Sustainable Groundwater Development Research Articles

Integration of geospatial-based algorithms for groundwater potential characterization in Keiskamma Catchment of South Africa

Groundwater supports over 2.4 billion people across the globe and is critical to food security. The spatial dynamics of groundwater vary from place to place. The irregularity of groundwater resource exploitation is recognized in drought-prone areas, putting pressure on the resource. Hence, accurate groundwater potential characterization is critical for sustainable development and management of groundwater, particularly in drought-prone environments. Therefore, this study aimed at utilizing remote sensing satellite data and geospatial-based (analytical hierarchy process (AHP) and frequency ratio (FR)) algorithms to characterize groundwater potential zones (GWPZs) in the Keiskamma Catchment of South Africa. Seven (7) selected factors, including geology, soil type, slope, rainfall, drainage density, lineament density, and land use land cover, were assigned weights based on the AHP and FR algorithms. The validation results showed that the FR model performed better than the AHP, with the area under curve (AUC) accuracies of 62% and 50%, respectively. Based on the findings of this study, we infer that FR is more reliable than AHP when characterizing GWPZ. Lastly, GWPZ maps produced will be beneficial for improving efficient planning, management strategies, and decision-making.

A new insight for geophysical and geospatial mapping quaternary alluvium of Indo-Gangetic plains for exploration and assessment of groundwater in Haryana, India

A comprehensive study on groundwater exploration and assessment was conducted, integrating geophysical, geological, lithological, and resistivity logging techniques for a holistic evaluation of groundwater resources in Haryana, India. The primary research objective was to gain insight into the geological composition of alluvial sand and its implications for groundwater occurrence in Haryana's semi-arid region. The study showcases high-resolution electrical resistivity tomography results alongside conceptual cross-sectional models and 3D lithological models, revealing buried channels that serve as groundwater sources and saturated sand as well as recharge conduits within the alluvial region of Haryana. Moreover, borehole drilling at two sites and resistivity logging data demonstrate a strong correlation between various lithologies and resistivity logs. Overall, groundwater prospect zones are delineated at depths ranging from 18 m to over 100 m based on resistivity values of aquifer zones inferred from electrical resistivity tomography models, as well as mapped thick sand layers with significant hydrogeological importance in the study area. This emphasizes the stress on the aquifer system, where groundwater is being extracted from deeper depths. The conceptual litho-sectional model reveals a thick sand signature at intermediate depths, indicating the presence of buried paleochannels extending from Galedwa (Kurukshetra) to Jubbal (Yamunanagar). Additionally, the 3D lithological models, along with the electrical resistivity tomography results, facilitate strategic planning for shallow and deep boreholes for groundwater exploration and prospecting, aiming at sustainable groundwater development and management of resources in both the present and future.

Water Governance in Tanzania – A Synthesis of Legal and Institutional Frameworks for Groundwater Management in the Upper Great Ruaha River Catchment

The importance of groundwater resources in buffering the effects of climate change on water scarcity and security is highly acknowledged worldwide. However, groundwater development and use can only be sustainable with a more robust policy and institutional arrangements related to water governance. The purpose of this study was to analyse the legal framework of water resource development and management in order to contribute in identifying policy constraints to sustainable groundwater resource development and management in Tanzania. The paper used information from literature reviews and data collected through qualitative methods using a case study of Usangu Plains in the Upper Great Ruaha River Catchment in Tanzania. The findings reveal that water governance institutional frameworks are well structured to provide guidelines on how water as a basic human resource can be utilised and properly managed, but most importantly, these institutional arrangements place disproportionate emphasis on groundwater. Attaining sustainable groundwater development and use requires new disclosures and narratives in water policy and law, integrating both surface and groundwater resources. The weaknesses identified in groundwater governance need to be taken on Board once, the existing water institutional frameworks open to perfection for sustainable utilisation of groundwater resources

Sustainable groundwater development using semi-supervised learning and community-led total forestry and pasture approach

