Assessment of characteristics and distinguished hydrological periods of a river regime     

Muhammad Abrar Faiz  Dong Liu  Muhammad Imran Khan  Tianxiao Li  Song Cui 《Environmental Earth Sciences》2018,77(21):729

This study was carried out to analyze the hydrological characteristics and assess the distinguished hydrological periods of Upper Indus Basin (UIB) Rivers of Pakistan. For this purpose, statistical analysis (variation coefficient, the auto-correlation coefficient, sequential Mann–Kendall’s test) and a proposed method for distinguishing hydrological periods (described in methodology section) were applied. The results revealed that all rivers reflect moderate variability. The results of auto-correlation displayed that the river flow observed at Astore gauging station only indicated independency, while for Gilgit, Hunza and Kachura guaging at Indus River exhibited 2, 2, 4-year lag. The mutation analysis indicated that after 1980, the change point occurred at all UIB rivers. During analysis, it was also observed that river regimes have the same hydrological periods (i.e., 4), but with different dates of occurrence. The Gilgit River showed a low high-flow hydrological period compared to Astore, Hunza and Kachora (Indus). This difference may be due to the river’s own area natural conditions. The current analysis may be helpful for planning and management of water resources, designing of hydraulic structures and to make better policies in response to agricultural water requirement downstream of UIB River.  相似文献   

Long-Term Power Transmission Failures in Southeastern Brazil and the Geophysical Environment     

Magda A. S. Duro  Pierre Kaufmann  Fernando C. P. Bertoni  Emilio C. N. Rodrigues  José Pissolato Filho 《Surveys in Geophysics》2012,33(5):973-989

High-voltage transmission networks represent a large electrical circuit just above the ground subjected to a number of transient overcharges of various kinds, some of which may lead to failures. Some failures might be related to anomalies of the geophysical environment. We have analyzed one unprecedented long series of transmission grid failures (9?years) on high-voltage networks located in S?o Paulo state, southeastern Brazil, from 1998 to 2006, which includes an important fraction of the past solar activity cycle 23. Ninety-five distinct failure causes were given by the power line operator to explain the transmission grid shut downs. Most failures were attributed to atmospheric discharges, corresponding to 1,957 failures out of a total of 4,572 for the whole period at 138?kV, and 170 out of 763 at 440?kV, respectively. They correspond to less than one ten thousandth of the actual number of atmospheric discharges recorded in the same area, demonstrating the grid’s high resilience to breakdowns due to lightning. A clear concentration of failures in the region’s thunderstorm season has been found. A significant 67 and 77?% reduction in the number of failure rates per year has been found for the 138 and 440?kV grids, respectively, for the period studied, in good correspondence with the decay in the sunspot numbers. No obvious correlation was found between power failures and the planetary index of geomagnetic activity or major geomagnetic storms in the period, either on short or on long time scales. Assuming that the dependence of the electrosphere/ionosphere-ground coupling on the external geophysical environment plays a major role in explaining the reduction in power failures as the solar cycle wanes, it is suggested that the increase in atmosphere conductivity caused by the larger cosmic ray flux then reduces the threshold voltage required to produce lightning strokes, so reducing their effectiveness in disrupting high-voltage power lines.  相似文献   

Monitoring toxic microalgae Ostreopsis (dinoflagellate) species in coastal waters of the Mediterranean Sea using molecular PCR-based assay combined with light microscopy   总被引：1，自引：0，他引：1  

Cecilia Battocchi  Magda Vila  Samuela Capellacci  Albert Reñé  Antonella Penna 《Marine pollution bulletin》2010,60(7):1074-7059

A molecular PCR-based assay was developed and applied to macrophyte and seawater samples containing mixed microphytobenthic and phytoplanktonic assemblages, respectively, in order to detect toxic Ostreopsis species in Mediterranean Sea. The specificity and sensitivity of the molecular PCR assay were assessed with both plasmidic and genomic DNA of the target genus or species using taxon-specific primers in the presence of background macrophyte DNA. The PCR molecular technique allowed rapid detection of the Ostreopsis cells, even at abundances undetectable within the resolution limit of the microscopy technique. Species-specific identification of Ostreopsis was determined only by PCR-based assay, due to the inherent difficulty of morphological identification in field samples. In the monitoring of the toxic Ostreopsis blooms PCR-based methods proved to be effective tools complementary to microscopy for rapid and specific detection of Ostreopsis and other toxic dinoflagellates in marine coastal environments.  相似文献   

