Academic literature on the topic 'Aerial photography in snow surveys'
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Journal articles on the topic "Aerial photography in snow surveys"
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Fox, A. J., and A. P. R. Cooper. "Climate-change indicators from archival aerial photography of the Antarctic Peninsula." Annals of Glaciology 27 (1998): 636–42. http://dx.doi.org/10.3189/1998aog27-1-636-642.
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Aerial photography has been used as a mapping tool in the Antarctic Peninsula region sinre the late 1920s. Following pioneering work by Wilkins in 1928, Ellsworth in 1934 and the British Graham Land Expedition in 1934-37, the Falkland Islands and Dependencies Aerial Survey Expedition carried out extensive aerial photography during the period 1955-57. Since then, many other aerial surveys have been carried out, and the result is an archive of aerial photography that, for some localities, spans 40 years. The production of maps both from different generations of photographs and satellite images has revealed many changes in the extent of ice cover with time. For example, changes in ice shelves such as the Wordie Ice Shelf, Larsen Ice Shelf and Müller Ice Shelf, are well recorded, and the termini of some glaciers have retreated. However, the most pervasive change is the consistent decline in the extent of small bodies of snow and ice. This paper shows how perennial snow or ice cover has decreased in the northern Marguerite Bay area, at 68°S. The correlation of the change with elevation and with climate records from Adelaide and Rothera research stations in the Antarctic Peninsula region is examined.
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Baroni, Carlo, Massimo Frezzotti, Maria Cristina Salvatore, Mirco Meneghel, Ignazio E. Tabacco, Luca Vittuari, Aldino Bondesan, Alessandro Biasini, Alessandro Cimbelli, and Giuseppe Orombelli. "Antarctic geomorphological and glaciological 1 : 250 000 map series: Mount Murchison quadrangle, northern Victoria Land. Explanatory notes." Annals of Glaciology 39 (2004): 256–64. http://dx.doi.org/10.3189/172756404781814131.
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AbstractGeomorphological and glaciological features are represented on a georeferenced satellite image mosaic of the Mount Murchison quadrangle, northern Victoria Land, Antarctica (73–74˚ S, 162–166˚30' E), at a scale of 1 : 250 000. Landforms and deposits of glacial and periglacial environments, forms related to mass wasting, wind action, weathering and geological structures are identified and mapped. The chronological sequence of landforms and deposits, morphography and lithology is also indicated. Glacier velocities (up to 180 ma–1) and ice-front fluctuations (1964–99) were determined by analysis of aerial photography and satellite imagery. Airborne radar surveys reveal that the greatest ice thickness (about 1500 m) is located in the grounding zone of Aviator Glacier. Up to 1000 mof ice bury the subglacial relief of Deception Plateau, Hercules Névé and the Deep Freeze Range. Snow accumulation rates (average = 170 kg m–2 a–1) exhibit an overall negative correlation with altitude and distance from the coast. The relationships among relict erosional landforms and volcanic activity provide chronological constraints for the palaeogeographic evolution of this sector of the Transantarctic Mountains.
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Fraser, R. H., I. Olthof, M. Maloley, R. Fernandes, C. Prevost, and J. van der Sluijs. "UAV PHOTOGRAMMETRY FOR MAPPING AND MONITORING OF NORTHERN PERMAFROST LANDSCAPES." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XL-1/W4 (August 27, 2015): 361. http://dx.doi.org/10.5194/isprsarchives-xl-1-w4-361-2015.
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Northern environments are changing in response to recent climate warming, resource development, and natural disturbances. The Arctic climate has warmed by 2–3°C since the 1950’s, causing a range of cryospheric changes including declines in sea ice extent, snow cover duration, and glacier mass, and warming permafrost. The terrestrial Arctic has also undergone significant temperature-driven changes in the form of increased thermokarst, larger tundra fires, and enhanced shrub growth. Monitoring these changes to inform land managers and decision makers is challenging due to the vast spatial extents involved and difficult access. <br><br> Environmental monitoring in Canada’s North is often based on local-scale measurements derived from aerial reconnaissance and photography, and ecological, hydrologic, and geologic sampling and surveying. Satellite remote sensing can provide a complementary tool for more spatially comprehensive monitoring but at coarser spatial resolutions. Satellite remote sensing has been used to map Arctic landscape changes related to vegetation productivity, lake expansion and drainage, glacier retreat, thermokarst, and wildfire activity. However, a current limitation with existing satellite-based techniques is the measurement gap between field measurements and high resolution satellite imagery. Bridging this gap is important for scaling up field measurements to landscape levels, and validating and calibrating satellite-based analyses. This gap can be filled to a certain extent using helicopter or fixed-wing aerial surveys, but at a cost that is often prohibitive. <br><br> Unmanned aerial vehicle (UAV) technology has only recently progressed to the point where it can provide an inexpensive and efficient means of capturing imagery at this middle scale of measurement with detail that is adequate to interpret Arctic vegetation (i.e. 1–5 cm) and coverage that can be directly related to satellite imagery (1–10 km<sup>2</sup>). Unlike satellite measurements, UAVs permit frequent surveys (e.g. for monitoring vegetation phenology, fires, and hydrology), are not constrained by repeat cycle or cloud cover, can be rapidly deployed following a significant event, and are better suited than manned aircraft for mapping small areas. UAVs are becoming more common for agriculture, law enforcement, and marketing, but their use in the Arctic is still rare and represents untapped technology for northern mapping, monitoring, and environmental research. <br><br> We are conducting surveys over a range of sensitive or changing northern landscapes using a variety of UAV multicopter platforms and small sensors. Survey targets include retrogressive thaw slumps, tundra shrub vegetation, recently burned vegetation, road infrastructure, and snow. Working with scientific partners involved in northern monitoring programs (NWT CIMP, CHARS, NASA ABOVE, NRCan-GSC) we are investigating the advantages, challenges, and best practices for acquiring high resolution imagery from multicopters to create detailed orthomosaics and co-registered 3D terrain models. Colour and multispectral orthomosaics are being integrated with field measurements and satellite imagery to conduct spatial scaling of environmental parameters. Highly detailed digital terrain models derived using structure from motion (SfM) photogrammetry are being applied to measure thaw slump morphology and change, snow depth, tundra vegetation structure, and surface condition of road infrastructure. <br><br> These surveys and monitoring applications demonstrate that UAV-based photogrammetry is poised to make a rapid contribution to a wide range of northern monitoring and research applications.
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Kerbes, Richard H., Katherine M. Meeres, James E. Hines, and David G. Kay. "Lesser Snow Geese, Chen caerulescens caerulescens, and Ross's Geese, Chen rossii, of Jenny Lind Island, Nunavut." Canadian Field-Naturalist 122, no. 1 (January 1, 2008): 34. http://dx.doi.org/10.22621/cfn.v122i1.540.
