Hydrogeological Investigations Research Articles

What Is the Impact of Leaky Sewers on Groundwater Contamination in Urban Semi-Confined Aquifers? A Test Study Related to Fecal Matter and Personal Care Products (PCPs)

Urban areas exercise numerous and strong pressures on water bodies, implying that different external anthropogenic factors also stress groundwater. Sewerage networks play an important role, being the place of wastewater flow. When sewerage deterioration conditions occur, aquifers can be contaminated by contaminants contained within wastewater. The study aims to verify the impact of sewerage leaks in urban semi-confined aquifers through a multidisciplinary approach. Geological, hydrogeological, hydrochemical, microbiological, and biomolecular investigations are carried out in a test site close to a sewer pipe, from February to October 2022. Microbiological analyses are carried out on a monthly basis, contextually to hydraulic head measurements in purpose-drilled piezometers. The presence of sandy intercalations and the prevalence of silt within the outcropping (about 10 m thick) aquitard makes the aquifer vulnerable to percolation from leaky sewers, therefore causing persistent microbial contamination in groundwater. The presence of fecal indicators (including pathogenic genera), corrosive and human-associated bacteria markers, is detected. The magnitude of microbiological impact varies over time, depending on hydrogeological factors such as dilution, hydrodynamic dispersion, and variation of the groundwater flow pathway at the site scale. As for personal care products, only Disodium EDTA is detected in wastewater, while in groundwater the concentrations of all the analyzed substances are lower than the instrumental detection limit.

Paleoenvironmental changes in river channel systems in alpine rockslide deposits exemplified by the Fernpass rockslide in the Tyrolian Außerfern District, Austria

This paper describes the instability of river channel systems in alpine rockslide deposits using the Fernpass Rockslide and the river Loisach in the Tyrolian Außerfern District (Austria) as an example of paleoenvironmental developments. This is the first investigation of this kind of the Fernpass, one of the most important Alpine north–south transport connections since the bronze age. It uses geomorphological, sedimentological, onomastic and hydrogeological investigations to reconstruct the course of a late Holocene river in this area and a probabilistic simulation for dating. Tracer tests assisted in investigating the potential groundwater connections of the river systems. The findings show that the Palaeoloisach runs on the orographically right side in a marginal valley of the Fernpass furrow and changes to the orographically left side of the furrow within the Rauth suburb in the village of Biberwier. A probabilistic simulation of the Narrenbichl slip event, which changed the course of the Palaeoloisach, dates the event to an age of 664 ± 116 BC. This investigation is an important contribution to understanding Quaternary postrockslide developments, how groundwater contributes to forming postrockslide channel systems and archaeological findings occurring in populated areas.

Evaluation of rock mass permeability along a borehole by integrating the techniques of geological features and logistic regression: a case study in Taiwan

When the budget for in situ hydraulic tests is constrained, cost-effective approaches for determining the variations in hydraulic conductivity along a borehole remain enticing for helping design and planning of groundwater-related engineering systems. This study proposes a practical method with probabilistic outputs for fulfilling engineering concerns. First, 474 sets of hydrogeological investigation and hydraulic test data of fractured rock masses in most of the watersheds of mountainous areas of Taiwan were collected. Then, seven geological indices [rock quality design (RQD), depth index (DI), gouge content design (GCD), lithology permeability index (LPI), fracture density (FD), fracture width (FW), and groundwater velocity (GV)] significantly correlated with rock mass permeability were identified. Third, using logistic regression analysis, the seven indices were used as explanatory variables, and the hydraulic conductivity was utilized as an outcome variable (its threshold value is 1 × 10−6 m/s) for developing prediction models of high groundwater potential zones along a borehole. All indices passed the collinearity test, indicating no collinearity between the indices. To make the prediction models proposed more flexible in practical applications, a total of 127 combinations based on the combination selection of seven explanatory variables were explored to develop various prediction models. Through the validation of the Hosmer–Lemeshow test, Omnibus test, and Wald test for all developed models, only 77 models were statistically significant. The 77 models were evaluated by three measures of Nagelkerke R2, SR (success rate), and AUC (area under the curve) to further understand the prediction performance of each model. The results show that the accuracy of the prediction model is positively correlated with the number of geological indices used. When all seven geological indices are used, Nagelkerke R2, SR, and AUC can reach the best values, which are 0.83, 91.6%, and 0.976, respectively. In conclusion, the prediction model developed by combining geological indices with logistic regression analysis can provide a more efficient way of understanding the hydrogeological conditions of a borehole site.

