Groundwater Protection Measures Research Articles

Pollution risk evaluation of groundwater wells based on stochastic and deterministic simulation of aquifer lithology

Groundwater pollution risk evaluation is an important basis for developing groundwater protection measures and management strategies, and its accuracy directly affects the effectiveness of protection measures. The heterogeneity of the aquifer significantly affects the transport process of pollutants, increasing the uncertainty of pollutant risk assessment. However, in the actual site, borehole data that reveal aquifer heterogeneity are costly, and only a limited number of borehole data are available, which cannot accurately describe the heterogeneity of the aquifer, thus limiting the accuracy of groundwater pollution risk assessment. In order to overcome the above problems, this paper proposes a groundwater pollution risk assessment framework based on the stochastic and deterministic simulation of aquifer lithology. Based on the statistical characteristics of the change of lithology type in the actual borehole, the framework uses Markov chain to generate some sets of random lithology field and transforms them into heterogeneity parameter field, so as to realize the stochastic assessment of the pollution risk of groundwater resource wells. Furthermore, combined with the pumping test data, the parameter field that is most suitable for the actual situation is selected to evaluate the pollution risk deterministically. Finally, the stochastic and deterministic results are combined to comprehensively evaluate the pollution risk of groundwater resource wells. Through a case study in a river valley plain, the feasibility of the above framework is verified, and good application effects are achieved. This study provides a feasible method for accurately assessing groundwater pollution risk, which is helpful to reduce the impact of uncertain factors on pollution risk assessment, and thus provides a more reliable basis for groundwater management and decision-making.

Analysis of Mercury in Aquifers in Gold Mining Areas in the Ecuadorian Amazon and Its Associated Risk for Human Health.

Gold mining activity is a source of supply in many areas of the world, and especially in developing countries, it is practiced illegally and by applying unsafe techniques. Particularly in Ecuador, artisanal and small-scale gold mining (ASGM) is widespread, and it is based on the use of toxic substances, such as mercury (Hg), in gold recovery. Hg is a heavy metal that is water-insoluble, which, once mobilized, poses a threat to both the environment and human health. This study analyzes Hg concentrations in the six provinces of Napo, Sucumbíos, Orellana, Pastaza, Morona Santiago, and Zamora Chinchipe of the Ecuadorian Amazon region to conduct a human health risk assessment. Significant differences in Hg levels were found between provinces, but concentrations were below MPL imposed by Ecuadorian regulations everywhere. Nevertheless, a worrisome picture emerges, especially with regard to the most vulnerable receptors represented by the child population. There are multiple factors of incidence that may affect the possible future development of the phenomenon, and with reference to the social, economic, and environmental context of the region, it can be concluded that it may be appropriate to plan further investigation to arrive at a more comprehensive assessment. The results of this study can be used by decision makers to plan further investigation and to implement monitoring networks, risk mitigation strategies, and groundwater protection measures.

Review on Biogeochemical Characteristics of Typical Antibiotics in Groundwater in China

The problem of antibiotic contamination in the environment has attracted much attention in recent years. However, studies on antibiotic contamination in groundwater have only emerged in the last 15 years. In this study, we systematically reviewed the detection methods, distribution characteristics, risk, fate, and sources of antibiotics in groundwater in China, listed the concentrations of the main antibiotic types, and obtained the maximum concentrations by comparing the literature published in the last 10 years. The results show that 65 antibiotics were detected in groundwater in China, with sulfonamides and quinolones receiving the most attention. Antibiotic concentrations are influenced by hydrogeological conditions and seasonal variations, and the ecological risk in most areas is low to medium risk, which is relatively manageable. The highest concentrations found in most of the literatures were in the range of 10–1000 ng/L, but the maximum concentration can reach 47,444.5 ng/L, which requires extra attention. In addition, this study makes recommendations for improving groundwater monitoring surveys and protection measures to prevent the antibiotic contamination of groundwater more effectively.

