Mughal road located in the high mountainous region of Kashmir Himalaya, India is prone to landslide hazards because of anthropogenic pressure and ongoing climate change. Landslides along the roads is one of the critical problems in hilly areas. Landslide vulnerability maps can serve as an effective tool for the planning and management of landslide disasters. The primary goal of the present study is to generate a Landslide hazard map along the Mughal Road. An integrated approach of Remote sensing GIS and AHP was used applied for this purpose. The eight most important landslide occurrence parameters including slope aspect, geology, elevation, slope angle, lineament buffer, drainage buffer, landuse/landcover and NDVI were employed in the present model. The Advanced Spaceborne Thermal Emission and Reflection Radiometer Digital Elevation Model and Linear Imaging Self-Scanning Sensor imagery were used to prepare these thematic layers in Arc GIS environment. The analysis of the final landslide hazard map reveals that, very low, low and moderate landslide hazard zones constitute 0.6%, 15.8% and 41.3% of the total area in the study region, respectively. While High and very high landslide hazard zones account for 30.2% and 12.2%, respectively of the total geographical area in the study region. Finally, an inventory of landslides has been used to validate the findings of the study. The landslide hazard zonation map has been also compared with the Landslide inventory map through the ROC-AOC method. The applied model produced an excellent result for landslide hazard mapping in the research region, as shown by the spatial effectiveness of the generated landslide hazard map validated by AUC (77.7% of accuracy). The study can be very useful for policy maker and construction planners.

Predicting turbidity (T), which represents the amount of fine sediment in water, is essential in effective water quality management. In this study, two ensemble learning models, XGBoost and light gradient boosting decision tree (LGB), were employed to predict T, using discharge (Q) as an independent variable. The input variables were classified into three groups based on the flow phase: rising limb, falling limb, and base flow, where different time–frequency datasets (2, 8, and 24 h) were utilized to develop the model. In the first model set (Model 1), each model was trained separately for every phase, and their performance was tested by applying each to the corresponding Q. Another model set using XGBoost and LGB was developed by considering the entire period without classification for a comparison purpose (Model 2). The results demonstrated that Model 1 which used data classified into three phases outperformed Model 2. Further analysis of the flood phase and hysteresis in the relationship between Q and T showed that different data distributions in the three phases determined the performance differences between Models 1 and 2. By considering these differences, Model 1 exhibited better performance compared to Model 2. The Shapley additive explanation (SHAP), a novel explainable artificial intelligence method, provided a reasonable interpretation of the difference in model predictions between Models 1 and 2.

As a pyroclastic rock type, ignimbrites may reveal varying degrees of welding depending on the temperature (> 535 ℃) and overburden pressure conditions during its formation. The welding degree of ignimbrites increases as the formation temperature and the thickness of the overburden deposit in the depositional environment escalate, which are the most crucial factors controlling the rate of welding in ignimbrites. With the increasing temperature, plastic deformation is observed in ignimbrites and the glassy minerals are being welded. Furthermore, the thickness of the overburden causes the deformation of the ash matrix in ignimbrites at the lower sections and the pumice grains are flattened at different rates. An increase in the degree of welding of ignimbrites causes an improvement in the physical and mechanical properties of the rock material as well. Within the scope of this research, petrographical, mineralogical, and geochemical studies were carried out on a total of 16 different ignimbrite types, which have different color and texture properties, obtained from three different regions of Turkey (Kayseri, Nevşehir, Ahlat) where ignimbrites extensively crop out, and the physical and mechanical properties of these samples were revealed. Consequently, a new welding classification was developed for ignimbrites considering the uniaxial compressive strength and dry unit weight. The proposed welding classification consists of six classes ranging from non-welded to highly welded. When the welding degrees of the selected ignimbrites are evaluated, Kayseri ignimbrites mostly exhibit moderate welding characteristics. Nevşehir ignimbrites, on the other hand, have a low welding degree whereas the degree of welding in Ahlat ignimbrites may vary from low to high. Additionally, long and short axis lengths of pumice grains in the ignimbrite specimens were determined by measuring under the microscope, and shape ratios were determined by different shape parameter evaluation methods. As a result, it has been concluded that the pumice grains in Kayseri and Ahlat ignimbrites have a more lenticular structure than the pumice grains in Nevşehir ignimbrites. Eventually, the welding degree classes of ignimbrites and the classification developed by using threshold values of the oblateness ratio (OR) values of pumice grains at different welding degrees are quite compatible. The proposed welding degree classification is of great importance in the selection of ignimbrites widely used as dimension stone and in terms of engineering classification of this rock type as well as it will guide to the scientific studies to be performed on ignimbrites with varying physical and mechanical properties.