The Application Effect of Remote Sensing Technology in Hydrogeological Investigation under Big Data Environment

The hydrogeological investigation is a work carried out by comprehensive utilization of various exploration methods to identify hydrogeological conditions in the target area, and develop and utilize groundwater resources. There are great differences in hydrogeological conditions in different regions. Hence, it is necessary to take exploration technology according to local conditions to master hydrogeological information as much as possible. Among them, the remote sensing (RS) technology can reflect the ground surveying and mapping results with high efficiency and precision through the analysis of satellite or aerial photographs, which is a commonly used method in the current hydrogeological investigation. According to satellite RS data, this work evaluates the distribution of groundwater levels in the study area and explores the geological and hydrogeological conditions of the groundwater system in the affected area. Firstly, the human-computer interactive interpretation method is used to analyze the topography and geomorphology conditions. Secondly, the spectral characteristic curve analysis method is used to extract the spectral characteristics of regional stratum lithology, and analyze and determine the lithology composition and structure of the aquifer. Thirdly, the single-band and multiband models of soil moisture RS estimation of groundwater level are implemented. Finally, the measured data are employed to verify and analyze the estimated value of the model. The results are in line with the actual value, and good results have been achieved.

Detection of Groundwater Table by Using Ground Penetrating Radar in Two Selected Sites/Northern Iraq

A non-damaging geophysical measurement technique test method ground penetrating radar (GPR) was carried out successfully in two sites in the middle and north of Iraq in order to investigate the feasibility of detecting the shallow underground water level in both selected sites. The results show that the groundwater depths in Baiji site were between 0.95m, and 1.2m, while in Hammam AL-Aleel site were between 1.0m to 1.1m near the river. It was also noticed in Hammam AL-Aleel site that the GPR image showed the appearances of dramatically and clear dissolving features that sometimes coincide with the level of groundwater which was approximately about 4m depth to the west of Northern Thermal Power Plant (NTPP), due to the existence of Fatha formation; while in the east of (NTPP) there was no solubility features due to the absence of Fatha formation and the presence of quaternary coarse sediments. This technique has been proved to be an effective detection method for underground water level and can serve as a reference for future application using the dependent physical property of permittivity and conductivity in engineering site investigation, hydrogeological investigations, and the detection of subsurface cavities.

Understanding of groundwater evolution through chemical and age dating information in the Yongding River alluvial fan in Beijing

Groundwater plays important roles in human community development and the urbanization process as the results of global environmental change and rapid population growth. A clear understanding of the vertical and horizontal spatial distribution characteristics of groundwater and sediment is the premise of efficient groundwater resource management and utilization in alluvial plains. To explore the evolution process of groundwater and the distribution of sediment in the Yongding River (YDR) alluvial fan, a typical profile from Mentougou to Fengheying was chosen to conduct an extensive hydrogeological investigation with multiple hydrochemical, isotopic, and age dating analyses, which represents one of the most typical hydrogeological units in the YDR alluvial fan. The analysis results show that (i) along the profile, the water’s chemistry type gradually changes from HCO3-Ca·Mg to HCO3-Na. The contents of coarse grain gradually decrease while fine particles regularly increase. Also, a similar evolution trend is found in the vertical direction. (ii) The annual renewable rate of groundwater is > 10% in the upper fan, 2%–8% nearby Daxing, and < 2% in Fengheying. (iii) In the proximal fan area, the average flow velocity of the single and double layer is about 65 m yr−1 and of approximately 18.9 m yr−1. From the mid fan to distal fan, the value of velocity and hydraulic conductivity decreases from 12.4 m yr−1 to 3.75 m yr−1 and from 8.54 m yr−1 to 0.64 m yr−1, respectively. (iv) The 14C analysis results indicate that the age of shallow and deep groundwater ranges from 5a to 60a and from 4000a to 12000a, respectively. The groundwater age increases with depth in the vertical direction and increases from northwest to southeast along in the alluvial fan in the horizontal direction. Understanding the evolution process of sediment and hydrochemistry in the YDR alluvial fan provides a valuable reference for groundwater resource development, utilization, and pollution prevention in the alluvial fan.

