Groundwater Level Measurements Research Articles

HRU-based Downscaling of GRACE-TWS to Quantify the Hydrogeological Fluxes and Specific Yield in the Lower Middle Ganga Basin

Precise volumetric assessments of different hydrological variables, such as precipitation, evapotranspiration, and groundwater components, are necessary for comprehensive water resource management. This presents several challenges, including topographical complexity and economic limitations, mainly when aiming for high temporal and spatial resolution.The satellite mission Gravity Recovery and Climate Experiment (GRACE) has greatly improved the ability to quantify variations in GWS. We have described a two-stage downscaling system that integrates SWAT Hydrological Response Units (HRUs) with GRACE-derived Terrestrial Water Storage Anomalies (GRACE-TWSA) using Artificial Neural Networks (ANN). Using data from the Global Land Data Assimilation System (GLDAS), GWS was derived with GRACE-TWSA and further downscaled to the HRU level. The GWS trend in most of the study areas has not shown any significant trend from 2001 to 2014. The mean increasing trend was 2.16 mm/year and the mean decreasing was 2.28 mm/year. Using a decision-tree-based CatBoost model, the GWS has been used as an independent variable to determine distributed groundwater levels within the study area. A strong correlation between measured groundwater levels and GWS was observed, and a regularised robust optimization was used to determine the Specific yield. The surface water and groundwater budgeting indicate that most Gangetic area blocks are water-stressed. The study offers an extensive approach to integrated water resource management by providing insights into groundwater availability, aquifer storage characteristics, and budgeting with HRU scale GWS estimates.

Monitoring of ground subsidence using PS-InSAR technique in the Southeast Texas (SETX) Region

The southeast Texas (SETX) coastal area, owing to its unique geographical location and geological attributes, is facing a spectrum of geological challenges, such as ground subsidence, flooding, and coastal erosion. This study endeavors to evaluate the recent instances of ground subsidence and their associated rates, focusing on comprehending their implications for flooding within SETX. Employing the Persistence Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR) technique, this study employs Sentinel-1 SAR satellite data with descending orbit observations spanning from January 2020 to March 2023. Our findings indicate that both the northwestern and eastern regions of Houston have been settled with rates up to 2 cm/year. This settlement trend is consistent with data derived from GPS and groundwater level measurements. This investigation explicitly shows the substantial temporal and spatial variations in subsidence rates, predominantly influenced by localized groundwater extraction due to urbanization (e.g., population growth, land development, etc.). By advocating for the integration of InSAR, GPS, and groundwater measurements, this research aspires to make valuable contributions toward the mitigation of subsidence and flood-related hazards in the SETX area.

Contribution of standardized indexes to understand groundwater level fluctuations in response to meteorological conditions in cold and humid climates

Understanding the fluctuations in groundwater levels in response to meteorological conditions is challenging, especially given the slow transit time associated with groundwater reservoirs and the short duration of time series for groundwater levels. Nevertheless, this knowledge is crucial for water resource management, especially given that global warming will drastically impact the hydrological dynamics in cold and humid climates. The objective of this work was to quantify how standardized indexes contribute to understanding groundwater level fluctuations in response to meteorological conditions in cold and humid climates and with short time series (10 to 23 years). The relationships between the standardized precipitation index (SPI), standardized temperature index (STI), global climate indexes, and standardized groundwater index (SGI) were analyzed. The reactivity of groundwater levels was examined between 2000 and 2022 using groundwater level measurements from 152 wells located between 46 °N and 52 °N in the province of Quebec (Canada). The results showed that the available time series were sufficient to provide new insights into the role of precipitation and temperature on groundwater fluctuations, demonstrating the usefulness of the indexes. One of the main contributions of this study was that hydrogeological systems in cold and humid climates go through an annual reset due to the prolonged freezing period. This annual reset was one of the drivers isolating year-to-year hydrogeological conditions, contributing to short-duration droughts.

