Статті в журналах з теми "Topographic site effect"
Щоб переглянути інші типи публікацій з цієї теми, перейдіть за посиланням: Topographic site effect.
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-50 статей у журналах для дослідження на тему "Topographic site effect".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте статті в журналах для різних дисциплін та оформлюйте правильно вашу бібліографію.
1
Ashford, Scott A., Nicholas Sitar, John Lysmer, and Nan Deng. "Topographic effects on the seismic response of steep slopes." Bulletin of the Seismological Society of America 87, no. 3 (June 1, 1997): 701–9. http://dx.doi.org/10.1785/bssa0870030701.
Анотація:
Abstract A frequency-domain parametric study using generalized consistent transmitting boundaries has been performed to evaluate the significance of topographic effects on the seismic response of steep slopes. The results show that the peak amplification of motion at the crest of a slope occurs at a normalized frequency H/λ = 0.2, where H is the slope height and λ is the wavelength of the motion. The importance of the natural site frequency is illustrated by the analysis of a stepped layer over a half-space. It was found that the natural frequency of the region behind the crest can dominate the response, relative to the topographic effect, for the conditions studied. Moreover, the effect of topography can be handled separately from the amplification due to the natural frequency of the deposit behind the crest of the slope. This concept of separating the amplification caused by topography from that caused by the natural frequency is advantageous to the development of a simplified method to estimate topographic effects.
2
Veeraraghavan, Swetha, Justin L. Coleman, and Jacobo Bielak. "Simulation of site and topographic effects on ground motion in Los Alamos, NM mesas." Geophysical Journal International 220, no. 3 (December 12, 2019): 1504–20. http://dx.doi.org/10.1093/gji/ggz448.
Анотація:
SUMMARY Mesas, which consist of an elevated area of land with a flat top and steep cliffs at the sides, are one of the common geological formations present in the Los Alamos region. Previous research has shown that geological formations such as sedimentary canyons can amplify soil response during earthquakes. There have also been parametric studies to understand the response of an idealized and isolated mountain/canyon under inclined plane waves. In this study, a 2-D linear anelastic soil domain, with topography modelled after the Los Alamos region with many mesas and canyons, is considered to understand site-specific topographic effects in the presence of non-isolated topographical features. Various earthquake sources configurations ranging from point sources to finite faults with varying rupture length, dip angles and spatial slip distributions are considered. To isolate the effect of topography, three other soil domains—a homogeneous half-space, homogeneous half-space with mesas and canyons, and a computational domain with just the soil properties from the Los Alamos region on a flat soil domain is also considered. 2-D site-response analyses of these soil domains under earthquake excitation show that the free-field response of the soil can be amplified or de-amplified depending on the topography of the region and the location of the station relative to the fault. These studies also show that even relatively small mesas with height less than 100 m can significantly amplify the response (by a factor of 2 or more), which differ from the much smaller amplification factors (≤1.2) specified by standard building codes such as Eurocode-8 (2000) for topographical features with a similar slope. De-amplifications are also fairly common, especially close to the canyons. The results from this study agree qualitatively with those from the ambient vibration study conducted by Stolte et al. on a mesa from the Los Alamos region. Thus, such site-specific studies provide important insights into the variability of the topographic amplification factors within a region of interest. Such knowledge is important in the design of safety-related critical infrastructure located within that region.
3
Fan, Gang, Fei Cheng Liu, Rui Zhi Wen, and Jian Jing Zhang. "Research of Earthquake Topographic Effect." Applied Mechanics and Materials 501-504 (January 2014): 1566–72. http://dx.doi.org/10.4028/www.scientific.net/amm.501-504.1566.
Анотація:
In this paper, the influence of topography on ground-motion intensity parameter, response spectrum, peak ground acceleration (PGA) and the ratio of response spectrum were studied based on the measured data from large scale shaking table test and observation stations in XiShan park for Wenchuan earthquake. The results show that: in the EW direction, the height do not affect PGD, SMA, VSI and HI, while V_RMS decreases slightly at the middle of the slope, the other intensity parameters increase with the increase of height. In the EW direction, the height has no influence on PGD, V_RMS, SMA, SED, A_RMS, VSI and HI, while other parameters increase as the height increase. In the UD direction, the height has no influence on SMV, PGD, V_RMS, SMV, ASI, VSI and HI, while A_RMS decreases at the middle of the slope, and the other intensity parameters increase as the height increase. Ignoring the local topographic effect, the amplitude of response spectrum increases with the increase of height at the part of short period (T1s), the part of long period (T>1s) is not effected by height. The ground motion will be amplified by local canyon topography, and the influence of local topography is larger than height. The research carried out in paper will deepen the understanding of topographic effect. 0 Preface Earthquake often cause extensive rock slope failures and various types of mass movement in mountainous areas. Catastrophic seismically-induced landsides are among the Earths most powerful geomorphic events, causing sudden and dramatic changes to the landscape, creating high risks to both infrastructures and life, and reputedly causing large economic losses. Seismic waves interacting with topography lead to amplification and deamplification of resulting ground motion. In the western mountainous areas of China, the topography is extremely complex, many large hydropower stations were built in narrow valleys and many large bridge piers were built on valleys and hillsides, so the research about topographic effect is essential to the seismic design of large-scale projects. Topographic effect is always analyzed with following three approaches: motion observation, analytical analysis and numerical analysis. The motion observation is regarded as the most efficient and common approach [1]. Long time ago, the researchers found that the intensity of buildings built on local convex topography was abnormal, in order to reveal the reason of abnormal intensity, array stations were constructed specially to study the effect of local convex topography on ground motion, some observation data were obtained. Some L-7 type strong motion seismographs were installed at the crest and foot of Kagel and Josephine mountain, California, by Lawrence L. Davis and Lewis R. West, the 2 array stations had recorded several aftershocks record of SanFernando earthquake, which occurred on February 9, 1971[. Some L-7 type strong motion seismographs were also installed at the crest, hillside and foot of Butler mountain, Nevada, to record blasting vibration in test site. In 1984, in order to observe the topographic effect of rocky mountain, 8 observation stations were installed by B. E. Tucker, five stations were placed in two tunnels with different elevation, the other three were placed at the surface of outcropped rock [. After the 1989 Loma prieta earthquake, dense array stations of seven digital and triaxial seismographs were mounted on Robinwood Ridge, which is located at 7.3km northwest of epicenter, to analyze the reason of seriously damage on high-strength buildings and cracks of ground [4,. In China, a earthquake observation station was constructed in XiShan Park, ZiGong, SiChuan province in 2007, which recorded the main acceleration time history of WenChuan earthquake perfectly, the establishment of this station offers valuable data to researchers for exploring the local topographic effect on ground motion [6]. In 2010, a research was conducted by Wang Haiyun and Xie Lili with traditional spectral ratio method, some significant conclusions were drawn about the influence of topographic effect on ground motion [7]. In this paper, WenChuan seismic wave was analyzed in time and frequency domain to explore the influence of topography on ground-motion intensity parameters, response spectrum and spectrum characteristic.
4
Hamilton, Gordon S. "Topographic control of regional accumulation rate variability at South Pole and implications for ice-core interpretation." Annals of Glaciology 39 (2004): 214–18. http://dx.doi.org/10.3189/172756404781814050.
Анотація:
AbstractSnow-accumulation rates are known to be sensitive to local changes in ice-sheet surface slope because of the effect of katabatic winds. These topographic effects can be preserved in ice cores that are collected at non-ice-divide locations. The trajectory of an ice-core site at South Pole is reconstructed using measurements of ice-sheet motion to show that snow was probably deposited at places of different surface slope during the past 1000 years. Recent accumulation rates, derived from shallow firn cores, vary along this trajectory according to surface topography, so that on a relatively steep flank mean annual accumulation is ∼18% smaller than on a nearby topographic depression. These modern accumulation rates are used to reinterpret the cause of accumulation rate variability with time in the long ice-core record as an ice-dynamics effect and not a climate-change signal. The results highlight the importance of conducting ancillary ice-dynamics measurements as part of ice-coring programs so that topographic effects can be deconvolved from potential climate signals.
5
Katebi, Mohammad, Behrouz Gatmiri, and Pooneh Maghoul. "A Numerical Study on the Seismic Site Response of Rocky Valleys with Irregular Topographic Conditions." Journal of Multiscale Modelling 10, no. 04 (December 2019): 1850011. http://dx.doi.org/10.1142/s1756973718500117.
Анотація:
This paper investigates topographic effects of rocky valleys with irregular topographic conditions subjected to vertically propagating SV waves of Ricker type using a boundary element code. Valleys with two intersecting slopes, [Formula: see text] and [Formula: see text], are modelled in order to study their combined effects on ground motion. Presented in the form of pseudo-acceleration response spectra, results of this work can be extended to similar topographies. The main findings are: (i) [Formula: see text] (the first slope angle) and [Formula: see text] (L is the half width of the valley and [Formula: see text] is its corresponding height) have amplifying effects, and [Formula: see text] (the second slope angle) has de-amplifying effects on the site response. (ii) [Formula: see text] has a straight effect on intensifying the effects of both [Formula: see text] and [Formula: see text]. (iii) The combined effects of slope angles have been found to be important in modifying the response so more than a single slope should be considered for seismic analysis. (iv) Engineers should use the maximum amplification of 2.4 in case of valleys with the first and second slope angles below [Formula: see text].
6
Ashford, Scott A., and Nicholas Sitar. "Analysis of topographic amplification of inclined shear waves in a steep coastal bluff." Bulletin of the Seismological Society of America 87, no. 3 (June 1, 1997): 692–700. http://dx.doi.org/10.1785/bssa0870030692.
