Drought risk assessment using remote sensing and GIS techniques   总被引：1，自引：0，他引：1  

Abdel-Aziz Belal  Hassan R. El-Ramady  Elsayed S. Mohamed  Ahmed M. Saleh 《Arabian Journal of Geosciences》2014,7(1):35-53

Beginning with a discussion of drought definitions, this review paper attempts to provide a review of fundamental concepts of drought, classification of droughts, drought indices, and the role of remote sensing and geographic information systems for drought evaluation. Owing to the rise in water demand and looming climate change, recent years have witnessed much focus on global drought scenarios. As a natural hazard, drought is best characterized by multiple climatological and hydrological parameters. An understanding of the relationships between these two sets of parameters is necessary to develop measures for mitigating the impacts of droughts. Droughts are recognized as an environmental disaster and have attracted the attention of environmentalists, ecologists, hydrologists, meteorologists, geologists, and agricultural scientists. Temperatures; high winds; low relative humidity; and timing and characteristics of rains, including distribution of rainy days during crop growing seasons, intensity, and duration of rain, and onset and termination, play a significant role in the occurrence of droughts. In contrast to aridity, which is a permanent feature of climate and is restricted to low rainfall areas, a drought is a temporary aberration. Often, there is confusion between a heat wave and a drought, and the distinction is emphasized between heat wave and drought, noting that a typical time scale associated with a heat wave is on the order of a week, while a drought may persist for months or even years. The combination of a heat wave and a drought has dire socio-economic consequences. Drought risk is a product of a region’s exposure to the natural hazard and its vulnerability to extended periods of water shortage. If nations and regions are to make progress in reducing the serious consequences of drought, they must improve their understanding of the hazard and the factors that influence vulnerability. It is critical for drought-prone regions to better understand their drought climatology (i.e., the probability of drought at different levels of intensity and duration) and establish comprehensive and integrated drought information system that incorporates climate, soil, and water supply factors such as precipitation, temperature, soil moisture, snow pack, reservoir and lake levels, ground water levels, and stream flow. All drought-prone nations should develop national drought policies and preparedness plans that place emphasis on risk management rather than following the traditional approach of crisis management, where the emphasis is on reactive, emergency response measures. Crisis management decreases self-reliance and increases dependence on government and donors.  相似文献   

The impact of subsurface geological structure on the groundwater occurrence using geophysical techniques in wadi El Kallabiyyah and wadi As Sabil,East Esna,Eastern Desert,Egypt     

Hosny M. Ezz El Deen  Ahmed N. El Sayed  Mostafa S. M. Barseem 《Arabian Journal of Geosciences》2014,7(6):2151-2163

The present study aims to explain some hydrogeological problems that are related to geological setting in two wadis: El Kallabiyyah and As Sabil East Esna. For this purpose, land magnetic, vertical electrical soundings, and two-dimensional electrical resistivity imaging profiles were measured. The lithological succession comprises Upper Cretaceous to Quaternary deposits that rest on a Precambrian basement rock. The results of the interpretation of the land magnetic measurements in wadi El Kallabiyyah represent the depth to the basement rock which ranges from 260 to 660 m and increases towards the northeast trend, but in wadi As Sabil, there is a large basin at the center of the wadi with the recorded depth to the basement reaching 1,300 m due to the effect of two normal faults (F1 and F2). The results of the interpretation of the vertical electrical sounding and two-dimensional imaging confirmed the presence of these faults in wadi As Sabil. The results of the geoelectrical measurements in wadi El Kallabiyyah represented the water-bearing layer at the third unit that consists of sands, gravels, boulders, and clays. The presence of clay will affect the potentiality of a drilled well. For wadi As Sabil, the results of geoelectrical measurements led to the lower part of the second unit which acts as a water-bearing layer that consists of sands, boulders, gravels, and clays. It can be concluded that the best site for drilling wells in wadi El Kallabiyyah is at vertical electrical sounding no.5 with a total depth of not less than 230 m. In wadi As Sabil, the drilled wells must be concentrated at the center and the downstream.  相似文献   

Late Miocene normal faulting beneath the northern Nile Delta: NNW propagation of the Gulf of Suez Rift     

Mohammad A. Sarhan  Richard E. Ll. Collier  Ahmed Basal  Mohamed Hamed Abdel Aal 《Arabian Journal of Geosciences》2014,7(11):4563-4571

