Intensification of future heat waves in Pakistan: a study using CORDEX regional climate models ensemble

Future trends in the occurrence of heat waves (HW) over Pakistan have been presented using three regional climate models (RCMs), forced by three different global climate models (GCMs) runs under RCP8.5 scenarios. The results of RCMs are obtained from CORDEX (Coordinated Regional climate Downscaling EXperiment) database. Two different approaches for the assessment of HWs are defined, namely Fixed and Relative approaches. Fixed approach is defined for a life-threatening extreme event in which the temperature can reach more than 45 °C for a continuous stretch of several days; however, Relative approach events may not be directly life-threatening, but may cause snow/ice melt flooding and impact on food security of the country in summer and winter seasons, respectively. The results indicate a consistent increase in the occurrence of HWs for both approaches. For the Fixed approach, the increase is evident in the eastern areas of Pakistan, particularly plains of Punjab and Sindh provinces which host many big cities of the country. It is argued that the effect of HWs may also be exacerbated in future due to urban heat island effect. Moreover, summer time HWs for Relative approach is most likely to increase over northern areas of the country which hosts reservoirs of snow and glacier, which may result in events like glacial lake outburst flood and snow/ice melt flooding. Furthermore, the increase in winter time HWs for Relative approach may affect negatively on the wheat production, which in turn can distress the overall food productivity and livelihoods of the country. It is concluded that this study may be a useful document for future planning in order to better adapt to these threats due to climate change.     

Neuro-fuzzy modelling in mining geochemistry: Identification of geochemical anomalies

Local and mine scale exploration models for anomaly recognition within known ore fields are discussed. Traditional geochemical exploration methods are based on multivariate statistical analysis, metallometry, vertical geochemical zonality and criteria of natural field geochemical associations, which suffer several shortcomings, including lack of a geostatistical generalised approach for separating anomalies from background. These shortcomings make the interpretation process time consuming and costly. Fuzzy set theory, fuzzy logic and neural network techniques seem very well suited for typical mining geochemistry applications. The results, obtained from applying the proposed technique to a real scenario, reveals significant improvements, comparing the results obtained from applying multivariate statistical analysis. Computationally, the introduced technique makes possible, without exploration drilling, the distinction between blind mineralisation and zone of dispersed ore mineralisation. The methodology developed in this research study has been verified by testing it on various real-world mining geochemical projects.     

Modeling of seawater intrusion in a coastal aquifer of Karaburun Peninsula,western Turkey

Seawater intrusion is a major problem to freshwater resources especially in coastal areas where fresh groundwater is surrounded and could be easily influenced by seawater. This study presents the development of a conceptual and numerical model for the coastal aquifer of Karareis region (Karaburun Peninsula) in the western part of Turkey. The study also presents the interpretation and the analysis of the time series data of groundwater levels recorded by data loggers. The SEAWAT model is used in this study to solve the density-dependent flow field and seawater intrusion in the coastal aquifer that is under excessive pumping particularly during summer months. The model was calibrated using the average values of a 1-year dataset and further verified by the average values of another year. Five potential scenarios were analyzed to understand the effects of pumping and climate change on groundwater levels and the extent of seawater intrusion in the next 10 years. The result of the analysis demonstrated high levels of electrical conductivity and chloride along the coastal part of the study area. As a result of the numerical model, seawater intrusion is simulated to move about 420 m toward the land in the next 10 years under “increased pumping” scenario, while a slight change in water level and TDS concentrations was observed in “climate change” scenario. Results also revealed that a reduction in the pumping rate from Karareis wells will be necessary to protect fresh groundwater from contamination by seawater.     

Engineering risk assessment on water structures under climate change effects

The increase in the average temperature in the lower atmosphere caused by climate change triggers changes in various elements of the hydrological cycle at different scales depending on location in the world. Although numerous published studies are concerned with the effect of climate change on hydrological elements such as temperature, precipitation, evaporation, wind, and runoff, unfortunately, the performance of water engineering structures is not taken into consideration. Nevertheless, as an integral part of the whole water resources systems, engineering structures such as dams, canals, culverts, and wells are also subject to climate change impacts. This examines the performance of engineering structures by taking into account how climate change impacts on the risk assessment formulation. For this purpose, the risk concept is redefined and the climate change impact is taken into account by a factor dependent on the positive or negative slope of the trend from the historical record. The risk levels are revised for 10-year, 50-year, and 100-year return periods. The application of the proposed methodology is given for precipitation records for three different meteorological stations in the southeastern European province of Turkey and for the same number of stations from central east-west belt over Saudi Arabia. It is observed that including the climate change factor in the risk calculation formulation generally leads to an increase in the return period and in the risk compared to conventional calculations. Therefore, it is recommended that rather than using the standard risk formulation, the simple, effective climate change risk approach, as suggested in this paper, be applied to future water engineering structure designs.     

Imaging fracture distributions of the Al-Khuff Formation outcrops using GPR and ERT geophysical techniques,Al-Qassim area,Saudi Arabia

Khuff Formation is of utmost importance in Saudi Arabia for oil and gas reservoir although it is composed mainly of limestone. This reason refers to the existence of intensive fractures which play a vital role in the increase in porosity and permeability of this formation. The fracture pattern in the study area was verified through 2D and 3D ground penetrating radar (GPR)-defined and electrical resistivity tomography (ERT)-defined surveys. In this respect, ten of 2D GPR surveys were collected along an intersected grid of profiles covering the study area while ERT data were collected along three profiles of the GPR grid. The results were interpreted in light of the field-based structural and stratigraphic assessment of the outcropping rocks. The analysis of the inverted ERT and filtered GPR sections revealed the presence of fractures. Several resistivity and electromagnetic reflection anomalies were laterally and vertically identified across the measured sections clarifying fractures that extend to a depth of 24 m in the limestone. Most fractures are oriented vertical to sub-vertical dipping both east-west and north-south.     