Groundwater investigation in the Dumoga area, north Sulawesi province, Indonesia

Dumoga is one of the areas in North Sulawesi Province, Indonesia, designated as an agriculture and food crop area. Groundwater is one of the sources of raw water and irrigation in this area. Therefore, it needs detailed information about the quantity and quality to support groundwater exploitation and management for sustainable use of groundwater resources. This study investigates the groundwater resource potential and quality, which has not been previously studied. The research methods used geological observation, springs mapping, geoelectrical survey, measurement of groundwater level, and physicochemical, including temperature, pH, total dissolved solids (TDS), and electrical conductivity (EC). The result shows that the Dumoga area has a high potential for groundwater resources, with sand and clayey sand as the main aquifers. Groundwater flows from around the research area to Dumoga River in the middle. Even though it has a high potential for groundwater resources, not all groundwater is recommended for irrigation water because of the quality, especially from the southwestern and eastern Dumoga areas.

Estimation of groundwater recharge from groundwater level fluctuations and baseflow rates around Mount Meru, Tanzania

Estimating groundwater recharge, direct runoff and baseflow is essential for understanding groundwater resource availability and managing groundwater systems. This study estimates groundwater recharge, direct runoff and baseflow on two slopes of Mount Meru: the northern and southern slopes using the water-table fluctuation (WTF) method and baseflow separation technique. High-frequency groundwater level measurements in five shallow wells over three hydrological years from 2018 to 2021 were analysed, while streamflow data in four gauging stations over nine hydrological years from 2010 to 2019 were used. The results of the WTF method show that the aquifer undergoes an average recharge of 544 mm/year and 90 mm/year on the south-western and north-eastern slopes, respectively. On average, this recharge is about 53% and 13% of the annual rainfall on each slope. The baseflow results show that the aquifer on the south-eastern and north-western slopes recharges an average of 88 mm/year and 54 mm/year, respectively, which is on average about 12% and 7% of annual rainfall, respectively. In general, the high recharge on the south-western slope is attributed to the high rainfall, and the high hydraulic conductivity and high hydraulic diffusivity of the pyroclastic deposits compared to the debris avalanche deposits on the north-eastern slope. In addition, debris avalanche deposits show homogeneous recharge conditions, while pyroclastic deposits show heterogeneous recharge conditions. The WTF method can be useful to identify areas of preferential recharge so that preferential groundwater flow paths can be mapped for focused recharge of surface runoff during the rainy season.

HUBUNGAN LAJU INFILTRASI TERHADAP PERMEABILITAS TANAH DAN MUKA AIRTANAH DI DAERAH DESA TAJUR KECAMATAN CITEUREUP

Infiltration is an important process in a hydrological system and acts as a medium for air infiltration into the soil. The process of infiltration in soil can be influenced by several factors, namely, rainfall, vegetation, land slope, land use, and soil moisture. Apart from this, other factors such as groundwater level and soil permeability also have an influence on the infiltration process, both of which are related to each other in terms of the rate of infiltration or air infiltration into the soil. If the infiltration process is disrupted, it results in the pooling of air on the ground surface, which affects the hydrological system. It is necessary to know how factors such as groundwater levels and soil permeability influence the infiltration rate. Based on this, the aim of this research is to determine the relationship. between infiltration rate, groundwater level, and soil permeability and their influence. The research method was carried out by taking data from direct groundwater level measurements and infiltration rate measurements, as well as samples for soil permeability analysis. Then an interpretation of the data obtained is carried out and presented in a map of the infiltration zone and soil permeability zone. The research area in Tajur Village has 2 infiltration zones, namely the slow-medium zone and the medium zone with medium and rather fast soil permeability and low-medium groundwater depth.