Characterizing groundwater heat transport in a complex lowland aquifer using paleo-temperature reconstruction, satellite data, temperature–depth profiles, and numerical models

Abstract. Heat is a naturally occurring, widespread groundwater tracer that can be used to identify flow patterns in groundwater systems. Temperature measurements, being relatively inexpensive and effortless to gather, represent a valuable source of information which can be exploited to reduce uncertainties on groundwater flow, and, for example, support performance assessment studies on waste disposal sites. In a lowland setting, however, hydraulic gradients are typically small, and whether temperature measurements can be used to inform us about catchment-scale groundwater flow remains an open question. For the Neogene Aquifer in Flanders, groundwater flow and solute transport models have been developed in the framework of safety and feasibility studies for the underlying Boom Clay formation as a potential host rock for geological disposal of radioactive waste. However, the simulated fluxes by these models are still subject to large uncertainties as they are typically constrained by hydraulic heads only. In the current study, we use a state-of-the-art 3D steady-state groundwater flow model, calibrated against hydraulic head measurements, to build a 3D transient heat transport model, for assessing the use of heat as an additional state variable, in a lowland setting and at the catchment scale. We therefore use temperature–depth (TD) profiles as additional state variable observations for inverse conditioning. Furthermore, a Holocene paleo-temperature time curve was constructed based on paleo-temperature reconstructions in Europe from several sources in combination with land surface temperature (LST) remotely sensed monthly data from 2001 to 2019 (retrieved from NASA's Moderate Resolution Imaging Spectroradiometer, MODIS). The aim of the research is to understand the mechanisms of heat transport and to characterize the temperature distribution and dynamics in the Neogene Aquifer. The simulation results clearly underline advection/convection and conduction as the major heat transport mechanisms, with a reduced role of advection/convection in zones where flux magnitudes are low, which suggests that temperature is also a useful indicator in a lowland setting. Furthermore, the performed scenarios highlight the important roles of (i) surface hydrological features and withdrawals driving local groundwater flow systems and (ii) the inclusion of subsurface features like faults in the conceptualization and development of hydrogeological investigations. These findings serve as a proxy of the influence of advective transport and barrier/conduit role of faults, particularly for the Rauw fault in this case, and suggest that solutes released from the Boom Clay might be affected in similar ways.

Hydrogeological parameterization of the landslide of Lamosano, (Eastern Italian Alps)

The area of the village of Lamosano, in the province of Belluno (North-East Italy), has been critically affected for several decades by a landslide that has caused significant damages to buildings and infrastructures. This instability process, involving almost the whole village, is set in a 30-meter thin layer of Quaternary deposits and marls. Groundwater flow within these deposits has been identified as one of the primary causes of the slope movement.With the purpose of identifying fundamental and useful parameters for the intelligent design of landslide countermeasures, a series of geological and hydrogeological investigations have been carried out.Through the analysis of 18 stratigraphic logs, a geological model for the subsoil was provided.The hydrogeological characterization concerned the realization of slug tests and point dilution tests to properly estimate the hydraulic conductivity (K) and the groundwater flow velocity (vd), respectively. Both investigations have been conducted on the five piezometers available in the study area. A satisfactory agreement has been detected between the K values and vd.The data provided in this study can be used as a basis for the efficient implementation of a coupled hydrogeological-mechanical model, which would considerably contribute to the mitigation of the landslide risk.