Анотація:
Abstract The effect of inclined shear waves on the seismic response of a steep bluff is analyzed using generalized consistent transmitting boundaries. The results of the frequency-domain analysis of a stepped half-space subjected to incident shear waves inclined from 0° to 30° show that the motion at the crest of the slope is amplified for waves traveling into the slope and attenuated for waves traveling away from the slope, as compared to the motion in the free field behind the crest of the slope. This amplification can be as much as twice that observed for vertically propagating waves. A time-domain analysis of bluffs at Seacliff State Beach, California, is used to estimate the effect of topography using realistic conditions, taking into account wave inclination and site effects. The analysis of the site shows that although topographic amplification does in fact nearly double the amplitude of the motion in some cases, this amplification is offset by reduced site amplification and by wave splitting at material interfaces. Thus, the actual peak acceleration occurring at the crest of the slope changes little with incident angle as compared to the amplification of the free-field motion and actually decreases in many cases. Though a more general study is recommended, these results suggest that wave orientation and inclination substantially increase topographic amplification; however, it may be adequate to only account for vertically propagating waves for site response and slope stability analyses where only the magnitude of acceleration is considered.
7
Kingdon, Robert, Petr Vaníček, and Marcelo Santos. "Modeling topographical density for geoid determinationThis article is one of a series of papers published in this Special Issue on the theme GEODESY." Canadian Journal of Earth Sciences 46, no. 8 (August 2009): 571–85. http://dx.doi.org/10.1139/e09-018.
Анотація:
In geoid computation, effects of real three-dimensional topographic masses on the Earth’s gravity field must be accurately quantified and, in the Stokes–Helmert scheme, replaced with effects of those masses condensed on the geoid. The most comprehensive modern schemes for evaluation of topographical effects account for terrain effects, use a spherical model of topography, and incorporate two-dimensionally varying models of topographical mass density. In this contribution, we employ a three-dimensionally varying model of topographical density. We use Newton’s integration to determine the direct topographical effect (DTE) on gravity and primary indirect topographical effect (PITE) on gravity potential. Lastly, we apply Stokes’ integration to calculate the DTE, PITE, and secondary indirect topographical effect (SITE) on geoidal height. We focus here on validation of our results and demonstration of our software’s capabilities. We present results for the simple geometrical shape of a disc under various rotations and for the anomalous density of lake waters. Effects on geoidal height for these simulations reach centimetre level, up to 2.2 cm in magnitude. For a simulation of the effects of neglected mass anomalies of the lakes, we find results reaching 0.8 cm in magnitude. We examine the behavior of our results as calculated using various step sizes for numerical integration and by comparing numerical results with analytical results for the specific case of a disc. These results suggest that the maximum percent error of our results is about 23.5% for the DTE on gravity and 7.6% for the PITE on gravity potential.
8
Dharmadasa, Vasana, Christophe Kinnard, and Michel Baraër. "Topographic and vegetation controls of the spatial distribution of snow depth in agro-forested environments by UAV lidar." Cryosphere 17, no. 3 (March 14, 2023): 1225–46. http://dx.doi.org/10.5194/tc-17-1225-2023.
Анотація:
Abstract. Accurate knowledge of snow depth distributions in forested regions is crucial for applications in hydrology and ecology. In such a context, understanding and assessing the effect of vegetation and topographic conditions on snow depth variability is required. In this study, the spatial distribution of snow depth in two agro-forested sites and one coniferous site in eastern Canada was analyzed for topographic and vegetation effects on snow accumulation. Spatially distributed snow depths were derived by unmanned aerial vehicle light detection and ranging (UAV lidar) surveys conducted in 2019 and 2020. Distinct patterns of snow accumulation and erosion in open areas (fields) versus adjacent forested areas were observed in lidar-derived snow depth maps at all sites. Omnidirectional semi-variogram analysis of snow depths showed the existence of a scale break distance of less than 10 m in the forested area at all three sites, whereas open areas showed comparatively larger scale break distances (i.e., 11–14 m). The effect of vegetation and topographic variables on the spatial variability in snow depths at each site was investigated with random forest models. Results show that the underlying topography and the wind redistribution of snow along forest edges govern the snow depth variability at agro-forested sites, while forest structure variability dominates snow depth variability in the coniferous environment. These results highlight the importance of including and better representing these processes in physically based models for accurate estimates of snowpack dynamics.
9
Baron, Julie, Ilaria Primofiore, Peter Klin, Giovanna Vessia, and Giovanna Laurenzano. "Investigation of topographic site effects using 3D waveform modelling: amplification, polarization and torsional motions in the case study of Arquata del Tronto (Italy)." Bulletin of Earthquake Engineering 20, no. 2 (December 3, 2021): 677–710. http://dx.doi.org/10.1007/s10518-021-01270-2.
Анотація:
AbstractThe combined effect of topography and near-surface heterogeneities on the seismic response is hardly predictable and may lead to an aggravation of the ground motion. We apply physics-based numerical simulations of 3D seismic wave propagation to highlight these effects in the case study of Arquata del Tronto, a municipality in the Apennines that includes a historical village on a hill and a hamlet on the flat terrain of an alluvial basin. The two hamlets suffered different damage during the 2016 seismic sequence in Central Italy. We analyze the linear visco-elastic seismic response for vertically incident plane waves in terms of spectral amplification, polarization and induced torsional motion within the frequency band 1–8 Hz over a 1 km2 square area, with spatial resolution 25 m. To discern the effects of topography from those of the sub-surface structure we iterate the numerical simulations for three different versions of the sub-surface model: one homogeneous, one with a surficial weathering layer and a soil basin and one with a complex internal setting. The numerical results confirm the correlation between topographic curvature and amplification and support a correlation between the induced torsional motion and the topographic slope. On the other hand we find that polarization does not necessarily imply ground motion amplification. In the frequency band above 4 Hz the topography-related effects are mainly aggravated by the presence of the weathering layer, even though they do not exceed the soil-related effects in the flat-topography basin. The geological setting below the weathering layer plays a recognizable role in the topography-related site response only for frequencies below 4 Hz.
10
Hoch, Sebastian W., and C. David Whiteman. "Topographic Effects on the Surface Radiation Balance in and around Arizona’s Meteor Crater." Journal of Applied Meteorology and Climatology 49, no. 6 (June 1, 2010): 1114–28. http://dx.doi.org/10.1175/2010jamc2353.1.
Анотація:
Abstract The individual components of the slope-parallel surface radiation balance were measured in and around Arizona’s Meteor Crater to investigate the effects of topography on the radiation balance. The crater basin has a diameter of 1.2 km and a depth of 170 m. The observations cover the crater floor, the crater rim, four sites on the inner sidewalls on an east–west transect, and two sites outside the crater. Interpretation of the role of topography on radiation differences among the sites on a representative clear day is facilitated by the unique symmetric crater topography. The shortwave radiation balance was affected by the topographic effects of terrain exposure, terrain shading, and terrain reflections, and by surface albedo variations. Terrain exposure caused a site on the steeper upper eastern sidewall of the crater to receive 6% more daily integrated shortwave energy than a site on the lower part of the same slope. Terrain shading had a larger effect on the lower slopes than on the upper slopes. At the lower western slope site the daily total was reduced by 6%. Measurements indicate a diffuse radiation enhancement due to sidewall reflections. The longwave radiation balance was affected by counterradiation from the crater sidewalls and by reduced emissions due to the formation of a nighttime temperature inversion. The total nighttime longwave energy loss at the crater floor was 72% of the loss observed at the crater rim.
11
Lu, Yu Xia, Kun Liu, Yu Cheng Shi, and Qian Li. "Seismic Response of a Hill in Wenxian, Gansu, Observed from Aftershocks of 2008 Wenchuan Earthquake." Advanced Materials Research 243-249 (May 2011): 3952–57. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.3952.
Анотація:
To help understand the ground motions of the topographic site, the workers of Seismic Bureau of Gansu province deployed a temporary array of seismometers around the Wenxian hill and recorded ground motions from Wenchuan aftershocks. Only 11 aftershocks were recorded on all stations across the hill, these data were collected to facilitate studies of site response, wave propagation effect, and correlations of mainshock damage with local site conditions. In this paper, we analyze the weak motion data as well as the strong-motion data, and conduct comparisons of peak ground accelerations, seismic spectra analysis, and spectral ratio analysis. A more complete description of the site’s amplification, its relationship to topography, and its relationship to earthquake source effects are provided. The result shows that the ground motion was consistently amplified at station at or near the top of the hill compared with stations at the base of the hill and the amplifications frequency dependent and has its maximum at the resonant frequency of the site.
12
McNab, W. Henry. "A topographic index to quantify the effect of mesoscale landform on site productivity." Canadian Journal of Forest Research 23, no. 6 (June 1, 1993): 1100–1107. http://dx.doi.org/10.1139/x93-140.
Анотація:
Landform is related to environmental factors that affect site productivity in mountainous areas. I devised a simple index of landform and tested this index as a predictor of site index in the Blue Ridge physiographic province. The landform index is the mean of eight slope gradients from plot center to skyline. A preliminary test indicated that the index was significantly associated with slope position and three classes of landform (ridge, slope, and cove). In a test with data from four locations, site index of yellow-poplar (Liriodendrontulipifera L.) was significantly correlated with landform index for each location (r = 0.45–0.65). Landform index and two other topographic variables together accounted for 31 percent of the variation in yellow-poplar site index throughout the Blue Ridge province. Landform index is a conveniently measured site variable that may be useful in various forestry-related applications, including multivariate analysis of the distribution and composition of forest vegetation.
13
John, Aji, Julian D. Olden, Meagan F. Oldfather, Matthew M. Kling, and David D. Ackerly. "Topography influences diurnal and seasonal microclimate fluctuations in hilly terrain environments of coastal California." PLOS ONE 19, no. 3 (March 29, 2024): e0300378. http://dx.doi.org/10.1371/journal.pone.0300378.