Phreatic Line Calculation of Reservoir Landslide under Complex Hydraulic Conditions—A Case Study

A seepage field, influenced by rainfall and reservoir water level fluctuation, is closely associated with the stability of the reservoir landslide. Understanding the phreatic line variation inside the landslide is of significant importance for the analysis and evaluation of slope stability. Currently, most of the boundaries of phreatic line analytical models and the hydrological conditions are simplified, resulting in discrepancies between the outcomes derived from these models and the actual situation. Given this, the newly proposed analytical model is refined by addressing the following two issues. Firstly, the consideration of variable-speed reservoir level fluctuations is incorporated, and secondly, the reservoir bank within the water-level fluctuation zone is treated as non-vertical. Under the combined effect of reservoir water level fluctuation and rainfall, the Boussinesq Differential Equation of unsteady seepage is established and applied to the Majiagou landslide in Three Gorges reservoir area. The results of the analytical solution are basically consistent with the measured groundwater level results, which has demonstrated the accuracy of the proposed model. Consequently, the proposed model can quickly and accurately calculate the groundwater level of landslides, which provides an effective means for the prediction and early warning of reservoir landslides.

Hydraulic parameters of Submenilite Formation of Ždánice Unit

This study aims to re-asses hydrodynamic tests of the Submenilite Unit of the Outer Carpathian Flysch Zone sediments, exposed at Přítlucká hora located near Rakvice village in South Moravian region, Czech Republic. We focused on four shallow, 6.0–7.6 m deep hydrogeological wells, drilled by Aqua Enviro s. r. o. company in 2005. The purpose of the drilling was a feasibility study for drainage of western part of Rakvice village. The sediments of the Submenilite Formation of the Ždánice unit that were drilled are dominated by compressed clays, claystones and siltstones, containing thin layers of sand and weathered sandstones. For the purpose of determining hydraulic parameters of underlying aquifer, the company conducted pumping and recovery tests on each of the wells. In this work, we used Jacob’s semilogarithmic method to interpret the measured groundwater level data. Hydraulic conductivity and transmissivity parameters were consequently calculated. The resulting transmissivity values range from 1.6 × 10–2 m2/d to 3.7 × 10–1 m2 /d and hydraulic conductivity value ranges from 3.6 × 10–3 m/d to 1.0 × 10–1 m/d. The calculated index of transmissivity Y corresponds to 4.32–4.57 and index of conductivity Z ranges between 5.80 and 6.27. The values of index of transmissivity Y from this study are generally comparable with results presented by previous authors and demonstrate very low transmissivity of the rocks of this unit mostly built by non-permeable pelitic rocks.

The Groundwater Resources in the Mazovian Lowland in Central Poland during the Dry Decade of 2011–2020

This article addresses the issue of droughts in recent years in Poland and their impact on the state of groundwater resources. This paper presents the challenges arising from the increasing demand for the use of groundwater for irrigation in agriculture, supplementing water shortages, and potential threats to the water supply of rural waterworks. The main part of this paper focuses on a small catchment area in the Mazovian Lowland, which is one of the driest regions in the country. This article includes definitions, characteristics, and causes of hydrologic and hydrogeologic droughts during the period 2011–2020. In the discussed area, there is generally one groundwater level of the Quaternary age, primarily recharged by rainfall infiltration, which is utilized by all dug wells and a number of drilled wells. The source material consisted of daily measurements of groundwater levels with a free surface from three piezometers located in different land use areas (forest, agricultural, and sparse development). Additionally, daily flows of the Zagożdżonka River at the Płachty Stare gauge station were examined, where the drying of the riverbed in the upper reaches has been observed in recent years. This study investigated the dynamics of hydrogeologic droughts in renewable groundwater resources and the rate of their decline in relation to hydrologic droughts of surface waters.