Groundwater is a critical resource for billions of people worldwide, providing a vital source of freshwater for agriculture, industry, and domestic use. However, over-extraction and mismanagement of groundwater resources have led to significant environmental and social challenges. This research presents a novel approach to address these issues through the integration of Semi-Supervised Learning (SSL) and the Community-Led Total Forestry and Pasture (CLTFP) approach. Our proposed methodology combines SSL techniques to predict and monitor groundwater levels, enabling more informed decision-making by authorities and stakeholders. By leveraging both labeled and unlabeled data, two different components including SSL and CLTFP are used, where SSL enhances the accuracy of predictions while reducing the need for costly and time-consuming data collection efforts. Furthermore, we advocate for the CLTFP approach, which promotes community engagement and sustainable land management practices. This strategy empowers local communities to actively participate in safeguarding groundwater resources, promoting sustainable farming, and reforestation efforts. The proposed method outperforms existing methods, achieving 98% accuracy, significant cost reduction, strong community engagement, and environmentally sustainable outcomes.

Deep learning models for groundwater level prediction based on delay penalty

Abstract In irrigation agriculture, predicting groundwater level (GWL) using deep learning models can help decision-makers coordinate surface water and groundwater usage, thus aiding in the sustainable development and utilization of groundwater. However, when making a long sequence prediction, prediction sequences often have severe delays affecting the availability of prediction results. In this paper, a new loss function is proposed to minimize the lag and oversmoothing on the prediction of GWLs. GWL, meteorology, and pumping data are collected via an irrigation Internet of Things system in Hutubi County, Xinjiang. Through Pearson's correlation analysis, historical potential evapotranspiration (ET0), groundwater extraction, and GWL were chosen to predict GWLs. Datasets were constructed through the proposed spatiotemporal data fusion method; then, the best model from the six deep learning models was selected by comparing the prediction capability of the datasets. Finally, the mean-squared error (MSE) loss function is replaced by the proposed loss function. Compared to the mean absolute error, MSE, and predicted sequence graphs, the new loss function significantly depresses the time delay with similar prediction accuracy.

Hydrogeological Analysis of Cretaceous and Tertiary Aquifers in Semiarid Sokoto Basin, Northwestern Nigeria: Implications for Sustainable Groundwater Development

Groundwater development in arid and semiarid regions is accelerated by expanded irrigation farming, industrialisation, and municipal water supply. This study provides a detailed hydrogeological analysis of sedimentary aquifers of the Sokoto basin, Northwestern Nigeria, for improved water resource development and management. Hydrogeological data, including static water level (Swl), pumping water level (Pwl), pumping test (Pt), and estimated yield (Ey), were analysed. A total of three hundred (300) observations on Swl, Pt, Pwl, Ey, and Hps were derived from boreholes and analysed using Factor analysis (FA) and Regression analysis (RA). Results showed that Gwandu Formation is the most prolific aquifer. Boreholes can yield more than 24000 litres per hour (L/h). This was followed by The Kalambaina limestone aquifer, which has the potential to yield about 15000 (L/h). However, the Taloka Formation is characterised by very poor aquifers in most of the basin, though along the Jega-Dogon Daji axis, boreholes can yield more than 24000 (L/h). Likewise, boreholes tapping the Wurno Formation can produce a maximum yield of 24000 (L/h). Estimated yields from boreholes were less than 1500 (L/h) from the Gundumi aquifer, and the maximum borehole yields were 17760 (L/h) in the Illo aquifer. Statistical modelling showed that all the analysed variables are significant concerning groundwater potentials and variability of borehole yields in the study area. Therefore, future groundwater resource development in the study area should be based on a proper analysis of the geological configurations of the Sokoto basin. This study provides an outlook on the groundwater potentials of the study area and aquifers that can provide a basis for sustainable groundwater development policy. Thus, the study has shown how multivariate and regression analysis can be used to study the hydrogeological conditions of a particular basin. Therefore, it is hoped that this study's findings will inspire other researchers to take a comparable approach.