Анотація:
Understanding the topographic basis for microclimatic variation remains fundamental to predicting the site level effects of warming air temperatures. Quantifying diurnal fluctuation and seasonal extremes in relation to topography offers insight into the potential relationship between site level conditions and changes in regional climate. The present study investigated an annual understory temperature regime for 50 sites distributed across a topographically diverse area (>12 km2) comprised of mixed evergreen-deciduous woodland vegetation typical of California coastal ranges. We investigated the effect of topography and tree cover on site-to-site variation in near-surface temperatures using a combination of multiple linear regression and multivariate techniques. Sites in topographically depressed areas (e.g., valley bottoms) exhibited larger seasonal and diurnal variation. Elevation (at 10 m resolution) was found to be the primary driver of daily and seasonal variations, in addition to hillslope position, canopy cover and northness. The elevation effect on seasonal mean temperatures was inverted, reflecting large-scale cold-air pooling in the study region, with elevated minimum and mean temperature at higher elevations. Additionally, several of our sites showed considerable buffering (dampened diurnal and seasonal temperature fluctuations) compared to average regional conditions measured at an on-site weather station. Results from this study help inform efforts to extrapolate temperature records across large landscapes and have the potential to improve our ecological understanding of fine-scale seasonal climate variation in coastal range environments.
14
Xu, Xiang, Paolo Vincenzo Genovese, Yafei Zhao, Yidan Liu, Eyasu Markos Woldesemayat, and Abraham Nathan Zoure. "Geographical Distribution Characteristics of Ethnic-Minority Villages in Fujian and Their Relationship with Topographic Factors." Sustainability 14, no. 13 (June 24, 2022): 7727. http://dx.doi.org/10.3390/su14137727.
Анотація:
The geographical distribution characteristics of villages characterised by ethnic minorities are determined by the selection of the site when the village was initially established. The location of inherited and well-preserved minority villages must be exceptionally compatible with the natural terrain, with a logical relationship. Nonetheless, the issue of village location, which is directly related to the development of the features of the geographical distribution, has received little attention from scholars. The average nearest proximity index, Voronoi, kernel density analysis, proximity analysis, and the Geographical Detector (GeoDetector) were used to analyse the geographic distribution characteristics of villages and their correlation with terrain, as well as the difference between the influence of each terrain factor. The findings indicated the following. (1) The geographical distribution of minority villages in Fujian Province is of the agglomeration type, with a significant “mononuclear” feature, and the topography has a facilitating effect on the clustering distribution of villages. (2) The geographical distribution of minority villages in each city of Fujian Province coexisted with the agglomeration type and the dispersion type, and the role of topography in promoting the agglomeration-type distribution of villages was not affected by the distribution density of villages. (3) The site selection of Fujian-minority villages is characterised by medium altitude, moderate slope, sun exposure, and no obvious hydrophilicity. Minority villages are mainly located in areas with an elevation of 202–647 m; a slope of 6–15°; a flat land aspect with a south slope, southeast slope, or southwest slope; and distance of 500–1500 m from 5–20 m wide rivers of level 2. (4) The site selection of Fujian minority villages is influenced by various topographic factors, such as elevation, slope, aspect, river buffer, river width, and river level, among which river width has the most substantial effect. (5) All topographic factors have a two-factor enhancing relationship with each other, aspect and slope have the most substantial effect and play a dominant role in site selection. The research findings illuminate the internal logic of the geographical distribution differentiation of villages characterised by ethnic minorities, which is critical for promoting the protection of modern ethnic-minority villages.
15
Cavallaro, Antonio, Antonio Ferraro, Salvatore Grasso, and Antonio Puccia. "2-D Seismic Response Analysis of a Slope in the Tyrrhenian Area (Italy)." Applied Sciences 11, no. 7 (April 2, 2021): 3180. http://dx.doi.org/10.3390/app11073180.
Анотація:
The Caronia area is located in the Tyrrhenian north-eastern sector of Sicily (Italy). Starting in 2010, attention focused on the study of landslides phenomena that occurred in this area, which caused significant economic damage to buildings and infrastructures and loss of productive activities. The site is characterized by geotechnical, geological and morphological heterogeneity, and for this reason the site is particularly prone to seismic topographic amplification effects. In this paper, the authors carried out numerical studies focused on the topographic seismic effect evaluation concerning the slope affected by the landslide phenomena. For this site, geotechnical characterization was available concerning both in-situ and laboratory tests; boreholes, piezometers, down-hole tests, multichannel analysis of surface waves tests, seismic tomographies and inclinometer measurements were carried out. Furthermore, 1-D and 2-D local seismic response analyses were carried out by using different synthetic seismograms related to the earthquake of Messina and Reggio Calabria on 28 December 1908. The results of the numerical analyses are presented in terms of response seismograms and response spectra at the surface.
16
İnce, G. Ç., and L. Yılmazoğlu. "Investigating the influence of topographic irregularities and two-dimensional effects on surface ground motion intensity with one- and two-dimensional analyses." Natural Hazards and Earth System Sciences 14, no. 7 (July 18, 2014): 1773–88. http://dx.doi.org/10.5194/nhess-14-1773-2014.
Анотація:
Abstract. In this work, the surface ground motion that occurs during an earthquake in ground sections having different topographic forms has been examined with one and two dynamic site response analyses. One-dimensional analyses were undertaken using the Equivalent-Linear Earthquake Response Analysis (EERA) program based on the equivalent linear analysis principle and the Deepsoil program which is able to make both equivalent linear and nonlinear analyses and two-dimensional analyses using the Plaxis 8.2 software. The viscous damping parameters used in the dynamic site response analyses undertaken with the Plaxis 8.2 software were obtained using the DeepSoil program. In the dynamic site response analyses, the synthetic acceleration over a 475-year return period representing the earthquakes in Istanbul was used as the basis of the bedrock ground motion. The peak ground acceleration obtained different depths of soils and acceleration spectrum values have been compared. The surface topography and layer boundaries in the 5-5' cross section which cuts across the study area west to east were selected in order to examine the effect of the land topography and layer boundaries on the analysis results, and were flattened and compared with the actual status. The analysis results showed that the characteristics of the surface ground motion change in relation to the varying local soil conditions and land topography.
17
Yılmazoğlu, L., and G. Ç. İnce. "Investigation of the influence of topographic irregularities and two dimensional effects on the intensity of surface ground motion with one- and two-dimensional analyses." Natural Hazards and Earth System Sciences Discussions 1, no. 6 (December 6, 2013): 7193–238. http://dx.doi.org/10.5194/nhessd-1-7193-2013.
Анотація:
Abstract. In this work, the surface ground motion that occurs during an earthquake in ground sections having different topographic forms has been examined with one and two dynamic site response analyses. One-dimensional analyses were undertaken using the Equivalent-Linear Earthquake Response Analysis program based on the equivalent linear analysis principle and the Deepsoil program which is able to make both equivalent linear and nonlinear analyses and two-dimensional analyses using the Plaxis software. The viscous damping parameters used in the dynamic site response analyses undertaken with the Plaxis software were obtained using the DeepSoil program. In the dynamic site response analyses, the synthetic acceleration over a 475 yr replication period representing the earthquakes in Istanbul was used as the basis of the bedrock ground motion. The peak ground acceleration obtained different depths of soils and acceleration spectrum values have been compared. The surface topography and layer boundaries in the 5-5' section were selected in order to examine the effect of the land topography and layer boundaries on the analysis results were flattened and compared with the actual status. The analysis results showed that the characteristics of the surface ground motion changes in relation to the varying local soil conditions and land topography.
18
Bouchon, Michel, and Jeffrey S. Barker. "Seismic response of a hill: The example of Tarzana, California." Bulletin of the Seismological Society of America 86, no. 1A (February 1, 1996): 66–72. http://dx.doi.org/10.1785/bssa08601a0066.
Анотація:
Abstract The Northridge, California, earthquake that strongly shook the city of Los Angeles in January 1994, produced one of the highest ground accelerations ever recorded in an earthquake, at a site located on top of a small hill in Tarzana, about 6 km south of the epicenter. The subsequent study of aftershock recordings obtained by a dense seismic array deployed on the hill a few days after the earthquake showed the existence of a strong amplification at stations located at the top of the hill, relative to stations near the base (Spudich et al., 1996). Resonances and polarization rotations were also observed. We investigate in this study the role that the topography of the site played on the observed ground motions and accelerations. To this aim, we perform numerical simulations and study the response of the three-dimensional topography of the site to incident shear waves polarized in different directions. The method used is a boundary integral equation scheme in which the Green's functions are calculated by the discrete wavenumber method. The results obtained show that the topography of the site, though quite gentle (the hill is less than 20-m high), strongly affects the ground motions in the frequency range between 2 and 15 Hz. Many of the observed characteristics of the seismic response at Tarzana are explained in part by its topography: the consistent amplification of ground motion at and near the top of the hill, the directional seismic response of the hill that results in a strong amplification of the ground motion transverse to the direction of elongation of the hill, the existence of a fundamental transverse oscillatory resonance mode of the hill at 3 to 5 Hz, the rotation of the polarization of ground motion, and the spatial variation of amplification over the hill at the fundamental resonance mode. The seismic response of the topography, however, does not fully explain the amplitude of the effects observed. The three-dimensional geological structure of the site must in some way amplify the effect of the topography to produce the observed seismic response. In spite of not being as strong as the observed effect, the topographic effect of the site is considerable. The ground motion is amplified by factors ranging from 30% to 100% at some locations in the frequency range from 2 to 15 Hz. Rapid spatial variations of ground-shaking intensities can take place over distance scales of a few tens of meters at high frequency. Finally, the results of the simulation indicate that the topography of the site amplified the large east-west accelerations recorded there during the Northridge mainshock by 30% to 40%.
