Assessment of Risk and Social Impact on Groundwater Pollution by Nitrates. Implementation in the Gallocanta Groundwater Body (NE Spain)

Groundwater is an essential resource for humans concerning freshwater supply; therefore, preserving and protecting its quality is necessary. Risk assessment, based on hazard, intrinsic vulnerability information and mapping, may be considered as a key aspect of sustainable groundwater management. An approach has been made by combining the Nitrogen Input Hazard Index and the hydrogeological parameters considered in a modified DRASTIC method. A three-level classification has been used to determine the degree of risk, and the thresholds have been established following measurable criteria related to the potential nitrate concentration in groundwater. The second part of the study focused on estimating the socioeconomic impact of groundwater pollution by relating the degree of risk and social vulnerability to groundwater pollution. The method has been tested in the Gallocanta Groundwater Body (Spain). As a result, a risk map and an impact map are provided. The risk map shows that 67% of the study area can be classified as moderate and high-risk areas, corresponding to high hazard sources located in moderate and high vulnerability zones, whereas the impact of groundwater pollution is classified as moderate in the whole groundwater body. The proposed analysis allows comparison between aquifers in different areas and the results required by water authorities to implement control and mitigation measures.

Geophysical investigations in the Radovna River Spring area (Julian Alps, NW Slovenia)

The Radovna River Valley is located in the north-western part of Slovenia in the Julian Alps, where there is an extensive intergranular aquifer whose depth to pre-Quaternary bedrock is unknown. Therefore, to obtain information about the depth of the valley and the geometry of the aquifer two geophysical methods were used in our study; ground penetrating radar (GPR) and seismic reflection method. The low-frequency GPR method has shown to be useful for determining the depth of the groundwater and the predominant groundwater recharge. Also, the high-resolution seismic method provided an insight about the morphology of the pre-Quaternary basement with the deepest point at 141 meters below surface. Measurements of hydrogeological parameters such as groundwater level and river discharge measurements were carried out in the study area. Both data analyses showed that groundwater level and river discharge are highly fluctuating and rapidly changing, indicating a well-permeable aquifer, implying that such an aquifer is extremely sensitive and vulnerable to extreme climate events. Both the geophysical methods and the hydrogeological information have provided important information about the morphology of the valley and the alluvial aquifer, as well as increasing the knowledge about the Radovna springs system, which will contribute very important information for future hydrogeological studies.

Prospects for exploration of hydrogen fields in riftogene structures of platforms (the case of the Dnieper-Donets Aulacogene)

This paper shows the prospect to find industrial-scale hydrogen accumulations in riftogenic structures of platforms using the example of the Dnieper-Donets Aulacogene, located in the southern part of the East European Platform. Within the Dnieper-Donets Depression, geological and geophysical methods indicate a significant number of deep faults and ring structures of volcanogenic and explosive origin promising increased hydrogen content. Possible locations of the most propitious areas of hydrogen concentration are associated with faults in rift systems and their nearest margins, as well as with explosive and volcanogenic ring structures with signs of modern activation. At a fine-grained level, the prospectivity of the area is determined not only by the specified structural relationship, but also by the set of geophysical characteristics (thermal, seismic, gravity, electrical conductivity, magnetic) and the corresponding geological and hydrogeological parameters. Areas for further more detailed investigations within the Sribne and other ring structures, Southern Near-Edge Fault, Northern Near-Edge Fault were identified based on the data on geological and geophysical materials, satellite images, and field work. We defined high-priority and low-priority territories. Areas for initial investigations using satellite images, gas sampling (hydrogen, helium, methane, etc.), primary geophysical surveys (with evaluation of intermediate reservoirs and cap rocks) were identified. The primary results can be used to plan pilot shallow drilling and wells sampling. The areas for priority deeper drilling and sampling are selected by the sum of results obtained and data comparison. The paper presents the results obtained 30 km east of Kyiv as an example of field assessment of H2 degassing in a local depression. The results show that hydrogen concentrations at depths of 0.45 to 1.5 m are near zero outside the local depression. The maximum values of H2 concentration (up to 3300 ppm 1.5 m deep) are characteristic of the point inside the depression.