DAMPAK EKSPLOITASI AIR TANAH SECARA BERLEBIHAN TERHADAP PEMENUHAN KEBUTUHAN AIR PENDUDUK DI DESA RAENYALE, KECAMATAN SABU BARAT KABUPATEN SABU RAIJUA

This study aims to determine (1) the impact of excessive exploitation of groundwater on the fulfillment of groundwater for residents in Raenyale Village (2) Strategies for overcoming the impact of excessive exploitation of groundwater on meeting the water needs of residents in Raenyale Village.The method used in this study is a quantitative descriptive research method to test hypotheses using statistical data tests. In this study there were 103 people who became the research sample consisting of people who used drilled wells, people who used dug wells and the head of Raenyale Village. Data collection methods used are questionnaires, interviews, observation and documentation. The results showed that (1). The impact of groundwater exploitation in Raenyale Village is that there are 17 dug wells which are experiencing drought due to excessive use of drilled wells which means that the community is forced to incur additional expenses by buying tanked water to meet the population's water needs. (2). The strategy for overcoming the impact of groundwater exploitation is that there are 13 people who make infiltration wells, plant trees around the well area and with community awareness and understanding of the importance of sustainable development and use of groundwater.

Geophysical research on the interplays between soil–rock variability and hydrogeological structures: a case study

Understanding the spatial variations in soil–rock profiles is crucial for identifying weathered rock layers and mapping geological structures, particularly in the complex feldspar-rich granitic terrain of Penang Island, Malaysia. This study employs a combination of electrical resistivity and seismic refraction tomographic techniques, along with borehole lithological data, in three distinct areas on the island. Its goal is to provide insights into surficial and subsurface soil–rock characteristics and water-bearing structures within the North Penang Pluton (including a part of the Sungai Ara axis) for sustainable groundwater development, addressing the needs of the region's growing population. The research identifies three distinct geological units at the near-surface: residual soils, highly to moderately weathered/fractured granitic layers and fresh bedrock, each with its hydrogeological properties. Promisingly, the weathered layers offer significant groundwater development potential, with deep weathered and potentially fractured zones exceeding depths of 30 m in the study area. These findings have substantial implications for sustainable groundwater development, especially in tropical hard-rock terrains. In addition, the study underscores the limitations of small geophysical spacings when probing deeper groundwater resources. This knowledge is essential for informed decision-making in water resource management and infrastructure development, addressing the ongoing global challenge of ensuring access to clean water resources amid population growth.

Hydrochemical Appraisal and Driving Forces of Groundwater Quality and Potential Health Risks of Nitrate in Typical Agricultural Area of Southwestern China

Elucidating the hydrogeochemical processes and quality assessment of groundwater holds significant importance for its sustainable development. In this paper, 53 groundwater samples were collected from a typical agricultural area in the northeastern Chongqing municipality in SW China. The integration of multivariate statistical analysis, ion ratio analysis, geomodelling analysis, the entropy water quality index, health risks assessment, and sensitivity analysis was carried out to explore the hydrochemical processes and quality assessment of groundwater in this study. The statistical results reveal that the cationic concentrations followed the order of Ca2+ > Mg2+ > Na+ > K+, while the anionic components were in the order of HCO3− > SO42− > NO3− > Cl−. Based on the Piper trilinear diagram, the hydrochemical types were shown as Ca-HCO3 and Ca-Mg-HCO3 types. Hierarchical cluster analysis indicated that the groundwater samples could be categorized into three groups. The hydrochemical compositions were primarily influenced by water–rock interactions (e.g., carbonate dissolution and silicate weathering). In terms of irrigation suitability, the sodium adsorption ratios (SARs) ranged from 0.05 to 1.82, and the electrical conductivity (EC) varied from 116 to 1094 μs/cm, indicating that most groundwater samples were suitable for irrigation. The entropy-weighted water quality index ranged from 15 to 94, suggesting that the groundwater samples were suitable for drinking purposes. Non-carcinogenic human health risks followed the order of children > adult females > adult males, within the average values of 0.30, 0.21, and 0.18, respectively. Sensitivity analysis showed that the parameters had the weight order of NO3 > body weight (BW) > ingestion rate (IR) > exposure frequency (EF). Hence, we recommend prioritizing the management of areas with high salinity levels, while avoiding the excessive use of nitrogen fertilizers, raising awareness among local residents about safe groundwater, and providing robust support for the sustainable development of groundwater in typical agricultural areas.