19
Maufroy, Emeline, Víctor M. Cruz-Atienza, and Stéphane Gaffet. "A Robust Method for Assessing 3-D Topographic Site Effects: A Case Study at the LSBB Underground Laboratory, France." Earthquake Spectra 28, no. 3 (August 2012): 1097–115. http://dx.doi.org/10.1193/1.4000050.
Анотація:
By means of three-dimensional (3-D) numerical simulations, including the Laboratoire Souterrain à Bas-Bruit (LSBB) topography, we carefully analyze site effects assessments yielded by two approaches: the classical site to reference spectral-ratio method (SRM) and the statistical median reference method (MRM). We show for both isotropic and double-couple point sources that a 94% reduction in the number of stations of a regularly spaced array yields MRM site-effect estimates within 5% of those obtained from the absolute regional median, and within 20% using a 98% station reduction with irregularly located sites. In contrast, the SRM yielded site-effect overestimates greater than 50% in some areas and up to 100% in specific sites, which makes the MRM much more robust than the SRM. We determined a 33% probability to exceed an amplification factor of 2, and an 8% probability to exceed a factor of 3 due to topography in the surroundings of the sharpest summit of the LSBB area.
20
Hough, S. E., K. H. Jacob, and L. Seeber. "High-Frequency Seismic Wave Propagation in Northeastern North America." Seismological Research Letters 61, no. 3-4 (July 1, 1990): 193–208. http://dx.doi.org/10.1785/gssrl.61.3-4.193.
Анотація:
Abstract A key element in the assessment of seismic hazard is the estimation of how energy propagation from a given earthquake is affected by crustal structure near the receiver and along the more distant propagation path. In this paper, we present data from a variety of sources in eastern North America recorded at epicentral distances of a few to 800 km, and characterize and interpret systematic features. Site effects have been classically considered in terms of amplification either within a sediment-filled valley or from a single topographic feature (Geli et al., 1988). We present evidence of high frequency (5–30 Hz) resonances observed in hard-rock recordings of both body waves and Lg waves, and suggest that site effect should be expanded regionally to include structural and topographic information over sufficiently large areas to include several wavelengths of any features that may interact with seismic waves in the frequency range of interest. A growing body of evidence suggests that ground motions at high frequencies recorded at large epicentral distances in eastern North America are controlled by resonance effects. We hypothesize that a fundamental difference between eastern and western North America spectra stems from a combination of differences in the character of topography and near-surface structure. Active tectonics of western North America gives rise to a complex crust that scatters seismic energy in a random manner and results in very effective attenuation of high frequencies. The older eastern North American crust contains scatterers that are more ordered, with characteristic length scales that give rise to resonance phenomena in the frequency band critical for earthquake hazard. We present preliminary analysis of topographic data from the Adirondack Mountains in New York that demonstrates the existence of characteristic length scales on the order of up to 1–3 kilometers. Features with these length scales will effectively scatter energy at frequencies in the 1 to 10 Hz range.
21
Chen, Tuo. "Seismic response analysis of loess site under far-field bedrock ground motion of the Wenchuan earthquake." PLOS ONE 16, no. 7 (July 30, 2021): e0254871. http://dx.doi.org/10.1371/journal.pone.0254871.
Анотація:
In this paper, considering the far-field seismic input, an accelerogram recorded in the bedrock at Wuquan Mountain in Lanzhou city during the 2008 Wenchuan Ms8.0 earthquake was selected, and numerical dynamic analyses were conducted. The one-dimensional equivalent linear method was implemented to estimate the ground motion effects in the loess regions. Thereafter, slope topographic effects on ground motion were studied by applying the dynamic finite-element method. The results revealed the relationship between the PGA amplification coefficients and the soil layer thickness, which confirmed that the dynamic response of the sites had obvious nonlinear characteristics. The results also showed that there was an obvious difference in the dynamic magnification factor between the short-period and long-period structures. Moreover, it was found that the amplification coefficient of the observation point at the free surface was greater than the point inside the soil at the same depth, which mainly occurred in the upper slope. Through this study, the quantitative assessment of ground motion effects in loess regions can be approximately estimated, and the amplification mechanism of the far-field ground motion mechanism can be further explained. In addition to the refraction and reflection theory of seismic waves, the resonance phenomenon may help explain the slope topographic effect through spectrum analysis.
22
Liu, Aijuan, Taiping Liu, Yulong Cui, and Hongchun Zheng. "Discussion on the Site Effect Coefficient and Topographic Effect Coefficient of Ground Motion Peak Acceleration and Its Relationship." IOP Conference Series: Earth and Environmental Science 218 (February 23, 2019): 012095. http://dx.doi.org/10.1088/1755-1315/218/1/012095.
23
Maufroy, Emeline, Víctor M. Cruz‐Atienza, Fabrice Cotton, and Stéphane Gaffet. "Frequency‐Scaled Curvature as a Proxy for Topographic Site‐Effect Amplification and Ground‐Motion Variability." Bulletin of the Seismological Society of America 105, no. 1 (December 2, 2014): 354–67. http://dx.doi.org/10.1785/0120140089.
24
Eliawa, Ali i. "Using Geological and Topographic Maps in Site Selection of Solid Waste Disposal." Al-Mukhtar Journal of Sciences 37, no. 1 (March 31, 2022): 29–40. http://dx.doi.org/10.54172/mjsc.v37i1.446.
Анотація:
Currently, land shortage for solid waste in most urban areas is a significant and growing potential problem. Although some efforts are made to decrease and recover the waste, landfill is still the most common process for waste disposal. Site selection of solid waste dumping in urban areas is a serious subject because of its huge effect on the economy, ecology, and environmental health. Consequently, several criteria must be created because of the difficulty of the parameters to select the process for combination in social, environmental and technical parameters. In this research, the most appropriate sites for locating dumping garbage are determined using the Geographical Information System (GIS) by implementing both methods Boolean logic model and Index overlay model. Based on several objectives, a provided spatial data set consisting of several maps in the form of layers, such as land use, geological distribution, landslides, etc., were used in the modeling process to choose the best site to dump the garbage of Chinchina city that used as a case in this application. The findings show that the Boolean logic model identified only two areas that met the criteria, whereas the Index overlay model identified three important classes through weight; unsuitable, moderate and suitable regions for construction waste disposal.
25
Wu, Yuan Chieh, and Meng Hsui Hsieh. "Site Response Analysis for a Site with the Dipping Bedrock and Liquefiable Layers Using FLAC 3D." Applied Mechanics and Materials 479-480 (December 2013): 1076–80. http://dx.doi.org/10.4028/www.scientific.net/amm.479-480.1076.
Анотація:
To get the precise input motion for seismic analysis of important structures located in liquefiable soil layers, this study demonstrates site response analysis using FLAC 3D [. Based on the previous earthquake diaster experiences and regulatory requirements for nuclear power plants (NPP), the seismic wave propagation in the site having dipping bedrock surface was modeled, also the excess pore water pressure during excitation process was added into the soil elements. The free-field site response model is used to generate the response spectra at different ground surface locations, and to predict the influence range of soil liquefaction. The analysis results show that soil liquefaction could reduce site amplification effect, and might have different degree of impact depending on natural frequency and soil pressure resistance of structures. The 3D model also can capture the soil unceratinties and reflect the real topographic effect in one computer run, so the current multiple one-dimensional equivalent linear analysis process could be improved. Therefore, the FLAC 3D model can fulfill nuclear regulatory requirement, and provide suitable ground-motion prediction for liquefiable soil sites and complex bedrock surface sites for the need of seismic evaluations of existing NPPs after Fukushima Dai-ichi Tragedy.
26
Salekin, Mason, Morgenroth, Bloomberg, and Meason. "Modelling the Effect of Microsite Influences on the Growth and Survival of Juvenile Eucalyptus globoidea (Blakely) and Eucalyptus bosistoana (F. Muell) in New Zealand." Forests 10, no. 10 (October 1, 2019): 857. http://dx.doi.org/10.3390/f10100857.
Анотація:
The effect of microsite on juvenile forest plantation yield is rarely explored. This is because juvenile plantation growth is considered to be reasonably homogenous due to a lack of resource competition between trees prior to canopy closure. However, models of juvenile plantation height growth and survival that are sensitive to microsite variation could aid decisions relating to site preparation, plantation establishment and early silvicultural treatments. In this study, juvenile Eucalyptus bosistoana and E. globoidea height growth and survival proportion were modelled against topographic and environmental microsite characteristics as independent variables. The experiment included three different sites situated in a sub-humid region of New Zealand. A total of 540 plots were planted with 18,540 trees in regular rows and columns. Micro-topographical variables significantly influenced height growth and survival proportion of both E. bosistoana and E. globoidea, but species differed in their responses. More sheltered microsites yielded greater height growth and survival for both species. The height of both species was influenced by wind exposure, morphometric protection, and distance from the nearest ridge. E. bosistoana height was also influenced by topographic position and surface plan curvature. Survival was affected by surface profile curvature for both species, while E. globoidea survival was also impacted by surface plan curvature and distance from the top ridge. This study identified microsite factors influencing juvenile height and survival of two Eucalyptus species.
27
Zou, Kailun, Guangshuang Duan, You Wu, Zhanyin Wang, and Xianzhao Liu. "Site Index Model for Southern Subtropical Masson Pine Forests Using Stand Dominant Height." Forests 15, no. 1 (December 31, 2023): 87. http://dx.doi.org/10.3390/f15010087.