Groundwater Distribution in Urban Settlement

Urban cities are noted for technological and economic advancement but are also the convergent localities for poverty, humans’ disparity, environmental degradations and the propagation of communicable diseases. This study examined groundwater distribution in urban settlement with a view to identify and proffer solutions to the associated problems of improper distribution of groundwater in such area. Literature search was employed mainly to unravel the various groundwater distribution techniques and inferences were made on how to improve the distribution techniques. The study reveal springs, sunk wells and boreholes as the main methods of groundwater distribution in urban areas. Urban settlement leads to uncontrollable rise in population which adversely affects the quantity and quality of the groundwater. There is a general decrease in quantity due to overexploitation while the quality degraded as a result of pollution from industrial waste and the people. In addition, pollution could be linked to saltwater intrusion since most urban regions of the world are in the coastal area. Groundwater distribution could be ameliorated through recharge management employing artificial recharge. Degraded groundwater quality could be treated to the standard of potable water. Protecting groundwater resources amidst the prevailing rapid urbanization represent a considerable challenge that can lead to escalating costs of provision of drinking water in the areas and cause considerable decrease in public health conditions. Also, as it is technologically difficult and economically expensive to treat a contaminated aquifer, groundwater protection measures must be sought beforehand.

English

The impact of certain unregulated land-use activities harms the quality of water resources and reduces the sufficiency of drinking water in many developing countries. This study aimed to capture the impact of such activities and evaluate the specific groundwater vulnerability using a modified DRASTIC approach. The DRASTIC-LuPa was proposed and implemented for Aba City, Nigeria by incorporating land-use and the impact of pumping layers to the “intrinsic” DRASTIC parameters. The results of the analysis revealed that the area classified as “low” was 15 and 79.1% as “medium” and 5.9% as “high” vulnerability classes for the DRASTIC. Whereas for the DRASTIC-LuPa model 3.2% for “low”, 54.3% for “medium”, 41.8% for “high” and 0.7% for “very high” were found. The transitions in the vulnerability classes of areas displaying “high” and “very high” found in the DRASTIC-LuPa model represent the impact of urban hotspots observed in the area. This result implies that groundwater protection measures should be implemented in the area designated with “low” and “medium” vulnerability classes and used for abstracting clean water for drinking purposes. The proposed model enhances the predictability and guarantees better transferability of the approach in urban settings with similar urban trends.   Key words: Drinking water, DRASTIC, groundwater, groundwater vulnerability assessment, Nigeria.

Implementation of groundwater protection measures, particularly resource-directed measures in South Africa: a review paper

Abstract This review paper on groundwater protection measures in South Africa focuses on the actual implementation of groundwater protection measures, in particular, the resource-directed measures (RDM) as described in Chapter 3 of the National Water Act (NWA). Significant catchment-wide implementation of RDM has taken place in a phased manner throughout various catchments since 2012. By 2015, approximately R380 million had been expended on the catchment-wide implementation of the water resource protection measures over a period of 15 years. Considerable effort went into refining the RDM methodology, taking into account the groundwater component of the overall resource. In this paper, we contend that RDM, in its present form, will not make a significant contribution to groundwater resource protection and security in the country. This is a major concern because the Groundwater Strategy of the Department of Human Settlements, Water and Sanitation (DHSWS) had declared the protection of groundwater as a national priority. This paper also examines institutional and governance arrangements (or lack thereof) as well as providing recommendations to support the effective implementation of groundwater protection provisions as prescribed by South Africa's water legislation.

Temporal Changes of Groundwater Quality within the Groundwater Depression Cone and Prediction of Confined Groundwater Salinity Using Grey Markov Model in Yinchuan Area of Northwest China

Due to long-term overexploitation, the Yinchuan area of China has formed a groundwater depression cone in the confined aquifer. The formation of the groundwater depression cone will have a great impact on the hydrochemical evolution of groundwater, thus affecting the groundwater quality and associated human health. To study the characteristics and evolution of the depression cone and its impacts on the confined groundwater quality, groundwater level data from 1990 to 2019 and groundwater quality data from 1991 to 2018 were collected and analyzed. Groundwater level charts were generated to delineate the evolution of the groundwater depression cone. Graphical approaches and correlation analysis were applied to reveal the general hydrochemical characteristics of the groundwater within the depression cone and the major factors affecting the hydrochemical evolution of the confined groundwater. Grey Markov model was used to predict the TDS concentration in the confined aquifer in 2019 and 2020. The results show that the groundwater level in the groundwater depression cone center has recovered to a certain extent since 1993 due to existing groundwater protection measures, but the horizontal area of the groundwater depression cone (the area confined by 1100 m groundwater level contour) has increased greatly and it has expanded to 310.51 km2 by 2019. Groundwater samples from the phreatic aquifer were mainly of SO4·Cl–Ca·Mg and HCO3–Ca·Mg types, and the confined groundwater was mainly of SO4·Cl–Na and HCO3–Ca·Mg types. Groundwater leakage from phreatic aquifer to the confined aquifer, dissolution and precipitation of minerals and cation exchange are important factors affecting the hydrochemical evolution of confined groundwater, and these factors have different effects in different years. The forecasted values of TDS concentration in 2019 and 2020 are 450.60 and 433.50 mg/L, respectively.

