Changes in precipitation extremes over arid to semiarid and subhumid Punjab,Pakistan     

Farhat Abbas  Ashfaq Ahmad  Mohammad Safeeq  Shafaqat Ali  Farhan Saleem  Hafiz Mohkum Hammad  Wajid Farhad 《Theoretical and Applied Climatology》2014,116(3-4):671-680

Asymmetrical monsoons during the recent past have resulted into spatially variable and devastating floods in South Asia. Analysis of historic precipitation extremes record may help in formulating mitigation strategies at local level. Eleven indices of precipitation extremes were evaluated using RClimDex and daily time series data for analysis period of 1981–2010 from five representative cities across Punjab province of Pakistan. The indices include consecutive dry days, consecutive wet days, number of days above daily average precipitation, number of days with precipitation ≥10 mm, number of days with precipitation ≥20 mm, very wet days, extremely wet days, simple daily intensity index, maximum 1-day precipitation quantity, maximum 5 consecutive day precipitation quantity, and annual total wet-day precipitation. Mann-Kendall test and Sen’s slope extremes were used to detect trends in indices. Droughts and excessive precipitation were dictated by elevation from mean sea level with prolonged dry spells in southern Punjab and vice versa confirming spatial trends for precipitation extremes. However, no temporal trend was observed for any of the indices. Summer in the region is the wettest season depicting contribution of monsoons during June through August toward devastating floods in the region.  相似文献   

Modeling of Mrihla anticline (Central Tunisian Atlas), combination fault propagation fold and halokenitic model     

Chawki Khalfi  Riadh Ahmadi  Farhat Rhekiss  Hazem Trigui  Jamel Ouali 《Arabian Journal of Geosciences》2014,7(2):811-818

The modeling study on the Mrihla anticline was carried out using two techniques, i.e., excess area law and balanced cross section. The results show that this structure is likely affected by at least two compressive phases. The interpretation of surface (bedding dips, thickness, lithology, etc.) and subsurface (seismic lines) data along the cross section indicates that the Mrihla structure has a shortening of about 525 m that is evolved above a detachment layer formed by gypsum Triassic formation. The top of this layer is situated at a depth of about 3,890 m from the top of the Aptian dolomitic level, known in Central Tunisian Atlas as Serdj Formation. The kinematic of the investigated structure is a combination of two deformation models. The first is the halokenitic model, defined by the flowing of Triassic ductile material upward toward the surface through the deep Mrihla fault, which is parallel to Mrihla anticline. The second is the fault propagation fold model, characterized by thin-skin deformation mechanics in relation with the movement of the Mrihla fault.  相似文献   

High grade metamorphic zone in the basement of Wadi Araba,Jordan     

J.S. Farhat 《Precambrian Research》1978,6(1):A21-A22

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Treatment of secondary effluents by infiltration-percolation process using sand fortified with activated charcoal     

M. Bali  H. Jridi  S. Farhat  B. Louhichi  R. Boukchina 《International Journal of Environmental Science and Technology》2017,14(6):1209-1216

The main purpose of this study was to investigate the ability of sand/granular activated charcoal mixture medium to treat urban wastewater effluents. Several laboratory experiments were conducted to determine the best combination ratio of sand/activated charcoal which would allow the optimum water purification. A comparative study was undertaken to evaluate the effect of the addition of activated charcoal on infiltration-percolation efficiency. Experiments demonstrated that fortifying sand medium with granular activated charcoal improved the pollutants removal efficiencies. Results showed that a combination ratio of 3:1 (by volume) of sand and granular activated charcoal gave the best depuration efficiency regarding organic matter, nitrogen and orthophosphorous. The mean removal rates of COD, NH₄–N and PO₄–P were 83.29, 95.85 and 65.21%, respectively. Furthermore, experiments demonstrated that a mixture of sand/activated charcoal in a 3:1 ratio resulted in the optimum oxidation capacity.  相似文献   

Geochronologic investigations of the Sudbury Nickel Irruptive and the Superior Province granites north of Sudbury     