Анотація:
Stand dominant height has a close relationship with stand productivity and is not much affected by stand density and thinning within a reasonable density range, making it an excellent indicator for estimating stand site quality. Topographic factors (altitude, aspect, slope, etc.) have a significant influence on the growth process of stand level, and the combination of different site factors increases the randomness of the evaluation of forest productivity. In this paper, with one-way ANOVA, it was determined that the effects of density and management mode on the Masson pine stand dominant height were not significant. The data on the Masson pine stand dominant height in the southern subtropics in Guangxi, China, were analyzed, and the GADA model was established using the nonlinear least squares method, the Bayesian approach, and the one-level nonlinear mixed-effects model with the topographic factor as the random effect, respectively. The results indicated that the nonlinear mixed-effects model had the best fitting performance and the highest prediction accuracy for stand site quality (a 0.27% improvement in R² compared to the least squares method and a 1.30% improvement in R² compared to the Bayesian approach), while the model obtained by the Bayesian approach had more elasticity and biological significance. In summary, when the data distribution is uniform and comprehensive, introducing terrain factors into the establishment of site index models can provide a more scientific basis for estimating the productivity of southern subtropical Masson pine stands under different site conditions. When the data distribution is uneven, applying the Bayesian approach can make the site index model more biologically meaningful. The stand site quality model can predict the potential production capacity of forests, which is an important basis and can support forest management and harvest prediction. The results of this study provide a theoretical and practical basis for the establishment of a reasonable site index model for the Masson pine stand.
28
Van Houtte, C., O. J. Ktenidou, T. Larkin, and A. Kaiser. "Reference stations for Christchurch." Bulletin of the New Zealand Society for Earthquake Engineering 45, no. 4 (December 31, 2012): 184–95. http://dx.doi.org/10.5459/bnzsee.45.4.184-195.
Анотація:
During the Canterbury earthquake sequence, the observed level of ground motion on the soft soils of Christchurch was very strong and highly variable. Many studies are now emerging that analyse the amplification effect of these soft soils, usually by estimating a frequency-dependent amplification function relative to a rock outcrop station, or ‘reference site’. If the rock outcrop has its own amplification due to weathering or topographic effects, then the calculated amplification for the soil sites can be compromised. This study examines ten seismic stations in Canterbury to determine the best reference site for Christchurch, using the horizontal-to-vertical spectral ratio (HVSR) method for S-wave shaking. More broadly, this study uses HVSR to expand existing knowledge of the dynamic characteristics of seismic stations in the Canterbury area. Most rock stations show their own local amplification effects that reduce their individual ability to be used as reference stations. The recently installed Huntsbury station (HUNS) appears to be the best reference site for Christchurch, but this will need to be verified when more records become available. In the meantime, the D13C temporary station is currently the best reference station for site effect studies in both Christchurch and Lyttelton.
29
Seynave, Ingrid, Jean-Claude Gégout, Jean-Christophe Hervé, Jean-François Dhôte, Jacques Drapier, Éric Bruno, and Gérard Dumé. "Picea abiessite index prediction by environmental factors and understorey vegetation: a two-scale approach based on survey databases." Canadian Journal of Forest Research 35, no. 7 (July 1, 2005): 1669–78. http://dx.doi.org/10.1139/x05-088.
Анотація:
Relationships between site index, environmental variables, and understorey vegetation were examined for Norway spruce (Picea abies (L.) Karst.) in the eastern part of France. The study area concerns all the native range of Norway spruce in France and the northeastern plains. The analysis is based on 2087 plots from the French National Forest Inventory database. The data measured on each plot cover topography, soil, geology, and vegetation. Additional environmental variables were estimated using two methods: climatic data estimated from a climatic model developed by Météo-France (AURELHY), and nutritional variables predicted from vegetation data and species indicator values. General linear model regression was used to predict site index as a function of environmental variables. The best model explains 64% of the site index variance and involves eight variables (elevation, mountain zone, topographic concavity, proportion of plot area occupied by rock outcrop, rock type, soil depth, pH, and C/N ratio). The two main results of this study are (i) the combination of large databases allowed the study of soilsite relationships and construction of a pertinent model, which covers a wide range of ecological conditions, and (ii) vegetation was found to be relevant to separate the effect of acidity from those of nitrogen nutrition on Norway spruce productivity.
30
Bao, Xin, Jingbo Liu, and Fei Wang. "Influence of Topographic and Geological Features on the Seismic Response of the Reef Site in the South China Sea." Journal of Marine Science and Engineering 11, no. 4 (April 21, 2023): 881. http://dx.doi.org/10.3390/jmse11040881.
Анотація:
Insufficient comprehension of the seismic impact of the reef terrain, geology, and material properties of the reefs in the South China Sea still presents considerable impediments in studying the seismic response of reef engineering sites and assessing their seismic safety. To surmount this challenge, a seismic response analysis model of the reef-seawater system is established. This model takes into account the fluid-solid interaction effect, the wave radiation effect of the infinite seawater layer and the semi-infinite seabed, as well as the seismic wave input process of the reef-seawater system. Through targeted parameter analyses, the impact of various factors, including the shear wave velocity, thickness, and slope of distinct reef layers, the width of the reef flat, and the dynamic coupling effect of seawater on the seismic response of reef sites, is thoroughly examined. It has been determined that the seismic response of the reef site is markedly amplified as the shear wave velocity decreases and the thickness of the uppermost reef layer increases. While the effects of the slope gradient of the topmost reef layer and the width of the reef flat on the seismic response of the reef site are chiefly observed in the edge area and the central area, respectively. The layer of seawater plays a crucial role in radiation damping, serving as a medium for the dissipation of seismic energy and thereby weakening the overall seismic response of the reef site.
31
I., Mahakata, Hungwe C., Ngoni M., Matindike S., Gonhi P., Masumba Y., and Kudzai M. "Topo-edaphic, Vegetation Cover and Type Influence on Spatial Distribution of Gullies in Sengwa Wildlife Research Area (SWRA), North West Zimbabwe." African Journal of Environment and Natural Science Research 4, no. 4 (October 4, 2021): 61–73. http://dx.doi.org/10.52589/ajensr-uo9bteux.
Анотація:
Gully erosion is a common phenomenon in arid and semi-arid areas and is mostly influenced by soil type, topography, vegetation type and cover. The objective of the study was to determine the effect of topo-edaphic, vegetation type and cover on gully occurrence, hence map their spatial distribution in SWRA. A conventional method was used where field visit to known gully sites was done. At each site, GPS points were marked at three points, that is, at the head site, the middle and lower end of the gully. Soil samples, gully width, depth, length, vegetation type and cover were recorded for each point where GPS coordinates were collected. GPS points were overlaid on SWRA processed vegetation, soil and topographic map for analysis on the spatial distribution of gullies. Fifty-six gullies were recorded with highly affected areas on the southwestern side of the park. Associated soils types were clay and loam of the Madumabisa mudstone, colluvial and alluvial located at altitudes below 1000 meters. Gully occurrences were sighted more in mopane dominated woodlands with few recorded in areas dominated by acacia woodlands and on the edges of miombo woodlands, which occupy the high grounds of SWRA. Gully length varied from 20m in less developed gullies to 2520m for mature gullies with volumes ranging between 52m3 and 4649.4m3. Hence, topography, soil type, vegetation cover and type influence gully location and occurrence. Future research should aim to monitor changes in gully development using remote sensing as it provides a great potential for monitoring gully changes across the landscape.
32
Rault, Claire, Wei-An Chao, Céline Gelis, Arnaud Burtin, Jui-Ming Chang, Odin Marc, Tz-Shin Lai, Yih-Min Wu, Niels Hovius, and Patrick Meunier. "Seismic Response of a Mountain Ridge Prone to Landsliding." Bulletin of the Seismological Society of America 110, no. 6 (July 21, 2020): 3004–20. http://dx.doi.org/10.1785/0120190127.
Анотація:
ABSTRACT During an earthquake, site effects can play an important role in triggering landslides. To document the seismic response of steep hillslopes, we deployed broadband seismometers across a mountain ridge in Taiwan, in an area with a high earthquake-induced landslide hazard. The ridge has a simple, representative shape, and landslides have previously occurred there. Our seismometer array has recorded continuously during more than 1 yr, with both ambient-noise and regional moderate earthquakes as sources. Processing horizontal and vertical signal components, we show that the ridge has a complex response, which we attribute to the combined effects of the subsurface geology and the topographic geometry. Amplification and directionality of ground motion are observed both high and low on the ridge, giving rise to localized, elevated, earthquake-induced landslide hazard. Our database contains earthquakes with mostly similar locations, making it difficult to determine the effect of earthquake back azimuth on the ridge response. A part of the ridge response, possibly due to topographic effects, seems to be explained by a model derived from a frequency scale curvature proxy at low frequency. If correct, this would be a promising first step toward improving local ground-motion estimation in mountain areas. However, the definition of appropriate scaling parameters of site effects based on geophysical measurements, for use in regional and global landslide hazard equations applicable to mountain areas with substantial regolith thickness, remains a significant challenge.
33
Liu, Zhiwei, Haiqiang Fu, Jianjun Zhu, Cui Zhou, and Tingying Zuo. "Using Dual-Polarization Interferograms to Correct Atmospheric Effects for InSAR Topographic Mapping." Remote Sensing 10, no. 8 (August 20, 2018): 1310. http://dx.doi.org/10.3390/rs10081310.
