Hydrological trend analysis with innovative and over-whitening procedures   总被引：1，自引：0，他引：1  

Zekâi Şen 《水文科学杂志》2017,62(2):294-305

Different statistical methodologies can be employed to identify possible trend components in any hydro-meteorological time series. A pre-whitening (P-W) procedure has been suggested to reduce the serial correlation effect on Mann-Kendall (M-K) trend analysis. In this paper, instead of P-W, an over-whitening (O-W) procedure is suggested, which generates serially independent series with the same trend slope value. Analytically necessary formulations for O-W are presented with a non-parametric but simple innovative trend assessment procedure, which are supported by extensive simulation studies. The applications of the methodology are presented for eight factual time series records from tropical, temperate and arid regions including temperature, rainfall, streamflow, relative humidity and CO₂ concentrations for different short and long durations. Relative humidity and CO₂ records are monthly time series and, hence, there are trend and periodicity components. It is noticed in all cases that the natural trends remain as they were after the O-W procedure, thus providing an opportunity to determine reliably the trends embedded even in the serially dependent series. The O-W procedure is applicable even in the cases of periodicity in the original records.  相似文献   

Dip‐adaptive singular‐value decomposition filtering for seismic reflection enhancement     

Milton J. Porsani  Bjorn Ursin  Michelângelo G. Silva  Paulo E. M. Melo 《Geophysical Prospecting》2013,61(1):42-52

We present a singular value decomposition (SVD) filtering method for the enhancement of coherent reflections and for attenuation of noise. The method is applied in two steps. First normal move‐out (NMO) correction is applied to shot or CMP records, with the purpose of flattening the reflections. We use a spatial SVD filter with a short sliding window to enhance coherent horizontal events. Then the data are sorted in common‐offset panels and the local dip is estimated for each panel. The next SVD filtering is performed on a small number of traces and a small number of time samples centred around the output sample position. Data in a local window are corrected for linear moveout corresponding to the dips before SVD. At the central time sample position, we sum over the dominant eigenimages of a few traces, corresponding to SVD dip filtering. We illustrate the method using land seismic data from the Tacutu basin, located in the north‐east of Brazil. The results show that the proposed method is effective and is able to reveal reflections masked by ground‐roll and other types of noise.  相似文献   

The Strandja Massif and the İstanbul Zone were once parts of the same palaeotectonic unit: new data from Triassic detrital zircons     

Semih Can Ülgen  Nalan Lom  Gürsel Sunal  Axel Gerdes  Ali Mehmet Celâl Şengör 《Geodinamica Acta》2018,30(1):212-224

Spatially continuous rock assemblages that share similar environmental evolution or structural features can be classified as a single tectonic unit. This approach enables to link dispersed units or massifs with each other and sometimes can be subjective, depending on the classification criteria. The relationship and the nature of the contact between the Strandja Massif and the ?stanbul Zone have been controversial due to the Cainozoic cover. Amalgamation of these units was claimed as early as the Aptian-Albian.

Lower Triassic sedimentary rocks, which are overlain by the Carboniferous flysch with a N-verging thrust fault are exposed NW of the ?stanbul Zone. This study reveals the spatial relationship between the Strandja Massif and the ?stanbul Zone deduced from the U-Pb dating and Lu-Hf isotopes of the detrital zircons from these Lower Triassic clastics. Our results show that the early Triassic basin was fed from a provenance that included arc-related Upper Carboniferous-Lower Permian magmatic rocks which is much more likely to be the Strandja Massif than the ?stanbul Zone. The second outcome of this study is that a unit that previously assigned to Palaeozoic turned out to be Triassic, which brings the Strandja Massif farther to the east, into the northern ?stanbul Zone.  相似文献   

GIS-based analysis of the Stream Length-Gradient Index for evaluating effects of active tectonics: a case study of Enfidha (North-East of Tunisia)     

Abdelkader Moussi  Noamen Rebaï  Ali Chaieb  Abdeljaouad Saâdi 《Arabian Journal of Geosciences》2018,11(6):123

