Effects of sand supply on the morphodynamics and stratigraphy of active parabolic dunes, Bigstick Sand Hills, southwestern SaskatchewanGeological Survey of Canada Contribution 20060654.

2008 ◽  
Vol 45 (3) ◽  
pp. 321-335 ◽  
Author(s):  
Chris H. Hugenholtz ◽  
Stephen A. Wolfe ◽  
Brian J. Moorman
Keyword(s):  
Vegetation Cover ◽  
Threshold Level ◽  
Aerial Photographs ◽  
Vegetation Development ◽  
Sand Supply ◽  
Sand Hills ◽  
Dune Form ◽  
Major Controlling Factor ◽  
The Individual ◽  
Ground Penetrating

Sand supply is a major controlling factor on parabolic dune form and stratigraphy in inland settings. In this study, aerial photographs, ground-penetrating radar (GPR), and stratigraphic analysis document the morphodynamics of an individual and compound parabolic dune in the Bigstick Sand Hills, southwestern Saskatchewan. Migration rates for the last 60 years are comparable, although the profile morphologies differ, with the individual dune having a more aerodynamic form. Stratigraphic facies are also similar in both dune types, but the overall internal architecture imaged by GPR differs considerably. Configurations of cross-strata parallel to the downwind axis represent dominant foreset development and lee-slope slipface advance of the individual dune, and impeded slipface development of the compound dune. Stratigraphy transverse to the downwind axis represents radial deposition and foreset development at the individual dune, and vertical accumulation at the compound dune. The overall difference in parabolic dune form and stratigraphy is attributed to variations in sand supply, which determine vegetation development and sedimentation processes along the crest and lee slope. Sand supplied from active blowouts upwind of the individual dune inhibits vegetation colonization on the dune, whereas an absence of sand supply upwind of the compound dune leads to high levels of vegetation cover on the dune. Once supply drops below a threshold level, vegetation cover increases, causing sediment deposition and vertical accretion, and ultimately changing dune form. Overall, this study demonstrates that local sand supply and feedback processes are critical to understanding dune development in vegetated, inland settings.

Attempted Understorey Characterization Using Aerial Photography in Kanha National Park, Madhya Pradesh, India

1991 ◽  
Vol 18 (1) ◽  
pp. 45-50 ◽  
Author(s):  
Mahesh C. Porwal ◽  
Parth S. Roy
Keyword(s):  
Vegetation Cover ◽  
National Park ◽  
Canopy Cover ◽  
Wildlife Habitat ◽  
Aerial Photographs ◽  
Understorey Vegetation ◽  
Cover Type ◽  
Black And White ◽  
Habitat Evaluation ◽  
The Individual

Remote sensing is being widely used in the fields of resource management, planning, and wildlife habitat evaluation. Canopy cover-type mapping has been done in most of the bioclimatic zones of India and widely abroad, using aerial photointerpretation techniques. In the present study an attempt has been made to develop a methodology for mapping understorey vegetation in part of Kanha National Park, using 1:10,000-scale black-and-white aerial photographs.The Park, one of the best for Tiger (Felis tigris) visibility and observation of other large carnivores and herbivores, has been mapped, with subdivision into 11 vegetation cover-classes and four density-classes, using aerial photographs, and each class has been visited in the field for understorey information concerning different physiographic units. Each category of canopy-cover was sampled in the field, and tree base-cover per hectare has been estimated.Vertical profiles have also been drawn in the main vegetation classes in order to understand the occurrence of understorey vegetation. It was found that a physiographic analysis coupled with canopy-cover type and density, with appropriate sampling in the individual vegetation strata, have together proved indicative of understorey vegetationtype. When the relationship between understorey vegetation and canopy-cover type is established, one can directly depict understorey limits spatially in conjunction with the main vegetation cover. Such an approach of mapping understorey vegetation using aerial photographs could be of immense value for wildlife habitat evaluation and park management.

scholarly journals Integrating Geophysical and Photographic Data to Visualize the Quarried Structures of the Roman Town of Bassianae

2021 ◽  
Vol 13 (12) ◽  
pp. 2384
Author(s):  
Roland Filzwieser ◽  
Vujadin Ivanišević ◽  
Geert J. Verhoeven ◽  
Christian Gugl ◽  
Klaus Löcker ◽  
...  
Keyword(s):  
Ground Penetrating Radar ◽  
Urban Infrastructure ◽  
Aerial Photographs ◽  
Surface Model ◽  
Data Sets ◽  
Buried Structures ◽  
Archaeological Prospection ◽  
Ground Penetrating ◽  
Geophysical Prospection ◽  
Strong Agreement

