Arabian Journal of Geosciences

The present study aims to develop an efficient predictive model for groundwater contamination using Multivariate Logistic Regression (MLR) and Random Forest (RF) algorithms. Contamination by ammonia is recorded by many authors at Sohag Governorate, Egypt and is attributed to urban growth, agricultural, and industrial activities. Thirty-two groundwater samples representing the Quaternary aquifer are collected and analyzed for major cations (Ca, Mg, and Na), ammonia, nitrate, phosphate, and heavy metals. Lead, magnesium, iron, and zinc variables are used to test the model with ammonia which is used as an index to the groundwater contamination. Spatial distribution maps and statistical analyses show a strong correlation of ammonia with lead and magnesium variables whereas iron and zinc show less correlation. For Random Forest (RF) model, the data is divided into 70% training and 30% testing subsets. The performance of the model is evaluated using the classification reports, and the confusion matrix. Results show (1) high performance of RF model to groundwater contamination with an accuracy of 93% and (2) the MLR accuracy increased from 70 to 83% when “SOLVER” and “C” parameters are modified. The study helps to identify the contaminated zones at the study area and proved the usefulness of the machine learning models for prediction of the groundwater contamination using the ammonia concentration.

With the increase of the depth of mining, the working environment of deep well is worse; in order to improve the working environment of deep mine, on the basis of a lot of practice, the idea of adjusting the temperature of the air flow in the mine was put forward. Take Jiaodong area as an example, on the basis of the model of surface temperature variation, the influence of surface temperature on the temperature of the mine has been established, obtaining the influence of surface temperature on the shallow layer of the mine area. In assumption of the roadway, the heat exchange process of the surrounding rock and the air flow in the shallow layer of the different seasons was analyzed, a model of the relationship between the geometry size of the roadway and the air temperature change was established, in order to control the temperature of the mine into the air temperature by using the shallow tunnel temperature effect and then to improve the working environment of the mine working environment to lay a theoretical foundation.

Geogrid-reinforced earth is an advanced composite material which is widely used in the construction of retaining wall which is often needed in the transportation structure. Different compaction methods have great differences in wall deformation and materials of soil reinforcement strain, which seriously affect the performance of retaining wall. Therefore, it is necessary to further study the influence of different compaction methods on the retaining wall behind the face plate. Through a series of numerical simulation tests, the influence depth of total displacement, tensile load of materials of soil reinforcement, settlement displacement of wall top, and compaction stress is analyzed, and the influence of different compaction methods on reinforced earth retaining wall near face plate is studied. The results show that there is a certain lightweight compaction width between 1 and 2 m, which makes the wall appear a “bow” shape with zero deformation at the top of the panel. When the lightweight compaction width is less than 0.5 m, the tensile load of the materials of soil reinforcement near the face plate changes significantly. When the stress is greater than 2 m, the internal stress and the stress difference between the two ends of the materials of soil reinforcement decrease. The deformation trend of the numerical simulation model of each compacted plate is consistent with the total displacement of the plate and the tensile load of the materials of soil reinforcement. The part of the wall top that is more than 4 m from the panel has nothing to do with the light compaction width value. The closer the wall is to the roof, the greater the maximum tensile load, compaction load, soil depth, and stress.

The NCEP/NCAR final analysis data set of 1° × 1° resolution from the Research Data Archive and the gridded rainfall data provided by the India Meteorological Department was used to identify the western disturbances (WDs) which resulted in precipitation over North India during the winter season between 2009 and 2018. Variation in potential vorticity (PV), tropopause undulations and changes in ozone mixing ratio were investigated over North India and neighbourhood. The changes in these parameters were then related to the nature of precipitation associated with WD when they affect North India. It was observed that there is a fall in the tropopause height over North India as a WD approached. The lowest tropopause height of (6000–10,000 gpm) was seen close to the system centre at 500 hPa. A positive potential vorticity anomaly (PVAn) was observed at upper tropospheric levels with peak value observed at 300 hPa. Positive potential vorticity advection (PVA) was also resulted in changes to the PV value, which was lesser by a factor of 10 compared to the role played by intrusion of the stratospheric air mass to the upper troposphere. Fall in tropopause height occurred concurrently with increase in the ozone mixing ratio in the upper troposphere, while WDs affected North India. The study highlights the importance of stratospheric-tropospheric exchange in influencing the intensity of precipitation resulting from WDs over North India.

