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171.
Coastal ecosystems such as mangroves fringing tropical coastlines have been recognized as natural protectors of the coastal areas against destructive attack of a tsunami. In this paper, the authors aim to investigate the interaction of a tsunami wave on a typical mangrove forest and to determine its performance in reducing the run-up. A laboratory experiment using a hydraulic flume with a mangrove forest model was carried out in which tests were conducted by varying the vegetation widths of 0, 1, 2 and 3?m and average densities of 8, 6 and 4 trees per 100?cm2 using a scale ratio of 1:100. Two conditions of water levels were considered in the experiments at several tsunami wave heights between 2.4 and 14?cm. The dam break method used in the experiments produced two types of waves. At low water condition, a bore was developed and subsequently, a solitary wave was produced during high water. The results of the experiments showed that in general, vegetation widths and densities demonstrate a dampening effect on tsunami run-up. A larger vegetation width was found to be more effective in dissipating the wave energy. The first 1?m width of mangrove forest could reduce 23?C32?% during high water and 31?C36?% during low water. Increasing the mangrove forest width to 2 and 3?m could further increase the average percentage of run-up reduction by 39?C50?% during high water and 34?C41?% during low water condition. It was also observed that densities of the mangrove forest do not influence the run-up reduction as significantly as the forest widths. For mangrove forest densities to be significantly enough to reduce more tsunami run-up, an additional density of 4 trees/100?m2 needs to be provided. The experiments also showed that mangrove roots are more effective in reducing the run-up compared to the trunks and canopies. The experiments managed to compare and present the usefulness of mangrove forests in dissipating wave energy and results produced are beneficial for initiating design guidelines in determining setback limits or buffer zones for development projects in mangrove areas. 相似文献
172.
Ali Ismail Abdulla Al-Juboury 《Arabian Journal of Geosciences》2009,2(4):337-364
Petrographic, geochemical, and scanning electron microscope analyses of the sandstone and mudstone units of the Upper Miocene
Injana Formation are presented. Furthermore, microprobe analysis for amphiboles, pyroxenes, garnet, and chromian spinels as
common heavy mineral species present is done to support other results for better understanding of the provenance history of
the Injana Formation. The sandstones of the Injana Formation consist of terrigenous carbonate lithic fragments as common type
of sedimentary rock fragments in addition to chert, argillaceous, and rare sandstone fragments. They also include metamorphic
and igneous lithic fragments, quartz, feldspars, and mica and generally, the sandstones are lithic arenites and immature.
Scanning electron microscopic analysis for the heavy minerals shows that they have been affected by dissolution due to chemical
etching and mechanical abrasion through several surface texture generated either in arid and semihumid environment or in diagenetic
environment. Clay mineralogy of the mudstone units indicates the presence of illite, chlorite, kaolinite, palygorskite, and
illite–smectite mixed layers. Bulk-rock and mineral phase geochemistry in addition to petrographic data suggest the derivation
of the Injana Formation from a nearby sources with contribution from igneous, metamorphic, and sedimentary provenance mainly
from the high lands in the northeastern parts of Iraq which comprise mainly the Zagros mountains and the older sedimentary
formations. 相似文献
173.
Mohd S. Abu Jabal Ismail Abustan Mohd Remy Rozaimy Hussam El Najar 《Arabian Journal of Geosciences》2017,10(12):257
The present study research investigation is aimed to assess the groundwater quality for the urban area in Khan Younis City, southern Gaza Strip, for multi-domestic purposes. The physicochemical analysis of the groundwater wells shows the major ions in the order of Na+ > Mg2+ > Ca2+ > B3+ > K+ and Cl? > HCO3 ? > SO4 2? > NO3 2? > F? > PO4 3?. Groundwater quality is classified as very hard-brackish water type. Ninety-five percent of the wells are classified as saline water type with high NO3 2? concentrations. Based on water quality index (WQI), the groundwater falls into one of three categories: fair water (10%), poor water (15%), very poor (45%), and worst (30%). The high WQI values are because of high Na+, Cl?, SO4 2?, and NO3 2? concentrations, while synthetic pollution index (SPI) values indicate that most about 80% of the wells are seriously polluted. Langelier Saturation Index (LSI) indicates that most of data are either slightly scale forming or corrosive water or slightly corrosive but non-scale forming, and 75% of the wells are suitable for construction purposes (have SO4 2? concentrations <300 mg/L). The groundwater reaches alarming situation, where almost chemically unsuitable for drinking purposes and the water to be used after proper treatment such as desalination. 相似文献
174.