Integrated Hydrogeological, Hydrochemical, and Isotopic Assessment of Seawater Intrusion into Coastal Aquifers in Al-Qatif Area, Eastern Saudi Arabia.

Seawater intrusion (SWI) is the main threat to fresh groundwater (GW) resources in coastal regions worldwide. Early identification and delineation of such threats can help decision-makers plan for suitable management measures to protect water resources for coastal communities. This study assesses seawater intrusion (SWI) and GW salinization of the shallow and deep coastal aquifers in the Al-Qatif area, in the eastern region of Saudi Arabia. Field hydrogeological and hydrochemical investigations coupled with laboratory-based hydrochemical and isotopic analyses (18O and 2H) were used in this integrated study. Hydrochemical facies diagrams, ionic ratio diagrams, and spatial distribution maps of GW physical and chemical parameters (EC, TDS, Cl−, Br−), and seawater fraction (fsw) were generated to depict the lateral extent of SWI. Hydrochemical facies diagrams were mainly used for GW salinization source identification. The results show that the shallow GW is of brackish and saline types with EC, TDS, Cl−, Br− concentration, and an increasing fsw trend seaward, indicating more influence of SWI on shallow GW wells located close to the shoreline. On the contrary, deep GW shows low fsw and EC, TDS, Cl−, and Br−, indicating less influence of SWI on GW chemistry. Moreover, the shallow GW is enriched in 18O and 2H isotopes compared with the deep GW, which reveals mixing with recent water. In conclusion, the reduction in GW abstraction in the central part of the study area raised the average GW level by three meters. Therefore, to protect the deep GW from SWI and salinity pollution, it is recommended to implement such management practices in the entire region. In addition, continuous monitoring of deep GW is recommended to provide decision-makers with sufficient data to plan for the protection of coastal freshwater resources.

Stability Evaluation of Medium Soft Soil Pile Slope Based on Limit Equilibrium Method and Finite Element Method

The stability of an open-pit slope is an extremely important factor related to the safe production of an open-pit mine. It is the first safety technical problem encountered and should be solved in the process of mine design and production. By the means of an engineering geology and hydrogeological investigation of the waste dump area of the Nayuan open-pit coal mine and numerical simulation research, this paper analyzes and studies the slope stability of the stope and waste dump of the Nayuan open-pit coal mine in detail and puts forward measures such as slope prevention and automatic monitoring to achieve the goal of protecting the slope of the stope and waste dump and the surrounding environment. The main research results are as follows: (1) The geotechnical physical and mechanical indexes of stope and waste dump are collected and analyzed, and the geotechnical mechanical indexes in this report were determined, which basically meet the requirements of slope stability analysis. (2) The limit equilibrium method and finite element method were used to analyze and evaluate the current slope stability of the Nayuan open-pit coal mine. It was concluded that the foundation of the waste dump is basically stable, and the potential landslide modes of the slope are arc-shaped sliding surface and arc-shaped straight-line sliding surface. The numerical simulation and checking results showed that the current stope and waste dump slope are stable. (3) According to the analysis and evaluation results of slope stability, feasible slope prevention measures are put forward. The research results are of great significance to the safety of important facilities in open-pit mines and provide a basis for the design and safety implementation of open-pit slope engineering.

Evaluating Water Table Rising Under Eastern Cairo (Metro Line)