India will generate about 283,470 MW of electricity by 2022. Seventy percent of the proposed energy demand is fulfilled by fossil fuel, out of which 54 % of demand is contributed by coal as reported by Krishna (2001). The coal production would be 850 Mt per year to fulfil the demand. Opencast mining plays a major role in meeting the demand of coal for thermal power generation leading to the use of large-capacity haul trucks. Carrying capacity of trucks/dumpers used in opencast mines has grown from 30 to 250 t in recent years. These ultra-capacity trucks/dumpers need well-designed haul roads. At present, design of new haul roads is based on past experience and empirical methods. The sub-grade, sub-base and/or base of haul road typically uses the overburden (O/B) materials which could be replaced by composite material at a particular layer for better performance. There are more than 165 opencast coal mines and many are near to thermal power stations. Present-generation fly ash (FA) from coal-based thermal power plants in India is 135 Mt/year and it is expected to increase to 300–400 Mt/year by 2016–2017 as reported by Çimento (2004). The usage percentage of fly ash is about 60 % leaving the rest as plant waste occupying a huge land area and creating environmental problems. The investigation has characterised fly ash (FA), mine overburden material (O/B) and lime (L). Geotechnical properties of untreated fly ash, mine overburden, fly ash–mine overburden mixes and lime-treated fly ash–mine overburden mixes were investigated using response surface methodology (RSM). Design-Expert software was used to establish the design matrix and to analyse the experimental data. The relationships between the percentage parameters (%FA + %O/B + %L) and experimentally obtained three responses (California bearing ratio (CBR), unconfined compressive strength (UCS) and BTS) were established. RSM was performed to optimize the interactions of input parameter which showed the best conditions for preparation of composite material. According to the obtained results, the model was developed and further analysis was conducted. The experimental values agreed with the predicted ones, thus indicating suitability of the model employed and the success of RSM in optimizing the composite material. Lime percentage, curing period was observed to have strong influences on the strength parameters of the developed FCMs. The best composite material obtained with highest CBR and UCS values.

Lateral movement of river channel within its valley with time is a universal phenomenon. Various processes of fluvio-geomorphological environment such as rapid valley fill deposition due to very low channel gradient and resultant migration of active channel, bank failure and bankline migration, frequent occurrence of floods, capturing of lower courses of the tributaries by the trunk streams, and abandonment of tracks and avulsion are the most prominent factors behind channel dynamics in the sub-Himalayan part of West Bengal. Additionally, human interventions in the form of engineering constructions (bridges, flood embankments, etc.), tea plantation, mining and quarrying, and agricultural encroachment have emerged as another dominant issue which is pulverizing the ways of natural channel adjustment as well as also the channel behaviors. Both these processes are carrying significant messages of immense vulnerability for the study area known for its geomorphological instabilities. The dynamics of channel adjustment in terms of lateral migration can be lucidly illustrated through the application of modern tools of geoinformatics, i.e., the techniques of remote sensing and geographic information system (GIS) which is widely capable of detecting as well as representing the changes that took place over space and time. A meticulous endeavor has been made to assess the channel dynamics of the Diana River of this concerned region for an 85-year spanning period to unveil the nature of channel migration in terms of changes in historical bankline and centerline positions and alterations in meander geometries through numeric and graphical methods coupled with field observations to define the overall zone of channel migration for three subsequent reaches of the Diana River.