Landfilling is a common practice worldwide for solid waste management. The leachate generated at landfill sites contains various organic and inorganic pollutants while it should be treated properly. In this study, the electrocoagulation (EC) process was recognized for its simplicity and effectiveness which was used for the treatment of leachate from the Djebel Chakir landfill site in northern Tunisia. In addition, we investigated the effect of microorganisms (e.g., bacteria, fungi, spore) on sludge production by the application of autoclaving treatment on raw leachate. The application of low current density (15 mA/cm2) within 2 h of treatment and using Al-Al electrodes revealed significant improvement of performance when autoclaving was applied. The chemical oxygen demand (COD) and nitrogen removal increased from 39 to 64% and from 13 to 30%, respectively. The sludge volume was reduced from 40 to 10%, and thus, its handling and disposal costs would be significantly decreased. The energy consumption rate was stable after 40 min of treatment at about 0.8 kWh/kg COD removed. Our study shows that removal of microorganisms by autoclaving prior to the EC process is promising for landfill leachate treatment. However, since autoclaving is far from being practical and cost-effective at full-scale plant, research on coupling EC with an alternative disinfecting process might be of great interest. 相似文献
175.
Ismail Hilal Jamal Eddine Stitou El Messari Jesus Gabriel Moreno Navarro Mohamed Draoui 《Arabian Journal of Geosciences》2017,10(8):197
Preventive protection of surface waters against pollution and the guarantee of the best quality water are the major challenges to provide a sustainable supply of drinking water for the future generations. In this article, we present a hazard mapping application for water contamination of the dam “9 April 1947” located in the northwest of Morocco. This study was motivated by the proliferation of many pollution sources in the study area knowing that the dam feeds the region of Tanger-Asilah that has over 3 million inhabitants. The methodology used was applied for the first time in the city of Freiburg-Ebnet in Germany under the TECHNEAU project funded by the European commission and based on weighting of the different sources of contamination according to three indices: the toxicity index, quantity index, and probability index. The multiplication of the three indices has given us a hazard index named HI varying between 0 and 120 depending on the harmfulness of hazard; the later index has been used to create the final contamination hazard map. The hazard map shows 65% of the watershed area is witnessing a very low danger, 22% of the watershed area is witnessing a low danger, 10% of the watershed area is witnessing a the high danger, and 3% of the watershed area is witnessing a moderate. 相似文献
176.
This case study considers the early development and recent changes that have occurred in the vicinity of Joo Chiat Road, Singapore,
which can be described as a ‘linear activity corridor’ linking the districts of Geylang, Katong and Marine Parade, immediately
east of Singapore’s urban core. Singapore’s Urban Redevelopment Authority (URA) has declared Joo Chiat to be a ‘Conservation
Area’, reflecting local-born Peranakan and Eurasian cultures, with similar status to other more central historic sites such as Chinatown, Kampong Glam, Little India
and Emerald Hill. But the story of Joo Chiat has evolved along a somewhat different trajectory from the more prominent, tourism-related,
heritage areas, with a multiplicity of interactions operating at the margins of the planning process. This has led to the
spatial infusion of potentially discordant, globally related, ‘entertainment and recreational’ activities into an area of
established urban identity and multiple attachments. When a policy of police containment was found to be inadequate in protecting
local residents from undesirable impacts, changes were eventually brought about through a combination of neighbourhood activism
and local political initiative. Through detailed land use inspections, press reports and strategic interviews, backed up by
secondary sources, the study highlights the impingement of marginalised, potentially disruptive ‘global’ elements into a local
heritage conservation area, and the importance of strong neighbourhood identity and community involvement as active components
in the process of conflict resolution. 相似文献
177.
1 INTRODUCTIONThe use of marine mussels for the biomonitoringpurposes is widely found in the literatures. However,the use of a particular tissue/organ for more accurateindicators of metal bioavailability and contaminationwere continually reported. For exa… 相似文献
178.