Innovative groundwater management in industrial park: Optimization and modelling of extraction system

The research presented in this paper focuses on the optimization and modelling of an innovative groundwater extraction system and addresses the challenge of managing the increased groundwater level in Nitra Industrial Park, where the Land Rover Jaguar car manufacturer is located. The primary objective of this research was to determine the optimal pumping rate of the system, ensuring the maintenance of the groundwater level at the required elevation without depleting the surrounding water resources. To achieve this goal, a numerical groundwater modelling approach was utilized, employing the TRIWACO simulation package and the finite element method (FEM). The study involved various simulations under steady and unsteady flow conditions, using hydrological, geological and hydrogeological data, including the results of three proposed pumping tests conducted by INGEO, Ltd. Company, as well as measured groundwater level data from boreholes monitored by the Slovak Hydrometeorological Institute (SHMI). Implementing transient groundwater flow simulations considered the impact of a 1000-year flash flood wave (Q1000). This paper presents results of numerical modelling results, offering insights into maintaining the required groundwater elevation while considering key parameters and uncertainties for design purposes. Additionally, on-site optimization was performed to ensure efficient system operation and minimize associated costs. In conclusion, this research contributes to sustainable groundwater management in the Nitra Industrial Park, addressing the challenge of the increased groundwater level and providing valuable findings to optimize the extraction system’s performance.

Study of changes in the induced wave field in mining waste storage facilities

An integrated approach to analyzing changes in the induced wave field in mining waste storage facilities for mineral waste is considered to localize potentially dangerous zones in the body of bulk structures using georadar sounding. It has been established that the zone of possible water saturation of rocks is perceived by the georadar signal as a transition to a medium with a higher dielectric constant and is reflected by the maximum amplitude of the signal. The boundaries of water saturation zones are not always sharply defined, but change smoothly depending on the degree of water saturation from a natural state unsaturated with moisture to complete saturation of soil pores. During GPR sounding, below the expected zone of water saturation, the soil structure is noticeably smoothed out, where, due to increasing attenuation, the signal amplitude sharply drops, which manifests itself in a noticeable decrease in the contrast of the wave pattern of the radargram. The use of intra-method integration by profiling on a permanent base and a common depth point with simultaneous synchronization of groundwater level measurements in a piezometer made it possible to identify and identify zones of increased water saturation in the dam body.

Application of Geoinformatics in Civil Engineering Design and Construction: A Case Study of Ile Oluji, SW Nigeria

Subsoil engineering site condition and modeling of engineering parameters has been carried out in Ile Oluji, Ondo State, Southwestern Nigeria, using geotechnical investigation, geophysical method, borehole logging, groundwater level measurement, and laboratory studies. Findings revealed that the soils are clayey of low-high plasticity/compressibility, with AASHTO classification of A-7-6. Based on average values of cohesion (48.4 KN/m2), angle of friction (17.4°), unconfined compressive strength (186.8 KN/m2), coefficient of permeability (2.13E-06 cm/s), activity (0.48), soaked CBR (7 %), MDD/OMC (1980 kg/m3/14.8 %), plasticity index (20.2 %), group index (6 %), compression index (0.0443), coefficient of volume compressibility (0.2041 m2/KN), depth to basement rock (22.2 m), static water levels 5.5 m (in well) and 21.8 m (in borehole), the soil is unsuitable for highway subgrade, subbase, and base courses. Thus, if it is expedient to use it as subgrade soil, the minimum recommended thickness is 241 – 513 mm (avg. 395 mm). The average allowable bearing capacity of the soil for square and round foundations are 268.4 KN/m2 and 267.95 KN/m2 respectively, with average total settlement of 18.3 mm for structural pressure of 100 KN/m2. For embankment, the suitability index (1.21) of the soil suggests a fair/expanding not collapsible construction material. The rock units in the area have high compressive/shear strength, modulus of elasticity, high crushing strength, low deformability; and presumable bearing capacity of 8, 000 – 10, 000 KPa when fresh, and 5000 – 7000 KPa when partly or slightly weathered. Thus are valuable as foundation constructions, aggregate in pavement, building stone, and armourstones. The correlation coefficient of the parameters are: MDD/PI vs. CBR (0.0043), LL vs. coefficient of consolidation (0.0608), PI vs. undrained shear strength/effective overburden (0.2706), PI vs. angle of shearing (0.0117), dry density vs. angle of shearing (0.0058), suitability index vs. CBRs (0.3644), clay contents vs. PI (0.1355).

