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1.
Sensitivity analysis of automatic landslide mapping: numerical experiments towards the best solution
The automatic detection of landslides after major events is a crucial issue for public agencies to support disaster response. Pixel-based approaches (PBAs) are widely used in the literature for various applications. However, the accuracy of PBAs in the case of automatic landslide mapping (ALM) is affected by several issues. In this study, we investigated the sensitivity of ALM using PBA through digital terrain models (DTMs). The analysis, carried out in a study area of Poland, consisted of the following steps: (1) testing the influence of selected DTM resolutions for ALM, (2) assessing the relevance of diverse landslide morphological indicators for ALM, and (3) assessing the sensitivity to landslide features for a selected size of moving window (kernel) calculations for ALM. Ultimately, we assessed the performance of three classification methods: maximum likelihood (ML), feed-forward neural network (FFNN), and support vector machine (SVM). This broad analysis, as combination of grid cell resolution, surface derivatives calculation, and performance classification methods, is the challenging aspect of the research. The results of almost 500 experimental tests provide valuable guidelines for experts performing ALM. The most important findings indicate that feature sensitivity in the case of kernel size increases with coarser DTM resolution; however, the peak of the optimal feature performance for the selected study area and landslide type was demonstrated for a resolution of 20 m. Another finding indicated that in combining a set of topographic variables, the optimal performance was acquired for a DTM resolution of 30 m and the support vector machine classification. Moreover, the best performance of the identification is represented for SVM classification. 相似文献
2.
Kamila Sztybor Tine L. Rasmussen 《Boreas: An International Journal of Quaternary Research》2017,46(2):212-228
The effect of seeping of methane on marine sediment records has been studied in four gravity cores from Vestnesa Ridge, Svalbard margin. The area shows acoustic signs in the form of flares indicating active methane gas seepage. For a better understanding of the timing and variability of the flux of methane in the past and the effects on potential proxies, a detailed study of the diagenetic processes that may affect the composition and structure of both sediments and foraminiferal shells is needed. Here we discuss deep‐sea records from methane‐influenced environments in three cores from an active and very heterogeneous seep‐area (pockmark) and one core from outside the pockmark for background. The results include the distribution and stable isotopes of authigenic carbonates and of benthic and planktonic foraminifera, magnetic susceptibility, AMS‐14C dates, sedimentary data and biostratigraphy. Extremely low δ13C values recorded in both benthic and planktonic foraminifera during the Bølling‐Allerød interstadials indicate possible increased methane flux beginning at late Heinrich event H1. The recorded low values are mainly a result of diagenetic overprint by methane‐derived authigenic carbonates. The δ18O signals of authigenic carbonates are close to those of foraminiferal calcite and thus the δ18O records remain a valid stratigraphical tool in methane seep sites, except in the case of severely encrusted samples. In addition, the records from the active pockmark show nearly constant values of low magnetic susceptibility in contrast to higher and more variable magnetic susceptibility values from the control station and other published records from normal sediments west of Svalbard. This phenomenon is probably caused by dissolution of magnetic minerals in the reducing environmental conditions of methane seep sediments, associated with anaerobic oxidation of methane and formation of paramagnetic minerals (pyrite). This process enables magnetic susceptibility to be used as a common diagnostic tool for identifying methane‐related palaeo‐reductive environments. 相似文献
3.
Landslide features identification and morphology investigation using high-resolution DEM derivatives
Natural Hazards - In the last decade, development in remote sensing techniques has opened new avenues for studying the evolution of landscapes dominated by mass wasting processes. Conventional... 相似文献
4.
Kamila Wawrzyniak 《Acta Geophysica》2010,58(1):49-82
The paper deals with the application of time-frequency methods, Continuous Wavelet Transform (CWT) and Matching Pursuit algorithm
(MP), to acoustic full waveform processing. The goal of the research is to present possible ways of application of these methods,
particularly for the precise identification of selected acoustic waves, waveform decomposition into separate waves, and determination
of zones of different elastic parameters in the geological profiles.
The simulations, developed methodology, and results of each method are discussed in detail. The Continuous Wavelet Transform
is used to improve qualitative interpretation. Time-depth-frequency plots for a given frequency are constructed to distinguish
the waves and identify gas-bearing zones. The Matching Pursuit has a better resolution in time-frequency space than CWT; thus,
it is used to extract individual waves from the whole acoustic waveform, i.e., decompose the signal. For the extracted waves,
the slowness is calculated. Results from MP methods are compared with their counterpart parameters obtained from the original
waveforms. Additionally, time-frequency decompositions are used for the determination of the frequency content of each wave
packet to get unique information about formation in situ. 相似文献
5.
Distribution and feeding ecology of three juvenile mojarras in a hypersaline tropical estuary in Northeastern Brazil 
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下载免费PDF全文 Although mojarra species usually demonstrate a wide distribution in tropical and subtropical estuaries, relatively little is known about the process influencing the spatial resource partitioning to nearshore habitats. Therefore, the aim of this study was check the existence of habitat and food partitioning among confamiliar species in a hypersaline estuary. The dietary compositions of three co‐occurring species of mojarras were determined, using samples collected with a beach seine from an inverse tropical estuary in Northeastern Brazil, during the rainy and the dry seasons of 2012. Eucinostomus argenteus and Ulaema lefroyi were abundant throughout the year, while Eugerres brasilianus was most abundant during the rainy season. Although these mojarras were found together in all areas of the estuary, there was evidence of habitat partitioning: E. argenteus and E. brasilianus were dominant in areas with submerged vegetation, while U. lefroyi was most abundant in areas with little habitat complexity and minimal shelter. All mojarras consumed, to different degrees, zooplankton, Bivalvia and Polychaeta. However, E. brasilanus also consumed a considerable amount of algae. Although the niches of the mojarra species appeared to significantly overlap, some resource partitioning patterns were apparent. While E. brasilanus was clearly different along the trophic niche, segregation of the other species was more important with respect to the spatial dimension. The different feeding strategies appear to minimize inter‐specific overlap and allow the co‐occurrence of these species in this hypersaline tropical estuary. 相似文献
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7.