The booming increase in population in last decades led to poor environmental condition in some areas in the capital city of Egypt. The main two tackled environmental impacts from the increased population, in this research, are the heavy traffic densities jam and groundwater rise in many areas in the city. The massive population causes traffic congestion in the capital due to the increased poor planned urban expansion. The groundwater rise is resulted from leakage from over loeaded and poorly maintained drinking and sanitary water networks. More than 40% of the capacity of these networks leaked to ground, moving, with the topographic gradient sub-surfable to the lower areas; transporting all pollutants and dissolved salts from soil to the aquifer. This, also, threatens the buildings stability and prevent the usability of these buildings. The government is currently exerting massive efforts and increasing the investments tremendously on solving the traffic congestions and implementing new roads. Zooming into the study area, replacing the non-working old metro track into a road to link between Mansheyet El-Bakry and El-Demrdash is faced with the high groundwater table occurring in the area. The main objective of the current research is, to evaluate the proposed alternatives for solving the traffic problem through implementing new road, taking into consideration conducting a suitable solution for the high groundwater table. Moreover, investigating the main causes of the groundwater rise and assess environmentally the impact on the study area. Several proposed alternatives were evaluated for solving the concerned issues through extensive field and hydrogeological investigations, pumping tests, and numerical model (GMS- modflow) to simulate the hydrogeological conditions of the study area and test the proposed solutions. The alternatives were, also, assessed through a designed weighted impact assessment to analyze the best solution. the weighting assessment factors include efficiency, initial and operational costs, extracted water volume, lower groundwater rise, building stability, construction feasibility. The comprehensive investigation and assessment indicated that the most effective solution. Nevertheless, prevention at source is also urgently needed through rehabilitation of drinking and sanitary water networks in the capital to minimize the seepage and losses percentage of the transported water. Keywords: Groundwater Rise, Cairo, traffic congestions, dewatering system, groundwater modeling, groundwater quality DOI: 10.7176/CER/14-6-03 Publication date: October 31 st 2022

Ground Penetrating Radar in Coastal Hazard Mitigation Studies Using Deep Convolutional Neural Networks

There is a long history of coastal erosion caused by frequent storm surges in the coastal regions of Australia, which imposes great threats to communities and infrastructures alongside the beach. Old Bar Beach, New South Wales, Australia, is one such hotspot famous for its extreme coastal erosion. To apply remedial measures such as beach nourishment effectively and economically, estimating/reconstructing the subsurface hydrogeology over the coastal areas is essential. A geophysical tool such as a ground-penetrating radar (GPR) which works on the principle of reflecting electromagnetic (EM) waves, can be conveniently deployed to delineate the soil and rock profiling, water-table depth, bedrock depth, and the subsurface structural features. Here, DeepLabv3+ architecture based newly developed deep convolutional neural networks (DCNNs) were used to establish an inherent non-linear relationship between the GPR data and the EM wave velocity. The presented DCNNs have a lesser number of layers, a lesser number of trainable (learnable) parameters, a high convergence rate and, at the same time, achieve prediction accuracy comparable to that of well-established DeepLabv3+ networks, having high trainable parameters and a relatively low convergence rate. Here, firstly the DCNNs were trained and validated on small 1D datasets. Each dataset contains a 1D GPR trace and a corresponding EM velocity model. The DCNNs turned out to be quite promising in the 1D case, with training, validation, and testing accuracy of approximately 95%, 94%, and 95%, respectively. Secondly, 1D trained weights were applied to 2D synthetic GPR data for EM velocity prediction, and the accuracy of prediction achieved was approximately 95%. Seeing the excellent performance of the DCNNs in the 2D prediction case using 1D trained weights, a large amount of 1D synthetic datasets (approximately 1.2 million) were generated and gaussian noise was added to it to replicate the real field scenario. Thirdly, topographically corrected GPR data acquired over the Old Bar Beach were inverted using the DCNNs trained on 1.2 million 1D synthetic datasets to obtain the subsurface high-resolution, high-precision EM velocity, and εr distribution information to understand the hydrogeology over the beach. The findings presented in this paper agree well with the previous hydrogeological studies carried out using GPR. Our findings show that DCNNs, along with GPR, can be successfully used in coastal environments for the quick and accurate hydrogeological investigation required for the implementation of coastal erosion mitigation methods such as beach nourishment.

