Mapping land subsidence over the eastern Beijing city using satellite radar interferometry*

Beijing City has suffered from groundwater-induced subsidence since the late 1930s and the over-exploration of groundwater could lead to subsidence as much as ?12.0 cm?yr^?1. Previous studies on the ground deformation at Beijing City mainly focused on the period before the year of 2014 when a mega-engineering project was launched to reduce water shortage in Beijing. To study the most recent ground deformation, 19 L-band ALOS-1 PALSAR images (June 2007–January 2011), 24 C-band Sentinel-1 SAR images (June 2015–November 2016) together with 9 ALOS-2 PALSAR acquisitions (September 2014–February 2017) were analysed in this work. Levelling measurements were exploited to verify the ALOS-1-based time series InSAR (TS-InSAR) result while Sentinel-1 and ALOS-2 result were cross-verified with each other. Furthermore, the whole study area was divided into four sub-zones, and the result indicated that the subsidence rates over five townships, Cuigezhuan, Jinzhan, Liyuan, Songzhuang and Yanjiao were accelerating and more attentions should be paid. On the contrary, the town centre of Douge Zhuang township experienced a decreasing trend between these two temporal-periods. Additionally, the time series measurements with respect to five selected measurement points and the profile line along the subsidence hot spots were analysed.     

Monitoring and analysing the Emirate of Dubai’s land use/land cover changes: an integrated,low-cost remote sensing approach

This study presents a modified low-cost approach, which integrates the spectral angle mapper and image difference algorithms in order to enhance classification maps for the purpose of monitoring and analysing land use/land cover change between 2000 and 2015 for the Emirate of Dubai. The approach was modified by collecting 320 training samples from QuickBird images with a spatial resolution of 0.6 m, as well as carrying out field observations, followed by the application of a 3?×?3 Soble filter, sieving classes, majority/minority analysis, and clump classes of the obtained classification maps. The accuracy assessment showed that the targeted 2000, 2005, 2010 and 2015 classification maps have 88.1252%, 89.0699%, 90.1225% and 96.0965% accuracy, respectively. The results showed that the built-up area increased by 233.721?km² (5.81%) between 2000 and 2005 and continues to increase even up and till the present time. The assessment of changes in the periods 2000–2005 and 2010–2015 confirmed that net vegetation area losses were more pronounced from 2000 to 2005 than from 2010 to 2015, dropping from 47,618 to 40,820?km², respectively. This study is aimed to assist urban planners and decision-makers, as well as research institutes.     

Capacity assessment of the Qattara Depression: Egypt as a sink for the global sea level rise

One of the most prominent geomorphological features in the Western Desert of Egypt is the occurrence of the Qattara Depression (20,800 km² or 2% of Egypt’s area), which has the deepest point in Africa. Topographic analysis of the depression was carried out using fine resolution digital elevation models acquired from the Advanced Spaceborne Thermal Emission and Reflection Radiometer-Global Digital Elevation Model (ASTER-GDEM) in order to assess the capacity of the depression. Results showed that the lower point in the depression occurs at ?136 m and its capacity at the sea level is 1340 billion m³, which equals 10 times the live storage capacity of the Lake Nasser behind the Aswan High Dam. Although the depression has the aptitude to be a reservoir for any augmentation in the sea level, detailed environmental impact assessment studies should be implemented to address geologic, climatic, biologic as well as socio-economic impacts.     

Mechanical behaviour study of soil polluted by crude oil: case of Sidi El Itayem oilfield,Sfax, Tunisia

The pollution of soils by xenobiotic organic substances such as crude oil constitutes major environmental risks, which are still badly evaluated. The environmental risks are caused by the direct contamination of the surrounding areas or by an effect on the living organisms in the soils, thus acting directly on man via the food chains. For these reasons, it is essential to study the effects of these pollutants in the soil. The general objective of the work was to better characterize the mechanical behaviour of sites polluted by crude oil in the short and medium terms (case of oilfield of Sidi El Itayem, Sfax, Tunisia under the supervision of the Franco-Tunisian Oil Company). The process consists of determining and comparing the physicochemical, mechanical and geotechnical characteristics of virgin soil and soil artificially polluted by crude oil according to various pollution rates reaching 15% of the weight of virgin soil. This process made it possible to generate scientific knowledge and data, which could allow the prediction of the effects of the latter in interaction with the soil.     