Hydraulic conductivity is one of the most challenging hydrogeological properties to appropriately measure due to its dependence on the measurement scale and the influence of heterogeneity. This paper presents a comparison of saturated hydraulic conductivities (K) determined for a quasi-homogeneous coastal sand aquifer, estimated using eight different methodologies, encompassing empirical, hydraulic and numerical modeling methods. The geometric means of K, determined using 22 methods, spanning measurement scales varying between 0.01 and 100 m, ranged between 3.6 and 58.3 m/d. K estimates from Cone Penetration Test (CPT) data proved wider than those obtained using the other methods, while various empirical equations, commonly used to estimate K from grain-size analysis and Tide-Aquifer interaction techniques revealed variations of up to one order of magnitude. Single-well tracer dilution tests provided an alternative for making preliminary estimates of K when hydraulic gradients were known. Estimates from the slug tests proved between 1.2 and 1.6 times larger than those determined from pumping tests which, with one of the smallest ranges of variation, provided a representative average K of the aquifer as revealed by numerical modeling. By contrast, variations in K with depth could be detected at small scales (~ 0.1 m). Hydraulic Profiling Tool (HPT) system data indicated that K decreases with depth, which was supported by the numerical model results. No scale effect on K was apparent when considering the ensemble of results, suggesting that hydraulic conductivity estimates do not depend on the scale of measurement in the absence of significant aquifer heterogeneities.

The sustainable use of groundwater resources requires that the components of a regional water balance are understood with a high degree of accuracy, especially in arid and semi-arid regions. Although groundwater recharge is one of the most important components of a groundwater balance, its rate is one of the most uncertain components. Despite the simplicity and widespread use of water balance method (WB) for estimating groundwater recharge in arid and semi-arid regions, the accuracy of the groundwater recharge estimation depends on the accuracy of the other components in this method, so a reduction in errors that are associated with measuring these can improve the accuracy of recharge estimation. Therefore, the main objective of the current paper was to present a method for estimating groundwater recharge based on minimization of the sum total error of the system water and groundwater balance equations simultaneously. A set of correction coefficients that reflect the error in estimation of each component of balance equations, were applied to different components in annual scale. Reasonable ranges, obtained from error analysis, were considered for the correction coefficients and the sum of absolute errors in the overall system water balance and groundwater balance equations was minimized for the period of study. The proposed method was used to estimate groundwater recharge in Mahvelat basin in Khorasan Razavi province of Iran, as a case study. The minimization process used in this research reduced the error of system water and groundwater balance equations by 55% and 65%, respectively. Moreover, as the results of optimization process on the correction coefficients, the recharge coefficients due to precipitation and irrigation return flow were estimated to be 2% and 16.5%, respectively.

In the high-level radioactive waste (HLW) repository, the concrete lining wrapped outside the bentonite buffer barrier releases strong alkaline solutions under the dual effects of groundwater and radiant heat. When the strong alkaline solutions acts on the bentonite, the alkalinity, and chemical properties of the bentonite would vary, affecting the safety of the HLW repository. In this paper, the reaction of the Gaomiaozi (GMZ) bentonite with KOH solution was carried out. The effects of pH, temperature, reaction time, and solid–liquid ratio (SLR) on the alkalinity and redox property of the bentonite suspension and the alkaline buffer capacity (ABC) of the bentonite were investigated. The alkaline buffer mechanism of the bentonite was discussed based on the variations in elemental compositions. It was found that the GMZ bentonite effectively reduced the pH value of the bentonite suspension. The reaction temperature, reaction time, and SLR were positively correlated with the decreasing range of pH value. There was a good linear negative correlation between pH and Eh of the bentonite suspension. Moreover, when the bentonite was in the strong alkaline solution, the silicate mineral dissolution, clay mineral phase transformation, and hydroxide precipitation occurred successively, continuously consuming the OH− of the solution. The silicate mineral dissolution increased with the increase in pH, temperature, and reaction time, but increasing the SLR had no significant effect on the silicate mineral dissolution. These could explain the effects of various influencing factors on the alkaline buffer characteristics of the bentonite. Based on the alkaline buffer mechanisms, the thickness of the bentonite buffer barrier without ABC was calculated to be 71.83 cm when the operation time was 10,000 a, which could be used for reference when designing the thickness of the bentonite buffer barrier.

