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1.
Nature,origin and evolution of a Late Pleistocene incised valley‐fill,Sunda Shelf,Southeast Asia 下载免费PDF全文
Faisal A. Alqahtani Howard D. Johnson Christopher A.‐L. Jackson Mohd Rapi B. Som 《Sedimentology》2015,62(4):1198-1232
Understanding the stratigraphic fill and reconstructing the palaeo‐hydrology of incised valleys can help to constrain those factors that controlled their origin, evolution and regional significance. This condition is addressed through the analysis of a large (up to 18 km wide by 80 m deep) and exceptionally well‐imaged Late Pleistocene incised valley from the Sunda Shelf (South China Sea) based on shallow three‐dimensional seismic data from a large (11 500 km2), ‘merge’ survey, supplemented with site survey data (boreholes and seismic). This approach has enabled the characterization of the planform geometry, cross‐sectional area and internal stratigraphic architecture, which together allow reconstruction of the palaeo‐hydrology. The valley‐fill displays five notable stratigraphic features: (i) it is considerably larger than other seismically resolvable channel forms and can be traced for at least 180 km along its length; (ii) it is located in the axial part of the Malay Basin; (iii) the youngest part of the valley‐fill is dominated by a large (600 m wide and 23 m deep), high‐sinuosity channel, with well‐developed lateral accretion surfaces; (iv) the immediately adjacent interfluves contain much smaller, dendritic channel systems, which resemble tributaries that drained into the larger incised valley system; and (v) a ca 16 m thick, shell‐bearing, Holocene clay caps the valley‐fill. The dimension, basin location and palaeo‐hydrology of this incised valley leads to the conclusion that it represents the trunk river, which flowed along the length of the Malay Basin; it connected the Gulf of Thailand in the north with the South China Sea in the south‐east. The length of the river system (>1200 km long) enables examination of the upstream to downstream controls on the evolution of the incised valley, including sea‐level, climate and tectonics. The valley size, orientation and palaeo‐hydrology suggest close interaction between the regional tectonic framework, low‐angle shelf physiography and a humid‐tropical climatic setting. 相似文献
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Faisal Alonaizi Roman Pevzner Andrej Bóna Mohammad Alshamry Eva Caspari Boris Gurevich 《Geophysical Prospecting》2014,62(2):197-209
Time‐lapse seismic analysis is utilized in CO2 geosequestration to verify the CO2 containment within a reservoir. A major risk associated with geosequestration is a possible leakage of CO2 from the storage formation into overlaying formations. To mitigate this risk, the deployment of carbon capture and storage projects requires fast and reliable detection of relatively small volumes of CO2 outside the storage formation. To do this, it is necessary to predict typical seepage scenarios and improve subsurface seepage detection methods. In this work we present a technique for CO2 monitoring based on the detection of diffracted waves in time‐lapse seismic data. In the case of CO2 seepage, the migrating plume might form small secondary accumulations that would produce diffracted, rather than reflected waves. From time‐lapse data analysis, we are able to separate the diffracted waves from the predominant reflections in order to image the small CO2 plumes. To explore possibilities to detect relatively small amounts of CO2, we performed synthetic time‐lapse seismic modelling based on the Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC) Otway project data. The detection method is based on defining the CO2 location by measuring the coherency of the signal along diffraction offset‐traveltime curves. The technique is applied to a time‐lapse stacked section using a stacking velocity to construct offset‐traveltime curves. Given the amount of noise found in the surface seismic data, the predicted minimum detectable amount of CO2 is 1000–2000 tonnes. This method was also applied to real data obtained from a time‐lapse seismic physical model. The use of diffractions rather than reflections for monitoring small amounts of CO2 can enhance the capability of subsurface monitoring in CO2 geosequestration projects. 相似文献
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Faisal Hossain 《Natural Hazards》2006,37(3):263-276
The three most important components necessary for functioning of an operational flood warning system are: (1) a rainfall measuring
system; (2) a soil moisture updating system; and, (3) a surface discharge measuring system. Although surface based networks
for these systems can be largely inadequate in many parts of the world, this inadequacy particularly affects the tropics,
which are most vulnerable to flooding hazards. Furthermore, the tropical regions comprise developing countries lacking the
financial resources for such surface-based monitoring. The heritage of research conducted on evaluating the potential for
measuring discharge from space has now morphed into an agenda for a mission dedicated to space-based surface discharge measurements.
This mission juxtaposed with two other upcoming space-based missions: (1) for rainfall measurement (Global Precipitation Measurement,
GPM), and (2) soil moisture measurement (Hydrosphere State, HYDROS), bears promise for designing a fully space-borne system
for early warning of floods. Such a system, if operational, stands to offer tremendous socio-economic benefit to many flood-prone
developing nations of the tropical world. However, there are two competing aspects that need careful assessment to justify
the viability of such a system: (1) cost-effectiveness due to surface data scarcity; and (2) flood prediction uncertainty
due to uncertainty in the remote sensing measurements. This paper presents the flood hazard mitigation opportunities offered
by the assimilation of the three proposed space missions within the context of these two competing aspects. The discussion
is cast from the perspective of current understanding of the prediction uncertainties associated with space-based flood prediction.
A conceptual framework for a fully space-borne system for early-warning of floods is proposed. The need for retrospective
validation of such a system on historical data comprising floods and its associated socio-economic impact is stressed. This
proposal for a fully space-borne system, if pursued through wide interdisciplinary effort as recommended herein, promises
to enhance the utility of the three space missions more than what their individual agenda can be expected to offer. 相似文献
4.