R.W. Hurst  J. Farhat 《Geochimica et cosmochimica acta》1977,41(12):1803-1815

RbSr ($\text{λ}\text{Rb}\text{= 1.39 × 10}{}^{\mathrm{?11}}\text{yr}{}^{\mathrm{?1}}\text{)}$ and U-Pb ($\text{λ 238 = 1.54 × 10}{}^{\mathrm{?10}}\text{yr}{}^{\mathrm{?1}}\text{, λ235 = 9.72 × 10}{}^{\mathrm{?10}}\text{yr}{}^{\mathrm{?1}}$) measurements were undertaken in the Sudbury area, Sudbury, Ontario to determine the ages of the Sudbury Nickel Irruptive, Superior Province granites north of Sudbury, Sudbury Breccia and subsequent metamorphism. The Sudbury Nickel Irruptive norite whole rock Rb-Sr data yield an age of $\text{1883 ± 136}\text{Myr}$ ($\text{I.R}\text{. = 0.7071 ± 0.0005}$; all results quoted at 2π level) while the Nickel Irruptive micropegmatite Rb-Sr system has been disturbed and does not yield an isochron. A plagioclase-whole rock pair from the norite near the norite-micropegmatite transition yields an age of 1866 Myr, which when taken in conjunction with field (Stevenson and Colgrove, 1968) and geochemical (Naldrettet al., 1970, 1972) data does not support the conclusion of gibbins and McNurr (1972) that the micropegmatite is a later intrusion rather than a differentiate of the magma which produced the norite. Rb-Sr studies of the Superior Province granites north of Sudbury yield an age of $\text{2698 ± 162}\text{Myr}$ ($\text{I.R.}\text{= 0.7019 ± 0.0012}$). U-Pb zircon studies of these granites and granitic clasts within the Sudbury Breccia yield an age of $\text{2.71 ± 0.05}$ Byr and suggest the breccia granitic clasts were derived from the Superior Province granites. The granitic rocks ~150 km north of Sudbury have been undisturbed for ~ 2.6 Byr based on Rb-Sr mineral studies, whereas the granites and Sudbury Breccia within ~ 15 km of the Nickel Irruptive, as well as the Sudbury norite at the perimeter of the Irruptive have been disturbed by the Penokean Orogeny 1.7–1.75 Byr ago. The Penokean event appears to have overprinted isotopic evidence of the Sudbury impact event at least in the area studied.  相似文献   

Bartonian orthophragminids with new endemic species from the Pirkoh and Drazinda formations in the Sulaiman Range,Indus Basin,Pakistan     

Nowrad Ali  Ali Osman Yücel  Muhammad Hanif  Syed Irfanullah Hashmi  Farhat Ullah 《Geodinamica Acta》2018,30(1):31-62

The Pirkoh and Drazinda formations in the Sulaiman Range, central Pakistan, yielded assemblages of (early) Bartonian orthophragminids, characterized predominantly by discocyclinids with a significant number of species probably endemic to Indian Subcontinent. The rarity of Asterocyclina and the absence of Orbitoclypeus and Nemkovella are noteworthy. Ten species of Discocyclina Gümbel and two species of Asterocyclina Gümbel, referable to the Shallow Benthics Zone (SBZ) 17 are described for the first time from Pakistan. The discocyclinids, i.e. Discocyclina praeomphalus, D. sulaimanensis, D. kutchensis, along with the new taxa established here, D. zindapirensis sp. nov., D. rakhinalaensis sp. nov., and D. pseudodispansa sp. nov., seem to be confined to the Indo-Pakistani region (Eastern Tethys). The Discocyclina dispansa, D. discus, D. nandori, and D. augustae lineages known from Western Tethys are also common in the Indian Subcontinent, as are asterocyclinids, such as Asterocyclina sireli and A. stellata. The upper part of the Drazinda Formation (‘Pellatispira beds’), referable to latest Bartonian and/or the early Priabonian, is poor in orthophragminids and is characterized by the occurrence of reticulate Nummulites, Heterostegina, Pellatispira and Silvestriella. The records of ‘Lepidocyclina of Caribbean affinity’ with large embryons from the Eocene of the Indian Subcontinent correspond to misidentified Discocyclina discus.  相似文献   

GIS技术在城市地下水重金属浓度识别与分级中的应用（英文）     

Sobia Ashraf  Farhat Abbas  Muhammad Ibrahim  Umer Rashid  Shoaib Khalid  Hammad Raza Ahmad  Khalid Rehman Hakeem  Tahir Majeed 《地理学报(英文版)》2015,(2):225-235

Groundwater is the most appropriate and widely used source of drinking water,which is increasingly threatened by pollution from industrial and agricultural activities.To check the severity of the problem,156 groundwater samples were collected from various depths(60-110 ft) of 52 different localities in Faisalabad city,the third largest metropolis in Pakistan,and analyzed for the metals(Zn,Cu,Cd,Ni,Pb,Mn and Fe) concentration in 2009.Quantification was done by using Flame Atomic Absorption Spectrophotometer technique and the results were compared with WHO standards for drinking water quality.Results showed that the levels of Cu,Mn and Fe were below the WHO standards while the concentrations of Zn,Cd,Ni and Pb were above the recommended levels of safe drinking water.Correlation analysis among the occurrence of these heavy metals revealed a highly significant and positive correlation of Mn with Zn and Fe.A significant and positive correlation of Cd was also found with Cu and groundwater depth showing that there is strong association between Cu-Cd pair and that the Cd concentration varies with depth of groundwater in the study area.Regional patterns of heavy metals occurrence were mapped using Geographical Information System(GIS) for the identification and demarcation of risk areas.The concentration maps may be used by policymakers of the city to mitigate groundwater pollution.  相似文献   