Local Scale Groundwater Vulnerability Assessment Using GIS-Based DRASTIC Model, Emphasis on Groundwater Quality

Groundwater vulnerability assessment is a basic work for groundwater exploitation and protection. The Chaoyang district of Beijing was selected and investigated in this study. Groundwater vulnerability index system in Chaoyang district was constructed based on hydrogeological settings of local region, the human influence and the DRASTIC model. The comprehensive vulnerability assessment was carried out with weights of 0.4 and 0.6 for the intrinsic vulnerability and the specific vulnerability, respectively. In this study, total 9 hydrogeological parameters were considered, and the diagram of groundwater vulnerability assessment results in Chaoyang District was obtained by using DRASTIC index and overlay weighted method. The groundwater quality is poor in the southwest of Chaoyang District. The correlation analysis between total hardness, total dissolved solids and vulnerability results was carried out, and the correlation results were 06 and 0.7, respectively. The area with high groundwater vulnerability is also the regions with serious groundwater pollution, indicating that the assessment results are objective and reasonable, which can provide prevention and control of groundwater reference for the management department in the future, so as to reduce the risk of pollution.

Pumping Well Layout Scheme Design and Sensitivity Analysis of Total Critical Pumping Rates in Coral Island Based on Numerical Model

Groundwater on small coral islands exists in the form of freshwater lenses that serve as an important water resource for local inhabitants and ecosystems. These lenses are vulnerable to salinization due to groundwater abstraction and precipitation variation. Determination of the sustainable yield from freshwater lenses is challenging because the uncertainties of recharge and hydrogeological characteristics make it difficult to predict the lens response to long-term pumping. In this study, nine pumping well layout schemes along a line are designed using the orthogonal experimental design method, and an optimal well layout scheme is determined by multi-index range analysis and comprehensive balance analysis method. The total critical pumping rates of the freshwater lens corresponding to different schemes are calculated by numerical simulation, and the sensitivity of the total critical pumping rates to hydrogeological parameters is analyzed. The results show that the calculation of the total critical pumping rates needs to be combined with the specific well layout scheme with consideration to the length of well screens, the number of wells and the distance between wells. The difference in total critical pumping rates between different schemes can be up to three times. The uncertainty of hydrogeological parameters has a great impact on the total critical pumping rates. Within the range of a 30% reduction in parameters, α and K are the key risk factors of pumping; within the range of a 30% increase in parameters, α, ne and K are the key risk factors; α-ne combined changes had the greatest impact. The management of freshwater lenses and the assessment of sustainable yield will continue to be important tasks for coral islands in the future, and this study can help with the sustainable exploitation of island freshwater lenses.

SOURCE: a semi-automatic tool for spring-monitoring data analysis and aquifer characterisation

It has become increasingly necessary to optimise mountain groundwater resource management and comprehend resource-recharging systems from a hydrogeological perspective to formulate adequate resource protection strategies. Analysing mountain spring behaviour and aquifer characteristics can be time-consuming, so new automated techniques and software tools are needed to estimate hydrogeological parameters and understand the exhaustion dynamics of groundwater resources. This paper introduces SOURCE, a new semi-automatic tool that automates the hydrogeological characterisation of water springs and provides proper estimations of the vulnerability index, as well as autocorrelation and cross-correlation statistical coefficients. SOURCE rapidly processed input data from the Mascognaz 1 spring (Aosta Valley) water probes and meteorological station to provide graphical outputs and values for the main hydrodynamic parameters. Having a single software package that contains all the main methods of water spring analysis could potentially reduce analysis times from a few days to a few hours.

ASSESSMENT OF CHANGES IN THE HYDROGEOLOGICAL CONDITIONS CAUSED BY WET-BASED CONSERVATION OF THE STYLSKYI QUARRY OPERATED BY “DOKUCHAEVSK FLUX AND DOLOMITE COMPLEX” PJSC USING MATHEMATICAL MODELLING

Extraction of minerals significantly affects the hydrogeological conditions of the environment. Active development of mining operations in the Donbas region determined the dominant influence of technogenic changes in geological environment on the formation of modern ecological conditions in the region. This applies not only to coal mining but also raw materials extraction (dolomites, limestone) for metallurgical plants mostly by quarrying. Recently, a significant environmental problem in the region has been the mines and quarries closure, envisaged by the program for restructuring the coal industry of Ukraine. Closure of mines or quarries through wet-based conservation is the least financially expensive, although it significantly increases the technogenic load on the natural environment. The object of research involved groundwater and surface water within the area of the Stylskyi and Skhidnyi (Vostochnyi) quarries of the “Dokuchaevsk flux-dolomite complex” PJSC, as well as Kipucha Krynytsa and Shevchenkivskyi water intake structures. The goal of research was to forecast changes in the hydrogeological conditions under the influence of wet-based conservation of the Stylskyi quarry. To achieve this goal, hydrogeological methods, mathematical modelling, and expert assessments were used. Consequently, a hydrogeological model of the research area was created, its functional correspondence to the natural-anthropogenic conditions was confirmed, and calculation hydrogeological parameters were specified. As a result, the forecast of changes in the hydrogeological conditions under the influence of wet-based conservation of the Stylskyi quarry was made. In particular, the following issues were determined: the dynamics of quarry flooding; the influence of this process on changes in water inflows to the Skhidnyi (Vostochnyi) quarry, Kipucha Krynytsa and Shevchenkivskyi water intake structures; possible flooding of settlements and swamping of the research area; changes in chemical composition and groundwater salinity; time of quarry draining at various intensity of water outflow to resume mineral production in case of need. We would like to emphasize that the forecasts made should be used when designing partial or full flooding of the Stylskyi quarry.