Large parts of the urban layout of the abandoned Roman town of Bassianae (in present-day Serbia) are still discernible on the surface today due to the deliberate and targeted quarrying of the Roman foundations. In 2014, all of the town's intramural (and some extramural) areas were surveyed using aerial photography, ground-penetrating radar, and magnetometry to analyze the site's topography and to map remaining buried structures. The surveys showed a strong agreement between the digital surface model derived from the aerial photographs and the geophysical prospection data. However, many structures could only be detected by one method, underlining the benefits of a complementary archaeological prospection approach using multiple methods. This article presents the results of the extensive surveys and their comprehensive integrative interpretation, discussing Bassianae's ground plan and urban infrastructure. Starting with an overview of this Roman town's research history, we present the details of the triple prospection approach, followed by the processing, integrative analysis, and interpretation of the acquired data sets. Finally, this newly gained information is contrasted with a plan of Roman Bassianae compiled in 1935.

Evolution of a beach–dune system following a catastrophic storm overwash event: Greenwich Dunes, Prince Edward Island, 1936–2005

2010 ◽  
Vol 47 (3) ◽  
pp. 273-290 ◽  
Author(s):  
Sojan Mathew ◽  
Robin G.D. Davidson-Arnott ◽  
Jeff Ollerhead
Keyword(s):  
Prince Edward Island ◽  
National Park ◽  
Aerial Photographs ◽  
Dune System ◽  
Aerial Photos ◽  
Sand Supply ◽  
Digital Elevation ◽  
Intense Storm ◽  
Geomorphic Units ◽  
Subsequent Stabilization

Greenwich Dunes, Prince Edward Island National Park, is a sandy mainland and barrier spit beach–dune complex stretching for about 10 km along the northeast shore of Prince Edward Island, Canada. In October 1923, surge associated with an intense storm produced catastrophic overwash along the whole length of the study area. Subsequent evolution of the system was quantified from historic aerial photographs taken in 1936, 1953, 1971, 1997, and 2005. Orthophoto mosaics were generated for each photo set using PCI Geomatica OrthoEngine, a digital photogrammetric software. Linear changes in shoreline position and areal changes in geomorphic units were evaluated for each photo set. In addition, digital elevation models (DEMs) were extracted from the 1953, 1971, and 1997 aerial photos, enabling analysis of topographic and volumetric changes. The 1936 photos show complete destruction of all foredunes, with overwash and transgressive dunes extending 300 to 600 m inland. A descriptive model of the stages of evolution of the system is proposed based on the processes controlling overwash healing and dune stabilization. Detailed topographic and volumetric changes associated with the development of an extensive transgressive dunefield and subsequent stabilization as a result of reduced sand supply due to the growth of a new vegetated foredune complex and vegetation colonization are doccumented for each stage. It was nearly 40 years before a continuous foredune system was re-established and a further 30 years before the inland transgressive dunes became completely stabilized.

Identification, investigation and classification of surface depressions and chalk dissolution features using integrated LiDAR and geophysical methods

2020 ◽  
Vol 53 (4) ◽  
pp. 620-644 ◽  
Author(s):  
Zoe Elizabeth Jeffery ◽  
Stephen Penn ◽  
David Peter Giles ◽  
Linley Hastewell
Keyword(s):  
Ground Penetrating Radar ◽  
Image Interpretation ◽  
Geophysical Methods ◽  
Integrated Approach ◽  
Study Data ◽  
Aerial Photographs ◽  
Geophysical Techniques ◽  
Karstic Features ◽  
Ground Penetrating

The chalk bedrock of the Hampshire Basin, southern England is an important aquifer and is highly susceptible to dissolution, making the development and presence of karstic features a widespread occurrence. These features are hazardous because they provide possible pathways to the underlying aquifer and therefore present potential site-specific contamination risks. There is also evidence of extensive extraction, through both mining and surface quarrying, of chalk, flint and clay over many centuries. Geophysical techniques consisting of electromagnetic (EM31) and ground-penetrating radar surveys were used to identify and characterize target features identified from desk study data. The ground-penetrating radar and EM31 interpretations allowed the classification of non-anthropogenic target features, such as diffuse buried sinkholes with disturbed and subsiding clay-rich infill and varying symmetrical and asymmetrical morphologies. We describe here the investigations of such features identified at Holme Farm, Stansted House, Hampshire. The combination of EM31 data and ground-penetrating radar profiles facilitated the identification of a palaeovalley, cavities and irregular rockhead. This investigation identified locations of aquifer contamination risk as some sinkholes have been sites for the illegal dumping of waste or the infiltration of fertilizers, leaking sewage pipes or animal waste. This potential source of contamination utilizes the sinkhole as a pathway into the highly transmissive White Chalk Subgroup of Hampshire and has caused contamination of the aquifer. We conclude that our integrated approach of geophysical techniques linked to aerial photographs and LiDAR image interpretation was highly effective in the location and characterization of dissolution structures, infilled former quarries and mining features at this site.