Are strandline meiofaunal assemblages affected by a once-only mechanical beach cleaning? Experimental findings     

Gheskiere T  Magda V  Greet P  Steven D 《Marine environmental research》2006,61(3):245-264

The increasing usage of sandy beaches as recreational resources has forced regional authorities of many tourist countries to remove all litter of fabricated origin and natural wrack from the beach. Consequently, a variety of heavy equipment has been developed during the last decades and is now used almost daily at many beaches. A field experiment, following a 'before-after-control-impact' (BACI) design, was conducted at the strandline of De Panne (Belgium) to investigate the impacts of mechanical beach cleaning on the strandline-associated meiofaunal assemblages, focussing on the free-living nematodes. Natural strandline assemblages were exposed to a one-off 5 cm deep mechanical beach cleaning and observed for 24 h. Differences between cleaned plots and those from control plots in terms of decreased percentage of organic matter, decreased total abundance and changed community structure were noticed from immediately after the experimental cleaning onwards and recovered to initial values after the following high water. Any impacts due to cleaning on species richness, Pielou's evenness and taxonomic diversity were shown to be minor in relation to the daily changes. Recolonization in the cleaned sediments is assumed to occur from the underlying sediments initiated by the elevated water table during the rising tide.  相似文献   

Practical applications of a nonlinear approach to analysis of earthquake-induced liquefaction and deformation of earth structures   总被引：2，自引：0，他引：2  

Zhi-Liang Wang  Faiz I. Makdisi  John Egan 《Soil Dynamics and Earthquake Engineering》2006,26(2-4):231-252

Seismic stability, liquefaction, and deformation of earth structures are critical issues in geotechnical earthquake engineering practice. At present, the equivalent linear approach is considered the ‘state of practice’ in common use. More recently, dynamic analyses incorporating nonlinear, effective-stress-based soil models have been used more frequently in engineering applications. This paper describes a bounding surface hypoplasticity model for sand [Wang ZL. Bounding surface hypoplasticity model for granular soils and its applications. PhD Dissertation for the University of California at Davis, U.M.I. Dissertation Information Service, Order No. 9110679; 1990; Wang ZL, Dafalias YF, Shen CK. Bounding surface hypoplasticity model for sand. ASCE, J Eng Mech 1990;116(5):983–1001; Wang ZL, Makdisi FI. Implementing a bounding surface hypoplasticity model for sand into the FLAC program. In: Proceedings of the international symposium on numerical modeling in geomechanics. Minnesota, USA; 1999. p. 483–90] incorporated into a two-dimensional finite difference analysis program [Itasca Consulting Group, Inc. FLAC (Fast Lagrangian Analysis of Continua), Version 4. Minneapolis, MN; 2000] to perform nonlinear, effective-stress analyses of soil structures. The soil properties needed to support such analyses are generally similar to those currently used for equivalent linear and approximate effective-stress analyses. The advantages of using a nonlinear approach are illustrated by comparison with results from the equivalent linear approach for a rockfill dam. The earthquake performance of a waterfront slope and an earth dam were evaluated to demonstrate the model's ability to simulate pore-pressure generation and liquefaction in cohesionless soils.  相似文献   

Fishing in the past: Historical data on sea fisheries landings in Belgium     

Ann-Katrien Lescrauwaet  Heidi Debergh  Magda Vincx  Jan Mees 《Marine Policy》2010

