Alaa A. Masoud

Relationship between Remotely Sensed Vegetation Change and Fracture Zones Induced by the 2008 Wenchuan Earthquake, China

The Wenchuan (汶川) earthquake triggered cascading disasters of landslides and debris flows that caused severe vegetation damage. Fracture zones can affect geodynamics and spatial pattern of vegetation damage. A segment tracing algorithm method was applied for identifying the regional fracture system through lineament extractions from a shaded digital elevation model with 25 m mesh for southern Wenchuan. Remote sensing and geographic information system techniques were used to analyze the spatiotemporal vegetation pattern. The relationship between vegetation type identified from satellite images and lineament density was used to characterize the distribution patterns of each vegetation type according to fracture zones. Broad-leaved forest, mixed forest, and farmland persist in areas with moderate lineament density. Deciduous broad-leaved and coniferous forest persists in less fractured areas. Shrub and meadow seem to be relatively evenly distributed across all lineament densities. Meadow, farmland, and shrub persist in the fractured areas. Changes of spatial structure and correlation between vegetation patterns before and after the earthquake were examined using semivariogram analysis of normalized difference vegetation indices derived from Landsat enhanced thematic mapper images. The sill values of the semivariograms show that the spatial heterogeneity of vegetation covers increased after the earthquake. Moreover, the anisotropic behaviors of the semivariograms coincide with the vegetation changes due to the strikes of fracture zones.

Applicability of computer-aided comprehensive tool (LINDA: LINeament Detection and Analysis) and shaded digital elevation model for characterizing and interpreting morphotectonic features from lineaments

Abstract Detection and analysis of linear features related to surface and subsurface structures have been deemed necessary in natural resource exploration and earth surface instability assessment. Subjectivity in choosing control parameters required in conventional methods of lineament detection may cause unreliable results. To reduce this ambiguity, we developed LINDA (LINeament Detection and Analysis), an integrated tool with graphical user interface in Visual Basic. This tool automates processes of detection and analysis of linear features from grid data of topography (digital elevation model; DEM), gravity and magnetic surfaces, as well as data from remote sensing imagery. A simple interface with five display windows forms a user-friendly interactive environment. The interface facilitates grid data shading, detection and grouping of segments, lineament analyses for calculating strike and dip and estimating fault type, and interactive viewing of lineament geometry. Density maps of the center and intersection points of linear features (segments and lineaments) are also included. A systematic analysis of test DEMs and Landsat 7 ETM+ imagery datasets in the North and South Eastern Deserts of Egypt is implemented to demonstrate the capability of LINDA and correct use of its functions. Linear features from the DEM are superior to those from the imagery in terms of frequency, but both linear features agree with location and direction of V-shaped valleys and dykes and reference fault data. Through the case studies, LINDA applicability is demonstrated to highlight dominant structural trends, which can aid understanding of geodynamic frameworks in any region.

Geotechnical Mapping of Najran Soils for Safe Urban Expansion, Najran Region, Saudi Arabia

One hundred eighty-three rotary-drilled boreholes from fifteen districts in Najran area, Kingdom of Saudi Arabia, were sampled and tested in the field and in laboratory to analyze the spatial variation in their geotechnical properties. Number of samples varied with the performed test including grain size distribution (668), Atterberg limits (24), moisture content (432), free swelling (49), direct shear strength (51), unconfined compression strength (37), and soil water chemistry of 168 samples were analyzed for Cl−, SO3−2, and CO3−), and 120 samples for pH. Descriptive statistics were appraised for clarifying the geotechnical variations among the districts and various AASHTO-classified soil types. GIS-based geostatistical kriging with minimum error achieved was used for preparing the spatial maps of the geotechnical parameters. Results showed that majority of soil samples were non-plastic. Hubuna district showed the larger LL (42%), PL (25%), and PI (20%) while Mefraq Al-Khamis recorded the lowest values of LL (23%), PL (19%), and PI (2%). Atterberg limits showed a northwestward increase to reach its maxima at Thar. Moisture content was larget in Khobash and showed local highs at Najran Al-Fahd and Al-Mashaliya.Fine sands prevailed north and east of Abu Shadad with local highs in Al-Mashaliya and Najran University. Silt and clay soils dominate in Najran Al-Fahd district. Local highs of free swelling were vivid at Abu Shadad, Khobash, Mefraq Al-Khamis, and Najran Al-Fahd districts. UCS showed largest in Najran University. Shear test friction angle showed lowest at Khobash and Abu Shadad districts dominated by coarse to medium sands and gravels and largest of 35° in Najran University and extends to Thar attaining the largest fine sand and gravel contents. Largest Cl− and SO3−2 contents characterized the districts of Thar, Al-Hosayniya and Hubuna while CO3− showed local high at Najran Al-Fahd district, the soils were acidic with pH lower than 5.5. Three main soil types according to AASHTO classification formed about 91% of the samples: A-1-b (56%), A-2-4 (23.5%), and A-3 (11.4%), were mapped and their geotechnical properties were characterized. Results can help efficient decision-making process to set proper management zones and prevent geotechnical risks where measures in the design and construction stages can be decided for future expansions and subsurface tunneling based on the district- and soil type-specific.

TUEF2016-environmental pollution: problem and solution

This special issue of Environmental Science and Pollution Research highlights selected papers presented at the 3rd International Environmental Forum held on 12–14 July 2016 in Tanta University, Egypt (TUEF2016), focused on Environmental Pollution: Problem and Solution. The forum brought together thought-leaders, researchers, scientists, engineers, academia, industry, investors, technology developers, planners, and policymakers met and presented their research results and findings in a compelling manner on novel technologies and applications for mitigating the most pressing 16 environmental problems listed below.

Uranium migration and favourable sites of potential radioelement concentrations in Gabal Umm Hammad area, Central Eastern Desert, Egypt

Abstract Airborne gamma-ray spectrometric data, covering Gabal Umm Hammad area, near Quseir City, in the Eastern Desert of Egypt, has been utilized to identify the uranium migration path, and U, Th and K-favorability indices. The following of the uranium migration technique enabled estimation of the amount of migrated uranium, in and out of the rock units. Investigation of the Taref Formation, Nakhil Formation, Tarawan Formation and Dawi Formation shows large negative amount of uranium migration, indicating that uranium leaching is outward from the geologic body toward surrounding rock units. Moreover, calculation of the U, Th and K-favorability indices has been carried out for the various rock units to locate the rocks having the highest radioelement potentialities. The rock units that possess relatively major probability of uranium potentiality include Mu′tiq Group, weakly deformed granitic rocks, and Trachyte plugs and sheets. Meanwhile, the rock units with major potential of Th-index are Taref Formation, Quseir Formation and Dawi Formation. The rock units with major potential of K-index are Dokhan volcanic and Mu′tiq group.