The north Egyptian continental margin has undergone passive margin subsidence since the opening of Tethys, but its post-Mesozoic history has been interrupted by tectonic events that include a phase of extensional faulting in the Late Miocene. This study characterizes the geometry and distribution of Late Miocene normal faulting beneath the northern Nile Delta and addresses the relationship of this faulting to the north–northwestwards propagation of Red Sea–Gulf of Suez rifting at this time. Structural interpretation of a 2D grid of seismic reflection data has defined a Tortonian–Messinian syn-rift megasequence, when tied to well data. Normal fault correlations between seismic lines are constrained by the mapping of fault-related folds. Faults are evenly distributed across the study area and are found to strike predominantly NW–SE to NNW–SSE, with some N–S faults in the north. Faults are interpreted to be <10 km in length, typically in the range 3–6 km. This suggests that rifting in the northern Nile Delta did not proceed beyond a continental rift initiation phase, with distributed, relatively small-scale faults. This contrasts with the Gulf of Suez Rift, where faulting continued to a more evolved fault localization phase, with block-bounding faults >25 km in length. Results suggest that future studies could quantify fault evolution from rift initiation to fault linkage to displacement localization, by studying the spatial variation in faulting from the northern Nile Delta, south–southeastwards to the Gulf of Suez Rift.  相似文献   

Utilization of SPOT 5 data for mapping gold mineralized diorite–tonalite intrusion,Bulghah gold mine area,Saudi Arabia     

Hesham Harbi  Ahmed Madani 《Arabian Journal of Geosciences》2014,7(9):3829-3838

The present study utilizes the processed SPOT 5 data to discriminate and to generate 1:10,000 geologic image map to delineate the mineralized diorite–tonalite intrusion around Bulghah gold mine area, Saudi Arabia. The rock units exposed in the area include gossan, marble, Hulayfah volcanics, diorite–tonalite, gneissose granite, and alkali granite. Gold mineralization at Bulghah mine is hosted mainly by Syn- to Late-tectonic diorite–tonalite intrusion aligned along N–S direction and is associated mainly with cataclastic zones and quartz veins. Gossans and jasparoidal gossans (Hulayfah group), recorded at the western side of Bulghah mine area as discontinuous small lenses, can be easily discriminated on 4/2 and 4/3 band ratio SPOT images by their white and black image signatures, respectively. Granitoids (gneissose granite and alkali granite) are easily discriminated in 3/2 ratio image, in which gneissose granite has gray image signature, whereas alkali granite has dark gray image signature. On the SPOT false color composite band ratios image (3/2 R, 4/2 G, and 4/3 B), gossan, marble, Hulayfah volcanics, diorite–tonalite, gneissose granite, and alkali granite have sky blue, blood red, bluish light brown, orange, brick red, and deep blue colors, respectively. Fusion of the false color composite SPOT ratios image (3/2 R, 4/2 G, and 4/3 B) with the high spatial resolution SPOT pan image is performed using IHS transformation method. The fused image is used to delineate the mineralized diorite–tonalite intrusion and to produce 1:10,000 geologic image map for Bulghah gold mine area. The present study reveals the usefulness of the processed SPOT 5 data for adding new extensions at the southern and northern boundaries of diorite–tonalite intrusion.  相似文献   

Microfacies and Depositional Environments of Miocene Isolated Carbonate Platforms from Central Luconia, Offshore Sarawak, Malaysia     

Hammad Tariq JANJUHAH  José Antonio GáMEZ VINTANED  Ahmed Mohamed AhmedSALIM  Ibrahima FAYE  Mumtaz Muhammad SHAH  Deva Prasad GHOSH 《《地质学报》英文版》2017,91(5):1778-1796

The Luconia Province – offshore Sarawak – is a key geological unit for understanding the distribution of hydrocarbon resources in Malaysia. Nevertheless, little effort has been made to address the palaeoenvironmental characteristics of the Tertiary carbonates in the key sector of Central Luconia. We study the sedimentology and petrography of core samples from a well in Central Luconia, for which thirteen microfacies have been identified reflecting different depositional settings. This is the first microfacies scheme elaborated for Luconian carbonates. Lithofacies and microfacies distribution are compatible with deposition in a reef complex, originating around a framework reef, within the euphotic zone. Sediments were deposited in environments of backreef, reef crest, and forereef. The fair weather wave base is marked by the presence of coralline red algae, foraminifera, decreasing degree of bioclast fragmentation and other microfacies features. As a result, a depositional-environmental model is constructed, depicting a reef complex built around a framework reef developed on the margin of an isolated platform. In addition, an innovative, preliminary time series analysis of facies, microfacies and depositional environment data reveal the existence of seasonal cycles in the stacking patterns of facies and microfacies.  相似文献   

