The chronostratigraphy of the latest Middle Pleistocene aeolian and alluvial activity on the Island of Hvar,eastern Adriatic,Croatia          下载免费PDF全文

Lara Wacha  Igor Vlahović  Sumiko Tsukamoto  Marijan Kovačić  Ozren Hasan  Davor Pavelić 《Boreas: An International Journal of Quaternary Research》2016,45(1):152-164

Pleistocene aeolian sands and alluvial deposits can frequently be traced along the Mediterranean coast. Such deposits also exist along the eastern Adriatic coast and the nearby islands. Four stratigraphical sections of these deposits were studied on the Island of Hvar with the purpose of establishing a chronological framework of the aeolian–alluvial depositional system, using luminescence dating and magnetic susceptibility stratigraphy. Luminescence dating was applied on coarse‐grained feldspar and quartz grains separated from the sands. Both quartz optically stimulated luminescence (OSL) and feldspar post‐IR infrared stimulated luminescence (pIRIR) age estimates are in good agreement, with values ranging between 167±24 to 120±12 ka (OSL) and 179±18 to 131±18 ka (pIRIR measured at 290 °C) after a fading correction for the pIRIR signal. The results can be clearly correlated to around the end of oxygen isotope stage (OIS) 6 and the beginning of OSI 5, indicating that the aeolian accumulation of sands was a result of the Penultimate Glacial and climate fluctuations at the beginning of the Last Interglacial. Variations in magnetic susceptibility (MS) data can be interpreted alongside these dating results; several stronger peaks detected at the very end of the Penultimate Glacial and the initial stage of the Last Interglacial cycle most probably indicates more intensive pedogenesis resulting from a more favourable climate, probably because of climate changes. Breccias related to major bounding surfaces in association with evidence of soil formation and bioturbation could be the result of more favourable climate conditions and changes during the transition from OIS 6 to OIS 5 (Penultimate Glacial–Last Interglacial). These results are in agreement with similar data from the wider Mediterranean area.  相似文献   

Lithologic mapping of a forested montane terrain from Landsat 5 TM image     

Taufique H. Mahmood  Khaled Hasan  Syed Humayun Akhter 《国际地球制图》2019,34(7):750-768

Thick forest cover and poor infrastructures are the major hindrances for detailed lithologic mapping in an inaccessible montane landscape. To overcome these limitations, we utilize a Landsat 5 TM image to map lithology using vegetation and drainage pattern as an indicator of underlying rock types in a heavily forested region of the Chittagong Hill Tracts area located in southeastern Bangladesh. We use supervised and unsupervised classifiers for a vegetation-based approach while on-screen digitization is used for drainage patterns-based mapping. Field observations were used for mapping lithology and evaluating accuracy. Overall, our results agree well with the current geologic map and improve it by providing a more spatially detailed distribution of the sandstone and shale. The performances of all approaches are good at the inner and outer flanks of anticlines located in the study area while the drainage pattern mapping performs best at the mid-flank area.  相似文献   

Modeling and simulating earthquake accelerograms using strong-motion data from the Istanbul, Turkey, region     

Kirsten L. Findell  Hasan U. Kylüglu  Ahmet . akmak 《Soil Dynamics and Earthquake Engineering》1993,12(1)

In order to simulate earthquake ground motions for the Instanbul (Turkey) region, acceleration time series from western Turkey are modeled by transforming the series into a stationary one which can be described by an autoregressive moving-average (ARMA) process. The ARMA and other parameters used in the stationary transformation are related to physical parameters (e.g. magnitude, distance to epicenter, depth to hypocenter and duration) via a regression analysis. To create simulations for a given set of physical parameters, the modelling procedure is reversed.  相似文献   

NARX neural network approach for the monthly prediction of groundwater levels in Sylhet Sadar,Bangladesh          下载免费PDF全文

Abdullah Al Jami  Meher Uddin Himel  Khairul Hasan  Shilpy Rani Basak  Ayesha Ferdous Mita 《地下水科学与工程》2020,8(2):118-126

Groundwater is important for managing the water supply in agricultural countries like Bangladesh. Therefore, the ability to predict the changes of groundwater level is necessary for jointly planning the uses of groundwater resources. In this study, a new nonlinear autoregressive with exogenous inputs(NARX) network has been applied to simulate monthly groundwater levels in a well of Sylhet Sadar at a local scale. The Levenberg-Marquardt(LM) and Bayesian Regularization(BR) algorithms were used to train the NARX network, and the results were compared to determine the best architecture for predicting monthly groundwater levels over time. The comparison between LM and BR showed that NARX-BR has advantages over predicting monthly levels based on the Mean Squared Error(MSE), coefficient of determination(R~2), and Nash-Sutcliffe coefficient of efficiency(NSE). The results show that BR is the most accurate method for predicting groundwater levels with an error of ± 0.35 m. This method is applied to the management of irrigation water source, which provides important information for the prediction of local groundwater fluctuation at local level during a short period.  相似文献   