Engineering and geological conditions of the north-western territory of Makhachkala due to flooding

Определение геоморфологических и геологических условий северо-западной площади г. Махачкалы, включая Новолакский район (Новострой), в связи с процессами засоления, осолонцевания и подтопления сельскохозяйственных земель. В настоящее время город интенсивно расширяется во все стороны. Особенно актуально изучение северо-западной территории г. Махачкалы в связи с подтоплением. Район относится к Прикаспийской низменности с отрицательными отметками рельефа. Отсутствие исследований по указанным проблемам может привести к нежелательным материальным и экологическим последствиям. В связи с подтоплением изменяются и несущие способности грунтов. Изменяются сейсмоакустические свойства грунтов, т.е. скорости распространения продольных (Vp) и поперечных (Vs) волн, а также соответствующие коэффициенты и декременты их поглощения. Цель работы. Определить границы слабо дренированных и весьма слабо дренированных зон, которые выявляют барражные участки территории, и гидрогеологические районы в зависимости от водопроводимости составных верхней и нижней толщ грунтов. Методы исследований. Сбор базы данных инженерно-геологических изысканий по химическому составу грунтовых вод и литологии покровных толщ грунтов. Сбор гидрогеологических параметров разных типов грунтов и гранулометрического состава песков целью интерпретации их фильтрационных свойств. Определение уклона рельефа местности с целью выявления зон дренированности территории. Результаты работы. Представлены таблицы химического состава грунтовых вод по 19-ти объектам и гидрогеологических условий площади по данным инженерно-геологических изысканий по 39-ти объектам, в том числе глубины залегания грунтовых вод, типа грунтов по сейсмичности, глубины залегания коренных пород, трех таксонов гидрогеологических районов, уклонов рельефа. Для выделенных гидрогеологических районов: для ГР-1 рекомендуется горизонтальный тип дренажа, для ГР-2 – вертикальный или комбинированный типы дренажа, для ГР-3 – подземный дренаж не эффективен. Указано о необходимости сейсмического микрорайонирования не только исследованного района, но и всего города Махачкалы, с перспективой дальнейшей застройки. Determination of the geomorphological and geological conditions of the north-western area of Makhachkala, including the Novolaksky district (Novostroy), in connection with the processes of salinization, alkalinization and flooding of agricultural lands. Currently, the city is intensively expanding in all directions. Particularly interesting is the study area of ​​the northwestern territory of Makhachkala due to flooding. It belongs to the Caspian lowland with negative relief marks. Lack of research on these problems can lead to undesirable material and environmental consequences. Due to flooding, the bearing capacity of the soil also changes. The seismoacoustic properties of soils change, i.e. the velocities of propagation of longitudinal (Vp) and transverse (Vs) waves, as well as the corresponding coefficients and decrements of their absorption. Aim.Determine the boundaries of poorly drained and very poorly drained zones, which reveal barrage areas of the territory, and hydrogeological areas, depending on the water permeability of the composite upper and lower soil strata. Methods. Collecting a database of geotechnical surveys on the chemical composition of groundwater and lithology of cover layers of soils. Collecting hydrogeological parameters of different types of soils and granulometric composition of sands in order to interpret their filtration properties. Determination of the slope of the terrain in order to identify the drainage zones of the territory. Results.Presented are tables of the chemical composition of groundwater for 19 objects and hydrogeological conditions of the area according to engineering and geological surveys for 39 objects, including the depth of groundwater, the type of soil in terms of seismicity, the depth of bedrock, three taxa of hydrogeological regions, slopes of the relief. For the selected hydrogeological regions: GR-1 - a horizontal type of drainage is recommended, for GR-2 - vertical or combined types of drainage, for GR-3 - underground drainage is not effective. It is indicated that it is necessary to seismic microzoning not only of the investigated area, but of the entire city of Makhachkala with the prospect of further development.