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We surveyed the Lesser Snow (Chen caerulescens caerulescens) and Ross’s geese (Chen rossii) of Jenny Lind Island, Nunavut, using aerial photography in June 1988, 1998, and 2006, and a visual helicopter transect survey in July 1990. The estimated number of nesting geese was 39 154 ± SE 2238 in 1988, 19 253 ± 2323 in 1998, and 21 572 ± 1898 in 2006. In 1988 an estimated 2.7% of the nesting geese were Ross’s. The July 1990 population of adult-plumaged birds was 25 020 ± 3114. The estimated percentage blue morph among Snow and Ross’s geese was 19.0% in 1988, 25.1% in 1989, 23.0% in 1990 and 21.1% in 2006. Estimated pre-fledged Snow Goose productivity was 47% young in 1989 and 46% in 1990. Combined numbers of Snow and Ross’s geese on Jenny Lind Island grew over 250 fold, from 210 adults in 1962-1966 to 54 100 adults in 1985. Numbers subsequently declined, to 42 200 in 1988, 25 000 in 1990, 20 300 in 1998, and 26 400 in 2006. Population decline between 1985 and 1990 was consistent with anecdotal reports by others that die-offs of Snow Geese occurred in 1984, 1985 and 1989, and with our August 1989 fieldwork which found evidence of habitat degradation and malnourishment of young geese. In spite of limited food resources on Jenny Lind Island, the colony continued to exist in 2006 at near its 1990 and 1998 levels. Further studies there could provide insights for management of the overabundant mid-continent Snow Goose population and its arctic habitats.
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Lendzioch, Theodora, Jakub Langhammer, and Michal Jenicek. "Estimating Snow Depth and Leaf Area Index Based on UAV Digital Photogrammetry." Sensors 19, no. 5 (February 28, 2019): 1027. http://dx.doi.org/10.3390/s19051027.
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This study presents a novel approach in the application of Unmanned Aerial Vehicle (UAV) imaging for the conjoint assessment of the snow depth and winter leaf area index (LAI), a structural property of vegetation, affecting the snow accumulation and snowmelt. The snow depth estimation, based on a multi-temporal set of high-resolution digital surface models (DSMs) of snow-free and of snow-covered conditions, taken in a partially healthy to insect-induced Norway spruce forest and meadow coverage area within the Šumava National Park (Šumava NP) in the Czech Republic, was assessed over a winter season. The UAV-derived DSMs featured a resolution of 0.73–1.98 cm/pix. By subtracting the DSMs, the snow depth was determined and compared with manual snow probes taken at ground control point (GCP) positions, the root mean square error (RMSE) ranged between 0.08 m and 0.15 m. A comparative analysis of UAV-based snow depth with a denser network of arranged manual snow depth measurements yielded an RMSE between 0.16 m and 0.32 m. LAI assessment, crucial for correct interpretation of the snow depth distribution in forested areas, was based on downward-looking UAV images taken in the forest regime. To identify the canopy characteristics from downward-looking UAV images, the snow background was used instead of the sky fraction. Two conventional methods for the effective winter LAI retrieval, the LAI-2200 plant canopy analyzer, and digital hemispherical photography (DHP) were used as a reference. Apparent was the effect of canopy density and ground properties on the accuracy of DSMs assessment based on UAV imaging when compared to the field survey. The results of UAV-based LAI values provided estimates were comparable to values derived from the LAI-2200 plant canopy analyzer and DHP. Comparison with the conventional survey indicated that spring snow depth was overestimated, and spring LAI was underestimated by using UAV photogrammetry method. Since the snow depth and the LAI parameters are essential for snowpack studies, this combined method here will be of great value in the future to simplify snow depth and LAI assessment of snow dynamics.
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Hu, Jianbo, Xiaomin Wu, and Mingxing Dai. "Estimating the population size of migrating Tibetan antelopes Pantholops hodgsonii with unmanned aerial vehicles." Oryx 54, no. 1 (April 26, 2018): 101–9. http://dx.doi.org/10.1017/s0030605317001673.
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AbstractData on the distribution and population size of the Near Threatened Tibetan antelope Pantholops hodgsonii are necessary to protect this species. Ground-based count surveys are usually carried out from a long distance to avoid disturbing the sensitive animals, and on calving grounds or along migration routes where they are seasonally concentrated. This can result in underestimation of population sizes if terrain features obstruct the view and high concentrations of animals make estimating numbers difficult. Here we test the efficacy of unmanned aerial vehicles (UAVs) for gathering population data for the Tibetan antelope. We conducted the study south of a known calving ground, at the foot of Sewu Snow Mountain, in the Chang Tang National Nature Reserve, China. The UAV did not appear to disturb the animals and resulted in more accurate counts than ground-based observations. A total of 23,063 Tibetan antelopes were identified in twelve orthoimages derived from c. 4,000 aerial photographs. In the first flight area 7,671 females and 4,353 calves were identified (proportion of calves: 36.2%). In the second flight area 7,989 females and 3,050 calves were identified (proportion of calves: 27.6%). Two flights over the same area revealed the direction and speed of moving Tibetan antelope groups. Image resolution, which can be controlled with flight planning, was an important factor in determining the animals’ visibility in the photos. We found that UAV-based surveys outperformed ground-based surveys, and that larger UAVs are preferable for this application.
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Knizhnikov, Yu F., V. I. Kravtsova, and I. A. Labutina. "Cartographic Remote-Sensing Monitoring of Glaciological Systems (Example, Mount El‛ Brus, U.S.S.R.) (Abstract)." Annals of Glaciology 9 (1987): 247–48. http://dx.doi.org/10.3189/s0260305500000872.