Анотація:
Atmospheric effect represents one of the major error sources for interferometric synthetic aperture radar (InSAR), particularly for the repeat-pass InSAR data. In order to further improve the practicability of InSAR technology, it is essential to study how to estimate and eliminate the undesired impact of atmospheric effects. In this paper, we propose the multi-resolution weighted correlation analysis (MRWCA) method between the dual-polarization InSAR data to estimate and correct atmospheric effects for InSAR topographic mapping. The study is based on the a priori knowledge that atmospheric effects is independent of the polarization. To find the identical atmospheric phase (ATP) signals of interferograms in different polarizations, we need to remove the other same or similar phase components. Using two different topographic data, differential interferometry was firstly performed so that the obtained differential interferograms (D-Infs) have different topographic error phases. A polynomial fitting method is then used to remove the orbit error phases. Thus, the ATP signals are the only identical components in the final obtained D-Infs. By using a forward wavelet transform, we break down the obtained D-Infs into building blocks based on their frequency properties. We then applied weighted correlation analysis to estimate the wavelet coefficients attributed to the atmospheric effects. Thus, the ATP signals can be obtained by the refined wavelet coefficients during inverse wavelet transform (IWT). Lastly, we tested the proposed method by the L-band Advanced Land Observing Satellite (ALOS)-1 PALSAR dual-polarization SAR data pairs covering the San Francisco (USA) and Moron (Mongolia) regions. By using Ice, Cloud, and land Elevation Satellite (ICESat) data as the reference data, we evaluated the vertical accuracy of the InSAR digital elevation models (DEMs) with and without atmospheric effects correction, which shows that, for the San Francisco test site, the corrected interferogram could provide a DEM with a root-mean-square error (RMSE) of 7.79 m, which is an improvement of 40.5% with respect to the DEM without atmospheric effects correction. For the Moron test site, the corrected interferogram could provide a DEM with an RMSE of 10.74 m, which is an improvement of 30.2% with respect to the DEM without atmospheric effects correction.
34
Durand, Sylvette, Stéphane Gaffet, and Jean Virieux. "Seismic diffracted waves from topography using 3-D discrete wavenumber‐boundary integral equation simulation." GEOPHYSICS 64, no. 2 (March 1999): 572–78. http://dx.doi.org/10.1190/1.1444564.
Анотація:
Compressional (P) and shear (S) wave diffraction by free‐surface topography plays a prominent part in the prediction of site responses for seismic risk estimation. Wave propagation modeling in 3-D media is required for an accurate estimation of these diffractions. We have extended the discrete wavenumber‐indirect boundary integral equation method for a 3-D geometry in the case of irregular topography. The Green’s functions are expressed as finite sums of analytical density functions over the horizontal wavenumbers using the spatial periodicity of the topography and a discretization of the surface. We show that the evaluation over vertical wavenumber [Formula: see text] of the analytical integral is possible because a new factor in 1/k2 exists. When the force point and the receiver point are at the same vertical position, we develop a numerical strategy to choose the sign of the exponential factor, which is not given by the analytical formulation. The free‐stress boundary conditions at the topography lead to a large linear system that can be solved to obtain the source density functions. Knowing these source density functions, we can compute the diffracted wavefield anywhere inside the medium. We have determined a useful optimal, imaginary frequency to obtain the displacement directly in the frequency domain, avoiding the necessity of returning to the time domain. We have then applied this method to investigate the effect of topography on the ground motion produced by a vertical incident P- or S-wavefield. Waveforms obtained for various topographic steepnesses and shapes show deterministic correlations between the maximum amplitude zone, the geometry of the 3-D topography, and the P- or S-wave incident field characteristics. The maximum amplitude of the diffracted displacement is found near topographic zones that have horizontal or vertical dimensions closely related to the wavelength of the incident field. The predicted ground motion maximal amplifications are twice those calculated in the case of a flat topography.
35
Miranda-Gallegos, Katia V., Armando Navarrete-Segueda, Jorge Cortés-Flores, M. Lourdes González-Arqueros, Estefanía E. Acosta-Pérez, and Guillermo Ibarra-Manríquez. "Landscape heterogeneity drives spatial distribution of palm community in a Neotropical rainforest reserve affected by defaunation." Botanical Sciences 101, no. 3 (June 5, 2023): 654–69. http://dx.doi.org/10.17129/botsci.3204.
Анотація:
Background: Our study presents the first assessment of the relationships between environmental heterogeneity and the palm community at the landscape scale at the northern boundary of tropical rainforest distribution in America.
Question: How does landscape-level heterogeneity (edaphic, topographic as well as the density, diversity, and tree biomass) shapes the palm community in a protected reserve affected by defaunation?
Study site and date: The study was carried out in Los Tuxtlas Tropical Biology Station, Veracruz, Mexico (2020).
Methods: We delineated landscape units (LUs) based on soil and geomorphology to characterize the biophysical mosaic. We built rank-abundance curves to compare the palm richness and their abundance among LUs. Permutational multivariate analysis of variance (PERMANOVA) and nonmetric multidimensional scaling (NMDS) were applied to detect shifts in the palm community across LUs.
Results: Integrating abiotic and biotic components by delimiting LUs allowed us to evaluate the multifactorial effect of environmental heterogeneity on the palm community. The density and composition of the palms changed significantly among the LUs, influenced by soil coarse fragments, elevation, slope inclination, and annual precipitation. Tree richness and density had a significant effect on the palm community only when analyzed in combination with the soil-topography variables.
Conclusions: The results reveal that there is high edaphic and topographic heterogeneity that influences palm species distribution at the landscape scale. The environmental heterogeneity approach allows capturing novel abiotic variation to explain the distribution patterns of palm species and their coexistence in highly diverse tropical communities.
36
Madugundu, Rangaswamy, Khalid A. Al-Gaadi, ElKamil Tola, Ahmed M. Zeyada, Ahmed A. Alameen, Mohamed K. Edrris, Haroon F. Edrees, and Omer Mahjoop. "Impact of Field Topography and Soil Characteristics on the Productivity of Alfalfa and Rhodes Grass: RTK-GPS Survey and GIS Approach." Agronomy 12, no. 12 (November 23, 2022): 2918. http://dx.doi.org/10.3390/agronomy12122918.
Анотація:
Understanding the spatial pattern of soil chemical properties along with the topologic indicators is essential for site-specific agriculture management. A study was conducted on a 50 ha field to investigate the effect of selected topographic indicators, including elevation (DEM), slope (SL), flow accumulation (FA) and Topographic Wetness Index (TWI) on forage crop production. The soil samples and yield data were obtained from the field inventory. Topographical parameters of elevation and slope were estimated with the use of a real-time kinematic global positioning system (RTK-GPS), and then the DEM was generated. The collected soil samples were analyzed for pH, EC, nitrogen and soil organic carbon. Sentinel-2 images were for the creation of yield maps of alfalfa and Rhodes grass. Subsequently, on the basis of DEM, the generated elevation, slope and FA model were then compared with the yield and soil chemical properties. Statistical analysis revealed that the SL, FA and TWI, which are associated with water distribution, were significantly related to crop yields. The FA showed a medium-to-non-significant correlation with the productivity of both alfalfa (R2 = 0.586; p = 0.015) and Rhodes grass (R2 = 0.578; p = 0.01). A significant inverse correlation was recorded between the SL and the yield of both crops (R2 = −0.591 to −0.617; p = 0.01). The yield map revealed that the majority of the area (37.56%) of the experimental field was occupied by the medium-yield class, followed by the high-yield class (33.03%).
37
Sendoya, Sebastian F., Paulo S. D. Silva, and Alejandro G. Farji-Brener. "Does inundation risk affect leaf-cutting ant distribution? A study along a topographic gradient of a Costa Rican tropical wet forest." Journal of Tropical Ecology 30, no. 1 (November 19, 2013): 89–92. http://dx.doi.org/10.1017/s026646741300076x.
Анотація:
Abstract:Successional state of forest and availability of pioneer plants are recognized factors affecting densities of leaf-cutting ants. However little is known about how abiotic factors can shape nest distributions. We investigated the effect of topography, soil, forest successional state and inundation risk on nest density and size of Atta cephalotes colonies along streams in a tropical wet forest in Costa Rica. In each forest type, we surveyed 12 sites, each site comprising five transects (10 × 100 m) varying in topography and proximity to streambeds. We found no difference regarding nest size or density between forest types or soil consociation. Nest density varied with topographic environment, with significantly higher nest density on slope tops (farther from streambeds) and without colonies in valley bottoms (closer to streambeds). Nests found in areas affected by the last great inundation before our study were scarcer and smaller than nests in non-flooded areas. We showed that inundation events favour an accumulation of Atta colonies towards higher sites, where they are also allowed to become larger and may survive longer. Inundation risk may be a strong force shaping the distribution of leaf-cutting ant nests in tropical floodplain forests, even concealing the relevance of successional state of forest.
38
Tucker, Denise A., Susan Dietrich, David L. McPherson, and Mimi T. Salamat. "Effect of Stimulus Intensity Level on Auditory Middle Latency Response Brain Maps in Human Adults." Journal of the American Academy of Audiology 12, no. 05 (May 2001): 223–32. http://dx.doi.org/10.1055/s-0042-1745601.
Анотація:
AbstractAuditory middle latency response (AMLR) brain maps were obtained in 11 young adults with normal hearing. AMLR waveforms were elicited with monaural clicks presented at three stimulus intensity levels (50, 70, and 90 dB nHL). Recordings were made for right and left ear stimulus presentations. All recordings were obtained in an eyes open/awake status for each subject. Peak-to-peak amplitudes and absolute latencies of the AMLR Pa and Pb waveforms were measured at the Cz electrode site. Pa and Pb waveforms were present 100 percent of the time in response to the 90 dB nHL presentation. The prevalence of Pa and Pb to the 70 dB nHL presentation varied from 86 to 95 percent. The prevalence of Pa and Pb to the 50 dB nHL stimulus never reached 100 percent, ranging in prevalence from 77 to 68 percent. No significant ear effect was seen for amplitude or latency measures of Pa or Pb. AMLR brain maps of the voltage field distributions of Pa and Pb waveforms showed different topographic features. Scalp topography of the Pa waveform was altered by a reduction in stimulus intensity level. At 90 dB nHL, the Pa brain map showed a large positivity midline over the frontal and central scalp areas. At lower stimulus intensity levels, frontal positivity was reduced, and scalp negativity over occipital regions was increased. Pb scalp topography was also altered by a reduction in stimulus intensity level. Varying the stimulus intensity significantly altered Pa and Pb distributions of amplitude and latency measures. Pa and Pb distributions were skewed regardless of stimulus intensity. Abbreviations: AMLR = auditory middle latency response, EEG = electroencephalography
39
Wahab, Ahmad Khairi Abd, Norasman Othman, Mohamad Hidayat Jamal, and Shairul Rohaziawati Samat. "Effect of Rainfall and Groundwater Level on Sandy Beach Profile." Applied Mechanics and Materials 567 (June 2014): 32–37. http://dx.doi.org/10.4028/www.scientific.net/amm.567.32.