Sustainable development and management of an aquifer system in western Turkey     

Jale?SakiyanEmail author  Hasan?Yazicigil 《Hydrogeology Journal》2004,12(1):66-80

This study presents the establishment of sustainable development and management policies for the Küçük Menderes River Basin aquifer system in western Turkey. Geological, hydrogeological, and geophysical data are used conjunctively to define various hydrogeological units and their geometry. Distributions of hydraulic-parameter values and recharge are estimated by geostatistical methods and hydrologic simulations, respectively. A finite-difference groundwater flow model is used to represent the unconfined flow in the aquifer system. The model has been calibrated under steady state and transient conditions. The resulting model was used to test seven management scenarios for a planning period of 21 years to determine the so-called safe yield and sustainable yield of the aquifer system and to investigate the potential impacts of four planned surface water reservoirs on groundwater resources in the basin. The results demonstrate that the continuation of the present pumping rates exceeds both the safe yield and the sustainable yield of the aquifer system. Consequently, the growing need for irrigation water should be met by the construction of the planned surface water reservoirs and the implementation of efficient water management policies and plans.

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Resumen Este estudio presenta el establecimiento de políticas sustentables de desarrollo y gestión en el sistema acuífero de la cuenca del río Küçük Menderes, al Oeste de Turquía, para lo que se ha utilizado datos geológicos, hidrogeológicos y geofísicos de forma conjunta de cara a definir diversas unidades hidrogeológicas y su geometría. La distribución de los parámetros hidráulicos y de la recarga ha sido estimada mediante métodos geoestadísticos y simulaciones hidrológicas, respectivamente. Se ha empleado un modelo de las aguas subterráneas en diferencias finitas para representar el flujo no confinado en el sistema acuífero, el cual se ha calibrado bajo condiciones estacionarias y transitorias. El modelo resultante ha sido usado para contrastar siete escenarios de gestión durante un período de planificación de 21 años con el fin de determinar el punto de explotación segura y sustentable del sistema acuífero, así como para investigar los impactos potenciales sobre los recursos subterráneos de los cuatro embalses superficiales que se hallan en proyecto. Los resultados demuestran que el mantenimiento de las tasas actuales de extracción del acuífero supera tanto el régimen de bombeo seguro como el sustentable del sistema. Por consiguiente, se debería compensar la necesidad creciente de agua para riego con la construcción de los reservorios superficiales previstos y con la implementación de políticas y planes de gestión eficiente del agua.

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Résumé Cette étude présente la proposition dune politique de développement et de gestion durables du système aquifère du bassin du Petit Mendérès dans louest de la Turquie. Des données géologiques, hydrogéologiques et géophysiques ont été utilisées conjointement pour définir les différentes unités hydrogéologiques et leur géométrie. Les distributions des paramètres hydrauliques et de la recharge ont été estimées respectivement par des méthodes géostatistiques et des simulations hydrologiques. Un modèle découlement souterrain aux éléments finis a été utilisé pour représenter lécoulement non captif dans le système aquifère. Le modèle a été calibré dans des conditions de régimes permanent et transitoire. Le modèle résultant a servi à tester sept scénarios de gestion pour une période de programmation de 21 ans, afin de déterminer les débits de prélèvement sûr et durable dans le système aquifère et détudier les impacts potentiels de quatre réservoirs deau de surface en projet sur les eaux souterraines du bassin. Les résultats montrent que la poursuite des prélèvements au débit actuel excède aussi bien le débit dexploitation de sécurité que celui durable pour le système aquifère. Par conséquent, les besoins croissants deau pour lirrigation doivent être satisfaits par la construction des réservoirs projetés et par la mise en place de politiques et de plans de gestion de leau efficace.

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The negative effect of environmental geological conditions of some geo-archaeological sites of North Coast and Alexandria     