Remote sensing applications to geological problems in Egypt: case study, slope instability investigation, Sharm El-Sheikh/Ras-Nasrani Area, Southern Sinai

The Sharm El-Sheikh/Ras-Nasrani area is one of the most attractive tourist resorts in Egypt particularly and in the world in general. The area has been rapidly growing during the last few years. Many construction projects including villages, hotels, beaches, and roads have recently been undertaken. The following study demonstrates the use of high-resolution satellite images, QuickBird imagery, acquired on June 2nd, 2007 (0.61 m spatial resolution), for detailed mapping of the recent developments and the slope instability hazard zones. The results were confirmed by field reconnaissance. Our findings indicate that there are many development areas threatened by unstable zones. The hazard areas have been delineated and classified, and a final slope instability hazard map has been established. Different factors were found to have a crucial impact on the slope instability, some natural and others man-made. These unstable localities need to be remediated and/or monitored to avoid any loss in property and/or lives.     

Enzyme Immunoassay for Pesticide Analysis Enzymimmunoassays zur Pestizidanalytik

Enzyme immunoassays profit from the unique properties of antibodies concerning their selectivity and affinity towards ligands, e.g. pesticides. The most commonly applied types belong to the class of competitive immunoassays with phase separation such as the ELISA. The principle is explained and illustrated using an atrazine assay as a representative example. Common error sources, especially cross-reactivities and matrix effects, are discussed. Interlaboratory tests demonstrate the presently available quality of enzyme immunoassays. An outlook is given on future developments.     

Predicting the surface tension of aqueous 1:1 electrolyte solutions at high salinity

The surface tension of the air/water interface is a phenomenon of particular interest in the water-unsaturated zone of porous media because it influences the contact angle and consequently the capillary water volume. A mechanistic model based on the modified Poisson-Boltzmann equation and the Pitzer theory is described and used to predict, under isothermal and isobaric conditions, the surface tension of 1:1 electrolytes at high salinity. These theories enable the determination of the electrical potential at the air/water interface and the activity coefficient of the ionic species in the bulk pore water, respectively. Hydration free energies of the structure-making and structure-breaking ions that influence the surface tension at high salinity are taken into account. Structure-making ions flee the air/water surface because they can better organize the water dipoles in bulk water than at the interface. Structure-breaking ions are positively adsorbed at the air/water interface because the bulk water can better organize their hydrogen-bonding network without these ions. The resulting surface tension increases and decreases, respectively, compared to the surface tension of pure water. The predictions are in good agreement with the surface tension data of 1:1 electrolytes (NaCl, KCl, HCl, NaNO₃, KNO₃, HNO₃ aqueous solutions) and the optimized parameters depend on the effective electrostatic diameters of cations and on the hydration free energies of the ions at the interface.     