Examining the change in groundwater flow patterns: A case study from the plain area of the Baiyangdian Lake Watershed, North China

Examining the evolution of groundwater flow patterns is critical to understanding the hydrological cycle and plays an important role in the sustainable management of water resources and ecosystems. In this study, the plain area of the Baiyangdian Lake Watershed (PBW) was chosen as a typical area for severe water scarcity and ecological crisis in the North China Plain. We investigated the temporal and spatial variability in groundwater flow patterns from a holistic view of the water cycle in the PBW and explored more sustainable water resources management using multiple methods, including field surveys, historical data review, statistical analysis, and numerical groundwater modelling. The results show that the groundwater storage decreased by 494 × 108 m3 across the PBW from 1965 to 2019, while the groundwater level presented a decreasing trend for most of the period, which resulted in changes of Baiyangdian Lake and groundwater interactions. Human factors, such as groundwater extraction and water transfer projects, significantly influenced the evolution of groundwater flow patterns by generating a greater contribution of human factors to groundwater balance (54.23%) than that of climate change (45.77%). The hydrodynamic simulations imply that the interaction between groundwater and Baiyangdian Lake was dominated by groundwater recharging the river under natural conditions, and the influence depth of the interaction zone was within about 80 m underground; however, under anthropogenic disturbance, their interaction was altered to the lake recharging groundwater, with a maximum influence depth up to 135 m. Furthermore, considering the systematicity and zoning of the water cycle, we proposed a combination of different strategies, including restricted groundwater exploitation, increased water diversion and water use efficiency, and managed aquifer recharge, which could restore groundwater levels and groundwater storage over a 20-year period to realize sustainable groundwater development. This study highlights the spatiotemporal groundwater flow patterns in a changing environment and the associated hydrogeological processes and provides insights towards the development of more effective water management strategies.

Particle Size Distribution and Composition of Soil Sample Analysis in a Single Pumping Well Using a Scanning Electron Microscope Coupled with an Energy Dispersive X-ray (SEM-EDX) and the Laser Diffraction Method (LDM)

Soil is a heterogeneous material, and its properties are vital from an agricultural perspective and for groundwater management. However, limited studies have been performed on the soil characteristics (soil texture, water-holding capacity, and soil compositions) of a single pumping well, especially in Malaysia. This article focuses on the soil characteristics and elemental analysis of a single borehole with 11 samples collected around Labu Kubong, Perak. The soil properties were analyzed in the context of particle size distribution (PSD) using the laser diffraction method (LDM), as well as soil composition for elemental analysis using a scanning electron microscope coupled with an energy dispersive X-ray (SEM-EDX). The LDM results revealed the average percentage of clay, silt, and sand to be 0%, 6%, and 94%, respectively, indicating most particles comprised sand particles which in percentages demonstrated a sandy texture with less silt content. Additionally, the water holding capacity is low because of major coarse sand particles in alluvial formations. Moreover, SEM-EDX outcomes displayed an average percentage of elemental composition reported as follows: C (40.77%), O (34.33%), Si (10.66%), Al (5.82%), Fe (1.10%), K (1.10%), As (0.05%), Na (0.04%), and Be (5.62%). Consequently, SEM-EDX outcomes showed these elements were derived from silicified quartz, feldspar, and iron-bearing minerals that originated from shale formations, and the presence of carbon indicates peat formation. Therefore, this study provides information on a single pumping well from an irrigation practice, and this study also recommends regional to global scale studies for supporting sustainable groundwater development worldwide.

