A hydrologic regression sediment-yield model for two ungaged watershed outlet stations in Africa     

Osama M. Moussa  Scot E. Smith  Ramesh L. Shrestha 《Environmental Geology》1991,17(3):177-183

A hydrologic regression sediment-yield model was established to determine the relationship between water discharge and suspended sediment discharge at the Blue Nile and the Atbara River outlet stations during the flood season. The model consisted of two main submodels: (1) a suspended sediment discharge model, which was used to determine suspended sediment discharge for each basin outlet; and (2) a sediment rating model, which related water discharge and suspended sediment discharge for each outlet station. Due to the absence of suspended sediment concentration measurements at or near the outlet stations, a minimum norm solution, which is based on the minimization of the unknowns rather than the residuals, was used to determine the suspended sediment discharges at the stations. In addition, the sediment rating submodel was regressed by using an observation equations procedure. Verification analyses on the model were carried out and the mean percentage errors were found to be +12.59 and –12.39, respectively, for the Blue Nile and Atbara. The hydrologic regression model was found to be most sensitive to the relative weight matrix, moderately sensitive to the mean water discharge ratio, and slightly sensitive to the concentration variation along the River Nile's course.  相似文献   

Die Weitwinkel-Himmelsaufnahme als Hilfsmittel für die Strahlungsforschung     

Inge Dirmhirn 《Theoretical and Applied Climatology》1957,8(3-4):336-351

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Studie über die Strahlungsvorgänge auf Gletschern     

Inge Dirmhirn 《Theoretical and Applied Climatology》1957,8(1):31-55

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Albedo boundaries on Mars in 1972: Results from Mariner 9     

R.M. Batson  J.L. Inge 《Icarus》1976,27(4):531-536

A map of “albedo” boundaries (light and dark markings) on Mars was prepared from Mariner 9 images. After special digital processing, these pictures provide detailed locations of albedo boundaries, which is significant in interpreting recent eolian activity. Derivation of absolute albedo values from the spacecraft data was not attempted. The map correlates well with telescopic observations of Mars after the 1971 dust storm.  相似文献   

Gold and Base Metals Associated with Uranium Mineralization in Some Lower Carboniferous Rock Units in the Wadi Abu El Mogheirat Area,Southwestern Sinai,Egypt     

Osama R. SALLAM  Abdalla S. ALSHAMI  Abd Elhadi A. ABBAS  E. GUIBAL 《《地质学报》英文版》2021,95(6):2087-2099

The Lower Carboniferous sediments at Wadi Abu El Mogheirat consist of four stratigraphic formations, from base upwards: Um Bogma, El Hashash, Magharet El Maiah and Abu Zarab formations. The most-concentrated radioactive anomalies at Wadi Abu El Mogheirat are in the middle member of the Um Bogma Formation. The gibbsitic marl in this formation shows the highest uranium contents (around 710 ppm). Gibbsitic marl and black gibbsite of the middle Um Bogma Formation show higher enrichment in Co, Cu, Mn, Ni, Pb, Zn, U, V, Ce and Th. Black gibbsite contains the highest total rare earth elements concentration, especially in terms of LREEs, while gibbsitic marl contains the highest content of HREEs. Anomalous contents of gold at Wadi Abu El Mogheirat are recorded for the first time in the gibbsitic marl (content: 10.4 ppm), black gibbsite (2.8 ppm) of the middle member of the Um Bogma Formation and in the siltstones of the El Hashash Formation (0.6 ppm). Gibbsitic marl shows the presence of uranothorite, celestite, zircon, atacamite, barite, xenotime and rutile. These characteristic demonstrate that the middle member of the Um Bogma Formation constitutes a potential source for gold. This conclusion is reinforced by the potential to exploit other metals such as Co, Cu, Mn, Ni, Pb, Zn, U, V, Th and Ce as by-products.  相似文献   

Early Eocene sea floor spreading and continent-ocean boundary between Jan Mayen and Senja fracture zones in the Norwegian-Greenland Sea     

Tsikalas  Filippos  Eldholm  Olav  Faleide  Jan Inge 《Marine Geophysical Researches》2002,23(3):247-270