Seismic microzonation for Penang using geospatial contour mapping

Shear wave velocity (V _s) and the fundamental site period of the subsurface condition are the primary parameters that affect seismic soil amplification in particular sites. Within the topmost layer of the soil, which measures 30 m, the average shear wave velocity V _s30 is commonly used to build codes for site classification for the design of earthquake-resistant structures and to conduct microzonation studies. In this study, the development of a microzonation map for V _s30 distribution, National Earthquake Hazard Reduction Program V _s30 site classification, and a fundamental site period for Penang are presented. The multichannel analysis of surface wave (MASW) test was conducted for more than 50 sites with available borehole data to develop the microzonation maps. The ten selected V _s profiles measured by MASW show a good correlation with the data obtained using empirical correlations in a previous study. The highest V _s values were identified at the northeastern and southeastern parts of Penang Island, corresponding to the shallow bedrock and the outcrop zone. Conversely, the lowest V _s values were found in the northwestern and southwestern parts of the Penang mainland owing to the thick layer of soft clay and silt deposits. The site period map shows the variation in site periods, with the highest value of 1.03 s at the western part of the Penang mainland and the lowest value of 0.02 s at the eastern part of the Penang Island. The microzonation maps developed in this study are vital to studies on seismic hazard and earthquake mitigation programs in Malaysia.     

On the depth to anomaly estimation using Karous and Hjelt filter in VLF-EM data

The Karous and Hjelt filter has been long time used as a qualitative interpretation of VLF-EM data. It is derived directly from the concept of magnetic fields associated with the current flow in the subsurface and resulted in a 2-D cross section showing the current density distribution at different depths. Practically, as the distance between measuring points increases, the total depth of the 2-D current density distribution section increases. Theoretically, the common guide to estimate the depth of penetration of an electromagnetic wave is the skin depth, which depends on the frequency of the electromagnetic wave and the conductivity of the host geological material, regardless of the distance interval between measuring points. Accordingly, the accuracy of the Karous and Hjelt filter regarding depth estimation of the anomaly is tested in this study. We proposed a conductive anomaly in a definite dimension and depth. The response of this conductive body is calculated as in-phase and out-of-phase synthetic VLF data via forward modeling. The synthetic VLF data is filtered by the Karous and Hjelt filter at 1, 5, and10 m of interval distance between measuring points. The present study showed that the Karous and Hjelt filter is characterized by a large degree of accuracy in depth estimation.     

The P3 kimberlite and P4 lamproite,Wajrakarur kimberlite field,India: mineralogy,and major and minor element compositions of olivines as records of their phenocrystic vs xenocrystic origin

Distinctly different groundmass mineralogy characterise the hypabyssal facies, Mesoproterozoic diamondiferous P3 and P4 intrusions from the Wajrakarur Kimberlite Field, southern India. P3 is an archetypal kimberlite with macrocrysts of olivine and phlogopite set in a groundmass dominated by phlogopite and monticellite with subordinate amounts of serpentine, spinel, perovskite, apatite, calcite and rare baddeleyite. P4 contains mega- and macrocrysts of olivine set in a groundmass dominated by clinopyroxene and phlogopite with subordinate amounts of serpentine, spinel, perovskite, apatite, and occasional gittinsite, and is mineralogically interpreted as an olivine lamproite. Three distinct populations of olivine, phlogopite and clinopyroxene are recognized based on their microtextural and compositional characteristics. The first population includes glimmerite and phlogopite–clinopyroxene nodules, and Mg-rich olivine macrocrysts (Fo 90–93) which are interpreted to be derived from disaggregated mantle xenoliths. The second population comprises macrocrysts of phlogopite and Fe-rich olivine (Fo 81–89) from P3, megacrysts and macrocrysts of Fe-rich olivine (Fo 85–87) from P4 and a rare olivine–clinopyroxene nodule from P4 which are suggested to have a genetic link with the precursor melt of the respective intrusions. The third population represents clearly magmatic minerals such as euhedral phenocrysts of Fe-rich olivine (Fo 85–90) crystallised at mantle depths, and olivine overgrowth rims formed contemporaneously with groundmass minerals at crustal levels. Close spatial association and contemporaneous emplacement of P3 kimberlite and P4 lamproite is explained by a unifying petrogenetic model which involves the interaction of a silica-poor carbonatite melt with differently metasomatised wall rocks in the lithospheric mantle. It is proposed that the metasomatised wall rock for lamproite contained abundant MARID-type and phlogopite-rich metasomatic veins, while that for kimberlite was relatively refractory in nature.