Study on Groundwater Function Zoning and Sustainable Development and Utilization in Jining City Planning Area

The sustainable development and utilization of groundwater resources are of paramount importance for the progress of society, the economy, and the environment. This study focuses on the planning area of Jining City and establishes an evaluation index system for groundwater functional zoning by analyzing key factors such as resource supply function, geo-environmental stability function, and ecological environmental protection function. To evaluate the groundwater functions, this study employs the barrel effect AHP. Through the overlay analysis of different groundwater functions, the planning area of Jining City is categorized into distinct zones based on their groundwater functions. These zones include centralized development and utilization areas (5.69%), decentralized development and utilization areas (65.67%), fragile geo-environmental areas (10.44%), ecological protection areas (8.38%), and unsuitable development and utilization areas (9.82%). The comprehensive zoning map of groundwater functions in the planning area of Jining City is generated. Taking into account the challenges posed by human activities, such as groundwater pollution, this study proposes recommendations for the sustainable development of groundwater in the planning area of Jining City. By systematically examining the functional zoning and sustainable management of groundwater, this study provides a scientific foundation for the responsible development and protection of groundwater resources.

Effects of downstream environmental flow release on enhancing the groundwater recharge and restoring the groundwater/surface-water connectivity in Yongding River, Beijing, China

The Yongding River (Beijing, China) was dry most times of the year, and groundwater storage was severely depleted. To address this issue, a river rehabilitation project was initiated. A downstream environmental flow release (EFR) project from upstream reservoirs has been implemented since 2019. This study evaluated the impact of EFR by constructing transient groundwater-flow and numerical tracer transport models to simulate the hydrogeological responses to the water release events in 2019–2020. The study identified two factors that significantly influence the river leakage rate, which are operational factors (i.e., water release rate and duration) and physical factors (i.e., hydraulic properties of the riverbed, regional hydraulic gradients, and groundwater depth) that determine the maximum water availability for groundwater recharge and maximum infiltration capacity, respectively. Predictive modelling was performed to assess the long-term effects of the proposed EFR scheme from 2021 to 2050, which showed that groundwater levels along the river will increase by 10–20 m by 2050. Groundwater storage is expected to be largely recovered and groundwater/surface-water connectivity in the middle reach of the river will be restored. This restoration will not only maintain the environmental flow for the benefit of ecosystems but also enhance groundwater recharge, promoting sustainable groundwater development in the region. Overall, this study provides valuable insights into the effectiveness of the proposed EFR scheme in achieving sustainable groundwater development in the region.

Predictive modeling and analysis of key drivers of groundwater nitrate pollution based on machine learning

Nitrate comtamination of shallow groundwater in agricultural intensification regions is a prevalent and global environment issue affecting food security, human health, and the water ecology. Developing a prediction model for groundwater nitrate contamination is crucial for protection of groundwater resources. Machine learning modeling offer potentials to predict contamination, but often fails to adequately screen input features in complex non-linear environments before modeling. Additionally, there is a tendency to overlook the interpretable description of the relationship between major water chemistry parameters and nitrate concentration after modeling, which hinders scientific decision-making by water resource managers. In this study, a dataset consisting of hydrochemical test results from 316 groundwater samples collected between 2011 and 2015 in intensive agricultural areas of Northeast China was collected. Prior to modeling, the dataset was grouped based on land use type, vadose zones types, and thickness. Based on the grouping of data sets, self-organizing map (SOM) and Spearman's coefficients were employed to identity the correlations between water chemical parameters and nitrate concentration (NO3–-N), which provided a logical basis for selecting the key input variables. A radial basis function artificial neural network (RBF ANN) prediction model and principal components regression (PCR) models was constructed using the dataset, and particle swarm optimization algorithm was applied to determine optimal parameter combinations of the RBF ANN. After conducting modeling, the advantages and disadvantages of RBF ANN and principal components regression (PCR) models were thoroughly examined and discussed, and the primary factors that impact nitrate concentrations in groundwater were analyzed using a PCR model. The results revealed that the RBF ANN model showed greater accuracy, while the PCR model offered better interpretability. Therefore, the integration of the two models is advantageous for nitrate prediction research. Human activities, rainfall, land-use types, vadose zones types and thickness are external factors that affecting nitrate concentration, and the difference between nitrification. Denitrification, and dissimilatory nitrate reduction to ammonium (DNRA) is internal driving factors for the change of nitrate concentration in the aquifer, and partially determine differences in the spatial distribution of aquifer nitrate concentrations under various land use types. This study provides a comprehensive approach for predicting nitrate pollution in groundwater under non-linear environmental conditions, supporting decision making in sustainable groundwater development, management, and conservation.

