Landslide susceptibility assessment in the Anfu County,China: comparing different statistical and probabilistic models considering the new topo-hydrological factor (HAND)

The present study is aimed at producing landslide susceptibility map of a landslide-prone area (Anfu County, China) by using evidential belief function (EBF), frequency ratio (FR) and Mahalanobis distance (MD) models. To this aim, 302 landslides were mapped based on earlier reports and aerial photographs, as well as, carrying out several field surveys. The landslide inventory was randomly split into a training dataset (70%; 212landslides) for training the models and the remaining (30%; 90 landslides) was cast off for validation purpose. A total of sixteen geo-environmental conditioning factors were considered as inputs to the models: slope degree, slope aspect, plan curvature, profile curvature, the new topo-hydrological factor termed height above the nearest drainage (HAND), average annual rainfall, altitude, distance from rivers, distance from roads, distance from faults, lithology, normalized difference vegetation index (NDVI), sediment transport index (STI), stream power index (SPI), soil texture, and land use/cover. The validation of susceptibility maps was evaluated using the area under the receiver operating characteristic curve (AUROC). As a results, the FR outperformed other models with an AUROC of 84.98%, followed by EBF (78.63%) and MD (78.50%) models. The percentage of susceptibility classes for each model revealed that MD model managed to build a compendious map focused at highly susceptible areas (high and very high classes) with an overall area of approximately 17%, followed by FR (22.76%) and EBF (31%). The premier model (FR) attested that the five factors mostly influenced the landslide occurrence in the area: NDVI, soil texture, slope degree, altitude, and HAND. Interestingly, HAND could manifest clearer pattern with regard to landslide occurrence compared to other topo-hydrological factors such as SPI, STI, and distance to rivers. Lastly, it can be conceived that the susceptibility of the area to landsliding is more subjected to a complex environmental set of factors rather than anthropological ones (residential areas and distance to roads). This upshot can make a platform for further pragmatic measures regarding hazard-planning actions.     

Groundwater condition based on geoelectrical technique and Dar Zarrouk parameters between El Alamein and El Dabaa—Egypt

El Alamein-El-Dabaa area lies in the western Mediterranean coastal zone of Egypt with about 50 km long. The aims of the present study are the shallow groundwater aquifer determination and calculate the electric parameters of the overburden to achieve the easiest way for detecting groundwater contamination and considered it during the planning of new development project(s). To attain this target, 44 vertical resistivity soundings using Schlumberger array of the maximum AB/2?=?1000 m in the form of four profiles were carried out. From the interpretation results, six geoelectrical layers have been established in the area, and iso-resistivity, depth to water, and isopach contour maps are presented. Four geoelectrical cross-sections (two geoelectrical cross-sections are parallel to the Mediterranean shoreline and the other two are normal to the Mediterranean shoreline) have been constructed. According to this work, the upper part of the Oolitic Limestone represents the shallow groundwater aquifer in this area and can be distinguished into two zones. The upper zone is brackish, whereas the lower one is saline. The geoelectrical succession reveals that the aquifer is free type. The depth to water ranges between 20 and 63 m; therefore, it is the choice as the best sites for groundwater exploitation. In the area under study, the depth to water and the thickness of the brackish increase towards the south side as well as the depth to the brackish water. The Dar-Zarrouk parameters clarified that there are some parts that may contaminate pathways and other parts are not.     

Kinetics of DTPA extraction of Zn,Pb, and Cd from contaminated calcareous soils amended with sewage sludge

The aim of this study was to determine the influence of sewage sludge (SLU) amendment on the desorption characteristics of zinc (Zn), lead (Pb), and cadmium (Cd) in contaminated calcareous soils. Three levels of SLU (0, 1, and 3% w/w) were added to the two calcareous contaminated soils. Samples were incubated for 30 days and equilibrated with 0.005 M DTPA for 0.25 to 240 h. The addition of SLU significantly increased the amount of DTPA-extractable Zn in soils. While the amounts of Cd, Pb, dissolved organic carbon (DOC), and pH showed a significant increase only in 3% w/w of SLU, with the exception of Cd desorption in 1% w/w of SLU, kinetics of Zn, Pb, and Cd extraction increased together with an increase in the level of applied SLU. The best models for describing desorption data were explicitly power function and Elovich. The rate constants of Zn and Pb had significant correlations with DTPA-extractable Zn and Pb, DOC and pH, which affect Zn and Pb desorption. Also, the rate constants of Cd had significant correlations with CEC that can be deemed as equivalent to the fact that Cd desorption is controlled by surface adsorption, particularly in the lower sludge application amount. These results can be used for management of sewage sludge application in contaminated calcareous soils.     