The Hizeh-Jan Kaolin Deposit of NW Iran:the TetradEffect in REE Distribution Patterns

The Hizeh-Jan kaolin deposit(northwest of Varzeghan, East-Azarbaidjan Province, NW Iran) is a product of the alteration of Eocene andesitic rocks. Based on mineralogical examinations, kaolinite, quartz, smectite, pyrophyllite, muscovite-illite, alunite, calcite, diaspore, goethite and hematite are the most abundant mineral phases in this deposit. The geochemical indicators, such as Y/Ho and Zr/Hf, indicate the non-CHARAC(non-Charge-radius control) behavior of these pairs, which are likely to be due to the occurrence of the tetrad effect phenomenon in this deposit. Simultaneous concave and convex shapes in the chondrite-normalized REE distribution patterns are a remarkable feature of the kaolin samples. Bivariate diagrams of the size of the third tetrad effect(T_3) versus geochemical parameters such as Y/Ho, Nb/Ta and Zr/Hf ratios display two distinct populations for the kaolin samples. The first population is characterized by high T_3 values(>0.13), which are near or on the fault zone. The second population is characterized by low T_3 values(<0.13), and are farther from the fault zone. The obtained results from the geochemical data have furnished compelling evidence that fluidrock interaction, overprint of hypogene processes by supergene ones, and structural control, are key controlling factors for the occurrence of tetrad effects in REE distribution patterns in the Hizeh-Jan kaolin deposit.     

Geo-environmental study of heavy metals of the agricultural highway soils,NW Jordan

This study investigated the status and distribution patterns of selected heavy metals in roadside soils along Irbid-North Shooneh Highway, Jordan. This highway has experienced a growing number of vehicles that are likely to influence the levels of heavy metals in the surrounding agricultural lands. The average concentrations of Cr, Co, Cd, Cu, Pb, Zn, and Ni were 16.0, 36.0, 11.0, 4.0, 79.0, 122.0, and 60.0 mg/kg, respectively. Cd, Pb, and Co showed average levels that are higher than the average world soil background values. Elevated levels of heavy metals were measured in surface soil layer which decreased with depth, and with distance from the roadway. The contamination factor (CF), pollution load index (PLI), single ecological risk (Ei), potential ecological risk index (PERI), and geo-accumulation index (Igeo) generally indicated that the roadside soils are contaminated with Cd, Pb, and Ni. Heavy metals in soils are of geogenic and anthropogenic origins. Weathering of parent rocks in Wadi Al-Arab catchment is the primary natural source, whereas agrochemicals, vehicle exhausts, degradation of surface wear and paint of vehicles, vehicle wear debris of tire, and brake lining are the main anthropogenic sources of heavy metals.     

Mathematical analysis of gravity anomalies due to an infinite sheet-like structure

Gravity anomalies caused by a thin infinite sheet are interpreted quantitatively based on an integral transform approach which is elegant and simple. The proposed technique depends on the modified Hilbert transform which is called “Sundararajan transform.” The amplitudes of the well-known Hilbert transform and Sundararajan transform are exactly the same but with a phase difference of 270° between them. The interpretation of gravity anomalies due to a thin infinite sheet has been implemented using the Sundararajan transform rather than the well-known Hilbert transform, yielding a straightforward solution. Parameters such as the depth to the top of the sheet (z), the inclination angle (θ), and the amplitude coefficient (K) have been analytically determined using simple mathematical equations. The origin of the causative target can be determined by the intersection point between Hilbert and Sundararajan transforms as well as the intersection point of the amplitudes of the analytic signal of the two transforms. The proposed technique has been first applied to synthetic data where the procedures are clearly illustrated. The effect of noise on the interpretation procedures of the proposed technique has been investigated, showing in general satisfactory results especially depth estimation. However, the most sensitive parameter to noise is the dipping angle, which can be misleading in high level of noise, whereas the least sensitive parameter is the depth. Strictly speaking, the noise does not significantly distort the depth estimation obtained with this proposed technique. Finally, the interpretation of the gravity anomaly across the Mobrun ore body, Noranda, Quebec, Canada, has been carried out using the proposed technique where the parameters are estimated and compared to the results that have been published in literatures using different techniques.     

Numerical analyses of tunnel collapse and slope stability assessment under different filling material loadings: a case study

To transfer the excess water from Sabzkouh River in central Iran to cities beyond the river, a mechanized tunnel is being excavated. During construction and support installation in the first 100 m, tunnel roof collapse occurred and was followed by ground settlement, so that a cavity was developed in ground surface. The cavity had to be filled in a short time before rainy season, since the water flow through cavity could extend the collapse area in both tunnel roof and ground surface. In order to fill the cavity, some filling methods with different materials consist of in situ soil, lightweight concrete, and pumice aggregate lightweight concrete (PALWC) were suggested. To analyse the load distribution and minimize the costs, a three-dimensional analysis was carried out. Tunnel support system was simulated numerically to further evaluate loading state on support system under different material loadings. Mohr-Coulomb material model was used to allow material failure. The modelling procedure was based on actual construction procedure. Firstly, in situ model was modelled without any excavation and was run to establish pre-stresses and displacement, then slope was supported, the tunnel was excavated and support was installed and finally cavity was simulated. The numerical results show that filling the cavity with soil will result in over loading on the support system and leads to instability of the slope. Other two suggested filling materials have acceptable load on support system, but PALWC was selected as the best filling material having minimum loading and guarantees slope stability.