Priority control factors for heavy metal groundwater contamination in peninsula regions based on source-oriented health risk assessment

Peninsula regions in China face serious environmental issues, such as heavy metal (HM) groundwater contamination. However, attempts to investigate the pollution sources and health risks of HM contamination in such regions require considerable resources and costs. Moreover, the priority control factors for groundwater HMs remain unclear. In this study, absolute principal component score/multiple linear regression (APCS/MLR) was used to quantify the groundwater pollution sources of typical peninsular areas in China, and a health risk assessment (HRA) was performed to assess the health risks caused by different sources. The results showed that the concentrations of Mn and Fe were higher than those of other HMs, and HM pollution was high in shallow groundwater. The dominant source of HMs in groundwater was agricultural activities (31.12 %), followed by natural sources (26.33 %), industrial activities (22.47 %), and atmospheric deposition (20.09 %). The non-carcinogenic risks to residents were acceptable, whereas the carcinogenic risks were high. Agricultural sources, atmospheric deposition sources, and Cr and As were identified as the priority control factors for HM groundwater contamination. This study has implications for improving the control of groundwater HM contamination in peninsula regions and ensuring sustainable groundwater development.

Characterization of drinking groundwater quality and assessment of human health risk in Xin’an spring basin, a typical mining and karst area of the northern China

Groundwater is an important natural resources of drinking water in mining area in Xin’an spring basin, northern China. To foster the sustainable development and utilization of groundwater, a total of 332 groundwater samples, including 147 pore groundwater, 95 fissure groundwater and 90 karst groundwater, were collected and hydrochemical parameters were applied to assess the groundwater quality and human health risks caused by oral ingestion. The results showed that the major chemical components of groundwater in Xin’an spring basin were HCO3−, SO42−, NO3−, Cl−, Ca2+, Mg2+, Na+, total hardness (TH), and total dissolved solids (TDS). The contents of TDS, TH, SO42−, NO3−, F−, Fe, Mn, Pb, and As in groundwater were exceed the standard of groundwater quality (SGQ) limits. The main hydrochemical types of groundwater were HCO3-Ca·Mg and SO4·Cl–Ca·Mg. The factors controlling the groundwater chemistry mainly were mineral weathering, evaporation, cation exchange, and anthropogenic input. The results of water quality assessment showed that the karst and fissure groundwater in study area was mainly excellent-good quality water, while pore groundwater was mainly good-medium quality water. The poor and extremely poor quality water was mainly distributed in Changzhi basin, and the greater contribution made by Pb, Mn, NO3−, Fe, SO42−, TH and TDS. The range of hazard index (HI) values of groundwater was 0.28 to 27.79, and the HI values mainly contributed by NO3−, F−, As, ingestion rate (IR) and exposure duration (ED). The cumulative carcinogenic risk (CCR) values ranged from 1.5 × 10–7 to 2.78 × 10–3, and the greater contribution made by Cr, As, Cd, IR and ED. The results of health risk assessment suggested that some parts of the study region may pose a significant non-carcinogenic risk and a high probability in developing cancer to local residents, and infants were at greatest risk to health, followed by children and adults, while teenagers were at least at risk. This study will provide a deeper insight into the water quality situation and geochemical evolution of groundwater in Xin’an spring area, and will assist decision-makers to formulate management strategies of drinking water safety for the study area.

Quantitative evaluation of the influence of rainfall changes and groundwater exploitation on the groundwater level: a case study of the northern Huangqihai Basin, China

Abstract Based on the hydrogeological perspective, the variation in the groundwater level (W) was selected as the analysis factor, and the rainfall changes and groundwater exploitation (QGE) were considered to be the influencing factors. The influence of the two factors on W in the northern Huangqihai Basin was analyzed qualitatively and quantitatively. Results showed that both rainfall and QGE showed increasing trends from 1996 to 2020, while the W values decreased. The correlation between QGE and W was weaker in wet years than in normal years but was the highest in dry years. The mutation time was determined to be 2004. Based on the slope-changing ratio of the cumulative quantity method and the elastic coefficient method, it was determined that the contribution of rainfall changes to W was 22.08% and that of QGE was 77.92%. This study highlights the effectiveness of the integration of qualitative analyses and quantitative evaluation for identifying the influence of external factors on groundwater and well documents that the elastic coefficient method can be used in this field. More attention should be focused on the scientific management of QGE to minimize its negative influence on the sustainable development of groundwater.