Kamila Wawrzyniak-Guz 《Acta Geophysica》2016,64(6):2356-2381
Mutual relationships between geological and geophysical data obtained by using methods of different scale are presented for the Miocene sandy-shaly thin-bedded formation and for the Zechstein carbonate formation. The common basis of laboratory results, well logging and seismic data was a recognition of elastic and reservoir properties of rocks. The common basis of laboratory results, well logging and seismic data were elastic and reservoir properties of rocks. Seismic attributes calculated from acoustic full waveforms were a link between the considered data. Seismic attributes strongly depend on small changes observed in rock formation related to lithology variations, facies changes, structural events and petrophysical properties variability. The observed trends and relationships of high correlation coefficients in the analysed data proved the assumption made at the beginning of research that common physical basis is a platform for data scaling. Proper scaling enables expanding the relationships determined from laboratory and well logging of petrophysical parameters to a seismic scale. 相似文献
8.
Żaneta Polkowska Mieczysław Sobik Marek Błaś Kamila Klimaszewska Barbara Walna Jacek Namieśnik 《Journal of Atmospheric Chemistry》2009,62(1):5-30
Hoarfrost and rime analysis was based on the collection of samples between 2003 and 2006 from 8 sites, which represent both
lowland (northern) and mountainous (southern) parts of Poland. On the other hand 4 of these sites belong to “urban” and 4
to “rural” category. pH, conductivity, SO42−, NO3−, Cl−, H+, NH4+, Ca2+, Mg2+, Na+, K+ have been determined in order to study the chemistry of hoarfrost and rime. Higher total inorganic ionic content (TIC) in
hoarfrost and rime (2.46 meq·l−1 and 1.23 meq·l−1 respectively) was observed when compared with precipitation (0.37 meq·l−1). Large variability of TIC and chemical composition of individual samples were typical at each of the measurement sites depending
on emission patterns, atmospheric conditions and local terrain topography. Higher concentrations of both hoarfrost and rime
occurred in southern (mountainous) rather than in northern (lowland) part of Poland which can be explained by worse pollutant
dispersion conditions in the south. The surprisingly low hoarfrost concentrations in urban coastal stations in the area of
the Bay of Gdansk were attributed to the cleaning effect of nocturnal breeze-type circulation, best pronounced in cool part
of the year. Due to relatively high pollutant concentration and long duration, hoarfrost and rime are at least significant
factors in environmental processes in different ecosystems in Poland. 相似文献
9.
Wojciech Tylmann Kamila Szpakowska Christian Ohlendorf Micha? Woszczyk Bernd Zolitschka 《Journal of Paleolimnology》2012,47(1):55-70
A three-year field study was conducted in Lake Suminko, Poland, to gain an understanding of the limnological variables that
influence the formation and spatial extent of annually laminated sediments in the lake. The water body is divided into three
depth strata, the mixolimnion, chemocline and monimolimnion, each defined by distinct values of temperature, electrical conductivity
and oxygen concentration. Typical for meromictic lakes, the monimolimnion remains perennially anoxic and is rich in dissolved
solids and nutrients. The annual pattern of particle flux in Lake Suminko is closely related to biochemical processes in the
euphotic zone. During winter months we observed very low accumulation rates of non-carbonaceous matter, while during the rest
of the year, three periods of calcite deposition were recorded (April, July–August, and October–November). The periods of
high calcite deposition corresponded with algal blooms and oxygen concentration maxima. Two principal factors contribute to
meromixis in Lake Suminko: (1) the basin is sheltered, preventing wind mixing, and (2) biochemical processes in the lake associated
with high lacustrine productivity. Meromictic conditions must control the formation and preservation of laminated sediments
in the lake because preserved laminations occur only in areas where the lake floor lies below monimolimnetic waters. 相似文献
10.
Żaneta Polkowska Kamila Skarżyńska Tadeusz Górecki Jacek Namieśnik 《Journal of Atmospheric Chemistry》2006,53(3):211-236
Formaldehyde levels were determined in various forms of atmospheric precipitation (rain, snow, road and roof runoff, throughfall) and deposition (rime, hoarfrost, dew) collected over twelve months at various locations in two large urban agglomerations and along two highways. HCHO was found in 303 of 500 samples analyzed, with concentrations ranging from 0.05 to 10.7 mg/dm3. The results confirmed the significant effect of vehicular traffic on formaldehyde levels in various forms of wet deposition. Correlations of formaldehyde levels with other parameters commonly monitored in precipitation and/or deposition were also examined. No correlation was found between HCHO levels and rain volume. On the other hand, positive correlations were found for hydrogen peroxide, non-sea-salt sulphate, nitrate, ammonia, and total organic carbon (TOC). In addition, the effect of selected meteorological parameters (temperature, wind speed, wind direction, rainfall) on the concentration of formaldehyde in various forms of precipitation and runoff (road runoff, roof runoff, throughfall) was studied. The only correlation found was that between HCHO concentration and daily rainfall. 相似文献