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Remote-sensing methods in monitoring the glacierization of Mount EI‛ brus are used to produce base and dynamic maps, and to obtain quantitative information (dynamic indices) about the rate, intensity, and variations of the process. The monitoring system is divided, according to scope and territory covered, into small-scale for total glacierization and the periglacial zone, medium-scale for separate glaciers, and large-scale (detailed) for part of the glaciers or sectors of the adjoining slopes. The approximate relationship of even scales is 1 : 4.Small-scale monitoring remote-sensing systems are important for making maps showing the complex characteristics of the glaciological system. A series of maps was produced including geographical, those of high-altitude zones, slope and exposure angles, geological, glaciomorphological, climatic (temperature, precipitation, and winds), distribution of direct solar radiation, hydrological (source of streams), seats of avalanches, and landslides. All these data serve as a cartographical basis in monitoring the glacierization of Mount EI‛ brus. They are compiled from remotely sensed and Earth-based data.Current monitoring on a small scale includes observations of the conditions which determine the existence of the glacial system - this includes data on winter snowfall and the period of snow cover. These observations were obtained from meteorological and resource satellites, and from scanner data of medium and high resolution. Also important are observations of changes in the outline of glaciers, times of snowfall and character of the distribution of snow, and its redistribution due to avalanches and snowstorms. High-resolution space photographs, small-scale aerial photographs, and aerovisual observations provide the data for these observations. It has been determined that the area of the glaciers of Mount El‛ brus has been reduced by 1 % in the last 25 years, i.e. the rate of its deglacierization dropped sharply as compared to preceding decades.The role of quantitative information gains importance in the medium-scale level of monitoring. Topographical maps of separate glaciers compiled from aerial photographs or data from ground stereo-photogrammetric surveys constitute the base maps at this level. The main method used in monitoring were large-scale surveys from aircraft, perspective surveys from helicopters, and phototheodolite surveys. Multi-date surveys of the glaciers provide data about the changes in their outlines and height, the character of their relief, their moraines, the amount of snow accumulation and ablation in separate years, the surface rates of ice flow and their fluctuations. The techniques by which quantitative information is obtained about changes in the glaciers are derived from processing the data of multi-date surveys. The organization and techniques of phototheodolite surveys have been improved. A theory evolved for determining the surface-ice movement by stereo-photogrammetric means and the technique for it has also improved; algorithms and programs for machine processing of the data of multi-date surveys (ground and from aircraft) have been producedAt this level of monitoring, it has been found that the retreat rate of most glaciers has slowed down and several glaciers are now in equilibrium. Several glaciers became active at the beginning of the 1970s and 1980s; this was accompanied by an increase in their height and forward movement. For example, activation of Kyukyurtlyu Glacier has been recorded (higher surface and increasing flow rate) which has caused the glacier to move forward 100 m. Surveys at an interval of 2 years recorded the beginning of the process of retreat of this glacier.Detailed monitoring is used to detect the mechanism of the dynamic processes and to study it on local representative sectors. On a glacier it may take the form of annual surveys of its tongue, which makes it possible to observe the processes of formation of moraines and glacio-fluvial relief. Studies may also be made of the mechanism of the movement of avalanches and landslides, deducing their quantitative characteristics and appraising the results of avalanches and landslides. Multi-date surveys of sectors of the slopes provide information about processes in the periglacial zone. At this level, regularly repeated ground stereo-photogrammetric surveys are the main means of observation.Glaciological remote-sensing monitoring provides a wealth of data for theoretical development in the field of glaciology. It makes it possible to forecast and produce warnings about hazardous processes and phenomena.
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Knizhnikov, Yu F., V. I. Kravtsova, and I. A. Labutina. "Cartographic Remote-Sensing Monitoring of Glaciological Systems (Example, Mount El‛ Brus, U.S.S.R.) (Abstract)." Annals of Glaciology 9 (1987): 247–48. http://dx.doi.org/10.1017/s0260305500000872.
Full textAbstract:
Remote-sensing methods in monitoring the glacierization of Mount EI‛ brus are used to produce base and dynamic maps, and to obtain quantitative information (dynamic indices) about the rate, intensity, and variations of the process. The monitoring system is divided, according to scope and territory covered, into small-scale for total glacierization and the periglacial zone, medium-scale for separate glaciers, and large-scale (detailed) for part of the glaciers or sectors of the adjoining slopes. The approximate relationship of even scales is 1 : 4. Small-scale monitoring remote-sensing systems are important for making maps showing the complex characteristics of the glaciological system. A series of maps was produced including geographical, those of high-altitude zones, slope and exposure angles, geological, glaciomorphological, climatic (temperature, precipitation, and winds), distribution of direct solar radiation, hydrological (source of streams), seats of avalanches, and landslides. All these data serve as a cartographical basis in monitoring the glacierization of Mount EI‛ brus. They are compiled from remotely sensed and Earth-based data. Current monitoring on a small scale includes observations of the conditions which determine the existence of the glacial system - this includes data on winter snowfall and the period of snow cover. These observations were obtained from meteorological and resource satellites, and from scanner data of medium and high resolution. Also important are observations of changes in the outline of glaciers, times of snowfall and character of the distribution of snow, and its redistribution due to avalanches and snowstorms. High-resolution space photographs, small-scale aerial photographs, and aerovisual observations provide the data for these observations. It has been determined that the area of the glaciers of Mount El‛ brus has been reduced by 1 % in the last 25 years, i.e. the rate of its deglacierization dropped sharply as compared to preceding decades. The role of quantitative information gains importance in the medium-scale level of monitoring. Topographical maps of separate glaciers compiled from aerial photographs or data from ground stereo-photogrammetric surveys constitute the base maps at this level. The main method used in monitoring were large-scale surveys from aircraft, perspective surveys from helicopters, and phototheodolite surveys. Multi-date surveys of the glaciers provide data about the changes in their outlines and height, the character of their relief, their moraines, the amount of snow accumulation and ablation in separate years, the surface rates of ice flow and their fluctuations. The techniques by which quantitative information is obtained about changes in the glaciers are derived from processing the data of multi-date surveys. The organization and techniques of phototheodolite surveys have been improved. A theory evolved for determining the surface-ice movement by stereo-photogrammetric means and the technique for it has also improved; algorithms and programs for machine processing of the data of multi-date surveys (ground and from aircraft) have been produced At this level of monitoring, it has been found that the retreat rate of most glaciers has slowed down and several glaciers are now in equilibrium. Several glaciers became active at the beginning of the 1970s and 1980s; this was accompanied by an increase in their height and forward movement. For example, activation of Kyukyurtlyu Glacier has been recorded (higher surface and increasing flow rate) which has caused the glacier to move forward 100 m. Surveys at an interval of 2 years recorded the beginning of the process of retreat of this glacier. Detailed monitoring is used to detect the mechanism of the dynamic processes and to study it on local representative sectors. On a glacier it may take the form of annual surveys of its tongue, which makes it possible to observe the processes of formation of moraines and glacio-fluvial relief. Studies may also be made of the mechanism of the movement of avalanches and landslides, deducing their quantitative characteristics and appraising the results of avalanches and landslides. Multi-date surveys of sectors of the slopes provide information about processes in the periglacial zone. At this level, regularly repeated ground stereo-photogrammetric surveys are the main means of observation. Glaciological remote-sensing monitoring provides a wealth of data for theoretical development in the field of glaciology. It makes it possible to forecast and produce warnings about hazardous processes and phenomena.
