence of sensitive benthic habitat

2018 ◽  
Vol 75 (5) ◽  
pp. 797-812 ◽  
Author(s):  
Beau Doherty ◽  
Samuel D.N. Johnson ◽  
Sean P. Cox
Keyword(s):  
Contact Area ◽  
Large Scale ◽  
Marine Protected Area ◽  
Cold Water ◽  
Sensor Data ◽  
Benthic Habitat ◽  
Commercial Fishing ◽  
Depth Sensor ◽  
Quality Of Data ◽  
Bottom Contact

Bottom longline hook and trap fishing gear can potentially damage sensitive benthic areas (SBAs) in the ocean; however, the large-scale risks to these habitats are poorly understood because of the difficulties in mapping SBAs and in measuring the bottom-contact area of longline gear. In this paper, we describe a collaborative academic–industry–government approach to obtaining direct presence–absence data for SBAs and to measuring gear interactions with seafloor habitats via a novel deepwater trap camera and motion-sensing systems on commercial longline traps for sablefish (Anoplopoma fimbria) within SGaan Kinghlas – Bowie Seamount Marine Protected Area. We obtained direct presence–absence observations of cold-water corals (Alcyonacea, Antipatharia, Pennatulacea, Stylasteridae) and sponges (Hexactinellida, Demospongiae) at 92 locations over three commercial fishing trips. Video, accelerometer, and depth sensor data were used to estimate a mean bottom footprint of 53 m2 for a standard sablefish trap, which translates to 3200 m2 (95% CI = 2400–3900 m2) for a 60-trap commercial sablefish longline set. Our successful collaboration demonstrates how research partnerships with commercial fisheries have potential for massive improvements in the quantity and quality of data needed for conducting SBA risk assessments over large spatial and temporal scales.

Experimental Investigation of Lab-Scale, Heat Exchanger Prototypes Designed to Provide Refugia for Trout

2021 ◽  
Author(s):  
Rajib Uddin Rony ◽  
Adam Gladen ◽  
Sarah LaVallie ◽  
Jeremy Kientz
Keyword(s):  
Heat Exchanger ◽  
Temperature Difference ◽  
Large Scale ◽  
Cold Water ◽  
Cooling System ◽  
Tube Bundle ◽  
Small Scale ◽  
Scaled Model ◽  
Average Temperature ◽  
Average Temperature Difference

Abstract In recent years Spring Creek in South Dakota, a popular fishing location, has been experiencing higher surface water temperatures, which negatively impact cold-water trout species. One potential solution is to provide localized refugia of colder water produced via active cooling. The present work focuses on the design and testing of a small-scale prototype heat exchanger, for such a cooling system. Various prototypes of the heat exchanger were tested in a 1/10th-scaled model of a section of the creek. A staggered, tube-bundle heat exchanger was used. The prototypes consisted of just the heat exchanger placed directly in the scaled-stream model and of the heat exchanger placed inside an enclosure with an aperture. The results show that, without the enclosure, the average temperature difference is 0.64 °C, with a corresponding heat transfer requirement of 1.63 kW/°C of cooling. However, with an enclosure, the average temperature difference is 1.95 °C, which required 0.59 kW/°C of cooling. Modifications to the enclosure decrease the average temperature difference but also decrease the standard deviation of the temperature difference. Thus, the cooling effect is more evenly spread throughout the water in the enclosure. This indicates that the enclosure design can be used to balance the requirements of obtaining a desired temperature difference with a relatively low spatial variation in that temperature difference. These results will be used to guide the design of the large-scale heat exchanger prototype.