Thick, soft alluvial clay was deposited in the Hachirogata reclaimed area in Akita Prefecture, Japan. The phenomenon of differential settlements of the irrigation structure occurring at the site lowers the function of the water supply to the irrigation channel. In this study, assuming that the differential settlement of the ground is due to salt leaching of the sediments, the effect of leaching on the physical and mechanical properties of Hachirogata clay was examined. It was confirmed that the liquid limit and plasticity index decreased due to the leaching, which indicates that the leached sample changed the flowability due to changes in the water content. From the consolidation tests, it was found that the leached clay had a delay in consolidation deformation, a decrease in permeability, and remarkable creep behaviour. According to the observations of the clay structure by scanning electron microscope, leaching caused the clay particles to change from a random arrangement to an impermeable parallel arrangement, and the resultant pore area increased. These results show that the changes in the clay structure due to leaching affect the physicochemical and mechanical properties, such as consistency limits and deformation characteristics. Therefore, it can be inferred that the occurrence of localised leaching is one of the factors that accelerates differential settlement.

Climate change represents an intractable problem which urges a prompt intervention to be resolved. One of climate change's most destructive calamities is flash flooding. On that caveat, this study tries to identify the zones most susceptible to flash floods by utilizing machine learning technique. Initially, a digital elevation model (DEM) has been utilized to delineate a basin located in the city of New Cairo, Egypt, where the flash floods occur frequently. Subsequentially, 12 flood causative factors were calculated and mapped via ArcMap. Furthermore, the depth of runoff was calculated via HEC-RAS and employed as a flood causative factor. Additionally, both flooded points and flood causative factors have been employed by utilizing the “GARP”* approach to produce the Flood Hazard Map (FHM). The state-of-art in this study is to predict the hazard degree of flash floods by utilizing the simulated runoff depth which has been used as flood causative factor in the selected machine learning technique. The FHM anticipated approximately 20% of the total area to have a very high hazard of floods, whereas, more than two-thirds of the study area has expected to have low and very low flood hazard. In addition, the receiver operating characteristic “ROC” approach has been applied to examine the FHM, which estimated the area under curve as 96.88%. Finally, decision-makers can utilize the generated map to better comprehend repercussion of flooding and make adequate preparations to alleviate this risk. *GARP: “Genetic Algorithm for Rule-set Prediction”.

With the large-scale application of nitrogen fertilizers in the agricultural area, the karst area in southwest China is increasingly polluted by nitrogen. Understanding the distribution, transportation, and sources of nitrogen is the premise for effective pollution control in the catchment. The present study used the nitrogen and oxygen isotopes technique to explore the dynamic changes and sources of nitrates during rainfall in various land uses in a typical karst catchment in southwestern China. The results of hydrochemistry composition indicated that agricultural activities have caused the deterioration of water quality, while intensive rainfall during the wet season has played a positive role in promoting it. NO3−–N was the major inorganic N, accounting for 78.7 ± 21.6% (N = 38) of the total nitrogen. Dryland and paddy field provided a large amount of nitrogen for the water environment by rain, which contributed to high NO3−-N concentration in spring (6.1 ± 0.9 mg/L) and runoff (7.2 ± 0.9 mg/L) at the catchment outlet. Nitrate isotopic compositions (δ15N–NO3− and δ18O–NO3−) and water isotopes (δD and δ18O–H2O) revealed that isotopic composition in dryland and paddy field was mainly affected by nitrification. Source analysis showed that dryland and paddy field was dominated by chemical fertilizers and manure, while precipitation and soil organic nitrogen were the major sources in abandoned land, forest and shrub. This study highlighted that land management and nitrogen fertilizer application should be reasonable to reduce the risk of nitrogen surplus in the water environment.

