Morphometric,statistical, and hazard analyses using ASTER data and GIS technique of WADI El-Mathula watershed,Qena, Egypt

An attempt to carry out morphometric, statistical, and hazard analyses using ASTER data and GIS technique of Wadi El-Mathula watershed, Central Eastern Desert, Egypt. Morphometric analysis with application of GIS technique is essential to delineate drainage networks; basin geometry, drainage texture, and relief characteristics, through detect forty morphometric parameters of the study watershed and its sub-basins. Extract new drainage network map with DEM, sub-basin boundaries, stream orders, drainage networks, slope, drainage density, flow direction maps with more details is very necessary to analyze different morphometric and hydrologic applications for the study basin. Statistical analysis of morphometric parameters was done through cluster analysis, regression equations, and correlation coefficient matrix. Clusters analyses detect three independents variables which are stream number, basin area, and stream length have a very low linkage distance of 0.001 (at very high similarity of 99.95%) in a cluster with the basin width. Main channel length and basin perimeter (at very high similarity of 99.83%) are in a cluster with basin length. Using the regression equations and graphical correlation matrix indicates the mathematical relationships and helps to predict the behavior between any two variables. Hazard analysis and hazard degree assessment for each sub-basin were performed. The hazardous factors were detected and concluded that most of sub-basins are classified as moderately to highly hazardous. Finally, we recommended that the flood possibilities should be taken in consideration during future development of these areas.     

3-D magnetic inversion and satellite imagery for the Um Salatit gold occurrence,Central Eastern Desert,Egypt

The Um Salatit is a gold occurrence situated in the Central Eastern Desert of Egypt. The studied area is characterized by an intensive imbrication zone of serpentinites and metavolcanic rocks. The integrated use of aeromagnetic and spectral reflectance remote sensing data has proved effective for mapping geology related to ore deposits. Spectral reflectance maps have been produced to discriminate various rocks, such as serpentinites, gabbros, and metavolcanic rocks. 3-D inversion of aeromagnetic data acquired over the Um Salatit study area produced a 3-D magnetic susceptibility model showing magnetic bodies surrounded by less magnetic host rock. The magnetic features are elongated ENE-WSW parallel to the major thrust fault and mapped the Um Salatit serpentinized rocks. Remote sensing data allow investigating surficial geological features and mapping the mineralized areas. Remote results, in conjunction with 3-D inversion of aeromagnetic data, demonstrate that gold occurrence in the study area was effectively restricted to the highly magnetic zone interpreted as host rocks.     

Tectonic evolution of the Karakoram metamorphic complex (NW Himalayas) reflected in the 3D structures of spiral garnets: Insights from X-ray computed micro-tomography

Spiral garnet porphyroblasts are known to record lengthy periods of deformation and metamorphism by preserving single or multiple FIAs (Foliation Intersection Axis) formed normal to tectonic shortening directions. Thanks to technological advances in X-ray computed micro-tomography (XCMT), FIAs can now be readily determined in relatively large samples in contrast to previous methods that require the preparation of a set of radial vertical and horizontal thin sections of samples. XCMT scanning not only alleviates tedious thin section based procedures but also illuminates the complete internal architecture of a rock sample allowing three-dimensional (3D) quantitative shape analysis of an individual porphyroblast as well as precise measurement of FIAs. We applied the technique to a sample from the Hunza Valley in the Karakoram metamorphic complex (KMC), NW Himalayas, containing numerous garnet porphyroblasts with spiral-shaped inclusion trails. The XCMT imaging reveals an E–W trending FIA within the sample, which is consistent with orthogonal N–S collision of the India-Kohistan Island Arc with Asia. Garnet long axes (X_GT) have variable plunges that define a broad sub-vertical maximum and a small sub-horizontal maximum. The X_GT principle maxima lie at N-090 and N-120. Smaller maxima lie at N-020 and N-340. Geometric relationships between X_GT axes and FIA orientation in the sample suggest that porphyroblast shapes are controlled by the geometry of the lens-shaped microlithons in which they tend to nucleate and grow. The orientation of inclusion trails and matrix foliations in the sample are correlated with three discrete tectono-metamorphic events that respectively produced andalusite, sillimanite and kyanite in the KMC. Late staurolite growth in the sample reveals how the rocks extruded to the surface via a significant role of roll-on tectonics, which can be correlated with the Central Himalayas.     

Morphological analysis and channel shifting of the Fulahar river in Malda district,West Bengal,India using remote sensing and GIS techniques

GeoJournal - The present study has been carried out to analyse and interpret the morphological changes and channel shifting along the Fulahar river in the Malda district. Fulahar river is one of...     

Seismic risk assessment of a steel building supported on helical pile groups

Acta Geotechnica - Designing structures to be the least vulnerable within earthquake-prone areas is a serious challenge for structural engineers. One common and useful tool that structural...     

Stochastic Modelling of Mineral Exploration Targets

Mathematical Geosciences - Mineral deposits are metal enrichment anomalies, occurring as local manifestations of the interplay between various geological processes that operate at a wide range of...     

Participatory action research: working beyond disaster toward prevention

Drawing on qualitative analyses of post-disaster effects on vulnerable rural communities in Pakistan, this paper puts forward a participatory action research stance as a next step or approach toward prevention. This approach stands in contrast to the current post-disaster relief model commonly practiced by many non-government organizations (NGOs). The participatory action research perspective was used to examine the qualitative evidence and provide a framework to effectively work with rural vulnerable communities. Qualitative analyses documented community wisdom and ideas toward prevention which, when potentially partnered with resources offered by NGOs, could dramatically reduce their vulnerability to natural disasters.     

Fertile Lithospheric Mantle Beneath the North African Plate: Evidence from Gharyan Lherzolite Xenoliths (Northern West Libya)

The late-stage basanite (～12–1 Ma) of the NNW-SSE extending Gharyan Cenozoic volcanics (Northern West Libya) contains numerous fresh lherzolite xenoliths. These xenoliths display magmatic protogranular and porphyroclastic textures. Chemistry of olivine (forsterite content –90–91, NiO = 0.26–0.39 wt %), orthopyroxene (Mg# = 0.91–0.92, Cr# = 0.03–0.07, Al₂O₃ = 3.64–4.43 wt %), clinopyroxene ((Wo_{45.59–48.61}, En_{45.89–48.80}, Fs_4.47–5.81), Mg# = 0.82–0.92, Al₂O₃ = 5.14–6.58 wt % and Cr₂O₃ = 0.5–0.95 wt %) and spinel (hercynite–picotite–Al-rich chromite spinels with Cr# = 0.08–0.11) refer to the fertile nature of Gharyan peridotites. Mantle source region was close to the primitive composition with low degrees of melting and depletion in melt (1.5% in average). However, it underwent metasomatism as illustrated by formation of secondary clinopyroxene (Wo_{37.96–44.77}, En_{47.44–54.18}, Fs_7.59–8.03) with high contents of Na₂O, and enrichment of the Al-spinel in TiO₂. The estimated pre-eruptive temperature ranges from 1066 to 837°C. Despite the Gharyan peridotite is similar to mantle components in many districts in Saharan belt of North Africa, it represents juvenile mantle source with minor refractory residues. This compositional heterogeneity is mainly attributed to the local effect of the interaction of the Gharyan mantle with the host basanite magma that may be related to the Cenozoic rifting of the Pan-African basement.     

The link between social capital and disaster recovery: evidence from coastal communities in Bangladesh

Natural Hazards - The purpose of this research is to explore the role social capital played in disaster coping and the recovery process among the southwest coastal villages of Bangladesh....