Relation between baroreflex sensitivity and cardiac vagal tone in humans

1994 ◽  
Vol 266 (1) ◽  
pp. H21-H27 ◽  
Author(s):  
M. Kollai ◽  
G. Jokkel ◽  
I. Bonyhay ◽  
J. Tomcsanyi ◽  
A. Naszlady
Keyword(s):  
Baroreflex Sensitivity ◽  
Regression Line ◽  
Systolic Pressure ◽  
Vagal Tone ◽  
Threshold Level ◽  
Dominant Factor ◽  
Cardiac Vagal Tone ◽  
The Individual ◽  
Method R ◽  
Maximum Threshold

The extent of dependence of cardiac vagal tone on arterial baroreceptor input has been studied in 12 healthy, young adult subjects. Cardiac vagal tone was defined as the chang in R-R interval after complete cholinergic blockade by atropine. Baroreflex sensitivity was determined with the "Oxford-method": R-R interval was regressed against systolic pressure. The interindividual correlation between cardiac vagal tone and baroreflex sensitivity for falling pressures was found to be significant, but not close (R = 0.81, P = 0.002). In each subject, the baroreflex regression line for falling pressures was extrapolated to the post-atropine R-R interval level; 50 mmHg was considered as minimum and 80 mmHg as maximum threshold level for the integrated baroreflex. From the relation between the individual regression lines and the minimum and maximum threshold levels, it was concluded that cardiac vagal tone could be generated by both baroreflex-dependent and -independent mechanisms, the ratio of which varies in different individuals, with the baroreflex-dependent mechanism being the dominant factor.

COLOR INFRARED AERIAL PHOTOGRAPHY TO IDENTIFY FORAGE LEGUMES IN HAY FIELDS

1981 ◽  
Vol 61 (2) ◽  
pp. 331-336 ◽  
Author(s):  
P. K. BASU
Keyword(s):  
Trifolium Pratense ◽  
Red Clover ◽  
Aerial Photographs ◽  
Forage Legume ◽  
Image Characteristics ◽  
Mixed Crop ◽  
Trifolium Pratense L ◽  
Medicago Sativa L ◽  
The Individual ◽  
Agricultural Areas

In September 1977 and 1978, color infrared (CIR) aerial photographs of mixed agricultural areas (approx. 132.7 km2) near Vernon and Carp, Ontario, and of forage legume test plots at Ottawa were taken at a scale of 1:6000. Extensive ground surveys were conducted within 2 wk after the photographic flights to verify CIR images of alfalfa (Medicago sativa L.), red clover (Trifolium pratense L.), trefoil (Lotus corniculatus L.), vetch (Vicia spp.) grasses and their mixtures in the original transparencies. A number of photographic image characteristics of legumes and grasses have been illustrated by which a reliable identification and subsequent quantification of legume components were made, particularly in fields that showed decline of a crop or when the individual components grew as separate patches in the same field. Photo-interpretation difficulties existed in distinguishing the components in a very uniformly mixed crop and recently cut fields.

scholarly journals Response of Forest to Climatic Events and Human Management at Fort Leavenworth, Kansas

2002 ◽  
pp. 1-24
Author(s):  
James S. Aber ◽  
Juliet Wallace ◽  
Matthew C. Nowak
Keyword(s):  
Tree Ring ◽  
Vegetation Cover ◽  
Vegetation Index ◽  
Forest Cover ◽  
Aerial Photographs ◽  
Forest Understory ◽  
Drought Severity ◽  
Upland Forest ◽  
Bottomland Forest ◽  
Bottomland Forests