Analisys of mud inrush water sources into underground working of the Sokolovskoe ore deposit

2020 ◽  
pp. 56-67
Author(s):  
E. Yu. Efremov
Keyword(s):  
Hydraulic Conductivity ◽  
Large Scale ◽  
Underground Mining ◽  
Temporal Distribution ◽  
High Water ◽  
The North ◽  
Initial Block ◽  
Groundwater Supply ◽  
Spatio Temporal ◽  
Inrush Water

There is a serious threat of groundwater inrush from overlying sedimentary layers for underground mining. When ore is extracted using block caving method, the area of overburden collapse over ore zone disrupts the natural structure of high hydraulic-conductivity and low hydraulic-conductivity layers. This process creates conditions for the accumulation and transfer of groundwater to mine workings, which lead to accidents, up to disastrous proportions. The research aim is to determine the spatio-temporal distribution of mud inrushes, and to identify groundwater supply sources of inrushes to reduce the geotechnical risks of underground mining in Sokolovskaya mine. Research methods include localization, classification, and analysis of monitoring data, comparison of mud inrushes distribution with geostatistical parameters of the main aquifers.The majority of large-scale accidents caused by mud inrushes are confined to the central and northern area of caved rock zone. The most risky stage of the ore body extraction is the initial block at the lower extraction level. The sources of water supply for the majority of the mud inrushes are high water level areas of the Cretaceous aquifer to the north and west of the mine. Rational targeted drainage aimed at draining the identified areas of the aquifer is the best way to reduce the risk of accidents.

scholarly journals Testing biodiversity theory using species richness of reef-building corals across a depth gradient

2019 ◽  
Vol 15 (10) ◽  
pp. 20190493 ◽  
Author(s):  
T. Edward Roberts ◽  
Sally A. Keith ◽  
Carsten Rahbek ◽  
Tom C. L. Bridge ◽  
M. Julian Caley ◽  
...  
Keyword(s):  
Species Richness ◽  
Large Scale ◽  
Coral Species ◽  
Environmental Gradients ◽  
Abiotic Factors ◽  
Empirical Support ◽  
Null Model ◽  
Local Scale ◽  
Small Scale ◽  
Energy Availability

Natural environmental gradients encompass systematic variation in abiotic factors that can be exploited to test competing explanations of biodiversity patterns. The species–energy (SE) hypothesis attempts to explain species richness gradients as a function of energy availability. However, limited empirical support for SE is often attributed to idiosyncratic, local-scale processes distorting the underlying SE relationship. Meanwhile, studies are also often confounded by factors such as sampling biases, dispersal boundaries and unclear definitions of energy availability. Here, we used spatially structured observations of 8460 colonies of photo-symbiotic reef-building corals and a null-model to test whether energy can explain observed coral species richness over depth. Species richness was left-skewed, hump-shaped and unrelated to energy availability. While local-scale processes were evident, their influence on species richness was insufficient to reconcile observations with model predictions. Therefore, energy availability, either in isolation or in combination with local deterministic processes, was unable to explain coral species richness across depth. Our results demonstrate that local-scale processes do not necessarily explain deviations in species richness from theoretical models, and that the use of idiosyncratic small-scale factors to explain large-scale ecological patterns requires the utmost caution.

Debris dams as habitat for aquatic invertebrates in forested headwater streams: a large-scale field experiment

2019 ◽  
Vol 70 (5) ◽  
pp. 734
Author(s):  
Brenda R. Baillie ◽  
Brendan J. Hicks ◽  
Ian D. Hogg ◽  
Michael R. van den Heuvel ◽  
Mark O. Kimberley
Keyword(s):  
Large Scale ◽  
Aquatic Invertebrates ◽  
Headwater Streams ◽  
Dam Removal ◽  
Aquatic Invertebrate ◽  
Invertebrate Communities ◽  
Debris Dams ◽  
Scale Field ◽  
Large Scale Field ◽  
Debris Dam

To evaluate the effects of debris dams on aquatic invertebrate communities, we sampled benthic invertebrates in debris dams and riffles in three forested headwater streams in New Zealand. As part of a large-scale field experiment, debris dams were subsequently removed from three treatment sections in each of the streams to assess effects on invertebrate communities. Prior to debris dam removal, total invertebrate densities in debris dams were not significantly different from those in riffles. However, densities of Ephemeroptera, Plecoptera and Trichoptera taxa were significantly higher in debris dams than in riffles. Debris dams contained a higher number of less common taxa (defined as <1% of total catch) and significantly higher densities of shredders. Densities for Coleoptera, Diptera and Trichoptera taxa were significantly higher in the autumn than in the spring. Non-metric multidimensional scaling axis scores indicated that both habitat and season had a significant effect on aquatic invertebrate community composition. At the reach scale, the effects of debris dam removal on the aquatic invertebrate communities were not statistically detectable because debris dams comprised only a small proportion of total habitat. However, these data highlight the importance of debris dams in contributing to the diversity of aquatic invertebrates in forested headwater streams.