Ibrahim Elkhedr Mogren Saad Qaysi Saleh Abdelrahman Kamal Ghrefat Habes Zaidi Faisal Hakami Ahmed 《Natural Hazards》2021,108(3):2613-2628
Natural Hazards - The main objective of this study is to detect the subsurface extension of salt diapirs and structural deformations in the city of Jazan and its suburbs using gravity data. Salt... 相似文献
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Obaid Aziz Alharbi Oumar Allafouza Loni Faisal K. Zaidi 《Arabian Journal of Geosciences》2017,10(2):35
The present study was carried out in the Mulaylih area which forms a part of Wadi Al Hamad in the Madinah Province of Saudi Arabia. Thirty groundwater samples from agricultural farms were collected and analyzed for various physio-chemical parameters including trace elements. The area is occupied by the Quaternary alluvium deposits which form shallow unconfined aquifers. Evaporation and ion exchange are the major processes which control the major ion chemistry of the area. The extreme aridity has results in high total dissolved solid values (average of 9793.47 mg/l). Trace element concentrations are low and are mainly attributed to geogenic sources (silicate weathering). Na-Cl groundwater type is the main hydrochemical facies found in the area. The waters are found to be oversaturated with calcite/aragonite and dolomite. The average nitrate concentration was found to be 134.10 mg/l and is much higher than the WHO recommended limit of 50 mg/l in drinking water. Their high values are mainly associated with the application of N-fertilizers on the agricultural farms. The average fluoride concentration in the study was found to be 1.54 mg/l. The relation between F and Cl and Cl and Na reveals that the fluoride concentrations are mainly attributed to geogenic sources. A comparison of the groundwater quality with the Saudi drinking water standards shows that the water is unfit for drinking. The high salinity and sodicity of the groundwater make it unfit for irrigation. Principal component analysis resulted in extraction of four principal components accounting for 79.5% of the total data variability and supports the fact that the natural hydrochemical processes (evaporation and ion exchange) control the overall groundwater chemistry. 相似文献
6.
Faisal Elias 《GeoJournal》2017,82(6):1165-1177
South Africa’s National Water Act and National Water Resource Strategy set out an ambitious societal vision with a strong focus on the redistribution of water resources towards the marginalised and on empowering historically disadvantaged communities including women. This vision is reflected in the framework for Integrated Water Resources Management (IWRM) that acknowledges women as pivotal in water management practices. Based on this premise, this paper examines the challenges women face in performing their roles in IWRM in rural South Africa. It draws on a study of a water user association that operates in the Limpopo Province of South Africa. The design of the study was qualitative in nature with a semi-structured interview as the main data collection tool. The interview involved 14 respondents from Limpopo. The results showed marked gender difference in terms of roles performed. Based on the study, three kinds of roles were revealed: domestic, productive and decision-making roles. Men were significantly involved in productive roles, giving low priority to domestic roles. The key factors found to affect the role of women in decision-making in IWRM were cultural practices, low self-confidence, low levels of capacity, and high workloads. These factors were identified as key institutional inherent within the specific society. As such, these findings have significant implications for the efforts aimed at promoting gender equality. Particularly, the impact of culture on women in water management raises concerns regarding gender issues in rural and remote areas where people are poorer and more culturally conservative. 相似文献
7.
Li Zhenya Ali Zulfiqar Cui Tong Qamar Sadia Ismail Muhammad Nazeer Amna Faisal Muhammad 《Natural Hazards》2022,111(1):547-566
Natural Hazards - The increase of frequency and severity of extreme weather events due to climate change gives evidence of severe challenges faced by infrastructure systems. Among them, the... 相似文献
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The relation between the water discharge (Q) and suspended sediment concentration (SSC) of the River Ramganga at Bareilly, Uttar Pradesh, in the Himalayas, has been modeled using Artificial Neural Networks (ANNs). The current study validates the practical capability and usefulness of this tool for simulating complex nonlinear, real world, river system processes in the Himalayan scenario. The modeling approach is based on the time series data collected from January to December (2008-2010) for Q and SSC. Three ANNs (T1-T3) with different network configurations have been developed and trained using the Levenberg Marquardt Back Propagation Algorithm in the Matlab routines. Networks were optimized using the enumeration technique, and, finally, the best network is used to predict the SSC values for the year 2011. The values thus obtained through the ANN model are compared with the observed values of SSC. The coefficient of determination (R2), for the optimal network was found to be 0.99. The study not only provides insight into ANN modeling in the Himalayan river scenario, but it also focuses on the importance of understanding a river basin and the factors that affect the SSC, before attempting to model it. Despite the temporal variations in the study area, it is possible to model and successfully predict the SSC values with very simplistic ANN models. 相似文献
10.
In situ U‐Th/Pb (LA‐ICP‐MS) monazite ages from the Hindu Kush of NW Pakistan provide new petrochronologic constraints on the tectonic evolution of the Himalaya–Karakoram–Tibet orogen. Monazites from two adjacent garnet + staurolite schist specimens yield multiple age populations that record the major Mesozoic and Cenozoic deformational, magmatic and metamorphic events along the southern margin of Eurasia. These include the accretion of the Hindu Kush–SW Pamir to Eurasia during the Late Triassic, followed by the accretion of the Karakoram terrane in the Early Jurassic. Younger Jurassic and Cretaceous ages record the development of an Andean‐style volcanic arc along the southern Eurasian margin, which ended with the docking of the Kohistan island arc and the emplacement of the Kohistan–Ladakh batholith during the Late Cretaceous. The initial Eocene collision of India with Eurasia was followed by widespread high‐temperature metamorphism and anatexis associated with crustal thickening within the Himalaya system in the Late Oligocene and Early Miocene. 相似文献