Анотація:
In Malaysia, rainfall distribution patterns are normally influenced by seasonal wind flow patterns coupled with local topographic features. Heavy rain spells and storms during the Northeast Monsoon will affect groundwater table elevation and the beach profile. The aim of this paper is to investigate the relationship between rainfall and groundwater elevation and their effect to beach profile change. This work was undertaken at the Desaru Beach, Johor. The rainfall, groundwater table, tides and beach profiles data were measured at the site. As a result, the findings revealed that the groundwater table is affected by rainfall intensity; higher during wet season and lower during dry season. Groundwater table near the coastline is also affected by the tides. However, the data showed that there is a lag time between rising and falling of groundwater table and tides. Finally, the beach profile was found to be eroded as the groundwater elevation increased on the beach.
40
Yasa, Enes. "Microclimatic comfort measurements evaluation of building physics: The effect of building form and building settled area, on pedestrian level comfort around buildings." Journal of Building Physics 40, no. 5 (July 27, 2016): 472–500. http://dx.doi.org/10.1177/1744259115621979.
Анотація:
Wind discomfort and the dangers that the wind may lead can be harmful in terms of comfort conditions of both indoor and outdoor environment of the building/buildings to be constructed or just completed. The extent of discomfort to pedestrian varies from inducing slightly unpleasant feeling to producing a falling down hazard. Typically, the cause of frequent occurrences of strong wind at pedestrian area is primary related to the configuration of building structures and/or topography in the vicinity of the pedestrian area. Depending on the characteristics of the wind including magnitude, uniformity, ambient temperature, and so on, the level of disturbance to users of pedestrian areas can be different. In this context, the regions where Necmettin Erbakan University temporary education buildings are located have a fairly intensive topography in terms of wind. Therefore, detailed analysis of the inside regions and the surrounding areas of education buildings in particular are performed in terms of microclimatic comfort and indoor energy recovery. Especially, the topography where university campus temporary educational buildings are located has very high wind climate conditions compared to the city of Konya climate conditions. In this study, pedestrian-level wind conditions around N.E.U. campus buildings and in urban areas and the topography of campus settlements were analyzed through on-site measurement with Delta OHM microclimatic instruments. The purpose of this study is to investigate the pedestrian-level comfort conditions around the project buildings suggested by concept architects together with microclimatic measurements of comfort conditions, in the light of current topographic and climatic conditions presented by the head architect. However, presentation of these topographic and microclimatic measurements around currently completed temporary classrooms of the university campus have not yet been completed. The topography of the university campus, which is at an altitude higher than that of Konya centrum, is exposed to an extremely high wind velocity. The pedestrian-level comfort conditions are measured using Delta OHM instrument. The study also aims to compare pedestrian-level comfort conditions at locations of various buildings. In addition, outdoor comfort survey was also conducted in the campus area. However, measurement results of the microclimatic measurement device, DeltaOHM, are evaluated in this study. It can be observed from the results that pedestrian-level comfort of current campus settlements around the buildings reach very discomforting levels. Since the university’s topography varies between very high and very low temperature levels and wind velocity values, climatic comfort problems are observed in the area. Some reasons for the discomfort problems observed in current settlement are; incorrect use of climatic parameters, incorrect directions of buildings, thermal effects due incorrect selection of materials used in constructions of buildings. In order to achieve thermal comfort, more studies are required on pedestrian-level comfort, use of passive design techniques such as correct direction of buildings and correct selection of materials utilized in the buildings based on their thermal effects. This would help university campus buildings consume less energy and maximize people’s satisfaction.
41
Eugster, Werner, Carmen Emmel, Sebastian Wolf, Nina Buchmann, Joseph P. McFadden, and Charles David Whiteman. "Effects of vernal equinox solar eclipse on temperature and wind direction in Switzerland." Atmospheric Chemistry and Physics 17, no. 24 (December 18, 2017): 14887–904. http://dx.doi.org/10.5194/acp-17-14887-2017.
Анотація:
Abstract. The vernal equinox total solar eclipse of 20 March 2015 produced a maximum occultation of 65.8–70.1 % over Switzerland during the morning hours (09:22 to 11:48 CET). Skies were generally clear over the Swiss Alps due to a persistent high-pressure band between the UK and Russia associated with a rather weak pressure gradient over the continent. To assess the effects of penumbral shading on near-surface meteorology across Switzerland, air temperature data measured at 10 min intervals at 184 MeteoSwiss weather stations were used. Wind speed and direction data were available from 165 of these stations. Additionally, six Swiss FluxNet eddy covariance flux (ECF) sites provided turbulent measurements at 20 Hz resolution. During maximum occultation, the temperature drop was up to 5.8 K at a mountain site where cold air can pool in a topographic depression. The bootstrapped average of the maximum temperature drops of all 184 MeteoSwiss sites during the solar eclipse was 1.51 ± 0.02 K (mean ± SE). A detailed comparison with literature values since 1834 showed a temperature decrease of 2.6 ± 1.7 K (average of all reports), with extreme values up to 11 K. On fair weather days under weak larger-scale pressure gradients, local thermo-topographic wind systems develop that are driven by small-scale pressure and temperature gradients. At one ECF site, the penumbral shading delayed the morning transition from down-valley to up-valley wind conditions. At another site, it prevented this transition from occurring at all. Data from the 165 MeteoSwiss sites measuring wind direction did not show a consistent pattern of wind direction response to the passing of the penumbral shadow. These results suggest that the local topographic setting had an important influence on the temperature drop and the wind flow patterns during the eclipse. A significant cyclonic effect of the passing penumbral shadow was found in the elevation range ≈ 1700–2700 m a. s. l., but not at lower elevations of the Swiss Plateau. This contrasts with an earlier theory that the anticyclonic outflow should reach as far as ≈ 2400 km from the center of the eclipse, which would have included all of Switzerland during the 2015 eclipse. Thus, measurable effects of penumbral shading on the local wind system could be even found at ≈ 2000 km from the path of the eclipse (that is, Switzerland during the 2015 eclipse), and our results tend to lend support to a newer theory that the anticyclonic cold-air outflow from the center of the eclipse only extends ≈ 1600 km outwards, with cyclonic flow beyond that distance.
42
Paolucci, Roberto. "Numerical evaluation of the effect of cross-coupling of different components of ground motion in site response analyses." Bulletin of the Seismological Society of America 89, no. 4 (August 1, 1999): 877–87. http://dx.doi.org/10.1785/bssa0890040877.
Анотація:
Abstract The effect of cross-coupling between the three components of ground motion in the evaluation of site-response functions, such as standard spectral ratios (SSRs) and horizontal-to-vertical spectral ratios (HVSRs), is analyzed in this article. Numerical analyses of the seismic response of fully 3D geological structures, namely, a real topographic irregularity and an ideal stratigraphic inclusion, have been carried out to obtain a 3D transfer function in the form of a 3 × 3 matrix. Each element of this matrix contains the frequency response in the ith direction due to an input motion in the jth direction. A synthetic set of acceleration time histories at the surface of the geological irregularity has been created by convolution with the 3D transfer function, using as input motion different real multicomponent strong-motion accelerograms recorded at stiff-soil or rock sites. The SSRs and HVSRs are calculated and compared with the theoretical 3D transfer function in order to highlight the effect of cross-coupling terms. These are found to generate a rather large dispersion in the site-response functions, as well as response peaks that could be misleading in the interpretation of both numerical and observed spectral ratios.
43
Yadav, Sushma, Shalini Garg, Sakshi Joshi, Anil Gupta, Ankit Srivastava, and Shikha Dogra. "Topographic Distribution of Carious Lesion on Young Permanent Mandibular Molars and Its Relation to Periapical Index Score of Apical Periodontitis: A Radiographic Analysis." International Healthcare Research Journal 4, no. 11 (February 21, 2021): OR14—OR18. http://dx.doi.org/10.26440/ihrj/0411.02385.
Анотація:
INTRODUCTION: Caries in young permanent teeth progress rapidly resulting in early pulp involvement which further progresses into loss of mineralized tissue and severe periapical pathologies. The Periapical Index scoring system (PAI) proposed by Ørstavik et al. in 1986 is an invaluable diagnostic tool used to evaluate periapical lesion extent and severity by 2D digital intraoral periapical radiographic analysis with minimal radiation exposure and hence treatment planning.AIM: To evaluate the relationship of the surface distribution of caries in young permanent molars, pulpal involvement and periapical index (PAI) score with respect to individual root forming young permanent mandibular molars. MATERIALS AND METHOD: In this retrospective single-centre study, 100 pulpally involved carious young permanent mandibular molars were included, selected from the departmental records between August 2018-2019. Topographic distribution of caries and radiographic analysis (using PAI) was evaluated to see the effect of anatomical site of caries, individual anatomical form of root, and extent & severity of apical periodontitis developed.RESULT: No significant correlation between the site of caries involvement and PAI score was observed. PAI score for distal roots was higher(PAI> 2) as compared to mesial root for pulpally involved carious young permanent first molars (p-value mesial root-0.576 , distal root-0.591)CONCLUSION: PAI score is independent of the topographic distribution of caries and no correlation was observed. Periapical radiolucency does not depend on caries distribution, either it is mesial, distal or occlusal.
