Evaporation estimates from Nasser Lake, Egypt, based on three floating station data and Bowen ratio energy budget   总被引：2，自引：1，他引：1  

Mohamed Elsawwaf  Patrick Willems  Andrea Pagano  Jean Berlamont 《Theoretical and Applied Climatology》2010,100(3-4):439-465

Nasser Lake is located in a hyper-arid region in the south of Egypt. Evaporation is by far the most important factor in explaining the water losses from the lake. To obtain better management scenarios for Nasser Lake, an accurate estimation of the lake evaporation losses thus is essential. This paper presents an update of previous evaporation estimates, making use of local meteorological and hydrological data collected from instrumented platforms (floating weather stations) at three locations on the lake: at Raft, Allaqi, and Abusembel (respectively at 2, 75, and 280 km upstream of the Aswan High Dam). Results from six conventional evaporation quantification methods were compared with the values obtained by the Bowen ratio energy budget method (BREB). The results of the BREB method showed that there is no significant difference between the evaporation rates at Allaqi and Abusembel. At Raft, higher evaporation rates were obtained, which were assumed to be overestimated due to the high uncertainty of the Bowen ratio (BR) parameter. The average BR value at Allaqi and Abusembel was used to eliminate this overestimates evaporation. Variance-based sensitivity and uncertainty analyses on the BREB results were conducted based on quasi-Monte Carlo sequences (Latin Hypercube sampling). The standard deviation of the total uncertainty on the BREB evaporation rate was found to be 0.62 mm day^?1. The parameter controlling the change in stored energy, followed by the BR parameter, was found to be the most sensitive parameters. Several of the six conventional methods showed substantial bias when compared with the BREB method. These were modified to eliminate the bias. When compared to the BREB-based values, the Penman method showed most favorably for the daily time scale, while for the monthly scale, the Priestley–Taylor and the deBruin–Keijman methods showed best agreement. Differences in mean evaporation estimates of these methods (against the BREB method) were found to be in the range 0.14 and 0.36 mm day^?1. All estimates were based calculations at the daily time scale covering a 10-year period (1995–2004).  相似文献   

Asteroids 1 ceres and 4 vesta: Objects of the Dawn space mission     

D. F. Lupishko  R. A. Mohamed 《Solar System Research》2009,43(6):475-482

The Dawn spacecraft of the NASA space mission to asteroids 1 Ceres and 4 Vesta was launched in September 2007. The choice of these two asteroids is deeply grounded: they are the largest and most massive objects of the main belt that are completely different in material composition, evolution history, and internal structure. Recently, the results of observations and numerical modeling have shown their amazing uniqueness: they both have experienced the complex process of thermal evolution and differentiation of their internal mineral resources, but have a completely different internal structure. Being the largest bodies, have they managed to resist the process of collisional evolution in the asteroid belt and have survived in their “primitive form.” Because of this, their study is very important from the point of view of cosmogonic problems regarding the asteroid belt and the Solar System as a whole. The present paper shortly reviews the recent progress in the study of Ceres and Vesta achieved due to observations performed on the Earth (including the polarimetric observations made by the authors) and from the Hubble Space Telescope (HST) before the long-term orbital investigations performed by the Dawn spacecraft.  相似文献   

Petrology and geochemistry of late archaean granitoids in the northern part of Eastern Dharwar Craton,Southern India: Implications for transitional geodynamic setting     

B. C. Prabhakar  M. Jayananda  Mohamed Shareef  T. Kano 《Journal of the Geological Society of India》2009,74(3):299-317

The results of field, petrographic and geochemical work of the granitoids of Hutti-Gurgunta area in the northern part of Eastern Dharwar Craton (EDC) is presented in this paper. This crustal section comprises polyphase banded to foliated TTG gneisses, middle amphibolite facies Gurgunta schist belt and upper greenschist facies Hutti schist belt and abundant granite plutons. The focus of the present study is mainly on basement TTG gneisses and a granite pluton (∼ 240 sq km areal extent), to discuss crustal accretion processes including changing petrogenetic mechanism and geodynamic setting. The TTGs contain quartz, plagioclase, lesser K-feldspar and hornblende with minor biotite while the granite contain quartz, plagioclase, K-feldspar and hornblende. Late stage alteration (chloritisation, sericitisation and epidotisation) is wide spread in the entire area. A huge synplutonic mafic body which is dioritic to meladioritic in composition injects the granite and displays all stages of progressive mixing and hybridization. The studied TTGs and granite show distinct major and trace element patterns. The TTGs are characterized by higher SiO₂, high Al₂O₃, and Na₂O, low TiO₂, Mg#, CaO, K₂O and LILE, and HFS elements compared to granite. TTGs define strong trondhjemite trend whilst granite shows calc-alkaline trend. However, both TTGs and granite show characteristics of Phanerozoic high-silica adakites. The granite also shows characteristics of transitional TTGs in its high LILE, and progressive increase in K₂O with differentiation. Both TTGs and granite define linear to sub-linear trends on variation diagrams. The TTGs show moderate total REE contents with fractionated REE patterns (La/Yb_N =17.73–61.73) and slight positive or without any significant Eu anomaly implying little amount of amphibole or plagioclase in residual liquid. On the other hand, the granite displays poor to moderate fractionation of REE patterns (La/Yb_N = 9.06–67.21) without any significant Eu anomaly. The TTGs have been interpreted to be produced by low-K basaltic slab melting at shallow depth, whereas the granite pluton has been formed by slab melting at depth and these melts interacted with peridotite mantle wedge. Such changing petrogenetic mechanisms and geodynamic conditions explain increase in the contents of MgO, CaO, Ni and Cr from 2700 Ma to 2500 Ma granitoids in the EDC.  相似文献   