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Babashkin, N. M., S. A. Kadnichanskiy, Yu I. Kuchinskiy, and S. S. Nekhin. "Choosing Aerial Photography Parametres For Modern Aerial Topographic Surveys." Geodesy and Cartography 870, no. 13 (December 31, 2012): 161–64. http://dx.doi.org/10.22389/0016-7126-2012-161-164.
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Burshtynska, Khrystyna, Andrzej Mazur, Maksym Halochkin, Yevhenii Shylo, and Iryna Zayats. "GEODESY, CARTOGRAPHY AND AERIAL PHOTOGRAPHY." GEODESY, CARTOGRAPHY AND AERIAL PHOTOGRAPHY 95,2022, no. 95 (June 28, 2022): 53–64. http://dx.doi.org/10.23939/istcgcap2022.95.053.
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The aim of the work is to investigate the accuracy of the DEM of nearshore areas using UAV material. One of the important issues in hydrological flood modelling is the high accuracy of the DEM. In the case of a complex relief type, which is associated with meandering riverbeds, it is proposed to use UAV surveys to create a DEM. Hydrological modelling involves the following main steps: creation of high precision DEMs, determination of Manning coefficients to account for the influence of the underlying surface and determination of water level changes based on the water level graph derived from observations at hydrometeorological stations. This research presents the construction of a high-precision DEM, based on a UAV survey. For high-precision modeling, the fundamental issue is the consideration of vegetation in the nearshore areas and the choice of the optimal time period for the survey. The aim of the study is to develop a methodology for the construction of a high-precision DEM from UAV data, investigate the possibilities of eliminating the influence of vegetation on point marks using software methods, determine planned channel shifts and compare the accuracy of DEM construction for surveys conducted in June 2017 and in November 2021. The section at the transition from the mountainous to marshy-hilly part of the Dniester River near the town of Stary Sambir, with complex morphometric and hydrological characteristics of the channel and banks at the site of the complex meandering of the river in a rugged ravine area was the study object of this work. Results. It was found that for 4 years between two surveys, the planned displacements of some points are up to 25-31 meters. A priori estimation of coordinates determination by points from the GNSS-receiver was carried out, the accuracy of point coordinates determination is 2-3 cm. The a priori estimate of the accuracy of determining the coordinates of points from the input survey data is: for plan coordinates - 4-6 cm for two survey periods, the error in determining the marks of points for different values of the baseline - 21-31 cm. It has been established, that the program methods of accounting of influence of high vegetation do not give the possibility of its full accounting, the average square error, in places of such vegetation makes 0,64 m. Therefore, it is necessary to carry out UAV survey in the leafless period of the year, early spring or late autumn. Scientific novelty consists in the study of the possibility of constructing a high-precision DEM for different types of vegetation from materials obtained from UAVs. The results can be used for hydrological modeling of river channels with complex hydromorphological characteristics.
Dissertations / Theses on the topic "Aerial photography in snow surveys"
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Grotefendt, Richard. "Accurate and cost-effective natural resource data from super large scale aerial photography /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/5454.
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Korpela, Ilkka. "Individual tree measurements by means of digital aerial photogrammetry." Helsinki : Finnish Forest Research Institute, Finnish Society of Forest Science, 2004. http://catalog.hathitrust.org/api/volumes/oclc/55872310.html.
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Knapp, Paul Aaron. "THE USE OF LARGE-SCALE AERIAL PHOTOGRAPHY FOR DETECTING CHANGES OF AN ARID RANGELAND IN SOUTHWESTERN ARIZONA." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/292059.
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Interpretation of large-scale color infrared and color aerial photography can be a labor and cost-effective means for inventorying and monitoring rangelands while maintaining accuracy. Ground measurements of vegetation cover at Organ Pipe Cactus National Monument were taken in 1975 and 1984. Large-scale (1:1200) color and color infrared aerial photo estimates were compared to these ground measurements through regression and correlation to check photo accuracy. Relationships between photo estimates and ground measurements of total vegetation and shrub cover were strong when using either film type. Color infrared photo estimates corresponded better with ground measurements for both tree cover and cactus cover than color photo estimates. Large-scale aerial photography is also useful for determining some of the causes of vegetation change. Evidence gathered from both sets of photos suggested that vegetation change at OPCNM was largely the result of domestic livestock removal and short-term climatic fluctuations.
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Bleier, Mary F. "Use of prior distributions from aerial photographs in forest inventory." Thesis, Virginia Tech, 1986. http://hdl.handle.net/10919/41543.
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Bayesian estimates of gross cubic- foot volume per acre were computed for four stand types (plantation pine, natural pine. hardwood. and mixed wood stands) using aerial photo volume tables as the prior information source. Aerial photographs provided a reliable source of information even though most photographs were nearly five years old.
For a given level of precision within a particular stand, Bayesian methods reduced the required field sample size up to 50% using all or half of the prior information available. Those priors which utilized a regression or a regression/topographic correction in the estimation of photo heights required less field information for the given precision level than those priors which used uncorrected or topographic corrected photo heights.
In order to obtain meaningful gains in sample size reduction corrections to the estimated photo heights
should be made. Although the uncorrected prior produced generally less biased estimates. the reduction in sample size was not as large as that observed using other prior types. Greater gains were attributed to the better accuracy of the prior distribution.
Although Bayesian methods are biased, it appeared that these methods tempered severely biased prior distributions. In the hardwood stand for example, the average bias present in the photo volume data amounted to -140%. After combining the prior with the field sample, the greatest average bias was -50%.
Bayesian methods performed better than the traditional estimation methods in terms of precision. In
a one to one comparison. the Bayes standard error was consistently less than its non-Bayes counterpart. The one exception to this trend was the regression prior from the hardwood stand. The poor performance of the prior was due to the weak height regression correction equation.
Modal priors utilized were not subject to the extreme input values for prior distribution development as
their conservative empirical prior counterparts were. Less overall variation was observed 1n the estimated values. Under the conditions for mode selection set forth in this project, modal priors provided another good source of prior information.Master of Science
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Metzler, Jacob W. "Use of Multi-temporal IKONOS and LANDSAT ETM+ Satellite Imagery to Determine Forest Stand Conditions in Northern Maine." Fogler Library, University of Maine, 2004. http://www.library.umaine.edu/theses/pdf/MetzlerJW2004.pdf.
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Holmström, Hampus. "Data acquisition for forestry planning by remote sensing based sample plot imputation /." Umeå : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2001. http://epsilon.slu.se/avh/2001/91-576-6086-7.pdf.
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Turton, Rachael Heather. "The impact of the radiation balance on snowmelt in a sparse deciduous birch forest." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/29567.