Geomorphic and lithologic characteristics of Wadi Feiran basin,southern Sinai,Egypt, using remote sensing and field investigations     

Ayman A Ahmed  Mohamed Abdelkareem  Asran M Asran  Tawfig M Mahran 《Journal of Earth System Science》2017,126(6):85

Wadi Feiran is an important drainage basin in southern Sinai Peninsula covering an area of about 1785 \(\hbox {km}^{2}\), its streams drain into the Gulf of Suez crossing variety of rocks and sedimentary units varied in age from Precambrian to Quaternary. Field investigations, geographic information systems (GIS) and remote sensing studies including Landsat-7 ETM+, Radarsat-1, and SRTM DEM were integrated to reveal its lithologic, geologic and geomorphic features. Besides the field investigations, rock units including basement and pre- and syn-rift sedimentary units were discriminated using band ratios and principal component analysis techniques (PCA). Such techniques revealed that the crystalline rocks covering W. Feiran are unaltered rocks lacking OH-bearing minerals. Radar data successfully displayed the structures and geomorphic features related to topography. Moreover, the techniques allowed the extraction of the dyke-like structures along faults and shear zones. This also characterized the topographic variations through analysis of the shaded terrain and the altitudinal profiles. The results of data integration, lineament analysis and lineament density maps revealed that the structural grain in the present study has four different trends: N20–45E, N30–45W, N–S and E–W. Based on analysis of radar data and geomorphic indices, W. Feiran is an asymmetrical basin, its left side occupies \(\sim \)34% of the total area that leads to a supposedly massive tilt towards the south which caused the southwestward slope.  相似文献   

Evolution of Pleistocene travertine depositional system from terraced slope to fissure-ridge in a mixed travertine-alluvial succession (Jebel El Mida,Gafsa, southern Tunisia)     

Mohsen Henchiri  Walid Ben Ahmed  Andrea Brogi  Mehmet Cihat Alçiçek  Ramdhane Benassi 《Geodinamica Acta》2017,29(1):20-41

The Quaternary stratigraphic record of Jebel El Mida, composed of continental deposits, is a useful example of concomitant travertines and alluvial deposition in an extensional setting. Travertine deposition occurred in a faulted Pleistocene alluvial fan giving rise to seven (recognised) facies interfingering with five other alluvial ones. The travertine depositional events indicate a tectonically driven evolution from terraced slope (facies group FC1–FC6) to a travertine fissure ridge-type depositing phase (facies group of FC1–FC7). Interfingering between travertine and alluvial facies indicates the co-existence of adjacent and time-equivalent depositional environments. The travertine deposition resulted from deep origin hydrothermal fluids channelled along damaged rocks volumes associated to a regional fault system, named as the Gafsa Fault (GF). The travertine–terrigenous succession in Jebel El Mida highlights the major role played by the GF in controlling: (i) the hydrothermal fluid flow, still active as also indicated by the numerous thermal springs aligned along the fault zone; (ii) paleoflow directions, discharge locations, volume, rate and fluctuations of the water supply. The paleoclimatic correlation with adjacent localities reveals that, at that time, humid episodes could have contributed to the recharge of the hydrothermal system and to the deposition of alluvial sediments.  相似文献   

Speciation and fractionation of phosphorus in biosolids-amended soils: effects of water treatment residual nanoparticles   总被引：1，自引：1，他引：0  

A. M. Mahdy  E. A. Elkhatib  A. M. Balba  G. E. Ahmed 《International Journal of Environmental Science and Technology》2017,14(8):1729-1738

Phosphorus (P) speciation and fractionation are useful tools for assessing P mobility and potential transfer to water bodies. The current study aims to evaluate drinking water treatment residual nanoparticles (nWTRs) effects on P species in biosolids-amended soils using sequential chemical fractionation and mineral equilibrium model. Three different soil types were selected (El-Bostan, Kafr El-Dawar, Borg Al-Arab), amended with biosolids (3%), and different rates of nWTRs were applied. The P fractionation results revealed that addition of nWTRs to biosolids-amended El-Bostan soil increased the immobile aluminum phosphates from 27.30 to 88.90, 92.20, and 94.93% at 0.10, 0.20, and 0.30% application rate, respectively. Similar trend was noticed in Kafr El-Dawar soil. In Borg Al-Arab soil, nWTRs significantly (p < 0.05) increased aluminum phosphate to only 71.73% at the highest application rate (0.30%) due to its high content of calcium carbonate (35.70%). Similarly, phosphorous speciation analysis revealed that application of nWTRs significantly increased the proportions of immobile phosphate form (P sorbed to Al hydroxide) and amorphous sodium aluminum phosphate. Thus, water degradation via eutrophication can be minimized by applying nWTRs to biosolids-amended soils.  相似文献   