Sea floor spreading anomalies in the Lofoten-Greenland basins reveal an unstable plate boundary characterized by several small-offset transforms for a period of 4 m.y. after opening. North of the Jan Mayen Fracture Zone, integrated analysis of magnetic and seismic data also document a distinct, persistent magnetic anomaly associated with the continent-ocean boundary and a locally, robust anomaly along the inner boundary of the break-up lavas. These results provide improved constraints on early opening plate reconstructions, which include a new anomaly 23-to-opening pole of rotation yielding more northerly relative motion vectors than previously recognized; and a solution of the enigmatic, azimuthal difference between the conjugate Eocene parts of the Greenland-Senja Fracture Zone if the Greenland Ridge is considered a continental sliver. The results confirm high, 2.36–2.40 cm yr^–1, early opening spreading rates, and are consistent with the start of sea floor spreading during Chron 24r. The potential field data along the landward prolongations of the Bivrost Fracture Zone suggest that its location is determined by a Mesozoic transfer system which has acted as a first-order, across-margin tectono-magmatic boundary between the regional Jan Mayen and Greenland-Senja Fracture Zone systems, greatly influencing the pre-, syn- and post-breakup margin development.  相似文献   

Oberflächentemperaturen der Gesteine im hochgebirge     

Inge Dirmhirn 《Theoretical and Applied Climatology》1952,4(1):43-50

Zusammenfassung Im Sommer 1950 und 1951 wurde auf dem Sonnblick in etwa 3050 m Seehöhe die Oberflächentemperature de Gesteine thermoelektrisch gemessen. An windstillen Tagen konnten bei wolkenlosem Himmel oder geringer Bewölkung Mittagstemperaturen bis 29°C an einer 6 cm dicken, horizontalen Platte beobachtet werden, das Minimum sank nachts auf–4°C ab. Diese starken Temperaturschwankungen wurden bei hohen Windgeschwindigkeiten erheblich abgeschwächt (bis 18°C). Ein Zusammenhang der Temperaturschwankung mit der Windgeschwindigkeit konnte angegeben werden. Auf gewachsenem Fels finden sich unter sonst gleichen Verhältnissen wesentlich geringere Tagesschwankungen. Durch die starken Temperaturvariationen der Gesteine wird die mechanische Verwitterung gefördert, die ihrerseits durch Staubbildung die Albedo der gesteinsnahen Gletscherflächen herabsetzt, den Strahlungshaushalt verändert und somit die Ablation der Gletscherränder fördert.

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Summary Surface temperatures of rocks were measured thermoelectrically on the Sonnblick at an altitude of about 3050 m during the summers 1950 and 1951. On calm days with no or little cloudiness midday temperatures up to 29°C could be observed on a horizontal plate 6 cm thick. The lowest temperature at night was–4°C. Such strong temperature variations were considerably reduced by high wind velocities (to 18°C). A relation between temperature variation and wind velocity could be established. On living rock, under equal conditions, considerably smaller diurnal variations were found. The great temperature variations of the rocks further their mechanical decay which, by producing dust, reduces the albedo of the glacier surface near the rocks, thereby changing the radiation economy and furthering the ablation of the borders of the glacier.

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Résumé On a mesuré au Sonnblick (3050 m) en été 1950 et 1951 la température superficielle des roches par voie thermoélectrique. Par ciel sans nuages ou peu nuageux et temps calme, on a mesuré à midi des températures atteignant 29°C sur une pierre horizontale plate, épaisse de 6 cm.; de nuit le minimum est descendu à–4°C. Ces grands écarts de température étaient notablement réduits (jusqu'à 18°) par vent fort. On a pu donner une relation entre la variation de température et la vitesse du vent. Les variations diurnes sur roches en place sont, toutes choses égales, plus faibles. Les fortes variations de température des roches accélèrent leur désagrégation mécanique; les poussières qui en résultent diminuent l'albédo des glaciers voisins, modifient par conséquent leur bilan de rayonnement et favorisent l'ablation des marges glaciares.