Geological and geophysical investigation of Kamil crater,Egypt     

Stefano Urbini  Iacopo Nicolosi  Antonio Zeoli  Sami El Khrepy  Ahmed Lethy  Mahfooz Hafez  Mohamed El Gabry  Ahmed El Barkooky  Aly Barakat  Mahomoud GOMAA  Ali M. Radwan  Mohamed El Sharkawi  Massimo D’orazio  Luigi Folco 《Meteoritics & planetary science》2012,47(11):1842-1868

Abstract– We detail the Kamil crater (Egypt) structure and refine the impact scenario, based on the geological and geophysical data collected during our first expedition in February 2010. Kamil Crater is a model for terrestrial small‐scale hypervelocity impact craters. It is an exceptionally well‐preserved, simple crater with a diameter of 45 m, depth of 10 m, and rayed pattern of bright ejecta. It occurs in a simple geological context: flat, rocky desert surface, and target rocks comprising subhorizontally layered sandstones. The high depth‐to‐diameter ratio of the transient crater, its concave, yet asymmetric, bottom, and the fact that Kamil Crater is not part of a crater field confirm that it formed by the impact of a single iron mass (or a tight cluster of fragments) that fragmented upon hypervelocity impact with the ground. The circular crater shape and asymmetries in ejecta and shrapnel distributions coherently indicate a direction of incidence from the NW and an impact angle of approximately 30 to 45°. Newly identified asymmetries, including the off‐center bottom of the transient crater floor downrange, maximum overturning of target rocks along the impact direction, and lower crater rim elevation downrange, may be diagnostic of oblique impacts in well‐preserved craters. Geomagnetic data reveal no buried individual impactor masses >100 kg and suggest that the total mass of the buried shrapnel >100 g is approximately 1050–1700 kg. Based on this mass value plus that of shrapnel >10 g identified earlier on the surface during systematic search, the new estimate of the minimum projectile mass is approximately 5 t.  相似文献   

Modelling the transverse behaviour of circular tunnels in structured clayey soils during earthquakes     

Cabangon  Lowell Tan  Elia  Gaetano  Rouainia  Mohamed 《Acta Geotechnica》2019,14(1):163-178

Acta Geotechnica - The paper presents novel results from advanced numerical simulations of the transverse behaviour of shallow circular tunnels in natural clays accounting for soil structure...  相似文献   

Characterization of Continental Intercalaire aquifer (CI) in the Tinrhert-East Area-Illizi Basin on the Algerian-Libyan Border     

BELOUANAS Hemza  MENANI Mohamed Redha 《地下水科学与工程》2019,7(2):115-132

This paper addresses the characterization of the Continental Intercalaire aquifer(CI) in the Tinrhert-East area of Illizi Basin on the Algerian-Libyan border, which belongs to the SASS1 system, one of the biggest transboundary aquifers in the world. This study concerns a superficies of 4 300 km~2. On the basis of Mud Logging borehole data conducted in this part of the aquifer, a realistic characterization of the aquifer was done. The thickness of the CI aquifer varies from 300 m in the south to 700 m in the north, and the depth ranges from 180 m to 320 m. The interpretation of the logs showed that the aquifer is characterized by a maximum net thickness in its southwestern part(more than 600 m), the porosity is very high, ranging from 30% in the west to 24% at the Libyan borders, the permeability is low to medium around 10~(-5) m/s, and the maximum transmissivity values of about 8× 10~(-3) m~2/s were recorded at the center of the study area. The depth of water varies from 235 m to 312 m, and the water flows from south to north, in accordance with the general direction observed in the CI aquifer in the Northern Sahara Aquifer System(SASS). The porosity values obtained from the interpretation of the sonic and density logs permit to estimate the water reserves of this aquifer considered fossil, at thresholds much higher than what was considered until now.  相似文献   