Large-scale cold water dispersant effectiveness experiments with Alaskan crude oils and Corexit 9500 and 9527 dispersants

2009 ◽  
Vol 58 (1) ◽  
pp. 118-128 ◽  
Author(s):  
Randy C. Belore ◽  
Ken Trudel ◽  
Joseph V. Mullin ◽  
Alan Guarino
Keyword(s):  
Large Scale ◽  
Cold Water ◽  
Crude Oils ◽  
Corexit 9500 ◽  
Dispersant Effectiveness

Exploring market orientation among Chinese small and medium-sized enterprises

2017 ◽  
Vol 11 (4) ◽  
pp. 617-636 ◽  
Author(s):  
Long Zhang ◽  
Ali Kara ◽  
John E. Spillan ◽  
Alma Mintu-Wimsatt
Keyword(s):  
Market Orientation ◽  
Business Performance ◽  
Large Scale ◽  
Empirical Support ◽  
Three Dimensions ◽  
Orientation Measurement ◽  
Content Type ◽  
Geographic Concentration ◽  
Marketing Orientation ◽  
Business Function

Purpose The role of marketing as a business function is rapidly changing in China. Consequently, their views on marketing orientation – whether it is accepted, rejected, modified or reframed – have been seriously impacted. This paper aims to report on the results of a survey among Chinese small- and medium-sized enterprise (SME) managers and their perceptions of the market-orientation philosophy. In particular, emphasis was placed on three dimensions of market orientation: intelligence generation, intelligence dissemination and responsiveness. The effect of market orientation on business performance was also examined. Design/methodology/approach The authors collected data from 214 managers from SMEs. These businesses were located in the cities of Beijing, Shanghai and Shenzhen. The commonly used market orientation (MARKOR) measure was used to test the hypotheses. Findings Consistent with the extant literature, the findings provided empirical support for the three dimensions of market orientation among Chinese SME. The authors also found that a positive relationship existed between Chinese SME market orientation and firm performance. Research limitations/implications This study provides major insights into the market orientation measurement and practices of SME in China. From a measurement perspective, the empirical support for MARKOR across a non-Western context is noteworthy. From a practitioner perspective, the implications relating to understanding Chinese SME and how these companies can best market their products and services to their respective markets are critical. Some of the limitations of our study relates to the sample size, convenience sampling and geographic concentration of the respondents. Originality/value This study addresses the gaps in the literature by exploring market orientation in non-large scale businesses as well as the adaptation of the concept in a non-Western cultural setting. The findings extend the conceptualization and application of market orientation to Chinese SME.

scholarly journals Combined Forces: Thinking and/or Feeling? How News Consumption Affects Anti-Muslim Attitudes through Perceptions and Emotions about the Economy

2018 ◽  
Vol 67 (2) ◽  
pp. 326-347 ◽  
Author(s):  
Laura Jacobs ◽  
Mark Boukes ◽  
Rens Vliegenthart
Keyword(s):  
Structural Equation ◽  
Large Scale ◽  
Dominant Role ◽  
Empirical Support ◽  
Equation Model ◽  
Conflict Theory ◽  
News Consumption ◽  
Group Conflict Theory ◽  
News Outlet

This study develops a model that contributes to our understanding of the complex relationship between economic motivations and anti-Muslim attitudes by analyzing the underexplored role of news consumption. Using a large-scale Dutch panel dataset ( n = 2694), we test a structural equation model theoretically grounded in group conflict theory, in which the relationship between news consumption and anti-Muslim attitudes is mediated by perceptions and emotions about the economy. Findings offer sound empirical support for the hypothesized model: news consumption increases pessimistic economic perceptions and negative emotions about the economy, which in turn strengthens anti-Muslim attitudes. The mechanism, however, largely depends on the type of news outlet and genre: watching television seems more decisive than reading newspapers; moreover, especially exposure to soft and popular news formats plays a dominant role.

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