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Mit 2 Textabbildungen.  相似文献   

<Emphasis Type="Italic">Integrated Remote Sensing and</Emphasis> Structural Analysis Studies of Tayyib Al-Ism Area,Northwestern Arabian Shield,Saudi Arabia     

Osama M. K. Kassem  Habes A. Ghrefat  Haider Zaman  Awni T. Batayneh  Saad Almogren  Yousef Nazzal  Eslam Elawadi 《Journal of the Indian Society of Remote Sensing》2016,44(1):91-99

Geological and structural mappings of Tayyib Al-Ism area were carried out using the rocks finite strain data, the Landsat-7 Enhanced Thematic Mapper Plus (ETM+) data and the field based observations. To analyze the finite strain in the studied rocks, the R_f /? and Fry methods are applied to feldspar porphyroclasts and mafic grains from nine metavolcano-sedimentary samples (Hegaf Formation), four diorite-gabbros suite samples (Sawawin Complex), two meta-granite samples (Ifal suite) and five Zuhd alkali granite samples. The obtained data indicate traces of high to moderate level of deformation in the meta-granite and metavolcano-sedimentary rocks. The axial ratios along the XZ section range from 1.70 to 4.80 for the R_f/? method and from 1.50 to 4.50 for the Fry method. A sub-vertical trend of short axes in association with sub-horizontal foliation is also observed. These informations allow us to conclude that a finite strain in the deformed granitic rocks is of the same order of magnitude as in the metavolcano-sedimentary rocks. The contacts between the metavolcano-sedimentary and granitic rocks in Tayyib al Ism area were formed during the granitic intrusions along some of the faults under brittle to semi-ductile deformation conditions. These faults have significantly influenced the geometry and style of rifting in the Red Sea during the Neogene. The finite strain was accumulated in the area during the process of deformation, which superimpose the already existed nappe structure. It indicates that the nappe contacts formed during the accumulation of finite strain. In addition to finite strain analysis, band ratio images (3/1, 5/3, 7/5) and Principal Component Analysis (PCA) technique have been used, which proved effective in mapping geological and structural features of various rock bodies exposed in the study area.  相似文献   

Glacial and climate history of the last 24 000 years in the Polar Ural Mountains,Arctic Russia,inferred from partly varved lake sediments     

Carl Regnll  Haflidi Haflidason  Jan Mangerud  John Inge Svendsen 《Boreas: An International Journal of Quaternary Research》2019,48(2):432-443

We present a well‐dated, high‐resolution and continuous sediment record spanning the last c. 24 000 years from lake Bolshoye Shchuchye located in the Polar Ural Mountains, Arctic Russia. This is the first continuous sediment succession reaching back into the Last Glacial Maximum (LGM) ever retrieved from this region. We reconstruct the glacial and climate history in the area since the LGM based on sedimentological and geochemical analysis of a 24‐m‐long sediment core. A robust chronology was established using a combination of AMS ¹⁴C‐dating, the position of the Vedde Ash and varve counting. The varved part of the sediment core spans across the LGM from 24 to 18.7 cal. ka BP. We conclude that the lake basin remained ice‐free throughout the LGM, but that mountain glaciers were present in the lake catchment. A decrease in both glacial varve preservation and sedimentation rate suggests that these glaciers started to retreat c. 18.7 cal. ka BP and had disappeared from the catchment by 14.35 cal. ka BP. There are no indications of glacier regrowth during the Younger Dryas. We infer a distinct climatic amelioration following the onset of the Holocene and an Early to Middle Holocene thermal optimum between 10–5 cal. ka BP. Our results provide a long‐awaited continuous and high‐resolution record of past climate that supplements the existing, more fragmentary data from moraines and exposed strata along river banks and coastal cliffs around the Russian Arctic.  相似文献   

Pore Fabric Anisotropy of the Cambrian–Ordovician Nubia Sandstone in the Onshore Gulf of Suez,Egypt: A Surface Outcrop Analog     

Elgendy  Nader T. H.  Abuamarah  Bassam A.  Nabawy  Bassem S.  Ghrefat  Habes  Kassem  Osama M. K. 《Natural Resources Research》2020,29(2):1307-1328

Natural Resources Research - Integrated studies on pore fabric anisotropy have increased the general understanding of fluid flow patterns through reservoir rocks. In this study, pore anisotropy was...  相似文献