Advances in Transboundary Aquifer Assessment

This Special Issue is intended to highlight both recent work to advance the physical understanding of transboundary aquifers and factors relevant in successful collaboration on transboundary groundwater resource use. The collected papers address: (1) the identification and prioritization of the needs and strategies for sustainable groundwater development and use, along with the complexities introduced by working across borders with differing governance frameworks, institutions, cultures, and sometimes languages; (2) the characterization of the physical framework of the aquifer, stressors on the aquifer system, and how those stressors influence the availability of groundwater in terms of its quantity and quality; and (3) the incorporation of stakeholder input and prioritization directly into the process of aquifer assessment and model building. The papers provide insights into the state of knowledge regarding the physical characterization of important transboundary aquifers, primarily along the U.S.–Mexico border and the opportunities for greater stakeholder involvement in resource evaluation and prioritization. They point the way towards a future focus that combines both of these aspects of transboundary aquifer assessment for informing groundwater management discussions by policymakers.

Deep Ensemble-Based Approach Using Randomized Low-Rank Approximation for Sustainable Groundwater Level Prediction

Groundwater is the most abundant freshwater resource. Agriculture, industrialization, and domestic water supplies rely on it. The depletion of groundwater leads to drought. Topographic elevation, aquifer properties, and geomorphology influence groundwater quality. As the groundwater level data (GWL) are time series in nature, it is challenging to determine appropriate metrics and to evaluate groundwater levels accurately with less information loss. An effort has been made to forecast groundwater levels in India by developing a deep ensemble learning approach using a double-edge bi-directed long-short-term-memory (DEBi-LSTM) model approximated with a randomized low-ranked approximation algorithm (RLRA) and the variance inflation factor (VIF) to reduce information loss and to preserve data consistency. With minimal computation time, the model outperformed existing state-of-the-art models with 96.1% accuracy. To ensure sustainable groundwater development, the proposed work is discussed in terms of its managerial implications. By applying the model, we can identify safe, critical, and semi-critical groundwater levels in Indian states so that strategic plans can be developed.

An integrated approach for aquifer characterization and evaluation in a complex geologic terrain (Cross River State, Nigeria): A contribution to support sustainable development and management of groundwater

Increasing agriculture, industrial and urban growth have resulted in the rapid and an haphazard development of groundwater resources through indiscriminate abstraction in the Cross River State (CRS), Nigeria. This has resulted in stress on groundwater, especially in areas with complicated geologic formations where reliable data are lacking. This paper focuses on understanding the hydrogeological characteristics of the different aquifers using an integrated approach. The methods applied are hydrogeological surveys together with interpretation of geological, geoelectrical and hydrochemical data. The results reveal six hydrogeological zones (HZs): HZs 1 (igneous and metamorphic rocks), 2 (sandstone and siltstone), 3 (massive, baked and fractured shale), 4 (sand, gravel, silt and clay), 5 (carbonate rocks) and 6 (basic intrusive rocks). Estimates of groundwater reserves indicate that the HZ 1 has the largest reservoir of stored fresh groundwater, estimated at 332,637.00 × 106 m3, while the highest yield is estimated to be 1085.53 m3/d from HZ 4. Groundwater chemistry showed that Na+ and Ca2+ dominated the cations, while Cl− and HCO3− dominated the anions. In general, major chemistry of the water is controlled by atmospheric input, weathering of silicate, carbonate minerals and ion exchange. In terms of drinking and irrigation quality, the groundwater showed low values of total dissolved solids, pH, hardness, dissolved oxygen and NO3− at few locations, while more than 50% of the samples have excellent quality for irrigation use. However, higher values were recorded in HZ 2, due to occurrence of brackish water.