Bioremediation of crude oil by <Emphasis Type="Italic">Bacillus licheniformis</Emphasis> in the presence of different concentration nanoparticles and produced biosurfactant     

H. S. El-Sheshtawy  W. Ahmed 《International Journal of Environmental Science and Technology》2017,14(8):1603-1614

This research work focuses on testing the bacterial strain Bacillus licheniformis for the bioremediation capacity of the crude oil. A biosurfactant and two different nanoparticles with different concentrations (0.05, 0.1, 0.2 g/100 ml) were applied separately to enhance the biodegradation process. The optimum biodegradation of crude oil was demonstrated at 60% of microcosms containing biosurfactant and nanoparticles after 7 days. The bacterial strain is highly potential to consume the total paraffins (iso- and n-paraffins) in crude oil samples. Accordingly, the best biodegradation of total paraffins was observed in microcosms containing (0.2 g) of Fe₂O₃, Zn₅(OH)₈Cl₂ (nps) and biosurfactant separately. Additionally, the consumption of specific member rings of polyaromatics depends on the type and the concentration of nanoparticles. Thus, this bacterial strain was considered as a good candidate to be applied in the bioremediation process of petroleum-contaminated sites using biosurfactant and specific concentration of (Fe₂O₃ and Zn₅OH₈Cl₂) nanoparticles.  相似文献   

Sedimentological and geoenvironmental evaluation of the coastal area between Al-Khowkhah and Al-Mokha,southeastern Red Sea,Republic of Yemen     

Ahmed R. El-Younsy  Mahmoud A. Essa  Saeed O. Wasel 《Environmental Earth Sciences》2017,76(1):50

The increasing anthropogenic activities (e.g., constructing touristic resorts) have led to notable changes in the Yemeni Red Sea coastal regions. In this context, recent sediments have been investigated to infer possible natural and man-induced processes on these coastal areas. The target area lies between longitudes 43°13′–43°30′E and latitudes 13°15′–13°55′N. It extends about 90 km along the coastline as a part of the Tihama plain. Geomorphologically, it forms a long-curved stretch with pronounced headlands, embayments and bays. Generally, it is covered by recent sediments (wadi, lagoon, beach and spit deposits along with sabkha, coastal dunes and mangrove). Textural studies reveal that most of the studied sediments are mainly poorly to moderately sorted and are composed mainly of sandy fractions with few gravel and mud, mostly bimodal with minor unimodal patterns. The igneous (granites) as well as basic (basalt, andesite and andesitic pyroclastics) and acidic (dacite and rhyolite) volcanic rocks of Tertiary age, which are exposed to the east of the study area, are believed to be the source of pyroxenes, amphiboles, epidotes, biotite, sphene, zircon, tourmaline and rutile, in a decreasing order of abundance. Moreover, smectite, kaolinite, chlorite, illite and palygorskite are the predominant clay minerals, mainly of detrital origin. The total carbonate content fluctuates from 37.41% (lagoon sediments) to 53.74% (sabkha sediments). The high amount of sea grasses, which covers the tidal flat zone and relates to the fine-grained sediments, accounts for the high organic matter content. The mineralogy of the source rocks has controlled the general distribution of major elements (Fe, Mg, Na, K and Mn) in the beach sediments. In such sediments, the concentrations of the heavy metals (Cu, Zn, Cd, Ni, Pb and Co) may reflect the sediment pollution using different approaches. The enrichment factors (EFs) of the trace metals for most samples reveal values that are greater than 1, referring to three groupings, which are: moderate to moderately severe (Zn, Cu and Mn), minor to moderate (Pb and Co) and zero to minor (Cd and Ni) enrichment. The EFs for Pb, Cd, Ni and Co metals (<5) may be attributed to the crustal materials and/or natural weathering processes. But, those for Zn, Cu and Mn (>5), especially in Al-Khowkhah–Abu-Zahr, Moushij–Zahari–Ruays, Yokhtol and Mokha localities, are possible of anthropogenic contributions.  相似文献