Characterization and Source History Modeling Using Low‐k Zone Profiles at Two Source Areas          下载免费PDF全文

David T. Adamson  Steven W. Chapman  Shahla K. Farhat  Beth L. Parker  Phillip deBlanc  Charles J. Newell 《Ground Water Monitoring & Remediation》2015,35(2):52-69

Like tree rings, high‐resolution soil sampling of low‐permeability (low‐k) zones can be used to evaluate the style of source history at contaminated sites (i.e., historical pattern of concentration and composition vs. time since releases occurred at the interface with the low‐k zone). This is valuable for the development of conceptual site model (CSM) and can serve as an important line of evidence supporting monitored natural attenuation (MNA) as a long‐term remedy. Source histories were successfully reconstructed at two sites at Naval Air Station Jacksonville using a simple one‐dimensional (1D) model. The plume arrival time and historical composition were reconstructed from the time initial releases that were suspected to occur decades earlier. At the first site (Building 106), the source reconstructions showed relatively constant source concentrations, but significant attenuation over time in the downgradient plume in the transmissive zone, suggesting MNA may not be an appropriate remedy if source control is a requirement, but attenuation processes are clearly helping to maintain plume stability and reduce risk. At the second site (Building 780), source concentrations in the transmissive zone showed an approximately a one order of magnitude over time, but apparently less attenuation in the downgradient plume. The source reconstruction method appeared to reflect site remediation efforts (excavation, soil vapor extraction) implemented in the 1990s. Finally, a detailed analysis using molecular biological tools, carbon isotopes, and by‐products suggests that most degradation activity is associated with high‐k zones but not with low‐k zones at these source areas. Overall, the source reconstruction methodology provided insight into historical concentration trends not obtainable otherwise given the limited long‐term monitoring data.  相似文献   

An assessment of the potential impact of climate change on flood risk in Mumbai   总被引：2，自引：1，他引：1  

Nicola Ranger  St��phane Hallegatte  Sumana Bhattacharya  Murthy Bachu  Satya Priya  K. Dhore  Farhat Rafique  P. Mathur  Nicolas Naville  Fanny Henriet  Celine Herweijer  Sanjib Pohit  Jan Corfee-Morlot 《Climatic change》2011,104(1):139-167

Managing risks from extreme events will be a crucial component of climate change adaptation. In this study, we demonstrate an approach to assess future risks and quantify the benefits of adaptation options at a city-scale, with application to flood risk in Mumbai. In 2005, Mumbai experienced unprecedented flooding, causing direct economic damages estimated at almost two billion USD and 500 fatalities. Our findings suggest that by the 2080s, in a SRES A2 scenario, an ??upper bound?? climate scenario could see the likelihood of a 2005-like event more than double. We estimate that total losses (direct plus indirect) associated with a 1-in-100 year event could triple compared with current situation (to $690?C$1,890 million USD), due to climate change alone. Continued rapid urbanisation could further increase the risk level. The analysis also demonstrates that adaptation could significantly reduce future losses; for example, estimates suggest that by improving the drainage system in Mumbai, losses associated with a 1-in-100 year flood event today could be reduced by as much as 70%.,We show that assessing the indirect costs of extreme events is an important component of an adaptation assessment, both in ensuring the analysis captures the full economic benefits of adaptation and also identifying options that can help to manage indirect risks of disasters. For example, we show that by extending insurance to 100% penetration, the indirect effects of flooding could be almost halved. We conclude that, while this study explores only the upper-bound climate scenario, the risk-assessment core demonstrated in this study could form an important quantitative tool in developing city-scale adaptation strategies. We provide a discussion of sources of uncertainty and risk-based tools could be linked with decision-making approaches to inform adaptation plans that are robust to climate change.  相似文献   

Contaminant plume classification system based on mass discharge   总被引：1，自引：0，他引：1  

Newell CJ  Farhat SK  Adamson DT  Looney BB 《Ground water》2011,49(6):914-919

Estimation of mass discharge has become an increasingly valuable analysis technique at sites with contaminated groundwater plumes. We propose a simple plume magnitude classification system based on mass discharge comprised of 10 separate magnitude categories, such as a "Mag 7 plume." This system can be a useful tool for scientists, engineers, regulators, and stakeholders to better communicate site conceptual models, prioritize sites, evaluate plumes both spatially and temporally, and determine potential impacts.  相似文献