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The representation of high-latitude surface processes and quantifying surface-climate feedbacks are some of the most serious shortcomings of present day Arctic land surface modelling. The energy balance of seasonally snow-covered sparse deciduous forests at high latitudes is poorly understood and inaccurately represented within hydrological and climate models. Snow cover plays an important role in wintertime fluxes of energy, water and carbon, controlling the length of the active growing season and hence the overall carbon balance of Arctic ecosystems. Snow cover is non-uniform and spatially variable, as wind redistributes snow from areas of exposed open tundra to sheltered areas within the forest, where a deeper snowpack develops. Low solar zenith angles, coupled with sparse deciduous leafless trees, cast shadows across the snow surface. The spatial distribution of canopy gaps determines the timing of direct radiation which penetrates down through the canopy to the snow surface. The forest canopy also excludes incoming longwave radiation and yet also emits longwave radiation to the snow surface. Consequently the forest canopy plays a key role in the radiation balance of sparse forests. To improve our knowledge of these complex processes, meteorological and field observations were taken in an area of highly heterogeneous birch Betula pubescens ssp. czerepanovii forest in Abisko, Sweden during the spring of 2008 and 2009. Detailed measurements of short and longwave radiation above and below the canopy, hemispherical photographs, tree temperatures and snow surveys were conducted to quantify the radiation balance of the sparse deciduous forest. An array of below canopy pyranometers found the mean canopy transmissivity to be 74 % in 2008 and 76 % in 2009. Hemispherical photographs taken at the pyranometer locations analysed with Gap Light Analyzer (GLA) showed reasonable agreement with a mean canopy transmissivity of 75 % in 2008 and 74 % in 2009. The canopy transmissivity was found to be independent of the diffuse fraction of radiation as the canopy is very sparse. A series of survey grids and transects were established to scale up from the below canopy pyranometers to the landscape scale. Hemispherical photographs analysed with GLA showed the sparse forest canopy had a mean transmissivity of 78 % and a mean LAI of 0.25, whereas the open tundra had a mean transmissivity of 97 % and a mean LAI of < 0.01. Snow surveys showed the sparse forest snow depth to vary between 0.34 and 0.55 m, whereas the snow depth in the open tundra varied between 0.12 and 0.18 m. Observations of canopy temperatures showed a strong influence of incident shortwave radiation warming the tree branches to temperatures up to 15 °C warmer than ambient air temperature on the south facing sides of the trees, and up to 6 °C on the north facing sides of the trees. To reproduce the observed radiation balance, two canopy models (Homogenous and Clumped) were developed. The Homogeneous canopy model assumes a single tree tile with a uniform sparse canopy. The Clumped canopy model assumes a tree and a grass tile, where the tree tile is permanently in shade from the canopy and the grass tile receives all the incoming radiation. These canopy models identified the need for a parameter that accounts for the spatial and temporal variation of the shaded gaps within the sparse forest. JULES (Joint UK Land Environment Simulator) is the community land surface model used in the UK Hadley Centre GCM suite. Modifications of the land-surface interactions were included in JULES to represent the shaded gaps within the sparse deciduous forest. New parameterisations were developed for the time-varying sunlit fractions of the gap (flit), the sky-view fraction (fv), and the longwave radiation emitted from the canopy (LWtree). These model developments were informed by field observations of the forest canopy and evaluated against the below canopy short and longwave radiation observed data sets. The JULES Shaded gap model output showed a strong positive relationship with the observations of below canopy shortwave and longwave radiation. The JULES Shaded gap model improves the ratio of observed to modelled short and longwave radiation on sunny days compared to the JULES model. The JULES Shaded gap model reduces the time to snow melt by 2 to 4 days compared to the JULES model, making the model output more aligned with in-situ observational data. This shortening of the modelled snow-season directly impacts on the simulated carbon and water balance regionally and has wider relevance at the pan-Arctic scale. When JULES Shaded Gap was evaluated on the global scale, it improved the modelled snowmass across large areas of sparse forest in northern Canada, Scandinavia and Northern Russia with respect to GlobSnow. The performance of the land surface-snow-vegetation interactions of JULES was improved by using the Shaded gap to model the radiation balance of sparse forests in climate-sensitive Arctic regions. Furthermore these observational data can be used to develop and evaluate high latitude land-surface processes and biogeochemical feedbacks in other earth system models.
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Jodry, Réal. "La télédétection multibande aéroportée MEIS II et DAEDALUS MSS appliquée à la cartographie forestière de la station Simoncouche /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1996. http://theses.uqac.ca.
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Silva, Hugo Amancio Sales [UNESP]. "Dinâmica da paisagem na microbacia hidrográfica do rio Mojuí, oeste do estado do Pará." Universidade Estadual Paulista (UNESP), 2013. http://hdl.handle.net/11449/93827.
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000755428.pdf: 1772727 bytes, checksum: 25340537986dda5d7885dbce168e3429 (MD5)Atualmente, as questões conservacionistas têm sido discutidas com grande ênfase pela sociedade em geral, principalmente sobre a paisagem amazônica. Dentro desse contexto está a bacia hidrográfica do rio Mojuí, localizada nos municípios de Santarém e Belterra, no estado do Pará. Esta vem sofrendo constantes explorações dos seus recursos naturais, principalmente devido à conversão de áreas com florestas em áreas agrícolas, principalmente para cultivo da soja. O objetivo deste trabalho foi caracterizar, mapear e quantificar, em escala de semi detalhe, as áreas das classes de cobertura vegetal e uso da terr0a no período de 11 anos, com o uso de imagens LANDSAT, órbita/ pontos 227/62, bandas TM 3, 4 e 5, referentes aos anos de 1999, 2005 e 2010, a dinâmica da paisagem na região. A seleção das imagens foi determinada considerando-se o período climático semelhante, com as mesmas circunstâncias de iluminação e cobertura de nuvens. Os limites da bacia foram estabelecidos pelos divisores topográficos que formam a área que drena para um ponto específico. Baseando-se nos dados obtidos no levantamento de campo e com o suporte da fotointerpretação das cenas dos sensores nos anos estabelecidos pela pesquisa, foi definida uma legenda temática para classificação da vegetação e uso do solo na bacia, sendo identificadas sete formas de coberturas vegetais e uso do solo na área de abrangência da bacia. Foram estabelecidas as seguintes classes de cobertura do solo...