In the River Goulbi Maradi Basin (RGMB), groundwater is a vital source of drinking water and plays a central role in the region’s socio-economic development. The quality and suitability of groundwater for irrigation and drinking-water remain inadequately understood. We examine hydrochemical analyses of 35 groundwater samples from the shallow alluvial (17) and underlying Continental Hamadien (CH) sandstone (18) aquifers and evaluate these against standard measures of their suitability for drinking water (World Health Organization (WHO) guideline values) and irrigation (i.e., sodium adsorption ratio, sodium percentage, and the residual sodium carbonate). Hydrochemical facies are principally of Na–HCO3 and Na–Cl types. Bivariate plots combined with saturation indices and electrical conductivity monitoring suggest that the main hydrogeochemical processes influencing groundwater quality are cation exchange in the CH aquifer and solute leaching from soils during focused recharge in the alluvial aquifer. 76% (13/17) of groundwater samples from the alluvial aquifer were suitable for irrigation compared to 38% (6/16) of the samples from the CH. The identification of high fluoride concentrations exceeding the WHO drinking-water guideline value (> 1.5 mg/L) in 33% (6/18) of samples from the CH aquifer and 18% (3/17) in the alluvial aquifer, and their respective attribution to the release of fluoride of geogenic origin through cation exchange and local use of fluorapatite fertilisers, provide valuable insight into efforts to address the on-going challenge of fluorosis in the Maradi region of Niger and more widely across African drylands. The health consequences of the widespread observation of Mn in concentrations exceeding the new WHO guideline value (0.08 mg/L) in the alluvial aquifer (6/9 samples), often alongside elevated Fe concentrations, are unclear.

In full-section excavated tunnel construction, the abnormal deformation of the surrounding rock, such as arch cracking and surrounding rock collapse, is often caused by insufficient timely support and over-excavation, which brings serious consequences to the project. In this paper, the geomechanical model is established to investigate the influence of different indexes on surrounding rock deformation. The deformation of surrounding rock can be divided into three stages, among which the earlier deformation caused by the construction in front of the monitoring section in the 1st stage accounts for 18% of the total deformation. The deformation caused by tunnel excavation in the second stage occupies 72%, and the lagging deformation in the third stage accounts for 10% of the total deformation. Furthermore, the critical indicators are screened out by the rough set algorithm. Finally, the prediction model of surrounding rock deformation of the full-section excavated tunnel is established based on the PSO-BP neural network. The validation results indicated that the prediction results from the integration model are in good agreement with the field observation results, and the prediction efficiency and accuracy are better than those of the numerical simulation and the single BP neural network. This study fully used tunnel monitoring data and proposed a deformation prediction model by investigating the correlation characteristics of the deformation data, which provides an essential reference for similar engineering research.

Clay mineralogy of Plio-Quaternary sediments of SE slopes of Medvednica Mt. was compared to that of the overlying weathering horizons. Three locations of Plio-Quaternary sediments, representing past weathering products, were sampled along with the overlying material, representing more recent weathering cycles. Particle size distribution, pH and cation exchange capacity (CEC) of the samples were analyzed. Bulk mineralogy was determined using X-ray diffraction (XRD). Clay mineralogy was determined, after carbonate cement, organic matter and free Fe oxides removal, on fractions < 2 and < 0.2 μm using XRD and Fourier-transform infrared spectroscopy (FTIR). Average layer charge of the expandable layers was determined using the O-D method. Major elements content was determined using inductively coupled plasma optical emission spectroscopy (ICP-OES). Bulk mineralogy comprises quartz, feldspars, mica, clay minerals and occasional Al and Fe (oxy)hydroxides. Clay mineralogy differs subtly between samples; dioctahedral expandable clay minerals dominate with illite and kaolinite present. Hydroxyl interlayering of expandables is noted in the surface samples, corresponding to lower CEC values. Average absolute layer charge of the expandable layers is higher in the surface samples and decreases with depth on two of the investigated locations. Overall, clay mineralogy of the Plio-Quaternary sediments reflects a more intensive weathering regime, confirmed by the presence of Al (oxy)hydroxides and lower absolute charge of the expandable layers. The weathered material and soil overlying these sediments shows heterogeneity in genesis, but corresponds to less intense weathering regime, confirmed by the formation of hydroxy-interlayered minerals and higher absolute charge of the expandable layers.

This paper presents the results of recharge estimation and water table variation analyses of the Coastal Aquifer System, located in the Rio Grande do Sul Coastal Plain (Brazil). Water-level data from 11 wells were processed and analyzed, applying autocorrelation and cross-correlation methods to evaluate the aquifer memory effect and mean response time to rainfall events. The seasonality of the response time was evaluated through splitting the data series in windows of 90 days, overlapped by 45 days. Recharge rates were obtained with the water table fluctuation (WTF) daily applications (RISE and MRC), considering specific yields of 20%, 25% and 30%. Water-level data smoothing with moving averages and time series filters were necessary, to remove level rises not associated with precipitation events within the aquifer average response time, The autocorrelation and cross-correlation displayed a variability of responses through the wells, with median response times of level to precipitation from 0, 1 and 2 days (wells in aquifer layers of fine to medium sands) to 10 days (wells in aquifer layers of higher clay content). The recharge rates of 0.74 to 2.42 mm day−1 and Recharge/Precipitation ratios from 19% to 46% were obtained (Sy = 25%, mean between RISE and MRC results). From these applications, the study presents the importance of level data processing and filtering to daily WTF applications and displays the differences in the behavior of the wells in the Coastal Aquifer System.