Remote sensing of paleodrainage systems west of the Nile River,Egypt     

Mohamed Abdelkareem  Farouk El-Baz 《国际地球制图》2017,32(5):541-555

Remotely sensed data show details of the geomorphic features and landscape evolution west of the Nile. The detected features include remnants of paleochannels, flutes and rock-mass movements. Fused radar/optical data, altitudinal profiles and 3D perspective view provided evidences of massive landslides that fully blocked the earlier Nile channel near to the Western Desert plateau. This channel was ~30 km west of the present Nile at ~100 m above the present level of the Nile. Subsequently, the fluvial activities shifted about ~10 km eastward, leaving behind several remnants of paleochannels, fluvial deposits, ancient landscape and Nilotic fauna. The automatic extraction of stream networks clearly depicts the developments of paleochannels. Our results revealed that fluvial activity switched from the Gallaba plain to the present Nile course through a series of tectonic and climatic changes. Furthermore, integration of radar and optical images provided an explanation for causes of the undulated forms ‘flutes’.  相似文献   

Retrieving spatial variations of land surface temperatures from satellite data–Cairo region,Egypt     

Mohamed E. Hereher 《国际地球制图》2017,32(5):556-568

Cairo region is characterized by a range of physiographic features, including: flat agricultural lands, bare sandy deserts, highlands, calcareous terrains and urban land use. A time series data-set (300 images) acquired from the Moderate Resolution Imaging Spectroradiometer for the period July 2002–June 2015 were utilized to retrieve the spatial variations in the mean land surface temperature (LST) for the above-mentioned surface features. Results showed that vegetation, topography and surface albedo have negative correlations with LST. Vegetation/LST correlation has the maximum regression coefficient (R² = 0.68) and albedo/LST has the minimum (R² = 0.03). Cultivated lands reveal the lowest mean LST (<32 °C), whereas industrial lands exhibit the highest LST (>40 °C) of Cairo region. There is a considerable urban heat island formed at Helwan south of Cairo, where heavy industries are settled. Industrial activities raised the mean LST of the region by at least 4 °C than the surrounding urban lands.  相似文献   

Fuzzy logic and multi-criteria methods for groundwater potentiality mapping at Al Fo’ah area,the United Arab Emirates (UAE): an integrated approach     

Mohamed Mostafa Mohamed 《国际地球制图》2017,32(10):1120-1138

This study has modified an approach based on fuzzy logic in a GIS and multi-criteria decision making (MCDM) for groundwater potentiality mapping in Al Fo’ah area, the United Arab Emirates. The proposed approach uses nine groundwater conditioning factors recognized by local hydrology experts. Each factor and class of each factor was given a weight and score based on its level of contributions to groundwater accumulation using analytical hierarchy process and MCDM. Our results revealed that the areas of very high harbouring groundwater are located at the foot of the Oman mountains and occupies an area of about 8.46 km² (4%) of the study area. We validated our results using the Relative Operating Characteristics. The area under the curve showed a ratio of 0.8957 (of 89.57%). The modified approach is timely and economically effective and can be applied in semi-arid regions to help hydrologists.  相似文献   

Study of Aerosol Direct and Indirect Effects and Auto-conversion Processes over the West African Monsoon Region Using a Regional Climate Model     

Zeinab SALAH  Ahmed SHALABY  Allison L.STEINER  Ashraf S.ZAKEY  Ritesh GAUTAM  Mohamed M.ABDEL WAHAB 《大气科学进展》2018,35(2):182-194

This study assesses the direct and indirect effects of natural and anthropogenic aerosols(e.g., black carbon and sulfate)over West and Central Africa during the West African monsoon(WAM) period(June–July–August). We investigate the impacts of aerosols on the amount of cloudiness, the influences on the precipitation efficiency of clouds, and the associated radiative forcing(direct and indirect). Our study includes the implementation of three new formulations of auto-conversion parameterization [namely, the Beheng(BH), Tripoli and Cotton(TC) and Liu and Daum(R6) schemes] in Reg CM4.4.1,besides the default model's auto-conversion scheme(Kessler). Among the new schemes, BH reduces the precipitation wet bias by more than 50% over West Africa and achieves a bias reduction of around 25% over Central Africa. Results from detailed sensitivity experiments suggest a significant path forward in terms of addressing the long-standing issue of the characteristic wet bias in Reg CM. In terms of aerosol-induced radiative forcing, the impact of the various schemes is found to vary considerably(ranging from-5 to-25 W m~(-2)).  相似文献