Hydrogeological investigation of fluoride ion in groundwater of Ruparail and Banganga basins, Bharatpur district, Rajasthan, India

Hydrogeological investigation of fluoride ion in groundwater of Ruparail and Banganga basins, Bharatpur district, Rajasthan, India

Applicability of d-excess and 17O-excess as groundwater tracers for determination of recharge area

Methods to determine the recharge elevation of groundwater using the altitude effect of δD and δ18O have been extensively applied in hydrogeological investigations. The secondary parameter d-excess has also been used as a groundwater tracer. In this study, to examine the usefulness of these tracers along with 17O-excess, ~160 groundwater samples were collected from a humid region at the foot of Mt. Fuji, Japan. The sampling area covered 40 × 45 km, with most sampling sites located below 1,000 m above sea level. The relatively low elevation and small scale of the basin allowed for examination of the elevation-dependence of groundwater isotopes. Using high-precision isotope analyses, a low lapse rate but clear elevation-dependence in spring waters was observed for d-excess (0.18‰·100 m−1). The recharge elevation determined by d-excess correlated with those by δD and δ18O, indicating that d-excess has high potential as a groundwater tracer for the determination of recharge elevation. On the other hand, 17O-excess in groundwater held small spatial variation, with an average of 25 per meg in the horizontal direction and a lapse rate of 0.6 per meg·100 m−1. The low lapse rate compared to the analysis error inhibits its usefulness as a tracer. The fact that the recharge elevation determined by δD, δ18O, and d-excess were similar indicates that the combination of these tracers could increase the reliability of the results.

Hydrogeological map of Albania at a scale of 1:200,000, principles of compilation and content – a document of Albanian pioneering hydrogeological research since the 1960s

The organized hydrogeological investigations in Albania started in 1959, while general hydrogeological prospecting started there in 1963 and finished in 1974. One of the hydrogeological prospecting main goals was the compilation of the hydrogeological map of Albania at a scale of 1:200,000. Hydrogeological maps may differ in content, representation, scale and format, but two main types of these maps are principal: general and/or special hydrogeological maps. The aforementioned map was published in 1985 following principles for general hydrogeological maps as defined in 1970 by IAH/UNESCO, which were subsequently adopted, but also further developed. The areal colours show hydrogeological classification of rocks and the basic elements shown on the map are hydrogeological units. Geological pattern forms the map background, while lithologic units are differed by green colour hatches. Different aquifers and hydrogeological structures identified during the investigations are also shown here, together with important water supply areas of productive drillings and springs. Groundwater quality, thermal springs, seawater intrusion areas and the relation between surface and groundwater can also be recognized. The map published in 1985 can be successfully used until nowadays, not only for the planning purposes, but also as a helping tool in many practical problems of the groundwater use solutions.

Spatial and temporal distribution of arsenic contamination in groundwater of Nawalparasi-West, Nepal: an investigation with suggested countermeasures for South Asian Region.

Nawalparasi-West/Parasi is one of the severely affected districts in the Terai lowlands of Nepal by arsenic (As) contamination in groundwater, exceeding standards of 10ppb (WHO) and 50ppb (Nepal Drinking Water Standard). This study presents the spatial and temporal distribution of As across 6km × 10km region in Parasi via meteorological, hydrogeological, physio-chemical, and sedimentological investigations in 31 communities for about 5years. In this study, water balance analysis was carried out for understanding the groundwater dynamics in the study area and its contribution to As elution. Gentle flow gradient and little to no infiltration was observed in the central region with relatively impervious silty clayey flood plain, where higher As concentrations were obtained compared to the northern Siwalik foothills and southern parts with coarser sediments. Similarly, higher As concentration (1048ppb) was recorded in the drier pre-monsoon season than the wet season (529ppb). The aquifer at 12 to 23m depth feeding 73% wells in the study area exhibited higher As concentration in reduced environment as opposed to the oxidizing state at 5- to 6-m and 30- to 50-m deep aquifers. Other constituents such as Fe, B, and Cr and their relation with As were analyzed. The results ofGERAS model analysis done for health risk assessment are also presented which show that under long-term exposure, the residents in Parasi were undertaking intolerable cancer risk of 1.1 to 6.4 × 10-3. This study further incorporates socio-economic sentimentsvital to analyze, and propose sustainable and cheap countermeasures for immediate implementation to reduce As exposure and health risk in Nepal, which is also highly applicable for other affected regions in South Asian Region.