As a critical natural resource, groundwater plays an important role in the stability of the geological environment and the balance of the ecosystem. The purpose of this study was to delineate the ecological sensitivity of the groundwater system in the Mi River basin of Eastern China and to provide a basis for future decision-makers to regulate groundwater. First, based on the available information and the specific situation of the study area, the evaluation index system of groundwater ecological sensitivity was constructed by selecting the influencing factors from four levels: groundwater system structure, natural environment, water resources, and social development. Then, the weights were assigned by the analytical hierarchy process (AHP) and entropy method, and the ecological sensitivity of the groundwater system was assessed by a geographical information system (GIS). The results showed that the ecologically moderately sensitive areas of the groundwater system were mainly distributed in the plain areas of Linqu and Qingzhou and the Shouguang area, accounting for 20.67% of the total area of the basin. The highly sensitive and extremely sensitive areas were distributed in the middle and lower reaches of the basin, accounting for 43.97% of the basin area. The insensitive and mildly sensitive areas were mainly located in the upstream areas of the watershed, accounting for 35.36% of the basin area. The results provide a basis for environmental protection in the Mi River basin and a reference for the protection and rational utilization of groundwater in the study area.

Yunnan Province of China is located in the southwest frontier, with high altitude, fragile geological environment, uneven spatial and temporal distribution of rainfall, and more localized rainfall and landslide geological hazards caused by rainfall are extremely common. Therefore, based on saturated–unsaturated seepage theory, it is of great engineering significance to deeply study the change law of internal seepage of slopes under different rainfall conditions and the influence of dynamic seepage on slope stability. In this paper, based on the saturated–unsaturated seepage theory, the soil–water characteristic curve and unsaturated permeability coefficient prediction model are determined, and GEO-Studio finite element software is used to explore the changes of seepage field, stress field, displacement field, and stability coefficient of the slope under different rainfall conditions from the perspectives of seepage mechanics and rock mechanics, and to reveal the changes of unsaturated soil The mechanical response mechanism of unsaturated soil slopes in the process of dynamic seepage and the influence of seepage on the stability of slopes. The results show that: (1) the volumetric water content and saturation of the shallow soil will increase rapidly when the unsaturated soil slope is affected by rainfall, and the pore water pressure, maximum shear stress, and total displacement in the corresponding area will increase with the increase of rainfall time; (2) the stability of the slope is closely related to the rainfall time, and the longer the rainfall time, the lower the stability coefficient. At the same time, it provides theoretical support for the study of similar landslide mechanisms and prevention engineering.

Isotopic methods have become an important tool in the study of natural processes and countless applications have proven valuable in several research areas. Geologically, strontium and neodymium isotopes also fractionate in Earth surface environments. The difference is that measured radiogenic isotope ratios are normalized to a fixed stable isotope ratio during analysis, so that any natural mass dependent isotope fractionation in analysed samples is canceled. All data was obtained from academic journals and has been spatialized in a Geographic Information System (GIS), the analysis of which has subsidized the identification, where data are more clustered or dispersed. Understanding the distribution of 87Sr/86Sr e εNd(0) in different regions of South America is very important to demonstrate how Nd/Sr signatures can be used to distinguish various terrains and localities on a regional scale, through the selection, organization, inventory, and arrangement of 386 data in sedimentary basins and crystalline shields.

Polyvinyl alcohol borate hydrogel was used due to its ability to absorb cations to remove excess cations of salinity and sodium from a number of soil samples collected from district 7 of Gonbadkavus city. The experimental data were obtained by measuring electrical conductivity, pH and the amount of sodium, potassium, magnesium and calcium ions of saturated soil extract using flame photometer and titration method at each stage of mixing hydrogel with soil. After obtaining the value of the sodium absorption ratio and exchangeable sodium percentage, it was found that these values decrease after each modification step. In the final modification stage, the soil becomes non-saline but remains sodic, and the reason for this fact is that its sodium cation content is much higher compared to other cations; hence, further modification steps are suggested to reduce the sodium content of the soil before its use for agricultural purposes. At the end, a table has been prepared which is used to compare the tolerable salinity of the seeds of different plants before and after modification.