Investigation of groundwater induced land subsidence in Ludhiana City using InSAR and Sentinel-1 data

Land Subsidence (LS) is a vertically downward motion of land surface due to various reasons such as natural processes and anthropogenic activities especially excessive exploitation of groundwater. LS has adverse effects on substantial infrastructural damage, severe environmental problems, extensive economic losses, and significant societal impacts. In this study, we investigated the LS of Ludhiana city, a densely populated, largest and major industrial city of Punjab state, India. We presented a comprehensive methodology of Short BAseline Subset Interferometric Synthetic Aperture Radar (SBASInSAR) for LS measurement using an open-source computational environment. We generated 197 interferograms from 65 Sentinel-1A images acquired in descending pass between September 2019–July 2022 for deriving radar line of sight (LOS) displacement time-series and mean LOS velocity. Deformation results showed that the southern, and south-eastern parts of the city had been consistently moving downward with a mean subsidence rate of 24.7 mm/yr, while in western, few small patches in eastern and northern regions it ranges from 2 to 21 mm/yr, 3–20 mm/yr and 4–16 mm/yr respectively. The standard deviation of mean LOS velocity was observed between 0.7 and 3.3 mm/yr with majority values < 2 mm/yr. SBASInSAR results were compared with six Groundwater Level (GWL) wells observations, and both measurements generally agreed well at GWL locations (W1–W6) except W1–W2. For assessing the influence of groundwater change on LS, a correlation analysis was performed, and correlation of 0.50, 0.47, 0.81, 0.77, 0.84, and 0.64 was observed at GWL stations (W1–W6) respectively. Overall comparison of InSAR and GWL measurements are found in good agreement and significantly correlated, which can provide sufficiently detailed information about LS.

A Case Study of Groundwater Potential for Agricultural Sustainability in Ambala District, Haryana by using Geospatial Approach

This study focuses on analyzing the behaviour of groundwater in the Ambala District using a Geographic Information Systems (GIS) approach. The Ambala District, located in 30.2862° N, 76.9643° E faces challenges related to groundwater availability and sustainability due to increasing water demand and potential environmental impacts. The research integrates various datasets, including hydrogeological parameters, groundwater level measurements, land use/land cover data, and geological information specific to the Ambala District. These datasets are processed and analyzed using GIS tools, enabling the identification of spatial patterns, trends, and relationships associated with groundwater behaviour. The analysis encompasses key aspects such as groundwater recharge areas, flow direction, aquifer characteristics, and vulnerability to contamination. By overlaying different thematic layers and conducting spatial analysis, the study identifies areas with high potential for groundwater recharge, areas of groundwater flow convergence or divergence, and regions prone to contamination risks from anthropogenic activities.

Predicting Groundwater Level using Temporal Attention Enhanced Graph Neural Network

A revolutionary approach for groundwater management is essential. To predicting the water levels using for integrating IoT sensors, cloud computing, and advanced data analysis methods. IoT sensors are employed for real-time measurement of groundwater levels, creating a robust dataset. The paper focuses on predicting future groundwater levels, a crucial aspect of sustainable resource management. To enhance predictive accuracy, a preprocessing algorithm, such as Min-Max normalization, is introduced to clean and normalize the collected data, ensuring its reliability. Additionally, a feature extraction algorithm, such as Principal Component Analysis (PCA), is implemented to identify relevant patterns and trends within the dataset, enhancing the efficiency of subsequent analysis. A novel classification algorithm, Spatial-Temporal Graph Convolutional Network, is introduced, enabling the identification of potential groundwater recharge areas. This classification algorithm leverages historical data and extracted features to categorize regions based on their suitability for groundwater renewal. Finally, this research uses a Temporal attention-enhanced graph Neural Network machine learning algorithm to predict groundwater levels in the next few years. This algorithm utilizes the preprocessed data and extracted features, identifying intricate patterns and trends in historical data to generate precise predictions for groundwater levels in the upcoming years.