Investigation of hydrogeological conditions of a fractured shale aquifer in Yala Area (SE Nigeria) characterized by saline groundwater

Geological, hydrogeological and geophysical investigations were carried out in Yala Area (SE Nigeria) to delineate potential zones for future groundwater development. The area is underlain by Turonian fractured shale rock intruded by basaltic rocks and saline water. High lineament density (> 30 km−1) recorded in the north suggest high permeable zone, compared with low lineament density (< 10 km−1) in the south and east. Geophysical results reveal four types of aquifers: an upper weathered, fractured shale aquifer with mean resistivity and thickness in the range 27–40 Ω m and 20–28 m and a lower fractured shale aquifer with mean resistivity in the range 28.5 to 36.0 Ω m and unresolved thickness; fractured saline shale aquifer with mean resistivity and thickness of 21 Ω m and 50 m; fractured silty shale aquifer with mean resistivity and thickness of 54.4 Ω m and 10 m and basaltic intrusive fractured shale aquifer with mean resistivity and thickness of 135.6 Ω m and 6 m. A broad range of aquifer parameters were obtained from resistivity data and pumping test. Groundwater quality on the mean indicated alkaline and good fresh water for drinking and irrigation use with minor level of salinization. Concentration of dissolved ions in the area are enhanced through weathering and ion exchange. On the basis of these data, the potential zones for groundwater harnessing have been delineated in Yala Area.

Analysis of Hydrogeological Investigation in Engineering Geology

Analysis of Hydrogeological Investigation in Engineering Geology

Geophysical and hydrogeological investigations of water leakage from a reservoir dam to a coastal aquifer: the Lebna Case Study (Northeastern Tunisia)

Geophysical and hydrogeological investigations of water leakage from a reservoir dam to a coastal aquifer: the Lebna Case Study (Northeastern Tunisia)

Influence of Hydrology and Sanitation on Groundwater Coliform Contamination in Some Parts of Western Bengal Basin: Implication to Safe Drinking Water

Access to clean water has been identified as one of the primary Sustainable Development Goals. Rapid urbanization is going on in developing nations creating additional pressure on water resources in most of these places which in turn also affects individuals which is largely reliant on proper sanitation and drinking water quality. In addition, open sanitation practice is becoming major public health problem in rural and in some urban areas in India. Groundwater contamination by pathogenic bacteria sourced from both sanitation system and surface water is becoming one of the major concerns now-a-days. The residents of the Ganges river basin in India are already stressed with natural arsenic pollution as well as other various types of water pollution, and microbial pollution from sanitation is a new addition to it. A field-based hydrogeological investigation with the identification of sanitation sites (surface and subsurface) was conducted in some parts of the Ganges basin, in and around a lower order distributary river, River Churni in West Bengal state, to identify the natural and human influences on sanitation drinking water pollution in a highly populated part of South Asia. Groundwater was found to be contaminated severely with total (TC) and fecal (FC) coliform bacteria. The abundance of TC was found to be the highest in monsoon season (78%) than in pre-monsoon (48%) and post-monsoon (29%) seasons. The results revealed that the groundwater samples from shallow depths and close to sanitation sites were highly contaminated with coliform bacteria than the deeper and higher distant (&amp;gt;30 m distance) ones. Shallow groundwater samples near to surface water (River Churni) source, other than sanitation sites, showed elevated TC levels. The occurrence of coliform bacteria in studied groundwater samples was observed to be positively correlated with conductivity, TDS, TOC, chloride, and sulfate, while the abundance was restricted by pH and temperature of groundwater. Thus, improper sanitation systems and contaminated surface water were identified as one of the major sources of pathogenic contamination of groundwater-sourced drinking water in the studied area, whereas improper human practices further complicate the scenario which needs to be managed properly.