This paper contains brief geological and hydrogeochemical information regarding hot waters circulating through the Seferihisar geothermal system using previous studies, as well as recorded and up-to-date data. The obtained analytical results were subjected to the computer programme AquaChem3.70 for determining the geothermal waters. The NaCl-type geothermal waters circulating in the system have a temperature range of 44 to 207 °C, with total dissolved solids (TDS) varying from 3229 to 29494.9 mg/l. The conductivity range of the samples is 5690–34400 µS/cm as the pH changes from 6.54 to 8.5. Chemical geothermometer calculations indicate reservoir temperatures varying between 59 and 246.2 °C. The water‒rock interactions led to various mineralogical changes in the area. X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray (XRD and SEM–EDX) analyses of the collected rock and clay samples have been interpreted as an integrant to the 2-year field observations. The results of the analyses show that the surface manifestations in the Tuzla and Doğanbey geothermal fields consist of the hydrothermal alteration products induced from the carbonates of sediments, ferromagnesian minerals of greenschist facies and silicates. Additionally, a uranium-oxide mineral, richetite, has been identified. Finally, the apparent geothermal potential of the system has been assessed.

Groundwater and springs are important water resources for domestic and agricultural uses in the Aso caldera in the volcanic region of Kumamoto, Japan. In addition, some springs play the role of tourist attraction. Previous studies have reported high fluoride (F−) levels in these water bodies; however, these studies were conducted more than 20 years ago and did not study the factors controlling the F− concentration in detail. In this study, to understand F− concentration in recent years and the controlling factors, water samples were collected at two artesian wells and 22 springs every 3 months from July 2020 to October 2021. Water samples showed a mean F− concentration ranging from 0.16 to 1.18 mg/L. Five of the 24 (20%) sampling sites showed a mean F− concentration above the Japanese drinking water standard of 0.8 mg/L. The water samples with higher F− concentrations were mainly distributed on the central cone sides, and represented Ca–SO4–HCO3 and Ca–SO4 types. In other words, the water samples evaluated as having an effect of hydrothermal water, based on a higher SO42− concentration or lower Cl−:SO42− molar ratio, showed higher F− concentrations. In terms of anthropogenic factors, fertilizer application was not an important factor controlling the F− concentration in spring and groundwater in the study area due to the distribution of upland fields. As a natural factor, although the general mechanisms of weathering and anion exchange of F-bearing minerals can be one of the factors controlling the F− concentration in the study area, it did not contribute to the entire study area due to the limited distribution of the strata containing the related minerals. Magmatic gases, including SO2, HF, and HCl, were considered to form hydrothermal water in the study area, and the effect of hydrothermal water could increase F−, SO42−, and Cl− in water samples. This mechanism was validated by the positive correlations between F− and SO42− and Cl−. Thus, magmatic gas constituted the main contribution to the increase in the F− concentration in the study area.

Climate and groundwater are always in a state of dynamic equilibrium. Subsurface systems contaminated by light non-aqueous phase liquid (LNAPL) present a challenge to understand the overall impact of water table dynamics, due to various interacting mechanisms, including volatilization, and LNAPL mobilization/dissolution along the groundwater flow direction and oscillating redox conditions. We investigated the impact of water table fluctuations on LNAPL natural attenuation and soil geochemical characteristics in semi-arid coastal areas under saline conditions. Four soil columns operated for 151 days under anoxic conditions where a layer of benzene and toluene were subjected to a stable and fluctuating water table associated with low and high salinity conditions. The bottom of stable and fluctuating columns reached an anaerobic state after 40 days, while the middle of stable column took 60 days. pH values of the fluctuating columns covered a wide range, and at the end shifted towards alkaline conditions, unlike the stable columns. In fluctuating columns, pore water sulfate decreased in the middle, but in stable columns, it decreased in the first 40 days, which suggested that sulfate was the primary electron donor and sulfate-reducing bacteria were present. At the source zone, benzene and toluene reached their maximum concentration after 30 and 10 days for the stable and the fluctuating columns, respectively. Significant decrease in benzene and toluene concentrations occurred under the fluctuating water table. Salinity did not affect benzene and toluene concentrations in the aqueous phase, although water table fluctuations have the most effect. Soil solid-phase analysis shows fluctuating columns have less toluene than stable columns. Solid-phase analysis showed the fluctuating columns have less benzene and toluene concentrations as compared to the stable columns.