Currently, conservation issues have been discussed with great emphasis by society in general, especially on the Amazon landscape. Within this context is Mojuí River watershed, located in the cities of Santarém and Belterra, in the state of Pará This comes under constant exploration of natural resources, mainly due to conversion of forest areas into agricultural areas, mainly for soybeans cultivation. The aim of this study was to characterize and quantify mapping , semi -scale detail , the areas of vegetation cover classes and land use in the period of 11 years as use of LANDSAT , orbit / points 227/62 , TM bands 3 , 4:05 , for the years 1999 , 2005 and 4 2010 , the landscape dynamics in the region . The selection of images was determined considering the similar climatic period, with the same lighting conditions and cloud cover. The boundaries of the basin were established by dividers that form the topographic area that drains to a specific point. Based on the data obtained in the field survey and with the support of photointerpretation the scenes of the sensors in the years established by research, has defined a thematic caption for vegetation classification and land use in the basin, identified seven forms of vegetation and land use in the catchment area of the basin. We defined the following classes of land cover: Rain Forest , Secondary Succession , Alluvial Rain Forest , Grassland , Degraded Grassland , Agriculture and Water Bodies . During the research it was observed that the Moju river watershed has lost 221.73 km² of natural vegetation cover (dense ombrophilous forest, alluvial dense ombrophilous forest). Until 1999 the dense ombrophilous forest class was the largest present at the watershed, however from 2005 on the agricultural class became the largest at that location, with an increase of approximately 518.11% of the initial research area. When the results were analyzed more ...
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Silva, Hugo Amancio Sales 1988. "Dinâmica da paisagem na microbacia hidrográfica do rio Mojuí, oeste do estado do Pará /." Botucatu:, 2013. http://hdl.handle.net/11449/93827.
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Orientador: Sérgio CamposBanca: Ellen Fitipaldi Brasilio Carrega
Banca: Maria Nazaré Martins Maciel
Resumo: Atualmente, as questões conservacionistas têm sido discutidas com grande ênfase pela sociedade em geral, principalmente sobre a paisagem amazônica. Dentro desse contexto está a bacia hidrográfica do rio Mojuí, localizada nos municípios de Santarém e Belterra, no estado do Pará. Esta vem sofrendo constantes explorações dos seus recursos naturais, principalmente devido à conversão de áreas com florestas em áreas agrícolas, principalmente para cultivo da soja. O objetivo deste trabalho foi caracterizar, mapear e quantificar, em escala de semi detalhe, as áreas das classes de cobertura vegetal e uso da terr0a no período de 11 anos, com o uso de imagens LANDSAT, órbita/ pontos 227/62, bandas TM 3, 4 e 5, referentes aos anos de 1999, 2005 e 2010, a dinâmica da paisagem na região. A seleção das imagens foi determinada considerando-se o período climático semelhante, com as mesmas circunstâncias de iluminação e cobertura de nuvens. Os limites da bacia foram estabelecidos pelos divisores topográficos que formam a área que drena para um ponto específico. Baseando-se nos dados obtidos no levantamento de campo e com o suporte da fotointerpretação das cenas dos sensores nos anos estabelecidos pela pesquisa, foi definida uma legenda temática para classificação da vegetação e uso do solo na bacia, sendo identificadas sete formas de coberturas vegetais e uso do solo na área de abrangência da bacia. Foram estabelecidas as seguintes classes de cobertura do solo ...
Abstract: Currently, conservation issues have been discussed with great emphasis by society in general, especially on the Amazon landscape. Within this context is Mojuí River watershed, located in the cities of Santarém and Belterra, in the state of Pará This comes under constant exploration of natural resources, mainly due to conversion of forest areas into agricultural areas, mainly for soybeans cultivation. The aim of this study was to characterize and quantify mapping , semi -scale detail , the areas of vegetation cover classes and land use in the period of 11 years as use of LANDSAT , orbit / points 227/62 , TM bands 3 , 4:05 , for the years 1999 , 2005 and 4 2010 , the landscape dynamics in the region . The selection of images was determined considering the similar climatic period, with the same lighting conditions and cloud cover. The boundaries of the basin were established by dividers that form the topographic area that drains to a specific point. Based on the data obtained in the field survey and with the support of photointerpretation the scenes of the sensors in the years established by research, has defined a thematic caption for vegetation classification and land use in the basin, identified seven forms of vegetation and land use in the catchment area of the basin. We defined the following classes of land cover: Rain Forest , Secondary Succession , Alluvial Rain Forest , Grassland , Degraded Grassland , Agriculture and Water Bodies . During the research it was observed that the Moju river watershed has lost 221.73 km² of natural vegetation cover (dense ombrophilous forest, alluvial dense ombrophilous forest). Until 1999 the dense ombrophilous forest class was the largest present at the watershed, however from 2005 on the agricultural class became the largest at that location, with an increase of approximately 518.11% of the initial research area. When the results were analyzed more ...
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Books on the topic "Aerial photography in snow surveys"
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Scurlock, John. Snow & spire: Flights to winter in the North Cascades Range. Silt, CO: Wolverine Publishing, 2011.
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Farrell, Susan. Evaluation of color infrared aerial surveys of wastewater soil absorption systems. Cincinnati, OH: U.S. Environmental Protection Agency, Water Engineering Research Laboratory, 1985.
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Johnson, Scott W. Fixed-wing aerial photography surveys of plastic debris on an Alaskan beach. [Seattle, Wash.]: Alaska Fisheries Science Center, National Marine Fisheries Service, U.S. Dept. of Commerce, 1992.
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Johnson, Scott W. Fixed-wing aerial photography surveys of plastic debris on an Alaskan beach. [Seattle, Wash.]: Alaska Fisheries Science Center, National Marine Fisheries Service, U.S. Dept. of Commerce, 1992.
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Tianjin shi nong ye qu hua wei yuan hui. Tu di zi yuan diao cha zhuan ye zu and Tianjin shi nong ye qu hua wei yuan hui. Ban gong shi, eds. Cai se hong wai hang kong yao gan ji shu zai Tianjin shi tu di zi yuan diao cha zhong di ying yong. Beijing: Ce hui chu ban she, 1985.
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Korpela, Ilkka. Individual tree measurements by means of digital aerial photogrammetry. Helsinki: Finnish Society of Forest Science ; Finnish Forest Research Institute, 2004.
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Trovillion, Ned. Natural resources survey of the Cypress, Illinois quadrangle: A partial inventory of the soil, water, plant & human resources of the area. Champaign, Ill.]: USDA, Natural Resources Conservation Service, 1999.
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Teti, Patrick Anthony. Novel aerial photography as an aid to sampling secondary structure in pine stands. Victoria, B.C: Pacific Forestry Centre, 2009.
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Ripple, William J. Assessing elk trail and wallow impacts in Mount Rainier National Park: Final report. Corvallis, Or: Environmental Remote Sensing Applications Laboratory - ERSAL, Oregon State University, College of Forestry, 1988.