Different groundwater behaviour in deep karst boreholes: the case of Jadro spring basin (Dinaric karst, Croatia)

The paper analyzes the data of groundwater level (GWL), groundwater temperature (TW), and electrical conductivity (EC) measurements in three deep piezometers (B1, B2, B3) in the Jadro spring basin, taken from October 2010 to December 2021. The variation of these parameters is analyzed at different time scales: annually, monthly, daily (24 hours), and hourly. They are compared with the data of the same parameters measured at the Jadro Spring. The analysis of the maximum observed rise and fall rates of the GWL showed that the piezometers were drilled in very different karst environments. Piezometer B1 is located in a karst matrix where the water flows predominantly in a diffuse laminar (slow-flow) regime. Piezometers B2 and B3 are located in a fault line where numerous large karst underground formations occur and rapid turbulent water flow takes place. The mean annual flows of the Jadro Spring strongly depend on the mean annual GWL-s in each of the piezometers. For much of the year (about 99%), the GWL in all three piezometers is more than 210 m below the ground surface. As the measuring sensors are located near the bottom of the piezometers, the groundwater temperature is almost stagnant. It is always at 12.5 ºC in piezometer B1 and behaves almost identically in piezometer B3. Water temperature is the highest in piezometer B2 and hovers around the average value of 13.5 ºC. At the Jadro Spring, the average water temperature is 12.95 ºC. The electrical conductivity values are the highest in piezometers B2 and B3, with an average of around 0.5 mS/cm. They are lower in piezometer B1, where they range around an average value of 0.465 mS/cm, while at the Jadro Spring, they vary from 0.40 mS/cm to 0.48 mS/cm, with an average value of 0.44 mS/cm. A distinct seasonal pattern in groundwater level behavior is evident across all piezometers. However, no discernible upward or downward trend is observed.

Hydrological consequences of controlled drainage with subirrigation

Controlled drainage with subirrigation (CD-SI) could be a viable measure to cope with the imbalance in water demand and supply in groundwater dependent regions. CD-SI has the potential to i) retain, ii) recharge and iii) discharge groundwater, i.e. anticipate both dry and wet weather extremes. The aim of this paper is to specify the hydrological consequences of CD-SI at field scale. Four field CD-SI pilots with varying geohydrological conditions in Dutch sandy Pleistocene uplands were monitored (minimum 5 years) to study the effects on groundwater level, soil moisture content and soil water potential. Dynamic modelling using the SWAP-model, calibrated with PEST, was used to quantify all water balance components for the field pilots, needed for responsible implementation of CD-SI. Using SWAP-PEST, measured groundwater levels and soil moisture conditions were reproduced sufficiently accurate. Both the water supply rates and the water and crest levels in the control pit of CD-SI systems could be simulated dynamically, which is an important improvement to earlier modelling approaches. Model calculations were used to study the hydrological responses of CD-SI for meteorological dry to wet years and for each of the field sites. Simulations show that transpiration increases with 38 to 206 mm in dry years for sites with respectively low and higher hydraulic resistances in the subsoil. Simulations also show that the required water volume can be large (664 – 728 mm, respectively). CD-SI could thus improve hydrological conditions for crop growth, but the success depends on subtle differences in geohydrologic characteristics.

