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361.
362.
This paper presents an approach to estimating the probability distribution of annual discharges Q based on rainfall-runoff modelling using multiple rainfall events. The approach is based on the prior knowledge about the probability distribution of annual maximum daily totals of rainfall P in a natural catchment, random disaggregation of the totals into hourly values, and rainfall-runoff modelling. The presented Multi-Event Simulation of Extreme Flood method (MESEF) combines design event method based on single-rainfall event modelling, and continuous simulation method used for estimating the maximum discharges of a given exceedance probability using rainfall-runoff models. In the paper, the flood quantiles were estimated using the MESEF method, and then compared to the flood quantiles estimated using classical statistical method based on observed data. 相似文献
363.
Mohammed A. Khairy Marit Kolb Christiane Schmidt Dieter W. Zachmann Alaa R. Mostafa Anwar A. EL‐Fiky Müfit Bahadir 《洁净——土壤、空气、水》2010,38(12):1184-1193
Sediment samples were collected from 30 different locations in Abu Qir Bay (Mediterranean Sea), East Alexandria, Egypt and analyzed for trace elements. The highest concentrations of most of the elements were observed in the nearshore stations in the vicinity of the major anthropogenic activities as industrial settlements, wastewater discharges, and agricultural drainage. In addition, mussel samples of Mactra corallina and Tapes decussata were collected corresponding to the sediment samples. Concentrations of As, Cd, Cr, Mn, and Zn in the mussel tissues were higher than concentrations in sediments, thus indicating their relatively high bioavailability. Sequential extraction procedure was performed on selected sediment samples. Significant correlations were observed between the concentrations of Cu, Mn, Pb, and Zn in the exchangeable fraction of the sediments and the corresponding tissues of M. corallina. The output of the risk assessment applied on the sediments revealed that adverse ecological effects to benthic species could occur and that a higher level of risk is expected from the exposure to Cd, Cr, Hg, and Zn. No adverse carcinogenic or non‐carcinogenic human health effects are expected from the consumption of the two mussel species from Abu Qir Bay. 相似文献
364.
Natural and anthropogenic influences in the northeastern coast of the Nile delta,Egypt 总被引:4,自引:0,他引:4
Landsat enhanced thematic mapper imagery (ETM) of 2002 and aerial photography of 1955, combined with published charts and
field observations were used to interpret coastal changes in the zone between Kitchener drain and Damietta spit in the northeastern
Nile delta, previously recognized as a vulnerable zone to the effects of any sea level rise resulting from global warming.
The interpretation resulted in recognition of several changes in nine identified geomorphological land types: beach and coastal
flat, coastal dunes, agricultural deltaic land, sabkhas, fish farms, Manzala lagoon, saltpans, marshes and urban centers.
Reclamation of vast areas of the coastal dunes and of Manzala lagoon added about 420 km2 to the agricultural deltaic land.
About 48 km2 of backshore flats, marshes, salt pans and Manzala lagoon have been converted to productive fish farms. The main
urban centers have expanded; nearly 12.1 km2 have been added to their areas, and new urban centers (Damietta harbor and the New Damietta city) with total area reach of
~35.3 km2 have been constructed at the expense of vast areas of Manzala lagoon, coastal dunes, and backshore flats. As a consequence
of human activities, the size of Manzala lagoon has been reduced to more than 65%. Shoreline changes have been determined
from beach profile survey (1990–2000), and comparison of 1955 aerial photographs and ETM satellite image of 2002 reveal alongshore
patterns of erosion versus accretion. The short-term rate of shoreline retreat (1990–2000) has increased in the downdrift
side of Damietta harbor (≃14 m/year), whereas areas of accretion exist within the embayment of Gamasa and in the shadow of
Ras El Bar detached breakwaters system, with a maximum shoreline advance of ~15 m/year. A sandy spit, 12 km long, has developed
southeast of Damietta promontory. These erosion/accretion patterns denote the natural processes of wave-induced longshore
currents and sediment transport, in addition, the impact of man-made coastal protection structures. 相似文献
365.
This paper compares the pattern of historical Eastern Nile Delta branches, delineated by geoelectric resistivity investigation, with the path of the Nile canyon of Messinian time revealed in seismic reflection. A close correlation is evident between the Late Quaternary Nile River channels and the Messinian canyons (wadies) in the eastern Nile Delta. This indicates that the Messinian canyons were a persistent topographic (or geomorphic) feature until historical branches. The results may also have implications for long-term patterns of subsidence in the delta area. 相似文献
366.