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Ripple, William J. Assessing elk trail and wallow impacts in Mount Rainier National Park: First year activities : final report for period August 1985 through July 1986. [Corvallis, Or: Environmental Remote Sensing Applications Laboratory (ERSAL), Oregon State University, 1986.
Find full textBook chapters on the topic "Aerial photography in snow surveys"
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"Benthic Habitats and the Effects of Fishing." In Benthic Habitats and the Effects of Fishing, edited by T. D. Clayton, J. C. Brock, and C. W. Wright. American Fisheries Society, 2005. http://dx.doi.org/10.47886/9781888569605.ch21.
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For ecologists and managers of seagrass systems, the spatial context provided by remote sensing has proven to be an important complement to in situ assessments and measurements. The spatial extent of seagrass beds has been mapped most commonly with conventional aerial photography. Additional remote mapping and monitoring tools applied to seagrass studies include optical satellite sensors, airborne multispectral scanners, underwater video cameras, and towed sonar systems. An additional tool that shows much promise is airborne, waveform-resolving lidar (light detection and ranging). Now used routinely for high-resolution bathymetric and topographic surveys, lidar systems operate by emitting a laser pulse, then measuring its two-way travel time from the plane to reflecting surface(s) below, then back to the detector co-located with the laser transmitter. Using a novel, waveformresolving lidar system developed at NASA — the Experimental Advanced Airborne Research Lidar (EAARL) — we are investigating the possibility of using the additional information contained in the returned laser pulse (waveform) for the purposes of benthic habitat mapping. Preliminary analyses indicate that seagrass beds can potentially be delineated on the basis of apparent bathymetry, returned waveform shape and amplitude, and (horizontal) spatial texture. A complete set of georectified digital camera imagery is also collected during each EAARL overflight and can aid in mapping efforts. Illustrative examples are shown from seagrass beds in the turbid waters of Tampa Bay and the relatively clear waters of the Florida Keys.
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Skrobala, Viktor, and Sofiya Marutyak. "PECULIARITIES OF THE TERRITORY OF THE CITY OF LVIV (UKRAINE) AND THEIR INFLUENCE ON THE HYDROLOGICAL REGIME AND EROSION PROCESSES." In European vector of development of the modern scientific researches. Publishing House “Baltija Publishing”, 2021. http://dx.doi.org/10.30525/978-9934-26-077-3-28.
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The object of research is the territory of the city of Lviv (Ukraine). Lviv (geographical coordinates: 49N50, 24E00) is the largest city in Western Ukraine, with a population of over 720,000 inhabitants. The city is located in the western part of the Volyn-Podilska Upland, on the line of the Main European Ridge of the Baltic and Black Sea basins. Subject of research is relief parameters (maximum, average and minimum heights, vertical dismemberment and steepness of the surface) and land use characteristics (building intensity, phytocenotic cover). The purpose of research is to study the features of the territory of Lviv from the standpoint of influence on the hydrological regime and erosion processes. Methodology. Peculiarities of the territory of Lviv were studied by processing topographic maps using aerial photography materials and route surveys. Morphometric analysis of the relief was performed on topographic maps of scale 1: 10000 by dividing the map into elementary squares with an area of 0.25 km2. The research covers an area of 100.25 km2 (401 elementary squares). Within the elementary squares, the maximum, average and minimum heights of the territory, the depth of local erosion bases, the average surface steepness, the intensity and nature of construction, and the features of vegetation were determined. Results. The territory of Lviv is characterized by a variety of relief conditions and related nature of surface use. On the basis of morphometric maps of maximum and minimum heights, vertical dismemberment and steepness of the surface, we can distinguish the flat peripheral part of the city and the middle band of elevations. The asymmetry of the territory of Lviv in relation to the watershed causes various potential dangers of erosion processes and related unproductive moisture losses. The intensity of construction increases from the periphery to the center, with the exception of modern multi-storey buildings of the Sykhiv massif and industrial areas in the western part of the city. Low specific weight of waterproof coatings is characterized by the eastern and northern parts of the city with a complex relief. The largest amount of greenery is concentrated in the eastern part of the city (Vysokyi Zamok Park, Shevchenkivskyi grove, Pohulyanka Forest Park, Lychakiv), where surfaces with maximum relative heights predominate. The great variety of the underlying surface on the territory of Lviv causes different conditions for the formation of surface runoff and associated unproductive moisture consumption. The high potential danger of erosion processes is primarily noted by the structural-denudation level of Roztochia, which is characterized by the highest values of surface steepness. Complex relief conditions, intensive anthropogenic impact determine the need for anti-erosion organization of the city and measures aimed at optimizing hydrological processes. Scientific novelty. One of the criteria that characterizes the degree of landscape transformation within the city is the intensity of construction, which is determined by the proportion of watertight areas in the overall balance of the territory. Peculiarities of spatial arrangement of elementary plots with different intensity of construction in combination with relief parameters and land use scheme are determined. Practical significance. Knowing the parameters of the terrain and the peculiarities of land use, it is possible to determine the potential intensity of erosion processes in the territory of Lviv, to assess the level of anthropogenic changes in the hydrological regime.
Conference papers on the topic "Aerial photography in snow surveys"
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Goldade, Bria, Benjamin J. Laabs, and Stephanie S. Day. "TRACKING THE EVOLUTION OF SEASONAL PRAIRIE SNOW IN EASTERN NORTH DAKOTA WITH UAS-BASED REPEAT AERIAL PHOTOGRAPHY." In 54th Annual GSA North-Central Section Meeting - 2020. Geological Society of America, 2020. http://dx.doi.org/10.1130/abs/2020nc-347974.
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Grigoriev, Gleb, Vladimir Gulin, Alexei Nikitin, Nikita Sivoy, Eugene Bondarev, Marat Islamuratov, Oksana Zakharova, Igor Karpov, Evgenii Liubimov, and Vladislav Votsalevskiy. "Integrated Droneborne Geophysics Application as a Tool for Exploration Optimization. Case Studies." In SPE Annual Technical Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/206250-ms.