Impact of Soil Surface Temperature on Changes in the Groundwater Level

The relationship between the soil surface temperature and groundwater level is complex and influenced by various factors. As the soil surface temperature increases, water evaporates quickly from the soil, which can lead to a decrease in the groundwater level. In this study, we analyzed the impact of soil surface temperature on changes in the groundwater level in the Bukhara region of Uzbekistan using data from 1991 to 2020. The Bukhara region experiences regular water shortages, increased soil salinization, and inefficient energy in lift-irrigated areas, which is a typical constellation of challenges to the water–energy–food–environment (WEFE) nexus. The soil surface temperature data were collected from the Hydrometeorological Service Agency, whereas groundwater level data were obtained from the database of the Amelioration Expedition under the Amu-Bukhara Basin Irrigation Systems Authority. We used linear regression analysis and Analysis of Variance (ANOVA) tests to establish the significance of the relationship between the soil surface temperature and groundwater level, as well as the impact of the location of the groundwater level measurements. The results indicate that the model was a good fit to the data, and both the intercept and the soil surface temperature were significant factors that affected groundwater level. The results further suggest that the strength of the relationship between solar radiation and soil surface temperature is very high, with a correlation coefficient of 0.840. This means that when solar radiation increases, soil surface temperature also tends to increase. The analysis also showed that 53.5% of the changes in groundwater level were observed by the regression model, indicating a moderately correlated relationship between the groundwater level and soil surface temperature. Finally, higher solar radiation leads to higher soil surface temperature and higher evapotranspiration rates, which can lead to a decrease in groundwater level. As a result, we observe that the soil surface temperature determines changes in the groundwater level in the study region.

Prediction of the Mine Water Inflow of Coal-Bearing Rock Series Based on Well Group Pumping

Previous scholarly investigations have mainly concentrated on examining water intake, particularly within the specific domain of coal mines. Nevertheless, the scholarly discourse lacks significant research on predicting water inflow in environments with complex multi-layer mineral distributions. The Yanlong mining area is a complex mine containing coal and bauxite. Forecasting the water inflow of bauxite deposits is crucial for designing mining drainage and formulating a mining plan in a coal-bearing rock series mining area. The water inflow on the roof and floor of bauxite was studied with various numerical simulation and analytical methods (such as the big well method). The hydrogeological conceptual and numerical model of the mining area was established by the MODFLOW module in Groundwater Modeling System (GMS (7.1)) software, and the measured groundwater level was identified and verified in the model. The results show that the model average values of R2, Ens, and PBIAS are 0.86, 0.81 and 2.71, respectively, indicating that the established numerical simulation model can accurately forecast water inflow into the aquifer. Taking No. XII orebody in the eastern Songshan Mining area as an example, a virtual well group consisting of 12 wells was set up, and the numerical model forecast a water inflow of 71,500 m3/d from the Taiyuan Formation aquifer in the bauxite ore roof, which was lower than the value predicted by the large well method (72,786.66 m3/d). The numerical method predicted an average water inflow of 59,000 m3/d and a maximum water inflow of 82,600 m3/d from the Majiagou Formation in the bauxite ore floor. A dependence has been established that the numerical method estimates water inflow with accuracy. Additionally, the model predicts future mining water inflow, and also provides a standard framework for estimating inflow in similar mining conditions.

Investigation of Subsurface and Geological Structures Contributing to Collapse Sinkholes in Covered Karst Terrain, Northeast Thailand

This study focuses on covered karst terrain situated in Phu Pha Man District, Khon Kaen Province, Northeast Thailand, where records of collapse sinkholes are limited. Here, we investigate the subsurface characteristics and potential causes of sinkhole formation within this area using geophysical methods, hydrogeological techniques, and precipitation analysis. We collected field data by measuring groundwater levels, and conducting electrical resistivity tomography (ERT) surveys. We identified eight cover-collapse sinkholes of various shapes and sizes. Analysis of the groundwater flow indicated that the predominant flow direction runs from north to southeast. Examination of rainfall data showed a progressive increase in total rainfall on a yearly basis, with a significant precipitation event preceding the initial occurrence of sinkholes. The ERT results revealed the presence of highly resistive bedrock, water-saturated layers, and potential cavities. Notably, the tomograms indicated variations in resistivity values, suggesting the presence of irregular surfaces of limestone bedrock and weathered zones as characteristics of karst settings. Intense precipitation is a possible dominant trigger for the formation of the sinkholes. This study contributes to understanding sinkhole formation in karst environments and provides key information for hazard mitigation, not only in the Phu Pha Man District but also in areas with similar geological settings.