Our study aims at calculating morphometric indices through the recourse to the Digital Elevation Model (DEM) and its attributes (hydrographic networks, watersheds, and reliefs). This quantitative measurement is used for the morphotectonical analysis of the Enfidha area (North-East of Tunisia) in the GIS environment and statistical platform. The Enfidha area is selected to analyze and identify neotectonic morphostructures on basis of the morphological evolution of the landscape. The coastal Enfidha plain is part of the Tunisian Sahel that is marked by its instability and frequent earthquakes that prove the presence of the recent deformation and active subsurface faults. This morphometric modeling in the geological investigation area reflects the morphotectonic spatial evolution in the Quaternary basins areas. Stream length (SL) proposed by Hack (1973) and denominated by Etchebehere et al. (2004) Revista do Instituto de Geociências USP, Série Científica, São Paulo 4(2):43–56 as the RDE index (Relation Declivity Extension) was used for application in the studies of neotectonic approach. RDE index is one of the morphotectonical indices that designates the tectonics anomalies in rivers. The variability in (RDE) values can indicate both a lithology resistance towards erosion and major active subsurface faults or low slope. Our geostatistical method is required to obtain RDE index maps based on lithological filtrations and value interpolations which are calculated in a drainage line network. This method calculates, measures, and validates spatial distribution of hack RDE index through a high statistical accuracy in a quantitative anomalies study. The RDE anomaly maps of the study area mirror the concurrence between anomaly zones, major active subsurface E-W faults, and local geological discontinuities related to neotectonical activities that affect the hydrographic network. This study proves that the RDE index can be especially used to detect the influence of active large-scale faults on the landscape evolution.  相似文献   

Capability of LISEM to estimate flood hydrographs in a watershed with predominance of long-duration rainfall events     

Vargas  Marcelle Martins  Beskow  Samuel  de Mello  Carlos Rogério  de Moura  Maíra Martim  Nunes  Maria Cândida Moitinho  Faria  Lessandro Coll  Aquino  Leandro Sanzi 《Natural Hazards》2021,109(1):593-614

Natural Hazards - Process-based hydrological models are of great importance to understand hydrological processes and support decision making. The LImburg Soil Erosion Model (LISEM) requires...  相似文献   

A combined structural and seasonal approach to assess wildfire susceptibility and hazard in summertime     

Bergonse  Rafaello  Oliveira  Sandra  Gonçalves  Ana  Nunes  Sílvia  da Câmara  Carlos  Zêzere  José Luis 《Natural Hazards》2021,106(3):2545-2573

Natural Hazards - Wildfire susceptibility and hazard models based on drivers that change only on a multiyear timescale are considered of a structural nature. They ignore specific short-term...  相似文献   

Porosity and mineralogy evolution during the decay process involved in the Chellah monument stones     

Abderrahim Samaouali  Larbi Laânab  Mohamed Boukalouch  Yves Geraud 《Environmental Earth Sciences》2010,59(6):1171-1181

The objective of this work is to study the decay process involved in the historical Roman Chellah located in the Rabat city (Morocco). This monument is made up of porous calcarenite stone. Several samples, taken from altered and unaltered blocks, were analyzed by the water saturation, the mercury intrusion porosimetry techniques and using the scanning electron microscopy coupled to energy dispersive X-ray spectrometer (SEM–EDX). To perform a reliable chemical analysis, some samples were also analyzed by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The mercury porosimetry results show a bimodal porous network for this porous material, the deterioration process of these stones involved an increase in porous volume of about 2%. The lowest porosity observed in the unaltered block is connected to the presence of sparitic cement which causes a partial inter-granular porosity clogging. The highest porosity of the deteriorated block without crust is due to the increase in inter-granular space. SEM photographs of the unaltered sample show the presence of the porous primary grains, of ovoid forms and millimeter-length sizes, and of the secondary grains, of rhombohedric forms and micro size. Porosity is essentially located between the primary grains and can be completely clogged by secondary precipitations. Various forms of deterioration are observed on the altered samples such as the dissolution of the secondary grains edges, wells of dissolution and also the presence of argillaceous residues on the surface. This last was also detected by the ICP-AES and EDX analysis which show an increase of the silicon and aluminum contents toward the surface.  相似文献   