Characteristics and temporal changes in forest cover from 1987 to 1997 were documented on the basis of remote sensing for two study forests at Fort Leavenworth, northeastern Kansas. Eight Landsat 5 Thematic Mapper (TM) datasets from the month of July cover the study period, which included a major drought in 1988-1989 and flooding along the Missouri River in 1993. Other data sources included kite aerial photographs, digital orthophotos, tree-ring cores, climatic records, and ground observations. Three study areas were evaluated from Landsat TM datasets: (1) the entire Fort Leavenworth area; (2) an upland, hardwood forest composed mainly of oaks; and (3) a bottomland, softwood forest dominated by cottonwood. Normalized Difference Vegetation Index (NDVI) values were derived from these three study sets and subjected to image differencing and principal-component analysis. The TM band 5:4 ratio was also analyzed for the two study forests. Values and trends derived from Landsat imagery were compared to data on tree-ring growth in upland oaks and regional climatic events. Annual growth of tree rings in upland oaks is tied closely to precipitation and the Palmer Drought Severity Index (PDSI); however, changes in NDVI values lag one to two years behind the onset of climatic events, particularly drought episodes. During the first year of drought (1988), vegetation cover in the upland and bottomland forests reacted in different ways: with a slight decline in the upland forest and a slight increase in the bottomland forest. The increased vegetation in the bottomland forest presumably resulted from more understory growth in dry hollows and potholes. In the second year of drought (1989), both forests suffered a marked decline in vegetation cover. NDVI values reached their minima for all categories (whole area, upland forest, and bottomland forest) in 1990, even though precipitation and tree-ring growth increased substantially that year. We conclude that changes in Landsat-derived NDVI values are out of phase with climatic events and variations in tree-ring growth for both upland and bottomland forests in northeastern Kansas and northwestern Missouri. Overall change (1987 to 1997) for NDVI values is down slightly for all categories of evaluation. This probably reflects reduced precipitation throughout the study period compared to the long-term average. Changes in vegetation took place mainly on the forest margins. Such changes are thought to result from microclimatic stress at forest edges. The bottomland study forest also was impacted by severe flooding in 1993. Routine human activities may have resulted in minor changes along the margins of both study forests. The bottomland forest was affected by intentional burning of the adjacent prairie in April 2000. Cottonwood trees at the forest edge were killed or injured by the prairie fire, which penetrated the forest understory some distance.

scholarly journals Preparedness for Study Abroad: Comparing the Linguistic Outcomes of a Short-Term Spanish Program by Third, Fourth and Sixth Semester L2 Learners

2009 ◽  
Vol 18 (1) ◽  
pp. 157-179 ◽  
Author(s):  
Lucile Duperron ◽  
Mark H. Overstreet
Keyword(s):  
Language Development ◽  
Study Abroad ◽  
Threshold Level ◽  
Optimal Timing ◽  
Language Experience ◽  
Short Term ◽  
Second Language Development ◽  
Studying Abroad ◽  
Short Term Study ◽  
The Individual

The present study examines second language development in a short-term program based on the number of courses that learners have completed prior to their abroad experience. However, it does not presume that longer seat time before studying abroad equals proportionately higher linguistic returns. Rather, it aims to describe what kind of language development occurs in the short-term study abroad environment based on learners’ previous language experience. This descriptive approach allows us to take into account the individual variation that characterizes study abroad learning outcomes (Segalowitz et al., 2004). It also brings a level of detail that is useful in investigating optimal timing conditions toward the study abroad experience, that is, a threshold level at which learners are primed to benefit most from study abroad (Segalowitz & Freed, 2004). 

scholarly journals Late-summer sea ice segmentation with multi-polarisation SAR features in C and X band

2016 ◽  
Vol 10 (1) ◽  
pp. 401-415 ◽  
Author(s):  
Ane S. Fors ◽  
Camilla Brekke ◽  
Anthony P. Doulgeris ◽  
Torbjørn Eltoft ◽  
Angelika H. H. Renner ◽  
...  
Keyword(s):  
Sea Ice ◽  
Late Summer ◽  
Aerial Photographs ◽  
First Year ◽  
Temporal Consistency ◽  
Sea Ice Thickness ◽  
Helicopter Flight ◽  
Air Temperatures ◽  
X Band ◽  
The Individual

Abstract. In this study, we investigate the potential of sea ice segmentation by C- and X-band multi-polarisation synthetic aperture radar (SAR) features during late summer. Five high-resolution satellite SAR scenes were recorded in the Fram Strait covering iceberg-fast first-year and old sea ice during a week with air temperatures varying around 0 °C. Sea ice thickness, surface roughness and aerial photographs were collected during a helicopter flight at the site. Six polarimetric SAR features were extracted for each of the scenes. The ability of the individual SAR features to discriminate between sea ice types and their temporal consistency were examined. All SAR features were found to add value to sea ice type discrimination. Relative kurtosis, geometric brightness, cross-polarisation ratio and co-polarisation correlation angle were found to be temporally consistent in the investigated period, while co-polarisation ratio and co-polarisation correlation magnitude were found to be temporally inconsistent. An automatic feature-based segmentation algorithm was tested both for a full SAR feature set and for a reduced SAR feature set limited to temporally consistent features. In C band, the algorithm produced a good late-summer sea ice segmentation, separating the scenes into segments that could be associated with different sea ice types in the next step. The X-band performance was slightly poorer. Excluding temporally inconsistent SAR features improved the segmentation in one of the X-band scenes.

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