G. El Diwani Ph.D. S. El Rafie Ph.D. S. Hawash Ph.D. 《International Journal of Environmental Science and Technology》2009,6(3):369-378
Residue of methanolic extract of Egyptian Jatropha curcas contains bioactive substances such as phenolic compounds, which succeeded to be used as natural antioxidants for the protection of oils and their corresponding biodiesel against oxidative deterioration. In the present work, the residue of Jatropha roots were extracted with methanol and resulting residues, were investigated regarding their content of total phenolic compounds by folin-Cioalteau assay. Further, the antioxidant activities of the extracts were characterized by the 2,2-diphenyl-1-picrylhydrazyl radical method and proved remarkable results. Oxidation stability of Jatropha oil, used fried oil and olive oil and their corresponding biodiesel obtained by conventional transesterification were tested using thermal oxidation. Natural antioxidants such as (α-trocopherol), synthetic antioxidants as butylated hydroxytoluene and natural Jatropha root extract were used in the present study in comparison to investigate their addition effect on the oxidative stability of oils and their corresponding biodiesel. In the rapied thermal treatment test, results showed that addition of butylated hydroxytoluene 0.25 % was able to stabilize Jatropha oil 6 h, but poorly stabiliz biodiesel. Addition of 0.25 % α-trocopherol to Jatropha oil showed less oxidation stability after 2 h thermal treatment. Crude root extract addition at 0.25% to Jatropha oil showed good stability up to 4 h thermal treatment while addition of root extract at 0.25 % to biodiesel showed better stability up to 6 h thermal treatment. Besides addition of 220 ppm crude root extract to biodiesel was enough sufficient to occure oxidative stabilization. Also Jatropha root residue addition at 400 ppm was effective antioxidant for fresh Jatropha oil. 相似文献
367.
Thébault H Rodriguez Y Baena AM Andral B Barisic D Albaladejo JB Bologa AS Boudjenoun R Delfanti R Egorov VN El Khoukhi T Florou H Kniewald G Noureddine A Patrascu V Pham MK Scarpato A Stokozov NA Topcuoglu S Warnau M 《Marine pollution bulletin》2008,57(6-12):801-806
The common mussel Mytilus galloprovincialis was selected as unique biomonitor species to implement a regional monitoring programme, the CIESM Mediterranean Mussel Watch (MMW), in the Mediterranean and Black Seas. As of today, and upon standardization of the methodological approach, the MMW Network has been able to quantify (137)Cs levels in mussels from 60 coastal stations and to produce the first distribution map of this artificial radionuclide at the scale of the entire Mediterranean and Black Seas. While measured (137)Cs levels were found to be very low (usually < 1 Bq kg(-1) wet wt) (137)Cs activity concentrations in the Black Sea and North Aegean Sea were up to two orders of magnitude higher than those in the western Mediterranean Basin. Such effects, far from representing a threat to human populations or the environment, reflect a persistent signature of the Chernobyl fallout in this area. 相似文献
368.
369.
Ahmed M. El Kenawy Juan I. López-Moreno Sergio M. Vicente-Serrano Mohammed S. Mekld 《Theoretical and Applied Climatology》2009,98(1-2):1-8
This paper investigates spatial variability of temperature trends over Libya in the second half of the 20th century. The study is based on complete and homogeneous time series of minimum, maximum, and mean temperature for ten observatories. During the investigated period (1951–1999), temperature trend analyses have experienced a downward trend in the maximum surface temperature (about –0.06°C decade–1) and an upward trend in the minimum surface temperature (about 0.23°C decade–1). Cooling tendency in maximum temperature is spatially more pronounced in inland stations compared to coastal stations. At the seasonal scale, maximum temperature cooling is more obvious in winter and spring, meanwhile minimum temperature warming is more pronounced in summer and fall. In accordance with global trends, the surface mean temperature has moderately risen at an average rate of 0.09°C decade–1. However, this trend has shown considerable temporal variability considering a more pronounced upward trend in summer and fall. In conjunction with other regional and global investigations, clear trends towards smaller diurnal range are presented (–0.28°C decade–1). 相似文献
370.
Severe weather has important social and economic impacts. Some studies have indicated that its intensity may increase over this century as a consequence of climate change induced by greenhouse gases. This study aims to investigate the possibility of a future increase in deep convective events over North America resulting from the evolution of favourable atmospheric conditions. Our analysis is based on an ensemble of projections performed using the Canadian Regional Climate Model (CRCM) at 45?km resolution, driven by different Global Climate Models (GCMs) and reanalyses. We concentrate our study on Convective Available Potential Energy (CAPE), vertical wind shear, and convective precipitation. Based on two different approaches to linking atmospheric conditions and severe weather, we find that the number of extreme weather events is expected to increase during the twenty-first century. In agreement with other studies on this subject, we find that CAPE is expected to increase, whereas wind shear is expected to decrease slightly. Through the analysis of the CRCM's convective precipitation outputs, we show that severe convective liquid precipitation events may become both more frequent and slightly more intense. Sensitivity experiments show that results depend on the driving GCM although they confirm the general conclusions. Additional experiments conducted with reduced humidity input at the lateral boundaries show the significant role that the humidity level of the driving GCMs has on simulated extreme regional events. At the regional level results are, in general, consistent with those found at the continental scale, but large inter-regional variations exist. 相似文献