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Abstract Unmanned aerial vehicles (UAV) have a great potential for geological exploration optimization at all stages. This study considers UAV implementation at different exploration stage. Integrated approach using unmanned aerial systems shows great effectiveness based on the completed surveys. Low-depth electrical exploration using the shallow electrical exploration method is one of the possible UAVs technologies with great potential. In this study there are several cases describing main field data acquisition, models and cross-sections processing. Unmanned aerial systems are applicable at all stages of the oil and gas value chain and are already an integral part of oil&gas production process. Now there are more than 70 unmanned aerial systems application scenarios. The main advantages of drones are that the use of this operational data collection tool allows: – to reduce the duration of collecting geospatial data by 70%, and the cost by 3 times; – make the best decisions quickly; – to realize additional potential for increasing efficiency (application at all stages of the production chain) – increase the production processes safety level The most promising and actively developing areas of technology application are: Geophysical surveys at different stages of geological exploration. Drones have great potential for application in non-seismic exploration methods in the early stages of geological exploration. In addition, UAV surveys are suitable for planning geological exploration and working out the conceptual arrangement of the terrain. The presence of an accurate digital elevation model at the start of work of the project team makes it possible to remove a number of uncertainties and questions about conducting field work on seismic exploration, the placement of infrastructure and corridor communications. Objective control of the capital construction progress. Another important area of drones application is aerial photography at all stages of capital construction. With the help of UAVs, it is possible to control such parameters as the status and quality of construction and installation works, equipment of contractors, compliance with safety and environmental standards, and others. To do this, the unmanned vehicle flies around the object with a given regularity, filming it from different angles. After aerial photography, special software stitches the results into photogrammetric products (digital terrain model, orthophotomaps, 3D models) with an accuracy of 4–6 centimeters. On the constructed models, you can calculate the dynamics by one or another parameter. Operational fieldwork and intrastructure monitoring. At the same time, one of the key goals of technology application is the creation of a network of autonomous stations with drones at all assets for remote control of the company's production processes. The first step in this direction was the joint pilot testing of an automated take-off and landing station with an unmanned aerial vehicle of a multi-rotor type. The use of the station will reduce the time and cost of collecting data on capital construction and infrastructure. Project teams will be able to react faster to changes. An automated take-off and landing station allows the use of unmanned aerial vehicles without human intervention. The drone can independently take off, perform the necessary operations, land and recharge. Thus, flight operations and data collection can be performed remotely without the constant presence of a specialist on site.
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Beckstead, Gary R. E., and Drum S. Cavers. "Stream Dynamics at Pipeline River Crossings." In 1996 1st International Pipeline Conference. American Society of Mechanical Engineers, 1996. http://dx.doi.org/10.1115/ipc1996-1943.
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Pipeline crossings of streams, whether large or small, must consider the ability of the stream channel to scour its bed and erode its banks. Case studies are presented to illustrate the kinds of dynamic environments which must be considered in designing pipeline stream crossings. These characteristics may be determined through the use of comparative historical aerial photography and site photographs and surveys. The case studies presented as examples in this paper include gullies, bedrock-lined channels, entrenched meandering streams, multi-channel wandering streams, degrading channels, alluvial fans, and major channels affected by regulation and man-made structures. Natural hazards such as debris jams and beaver dams are also discussed. For each case study, the characteristics of the channels are described, the design approach discussed and site-specific constraints presented which affected the final design.
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Bustinza, Juan A., Ricardo J. Rocca, Marcelo E. Zeballos, and Roberto E. Terzariol. "Rerouting of a Pipeline due to Landslide Reactivation in an Andean Valley." In ASME 2013 International Pipeline Geotechnical Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/ipg2013-1960.
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The bi-national pipeline Loma de la Lata (Argentina)-Talcahuano (Chile) belonging to Gas del Pacifico, crosses the Andes at Latitude 37.1° South (Buta Mallin pass), following the Lileo river valley. In the region, there are large ancient landslides within an area of about 50 km2, which have been attributed to Holocene glaciations and seismic activity. In the winter of 2005, when snow limited the access to the area, it was found a pressure loss, that later was attributed to a landslide in a sector of the south bank of the valley. The adiabatic expansion generated a considerable volume of frozen soil around the pipe. The following summer it was studied the characteristics of the sliding and analyzed different solutions of the affected section. The geotechnical study showed details of the slipped area and its relationships with ancient landslides. It was found by comparative analysis of aerial photographs that an old slide about 1 km3 was not fully reactivated. The general morphology has remained unchanged at least in the last 50 years, when the oldest aerial photography was taken. As additional verification, it was found that a small set of cascading ponds located in the slipped mass, has remained stable at that time, bearing the influence of the great 1960 Mw = 9.6 Valdivia earthquake. It was identified tension cracks delimiting the slipped area that was a modest portion of the historical landslide. Geotechnical parameters were estimated by back analysis of the land involved and it could establish a model for sliding mass process. A general analysis of long-term stability took into account the influence of distant earthquakes such as the subduction zone, which has a recurrence of about 100 years and other local seismic sources. Prior to define the most appropriate solution, a 250 meters long trench was dug preventively releasing the pipeline from the terrain to avoid new deformations. Among the solutions considered were the construction of an absorption system with movement monitoring, or the relocation of the trace on the opposite bank of the river. It was decided to adopt the latter solution due to the difficulty of ensuring the stability of the terrain and the inaccessibility during the winter. It implied an additional river crossing and consequently, the need to monitor the stability of the channel to the river erosion.
Reports on the topic "Aerial photography in snow surveys"
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Provencher, L., and J. M. Dubois. Interpretation guide of natural geographic features from ETM+ Landsat imagery and aerial photography: permanent snow and ice. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 2005. http://dx.doi.org/10.4095/314957.
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Kopp, Gregory A., David Sills, Emilio S. Hong, and Joanne Kennell. Northern Tornadoes Project. Northern Tornadoes Flyover Project: Summary Technical Report of the Year 1 Pilot Study. Western Libraries, Western University, January 2018. http://dx.doi.org/10.5206/ntpr181.
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12 January 2018 The objectives of the Year 1 Pilot Study were to (i) develop a methodology for determining tornado occurrence in Northern Ontario, and (ii) obtain research quality data for at least one event. Because of the isolation of many regions, the approach assumed the use of radar data analysis combined with aerial surveys. These objectives were achieved. Aerial surveys were conducted for a total of seven events in Ontario and southern Quebec and 15 confirmed or probable tornadoes identified. Archival geo-tagged imagery was obtained for six of these events. Ten confirmed or probable tornadoes were identified in Ontario, five of which were not in the OSPC database. In addition, 5 tornadoes were confirmed in Quebec. For the 2017 season, the OSPC had a list of 10 verified tornadoes, as of December 21, 2017. The pilot project raises this number to 15. In total, 4 EF2 tornadoes and 1 EF3 tornado were identified via aerial photography. The remainder were EF1 or EF0. UPDATE – 23 April 2018 Based on the analysis of newly available Planet.com high-resolution satellite imagery and related tools, several events were reassessed and a number of additional tornadoes were discovered. Overall, an additional three tornadoes were added to 2017 count. The updated events are listed in a revised 2017 summary table appended at the end of this document.