A New Probabilistic Seismic Hazard Analysis for the Vrancea (Romania) Seismogenic Zone     

Mäntyniemi  P.  Mârza  V.  Kijko  A.  Retief  P. 《Natural Hazards》2003,29(3):371-385

In this paper we apply a probabilistic methodology to map specific seismic hazard induced by the Vrancea Seismogenic Zone, which represents the uttermost earthquake danger to Romania as well as its surroundings. The procedure is especially suitable for the estimation of seismic hazard at an individual site, and seismic hazard maps can be created by applying it repeatedly to grid points covering larger areas. It allows the use of earthquake catalogues with incompletely reported historical and complete instrumental parts. When applying themethodology, special attention was given to the effect of hypocentral depth and the variation of attenuation according to azimuth. Hazard maps specifying a 10% chance of exceedance of the given peak ground acceleration value for an exposure time of 50 years were prepared for three different characteristic depths of earthquakes in the Vrancea area. These maps represent a new realistic contribution to the mitigation of the earthquake risk caused by the Vrancea Seismogenic Zone in terms of: (1) input data (consistent, reliable, and the most complete earthquake catalogue), (2) appropriate and specific attenuation relationships (considering both azimuthal and depth effects); and (3) a new and versatile methodology.  相似文献   

On the Correction of Spatial and Statistical Uncertainties in Systematic Measurements of 222Rn for Earthquake Prediction     

Fatih Külahcı  Zekâi Şen 《Surveys in Geophysics》2014,35(2):449-478

In earthquake prediction studies, the regional behaviour of accurate ²²²Rn measurements at a set of sites plays a significant role. Here, measurements are obtained using active and passive radon detector systems in an earthquake-active region of Turkey. Two new methods are proposed to explain the spatial behaviours and the statistical uncertainties in the ²²²Rn emission measurements along fault lines in relation to earthquake occurrence. The absolute point cumulative semivariogram (APCSV) and perturbation method (PM) help to depict the spatial distribution patterns of ²²²Rn in addition to the joint effects of the K _dr, the radon distribution coefficient, and the perturbation radon distribution coefficient (PRDC). The K _dr coefficient assists in identifying the spatial distributional behaviour in ²²²Rn concentrations and their migration along the Earth’s surface layers. The PRDC considers not only the arithmetic averages but also the variances (or standard deviations) and the correlation coefficients, in addition to the size of the error among the ²²²Rn measurements. The applications of these methodologies are performed for 13,000 ²²²Rn measurements that are deemed to be sufficient for the characterization of tectonics in the Keban Reservoir along the East Anatolian Fault System (EAFS) in Turkey. The results are evaluated for the ?çme earthquake (M _L 5.4, 5.7 km, 23 June 2011), which occurred in the vicinity of the EAFS.  相似文献   

Response of estuarine meio- and macrofauna to in situ bioremediation of oil-contaminated sediment     

Schratzberger M  Daniel F  Wall CM  Kilbride R  Macnaughton SJ  Boyd SE  Rees HL  Lee K  Swannell RP 《Marine pollution bulletin》2003,46(4):430-443

Numerous studies have demonstrated the efficacy of bioremediation for enhancing oil removal but the ecological effect on shoreline biota is unclear. Therefore, a field experiment was designed at an intertidal sandflat in SW England to assess the effects of nutrient addition to oiled sediments on meio- and macrofauna for a period of up to 45 weeks. Natural assemblages were exposed to different types of experimental treatments (no oil, oil alone, oil treated with slow-release fertiliser or liquid fertiliser). Bioremediation stimulated the microbial population and increased oil biodegradation. This, however, did not result in faster recolonisation rates of fertilised versus non-fertilised oiled sediments. Mild effects of oil and bioremediation treatments on benthic fauna were observed, including short-term shifts in dominance patterns. Decreased abundance of dominant species in the oiled compared to unoiled sediments resulted in significantly higher evenness of benthic assemblages within the first 11 weeks of the experiment.  相似文献