The Konya Closed Basin is an important basin in central Turkey, in terms of its geographic position, Quaternary infills, and well-preserved archeological sites. It comprises Quaternary lake marls and other, mainly fine grained, sediments with locally in excess of 400 m. Geochemical data for samples taken from the 7-m-deep Adakale trench from the late Quaternary lacustrine sediments in the Konya Closed Basin are presented and have been used as proxies to elucidate the past climatic changes, weathering regime, redox conditions, and productivity. Climate changes observed in the studied samples for last 50,000 years were represented by oscillations in weathering processes, detrital input, redox conditions, water levels, and paleoproductivity. Geochemical data show that three periods of high detrital input (high Si+Al+K+Ti+Fe, high Ti/Al, Rb/Sr, low Ca and low Si/Ti), four periods of anoxic conditions (low Mn and Th/U and high Ni/Co, Mo/Al and V/Cr), and four periods of higher productivity (high Cu/Al, Ni/Al, Ca/Al, Ba/Al Si/Ti and Ca/Ti) were effective in the study area. These periods are corresponding to climatic changes during last glacial periods, the warm climate of Dansgaard-Oeschger (D/O) events (D/O 2-12) and the cold climate of Heinrich events (H 2-5).

The spatial and temporal characteristics of aerosol optical properties (AOP) were analyzed in order to find out the hotspot aerosol sources over Iraq and surrounding regions. The correlation of AOP with the frequency of dust events (dust storm (DS), rising dust (RD), suspended dust (SD)) over 12 Iraqi stations is evaluated during the study period (January 2005–December 2014). The AOP: aerosol absorption optical depth (AAOD), aerosol extinction optical depth (AOD), and aerosol single scattering albedo (SSA) at 388 and 500 nm and aerosol index (AI), are derived from the Ozone Monitoring Instrument (OMI) on board the Aura satellite. Three well-known spatial interpolation techniques: inverse distance weighting, radial basis function with three sub-types, and kriging with three sub-types, are examined in ArcGIS software. Statistical analysis is applied to compute the station probability of dust events and its correlation with AOP. Results showed that the spline with the lowest RMSE and MPE near zero is the optimum method for estimating AOP. The spatial mean of AAOD, AOD, and AI (SSA) have the same pattern with high (low) mean values over the south and northwest of Iraq, Kuwait, and the northeast of Saudi Arabia. The seasonal variability of AAOD and AOD over the Iraqi stations showed that high (low) values occurred during spring and summer (winter) and concluded that AAOD is a responsible component for variation in AOD. DS and RD probability is higher over stations in the middle and south of Iraq than the stations in the north. High SD probability is over Mosul, Baghdad, and Nasiriya stations. The correlation of AOP with dust events suggests that the AAOD component is more important in the study of DS than SSA and AI while AI is a good index for the study of RD and SD in the study region.

Geochemical analysis of Crassostrea cucullata shells was carried out to study the pollution of the Iraqi aquatic brackish and marine environments. Samples of shells and water were collected from the intertidal zone at seven different stations (Fadakia, Rass Al Bishah, Khor Abdullah, Khor Shytianah, Hacham Island, Khor Al Zubair, and Shatt Al Basra) during low tide period from March to August 2011 from the Shatt Al-Arab, Shatt Al-Basra and Iraqi coasts along the North Arabian Gulf. The hydrochemical analysis reflects three zones of water salinity, Fadakia and Shatt Al Basra of Brackish water with total dissolve solid (TDS) range (15,148–18,130 ppm), Rass Al Bishah of saline water with TDS range (34,123–36,521 ppm), and the other marine coastal sites of saline water with TDS range (39,215–45,220 ppm). The geochemical analysis results show that positive correlation was found between water salinity of the sampling sites and the chemical constituents CaO %, MgO %, K2O %, Na2O %, LOI %, Sr/Ca, and Mg/Ca and the trace elements Co, Ni, Rb, Sr, Zn, Cu, Ba, Cr, and Pb concentrations, while negative correlation was found between water salinity and SiO2, Al2O3, P2O5, and Fe2O3 percentages in the calcite shell of C. cucullata. It is good to use the mineralogical evidence of C. cucullata shells with their living aqueous habitat to build an aqueous environment pollution models. Thus, the shells of C. cucullata were found to be a useful tool for monitoring contamination in the Iraqi aquatic brackish and marine environments.