Chee Kong Yap Ahmad Ismail Abdul Rahim Ismail Soon Guan Tan 《湿地科学》2006,4(4):247-252
The distribution and concentrations of Cd, Cu, Pb and Zn were determined in the gills and remaining soft tissues of Perna viridis collected from 12 geographical sites ( 10 from the west and 2 from the east coastal waters) of Peninsular Malaysia. All samples showed that the levels of Cd, Pb and Zn were generally higher in the gill than those in the remaining soft tissues. These results could be due to the fact that gills are the first organ of metal accumulation and larger surface area with mucus sheets in the organ. Since the mussel gill is a better accumulator of Cd, Pb and Zn of ambient seawater than remaining soft tissue, it is a potential indicator of ambient levels of dissolved metals in the ambient seawater. However, further validations based on laboratory conditions are needed. 相似文献
179.
Chee Kong Yap Ahmad Ismail Ching How Low Soon Guan Tan 《湿地科学》2007,5(4):311-321
Three different aquatic ecosystems(an urban pond,Kelana Jaya Pond;a polluted river,Sepang River;and the intertidal and offshore areas of the west coast of Peninsular Malaysia)with different sets of ecological backgrounds and human activities were reviewed and assessed for the levels of Cu and Zn contamination with special reference to those found in polluted sediments collected from the Sepang River.The discussion on the contamination levels of Cu and Zn in the aquatic environment of Peninsular Malaysia was based on a comparison of the metal contamination of 4 kinds of aquatic environments.The comparison of 4 different areas was based on ① total concentrations of 2 metals;② the concentrations and percentages of the nonresistant(EFLE,acid-reducible and oxidisable-organic)and resistant geochemical fractions;and ③ correlation coefficients(R-values)based on data of 4 areas separately and a combination of 4 areas.The Sepang River recorded nonresistant fractions of 63.1% for Zn and 55.8% for Cu in addition to slightly lower metal concentrations when compared to those(60%-70%)reported before the shutting down of the piggery activities in that area.These nonresistant metal percentages(55%-63%)indicated that the metal concentrations were still dominated by anthropogenic sources since nonresistant fraction of metals were mostly contributed by anthropogenic sources.The positive results from the four different aquatic environments assessed here provided strong evidence to show that Malaysia's aquatic environment had received anthropogenic Cu and Zn.The present study also showed that the percentage of the nonresistant fraction and the R-values based on correlation analysis of Cu and Zn could be used as indicators of Cu and Zn pollution in the Malaysian aquatic ecosystem.Based on the present data,the correlation coefficients(R-values)are potential indicators of EFLE Cu and acid-reducible Cu of the sediments.The use of R-values as indicators of metal pollution is suggested and it is applicable to other heavy metal data although it should be improved in future studies. 相似文献
180.
Inferring Low Cloud Base Heights at Night for Aviation Using Satellite Infrared and Surface Temperature Data 总被引:1,自引:0,他引:1
A nighttime image product that depicts areas of the lowest cloud base heights has been developed by combining brightness temperature
data from the Geostationary Operational Environmental Satellite (GOES) Imager InfraRed (IR) bands centered at 3.9 μm and 10.7
μm, with hourly shelter temperatures from surface observing sites and offshore marine buoys. A dependent data sample showed
a good correlation between the surface temperature minus IR cloud top temperature differences versus measured cloud base heights.
Histogram analysis indicated that a temperature difference of less than 4-C related to a > 50% frequency of ceilings below
1000 ft above ground level, the threshold for Instrument Flight Rules (IFR). Using this result as a model, an experimental
Low Cloud Base image product was developed that highlights regions of likely IFR ceilings. Validation of the Low Cloud Base
product for two separate periods resulted in Probabilities of Detection of 67% and 72% and False Alarm Rates of 6% and 11%,
respectively. Some regional variation observed could be related to the relative frequency of multi-layered overcast conditions.
The biggest factor leading to underdetection of IFR ceilings by the GOES Low Cloud Base product is the presence of overlying
clouds, including thin cirrus contamination. The GOES Low Cloud Base product shows potential for use as guidance for aviation
meteorologists over both continental and marine areas. 相似文献