Laboratory measurements of vortex-induced sediment pickup rates

In the present study,vortices were generated in open channel flow with a cross-flow cylinder installed horizontally near the bed.Sediment pickup rates were then measured over the channel bed downstream the cylinder using a sediment lift.The experimental data show that the pickup rate increases exponentially in the presence of vortices.Two different relationships can be clearly observed between the pickup rate and the maximum root-mean-square (rms) value of the streamwise velocity fluctuation,one for the cylinder-obstructed flow and the other for the unobstructed flow.The results imply that the vortex-induced sediment pickup cannot be explained based on the traditional boundary layer theory.     

Petrophysical,seismic structural and facies analysis of the Miocene reservoirs of East Morgan oil field,Gulf of Suez,Egypt

The Gulf of Suez is characterized by the presence of many hydrocarbon-bearing fields including reservoirs ranging in age from the Palaeozoic to the Tertiary. East Morgan oil field is one of the promising oil fields which are located in the southern part of the Gulf of Suez and tapping hydrocarbon deposits and potentials of the Miocene age. The purpose of this work is to evaluate the Miocene sediments of the Asl and Hawara Formations in East Morgan oil field (western sub-basin) through carrying out an integrated petrophysical, seismic structural and sequence stratigraphy study. Quantitative well logging analyses are carried out over Asl and Hawara Formations to throw light over their hydrocarbon potentiality. Good oil saturation is exhibited by the sand sections of Asl Formation, and fair to good are assigned for those of Hawara Formation in the Belayim dip province. On the other hand, a little hydrocarbon saturation is represented by both formations to the south of the study area in the Morgan accommodation zone (MAZ). The estimated petrophysical parameters of Asl reservoir throughout the study area range between 4 % and 10 % for effective porosity, 18 % and 89 % for shale volume and 2 % and 48 % for hydrocarbon saturation. Meanwhile, the ranges of 1–8 %, 20–98 % and 2–32 % are given for Hawara Formation for effective porosity, shale volume and hydrocarbon saturation, respectively. The lateral distribution maps show that the central and the western parts of the MAZ attain the best petrophysical parameters and hydrocarbon potentiality. Seismic facies analysis, structural framework and depositional history of the study area were studied through interpreting the seismic reflection data of 27 seismic profiles. A number of geo-seismic cross sections are constructed and interpreted to investigate the structural setting of the study area and clarify the main structural elements that affect the hydrocarbon bearing reservoirs. A group of simple NW–SE step-like normal faults, parallel to the Clysmic trend, is found cutting through the reservoir rocks at the bottom layers of the section (Rudeis Formation) and extending upwards to overlying layers (Zeit Formation). Some graben- and horst-shaped structures are found and usually bounded by two sets of oppositely dipping normal step-like cross faults. The seismic facies and sequence analysis revealed that the Miocene rocks are subdivided into two major third-order depositional sequences (S1 and S2), separated by two major depositional sequence boundaries (DSB1 and DSB2). The first sequence (S1, Lower–Middle Miocene rocks) is of prime interest, as it encounters the main hydrocarbon reservoirs in the study area (Asl and Hawara Formations that are equivalent to Rudeis Formation). The seismic facies of this sequence are characterized by low to moderate amplitude, discontinuous horizons and bounded by the depositional sequence boundary (DSB1) at the top. The reflection geometry at the cycle boundaries is considered as erosional truncation, toplaps and even concordant along the upper boundary of the cycle. The external form of these sediments is considered as sheet-like and wedge-shaped units. The entrapment of hydrocarbons seems to be of a combined effect of the stratigraphic and structural elements. It appears clear that both of the step-like structural fault system and the lateral variation of facies are the key parameters that control the accumulation of hydrocarbon in this area and in East Morgan field as a whole.     

A step beyond susceptibility: an adaptation of risk framework for monetary risk estimation of gully erosion

Natural Hazards - In an effort to improve the previous gully susceptibility assessments in Iran, we attempted to conglomerate the notions of susceptibility, vulnerability, and exposure associated...     

Efficiency Evaluating of Automatic Lineament Extraction by Means of Remote Sensing (Case Study: Venarch,Iran)

One of the main geological evidence for many ore-bearing deposits and mineralized regions is the existence of points in highly fractured zones and the fragmentation intensity resulted from development of hydrothermal alteration along the fractures, the process leading to the occurrence of ore deposits. In this paper, a new algorithm has been proposed including a set of image processing techniques for detection the lineaments in satellite images by means of programming in MATLAB environment. The set of utilized methods includes line segment extraction by EDLine algorithm, merging line segments by Tavares method and linking the resulting line segments based on the collinearity and proximity criterion. The tectonic structures were stabilized by B-Spline curve fitting. The proposed algorithms were implemented on the ASTER image of a structurally multiple fractured region located in the central Iran, and the lineament map of Venarch area has been depicted. The results obtained from the proposed algorithms indicate a high accuracy of the operations detection of 80% for the reference map lineaments and the overall accuracy of the method is effectively reported as 62%. Combination of the above algorithms proposes a new method that precisely resulted in obtaining image processing of geological evidence for increasing the accuracy and decreasing the risk, before any field operations.