In Belgium, centralized reporting on landings of sea fisheries at the species level started in 1929. This paper summarizes the process and the results of integrating time-series, based on fragmented and disperse data sources for the period 1929–1999. The resulting database contains data by species (41), by port of landing in Belgium (4) and in ‘foreign ports,’ and by fishing area of origin (31). After quality control, total reported landings over the period 1929–2008 amounted to 3,320,518 tonnes, of which 90% was landed in the Belgian ports. After a maximum of 75,370 tonnes in 1947, annual landings declined steadily to only 26% of this peak by 2008. Currently, landings are below those achieved in 1929. The most important species in terms of landings (1929–1999) were cod (17% of all landings) and herring (16%). In terms of economic value, sole (31%) and cod (15%) were the most valuable. Close to 73% of all landings originated from 5 of the 31 fishing areas. Twenty percent of all landings (1929–1999) originated from the ‘coastal waters’, while these waters contributed nearly 60% of all landed pelagic species and 55% of all landed ‘molluscs and crustaceans’. Compared to the currently available ICES data, this local database offers advantages in temporal coverage (data from 1929 onwards), temporal scale (monthly values), and at the taxonomic level. It also provides more detailed information at the spatial scale of the southern and central North Sea, and it is the only source of historical information on landings originating from the coastal waters. Given the importance of the shallow and productive ‘Flemish banks’ as a local source of food in historical and recent times, this data is valuable for further research on the productivity of the coastal ecosystem and the local impact of fisheries. The database broadens the historical view on fisheries, underlines the decline in landings since reporting started, and serves as a basis for further (fisheries) research and policy-making in Belgium.  相似文献   

Short-term changes in nematode communities from an abandoned intense sand extraction site on the Kwintebank (Belgian Continental Shelf) two years post-cessation   总被引：1，自引：0，他引：1  

Vanaverbeke J  Vincx M 《Marine environmental research》2008,66(2):240-248

We investigated short-term changes (two years) in nematode communities (density, diversity, biomass and community composition) in an area on the Kwintebank (Belgian Continental Shelf) that was closed for sand extraction activities and compared these patterns to nematode community characteristics from another area on the Kwintebank were sand extraction was still ongoing. Six stations were sampled in 2003 and 2004 and nematode community composition and univariate measures of diversity were compared with values obtained during the extraction period and with a "pre-impact situation" sampled in 1978. Although nematode density, diversity and biomass did not change two years after cessation of the exploitation, nematode community composition did and was more stable than in the extracted site. This is attributed to the absence of continuous disturbances associated with the extraction activities such as the creation and filling up of dredge furrows. As a consequence of the typical life history traits of nematodes, recovery seems to follow different pathways when compared to macrobenthic recovery from the same impact.  相似文献   

Diversity and Abundance of Scleractinian Corals in the East Coast of Peninsular Malaysia: A Case Study of Redang and Tioman Islands     

Akmal  Khodzori Fikri  Shahbudin  Saad  Faiz  Mohd Hanapiah Muhammad  Hamizan  Yusof Muhammad 《Ocean Science Journal》2019,54(3):435-456

Ocean Science Journal - The species lists of scleractinian hard corals in Peninsular Malaysia have not been updated for 15 years. The present study aimed to determine the diversity and abundance...  相似文献   

Effects of organic enrichment on nematode assemblages in a microcosm experiment   总被引：2，自引：0，他引：2  

Maickel Armenteros  Jos Andrs Prez-García  Alexei Ruiz-Abierno  Lisbet Díaz-Asencio  Yusmila Helguera  Magda Vincx  Wilfrida Decraemer 《Marine environmental research》2010,70(5):374-382

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Synthesis,Mechanism, and Performance Assessment of Zero‐Valent Iron for Metal‐Contaminated Water Remediation: A Review     

Sana Ullah  Palwasha Faiz  Siwen Leng 《洁净——土壤、空气、水》2020,48(9)

Recently, increased industrial and agriculture activities have resulted in toxic metal ions, which has increased public concern about the quality of surface and groundwater. Various types of physical, biological, and chemical approaches have been developed to remove surface and groundwater metal ions contaminants. Among these practices, zero‐valent iron (ZVI) is the most studied reactive material for environmental clean‐up over the last two decade and so. Although ZVI can remove the contaminants even more efficiently than any other reactive materials. However, low reactivity due to its intrinsic passive layer, narrow working pH, and the loss of hydraulic conductivity due to the precipitation of metal hydroxides and metal carbonates limits its wide‐scale application. The aim of this work is to document properties, synthesis, and reaction mechanism of ZVI for the treatment of metal ions from the surface and groundwater in recent 10 years (2008–2018). So far, different modified techniques such as conjugation with support, bimetal alloying, weak magnetic field, and ZVI/oxidant coupling system have been developed to facilitate the use of ZVI in various environmental remediation scenarios. However, some challenges still remain to be addressed. Therefore, development and research in this field are needed to overcome or mitigate these limitations.  相似文献