44
Danskin, Scott, Pete Bettinger, and Thomas Jordan. "Multipath Mitigation under Forest Canopies: A Choke Ring Antenna Solution." Forest Science 55, no. 2 (April 1, 2009): 109–16. http://dx.doi.org/10.1093/forestscience/55.2.109.
Анотація:
Abstract Evaluating the accuracy of global positioning system (GPS) receivers in applications under forest canopies has become an area of increasing interest. Reducing the error experienced by multipath present under forested conditions has also been a significant concern. We present results of assessing a choke ring antenna solution to the reduction of multipath effects under forest canopies. This system serves to increase the accuracy of positional fixes as well as provide a baseline for assessing multipath effects. We assessed these by comparing results to data collected by separate antenna configurations (yet same receiver) on varying slope positions and canopy conditions. Using a choke ring antenna, we found horizontal position accuracy of differentially corrected data to range from 0.32 to 0.88 m root mean square error reported at 95% confidence across a topographic gradient during leaf-on conditions. Under leaf-off conditions the horizontal position accuracy ranged from 0.35 to 0.69 m. Similar differentially corrected data collected using a standard beacon antenna showed that horizontal position accuracy ranged from 4.9 to 6.1 m during leaf-on conditions and from 3.3 to 5.8 m during leaf-off conditions. When sampled, the data from the two systems were collected within 1 minute of each other; thus, we assume a very similar plane and satellite arrangement. Coupled with topographic factors, a minimum multipath error effect could be determined for this receiver for given site conditions by taking the difference between the two levels of error.
45
Pang, H., S. Hou, S. Kaspari, and P. A. Mayewski. "Influence of regional precipitation patterns on stable isotopes in ice cores from the central Himalayas." Cryosphere 8, no. 1 (February 25, 2014): 289–301. http://dx.doi.org/10.5194/tc-8-289-2014.
Анотація:
Abstract. Several ice cores have been recovered from the Dasuopu (DSP) Glacier and the East Rongbuk (ER) Glacier in the central Himalayas since the 1990s. Although the distance between the DSP and the ER ice core drilling sites is only ~ 125 km, the stable isotopic record (δ18O or δD) of the DSP core is interpreted in previous studies as a temperature proxy, while the ER core is interpreted as a precipitation proxy. Thus, the climatological significance of the stable isotopic records of these Himalayan ice cores remains a subject of debate. Based on analysis of regional precipitation patterns over the region, we find that remarkable discrepancy in precipitation seasonality between the two sites may account for their disparate isotopic interpretations. At the ER core site, the Indian summer monsoon (ISM) precipitation is dominating due to topographic blocking of the moisture from westerlies by the high ridges of Mt. Qomolangma (Everest), which results in a negative correlation between the ER Δ18O or δD record and precipitation amount along the southern slope of the central Himalayas in response to the "amount effect". At the DSP core site, in comparison with the ISM precipitation, the wintertime precipitation associated with the westerlies is likely more important owing to its local favorable topographic conditions for interacting with the western disturbances. Therefore, the DSP stable isotopic record may be primarily controlled by the westerlies. Our results have important implications for interpreting the stable isotopic ice core records recovered from different climatological regimes of the Himalayas.
46
Arneitz, P., B. Meurers, D. Ruess, C. Ullrich, J. Abermann, and M. Kuhn. "Gravity effect of glacial ablation in the Eastern Alps – observation and modeling." Cryosphere Discussions 6, no. 6 (December 3, 2012): 4977–97. http://dx.doi.org/10.5194/tcd-6-4977-2012.
Анотація:
Abstract. Absolute gravity measurements have been regularly performed in the Austrian Eastern Alps since 1985 until present. A gravity increase of 300 nm s−2 has been observed so far. The gravity trend is explained by ablation effects within surrounding glaciers. Ice thickness changes derived from 3 successive glacier inventories of 1969, 1997 and 2006 are used for quantitative 3-D modeling based on rectangular prisms with basis areas of ≤ 8 m × 8 m. Local topographic changes due to man-made mass displacements close to the measuring site are modeled by a polyhedron approach. 2/3 of the observed gravity increase can be explained by the ablation model response and man-made effects. A positive trend of about 100 nm s−2 remains. The origin of the residual trend remains open. Correcting for geodynamical processes like Alpine uplift or postglacial deformation is expected to cause a slight increase of this trend. The observed gravity signal shows seasonal gravity variations as well which are probably due to snow cover effects but cannot be quantified due to the lack of appropriate snow cover information.
47
Arneitz, P., B. Meurers, D. Ruess, C. Ullrich, J. Abermann, and M. Kuhn. "Gravity effect of glacial ablation in the Eastern Alps – observation and modeling." Cryosphere 7, no. 2 (March 21, 2013): 491–98. http://dx.doi.org/10.5194/tc-7-491-2013.
Анотація:
Abstract. Absolute gravity measurements have been regularly performed in the Austrian Eastern Alps since 1985. A gravity increase of 300 nm s−2 has been observed so far. The gravity trend is explained by ablation effects within surrounding glaciers. Ice thickness changes derived from 3 successive glacier inventories of 1969, 1997 and 2006 are used for quantitative 3-D modeling based on rectangular prisms with basis areas of ≤ 8 m × 8 m. Local topographic changes due to man-made mass displacements close to the measuring site are modeled by a polyhedron approach. Two-thirds (2/3) of the observed gravity increase can be explained by the ablation model response and man-made effects. A positive trend of about 100 nm s−2 remains. The origin of the residual trend remains open. Correcting for geodynamical processes like Alpine uplift or postglacial deformation is expected to cause a slight increase of this trend. The observed gravity signal shows seasonal gravity variations as well, which are probably due to snow cover effects but cannot be quantified due to the lack of appropriate snow cover information.
48
Pampalone, Vincenzo, Alessio Nicosia, Vincenzo Palmeri, Maria Angela Serio, and Vito Ferro. "Rill and Interrill Soil Loss Estimations Using the USLE-MB Equation at the Sparacia Experimental Site (South Italy)." Water 15, no. 13 (June 28, 2023): 2396. http://dx.doi.org/10.3390/w15132396.
Анотація:
A reliable prediction of event soil loss at the plot scale can be obtained by Universal Soil Loss Equation (USLE)-type models. For the Sparacia site (South Italy), the USLE-MB model was recently developed, in which the effect of the erosive agent is modeled using the rainfall erosivity index of the USLE by a power b1 > 1 of the runoff coefficient QR. In this investigation, the model is parameterized separately using plot data collected for rill and interrill events that occurred in the Sparacia experimental area. The values b1 = 1.406 and b1 = 1.012 were obtained for the interrill and rill databases, respectively, which revealed a different effect of the runoff coefficient on soil loss due to the two erosive processes. Different relationships expressive of topographic factors were also deduced. The USLE-MB estimation performance significantly improved when operating the distinction between the two databases compared with the model parameterized on the complete database. The model was particularly reliable in estimating the highest event soil loss values, which were associated with the occurrence of rills. Finally, the proposed parameterization procedure lends itself to being tested in the framework of empirical soil loss modeling.
49
Xue, Yixuan, Xiaolin Zhu, Zihao Wu, and Si-Bo Duan. "Retrieval of Land Surface Temperature over Mountainous Areas Using Fengyun-3D MERSI-II Data." Remote Sensing 15, no. 23 (November 23, 2023): 5465. http://dx.doi.org/10.3390/rs15235465.
Анотація:
Land surface temperature (LST) is an important physical quantity in the energy exchange of hydrothermal cycles between the land and near-surface atmosphere at regional and global scales. However, the traditional thermal infrared transfer equation (RTE) and LST retrieval algorithms are always based on the underlying assumptions of homogeneity and isotropy, which ignore the terrain effect influence of a heterogeneous topography. It can cause significant errors when traditional RTE and other algorithms are used to retrieve LST in such mountainous research. In this study, the mountainous thermal infrared transfer model considering terrain effect correction is used to retrieve the mountainous LST using FY-3D MERSI-II data, and the in situ site data are simultaneously utilized to evaluate the performance of the iterative single-channel algorithm. The elevation of this study region ranges from 500 m to 2200 m, whereas the minimum SVF can reach 0.75. Results show that the spatial distribution of the retrieved LST is similar to topographic features, and the LST has larger values in the lower valley and smaller values in the higher ridge. In addition, the overall bias and RMSE between the retrieved LSTs and five in situ stations are respectively −0.70 K and 2.64 K, which demonstrates this iterative single-channel algorithm performs well in taking into account the terrain effect influence. Accuracy of the LST estimation is meaningful for mountainous ecological environmental monitoring and global climate research. Such an adjacent terrain effect correction should be considered in future research on complex terrains, especially with high spatial resolution TIR data.
50
Kamyo, Torlarp, Sura Pattanakiat, Lamthai Asanok, Khanitin Samanmit, Arnon Cherpaiboon, Sathid Thinkamphaeng, and Dokrak Marod. "Predicting the Natural Suitability of Teak (Tectona grandis L.f.) at Mae Yom National Park, Phrae Province, Thailand Using Logistic Regression Model." Journal of Environmental Science and Management 24, no. 2 (December 31, 2021): 48–53. http://dx.doi.org/10.47125/jesam/2021_2/05.
Анотація:
The natural suitability of teak (Tectona grandis L.f.) at Mae Yom National Park, Phrae Province, Thailand was investigated using logistic regression. The study identified the relationship between key physical and soil properties with the presence of teak at natural sites, and applied a geographic information system platform to identify potential natural sites of teak. Fourteen variables were included in the model, five of these were found to have a significant effect (p < 0.05). Elevation was the most significant topographic variable, whereas magnesium, organic matter, potassium, and calcium were the most significant soil variables. The site prediction had 91.8% accuracy for identifying areas with high, moderate, and low probabilities of being suitable natural habitats for teak. These areas covered 87.63, 244.33, and 163.54 km2, respectively.