Hani Ibrahim  Gamal Kamh 《Environmental Geology》2005,49(2):179-187

Three geo-archaeological sites at the North Coast and Alexandria, namely, the Alexandria wall (El Shalalat Park site), Abu Soir temple, and Marina excavations, were investigated to determine the negative impact of a salty environmental condition. The monuments suffer from rock decay of different rates. The geo-archaeological sites were built mainly from oolitic limestone blocks (i.e., the Alexandria wall at the El Shalalat Park site and Abu Soir temple) or excavated on them (i.e., Marina excavations). Field inspection and a lab analysis were carried out to understand the weathering mechanism. Salt weathering criteria such as disintegration, pitting, scaling, exfoliation, and honeycomb are observed on the Alexandria wall and upper parts of the Abu Soir temple, while dangerous cracks are detected on the Marina excavation tombs. The petrographic study of the oolitic limestone samples shows that they consist mainly of oolities and drusy sparite as a cement (oolitic grainstone). Some oolities have quartz grains as nuclei. Hydrochemical analysis shows that the total dissolved salts of extracted solutions of the North Coast quarry samples range from 539 to 686 ppm and dramatically increase (i.e., ten times) for extracted solutions from monument samples, ranging from 5395 to 6880 ppm. The dominant cation is sodium while the dominant anion is chlorine. Acid insoluble residue analysis shows that the carbonate content ranges from 89.2% to 96.4% for fresh samples from quarries and from 9.2% to 94.8% for weathered monument samples. The weight loss of the quarry oolitic limestone samples range from 30.7% to 32.7% and its physical and mechanical properties become worse after being subjected to 15 cycles of a durability simulation soundness test (using a sodium sulphate solution). Our main recommendations are to use suitable grouting for binding the cracks, high durability reconstruction rocks, and suitable cleaning methods to remove salts from the monuments.  相似文献   

Ground deformation of Papandayan volcano before, during, and after the 2002 eruption as detected by GPS surveys     

Hasanuddin Z. Abidin  H. Andreas  M. Gamal  Ony K. Suganda  Irwan Meilano  M. Hendrasto  M. A. Kusuma  D. Darmawan  M. A. Purbawinata  A. D. Wirakusumah  F. Kimata 《GPS Solutions》2006,10(2):75-84

Papandayan is an A-type active volcano located in the southern part of Garut Regency, about 70 km southeast of Bandung, Indonesia. Its earliest recorded eruption, and the most violent and devastating outburst, occurred in 1772. The latest eruptions occurred in the period from 11 November–8 December 2002, and consisted of phreatic, freatomagmatic, and magmatic types of eruption. During the latest eruption period, GPS surveys were conducted at several points inside and around the crater in a radial mode, using the reference point located at the Papandayan observatory, about 10 km from the crater. At the points closest to the erupting craters, GPS displacements up to a few decimeters were detected, whereas at the points outside the crater, the displacements were at the centimeter level. The magnitude of displacements observed at each point also showed a temporal variation according to the eruption characteristics. The results show that deformation during eruption tends to be local, e.g. just around the crater. The pressure source is difficult to be properly modeled from GPS results, due to the limited GPS data available and differences in topography, geological structure, and/or rheology related to each GPS station.  相似文献   

Variation of Chemical Parameters in the Depth Profile of The River Champanala     

R. Hasan 《洁净——土壤、空气、水》1984,12(6):679-683

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The lamprophyres of Afyon stratovolcano,western Anatolia,Turkey: description and genesis     

Erkan Aydar  Hasan Bayhan  Alain Gourgaud 《Comptes Rendus Geoscience》2003,335(3):279-288

The Afyon stratovolcano exhibits lamprophyric rocks, emplaced as hydrovolcanic products, aphanitic lava flows and dyke intrusions, during the final stages of volcanic activity. Most of the Afyon volcanics belong to the silica-saturated alkaline suite, as potassic trachyandesites and trachytes, while the products of the latest activity are lamproitic lamprophyres (jumillite, orendite, verite, fitztroyite) and alkaline lamprophyres (campto-sannaite, sannaite, hyalo-monchiquite, analcime–monchiquite). Afyon lamprophyres exhibit LILE and Zr enrichments, related to mantle metasomatism.  相似文献   

Land subsidence characteristics of Jakarta between 1997 and 2005, as estimated using GPS surveys   总被引：4，自引：0，他引：4  

Hasanuddin Z. Abidin  H. Andreas  Rochman Djaja  Dudy Darmawan  M. Gamal 《GPS Solutions》2008,12(1):23-32

Jakarta is the capital city of Indonesia with a population of about 12 million people, inhabiting an area of about 625 km². It is well known that several areas in Jakarta are subsiding rapidly. There are four different types of land subsidence that can be expected to occur in the Jakarta basin, namely: subsidence due to groundwater extraction, subsidence induced by the load of constructions (i.e., settlement of high compressibility soil), subsidence caused by natural consolidation of alluvial soil and tectonic subsidence. In addition to the leveling method, Global Positioning System (GPS) survey methods have been used to study land subsidence in Jakarta. In this paper, we characterize subsidence in the Jakarta basin using eight episodic/campaign GPS surveys between 1997 and 2005. The estimated subsidence rates are 1–10 cm/year. The observed subsidence rates in several locations show a positive correlation with known abstraction volumes of groundwater extraction. These basin-wide series of GPS measurements show how this type of measurement can play an important role in multiple public policy decision making in this rapidly growing area.  相似文献