Land–water–energy nexus in agricultural management for greenhouse gas mitigation

Agriculture plays an important role in global climate change. The interaction and efficiency of use of land, water, and energy in agricultural activities are the principal factors affecting greenhouse gas (GHG) emissions and food production. However, comprehensive analysis exploring the mechanism of the land–water–energy system in agricultural production remains lacking. This study developed such a framework based on regional agricultural GHG emissions by combining top-down analysis that considered cross-sectoral interactions with bottom-up analysis that addressed the context-specific conditions of resources and technology. We employed the proposed framework to analyze the interaction of land–water–energy and factors influencing agricultural GHG emissions and to explore mitigation measures based on a case study of the Sanjiang Plain (China). Results showed cropland on the Sanjiang Plain produced 1.8 million tonnes of protein and released 10.9 million tonnes of CO2eq in 2015 using 3.0 million ha of arable land, 12.1 billion m3 of water, and 100.4 PJ of energy. Owing to their high input of resources and flooded cultivation, rice fields produced 29% of total crop protein but consumed 51% of total crop water use, 43% of total crop energy use, and emitted 54% of total crop GHG (CO2eq). Structural adjustment through conversion of half the paddy fields into dryland crops (e.g., wheat) could mitigate GHG emissions by 18.8% in 2020 compared with the baseline scenario. However, such change would be almost impossible given the Sanjiang Plain is one of China’s most important rice-producing areas. If integrated technology improvements were adopted, e.g., advanced crop–soil nutrition management, groundwater protection measures, water-saving irrigation technology, and low-carbon energy technology, GHG emissions could be reduced by 23.9% without sacrificing food production. This study used the nexus approach to analyze agricultural GHG emissions, providing a framework for sustainable agricultural management and a reference for understanding the land–water–energy nexus.

Estimation of Nitrate Trends in the Groundwater of the Zagreb Aquifer

Nitrates present one of the main groundwater contaminants in the world and in the Zagreb aquifer. The Zagreb aquifer presents the main source of potable water for the inhabitants of the City of Zagreb and it is protected by the Republic of Croatia. The determination of contaminants trends presents one of the main tools in groundwater body status and risk assessment. In this paper, the use of regression analysis on the aggregated data, together with confidence and prediction intervals, at different observation scales has been evaluated. Nitrate concentrations are generally decreasing in almost all areas, observed at different observation scales. It has been shown that linear regression can be efficiently used in the estimation of nitrates trends. Results showed that the calculation of confidence and prediction intervals can provide more useful conclusions than the calculation of the trend’s statistical significance. Also, the results suggest that confidence and prediction intervals can be used in groundwater body chemical status and risk assessment, respectively. Data smoothing and data aggregation are generally desirable, but have certain limitations. If too much data is aggregated, trend estimation by regression analysis can point to false conclusions. Evaluation of trends at different observational scales can provide more realistic trend estimation, as well as more precise identification of areas where groundwater protection measures should be implemented.

Development and application of a novel method for regional assessment of groundwater contamination risk in the Songhua River Basin

The main objective of this study is to quantify the groundwater contamination risk of Songhua River Basin by applying a novel approach of integrating public datasets, web services and numerical modelling techniques. To our knowledge, this study is the first to establish groundwater risk maps for the entire Songhua River Basin, one of the largest and most contamination-endangered river basins in China.Index-based groundwater risk maps were created with GIS tools at a spatial resolution of 30arc sec by combining the results of groundwater vulnerability and hazard assessment. Groundwater vulnerability was evaluated using the DRASTIC index method based on public datasets at the highest available resolution in combination with numerical groundwater modelling. As a novel approach to overcome data scarcity at large scales, a web mapping service based data query was applied to obtain an inventory for potential hazardous sites within the basin.The groundwater risk assessment demonstrated that <1% of Songhua River Basin is at high or very high contamination risk. These areas were mainly located in the vast plain areas with hotspots particularly in the Changchun metropolitan area. Moreover, groundwater levels and pollution point sources were found to play a significantly larger impact in assessing these areas than originally assumed by the index scheme. Moderate contamination risk was assigned to 27% of the aquifers, predominantly associated with less densely populated agricultural areas. However, the majority of aquifer area in the sparsely populated mountain ranges displayed low groundwater contamination risk.Sensitivity analysis demonstrated that this novel method is valid for regional assessments of groundwater contamination risk. Despite limitations in resolution and input data consistency, the obtained groundwater contamination risk maps will be beneficial for regional and local decision-making processes with regard to groundwater protection measures, particularly if other data availability is limited.

Guidelines to groundwater vulnerability mapping for Sub-Saharan Africa

An approach to solving the challenges encountered in groundwater vulnerability assessment in Sub-Saharan African countries is discussed in this paper. The aim of this review is to highlight the gaps and difficulties encountered and provide guidelines for groundwater protection measures in sub-Saharan African countries, particularly countries without specific regulations and methodology of carrying out aquifer vulnerability assessments. Highlighted difficulties in groundwater vulnerability mapping in Sub-Saharan Africa include limited data, shortage of skilled professionals, inapplicability of most existing vulnerability methods and non-availability of funds. The numerical, travel time and parametric vulnerability approaches were recommended for use in sub-Saharan Africa based on the unique geomorphological features of the African continent. The goal of outlining the challenges and providing a guideline was to minimise the impact of groundwater pollution and to prioritise groundwater mapping in an aquifer protection assessment.

Insights and participatory actions driven by a socio-hydrogeological approach for groundwater management: the Grombalia Basin case study (Tunisia)

Sustainable groundwater management strategies in water-scarce countries need to guide future decision-making processes pragmatically, by simultaneously considering local needs, environmental problems and economic development. The socio-hydrogeological approach named ‘Bir Al-Nas’ has been tested in the Grombalia region (Cap Bon Peninsula, Tunisia), to evaluate the effectiveness of complementing hydrogeochemical and hydrogeological investigations with the social dimension of the issue at stake (which, in this case, is the identification of groundwater pollution sources). Within this approach, the social appraisal, performed through social network analysis and public engagement of water end-users, allowed hydrogeologists to get acquainted with the institutional dimension of local groundwater management, identifying issues, potential gaps (such as weak knowledge transfer among concerned stakeholders), and the key actors likely to support the implementation of the new science-based management practices resulting from the ongoing hydrogeological investigation. Results, hence, go beyond the specific relevance for the Grombaila basin, showing the effectiveness of the proposed approach and the importance of including social assessment in any given hydrogeological research aimed at supporting local development through groundwater protection measures.

Identification of hydrogeological windows based on large-scale mapping of the geological and hydrogeological conditions in Moscow

An original procedure for mapping hydrogeological windows is based on studying the geological structure of the massif overlaying the Podol’sko-Myachkovskii aquifer, changes in the hydrodynamic and hydrogeochemical conditions in the zone of “windows”; as well as calculating the travel time of contaminants in the vertical flow from the Meso-Cenozoic to Podol’sko-Myachkovskii Carboniferous aquifer. Both the areal and vertical distributions of low-permeability deposits are taken into account along with the variations of their thickness and permeability. The results obtained can be used in the development of groundwater protection measures and economic activity regulations in areas with hydrogeological windows.

Depletion control and analysis for groundwater protection and sustainability in the Xingtai region of China

Excessive groundwater withdrawal from the Ordovician karstified limestone aquifer near the city of Xingtai in China has created many cones of depression in piezometric levels of the groundwater (>100 m of drawdown), potentially affecting groundwater-dependent environments and threatening urban water supplies. Groundwater investigations and numerical modeling were undertaken to determine the factors that have caused groundwater depletion in the region so that groundwater protection measures could be developed and implemented. These investigations found the major cause of groundwater depletion was water drainage from iron ore mines in the region which had the largest effect on piezometric levels in the aquifer. Based on the integrated study, comprehensive methods of controlling depletion are proposed and tested successfully for groundwater protection in the region. These methods mainly include: outcrop recharging the aquifer; optimization in usage and allocation of water resources regionally; the use of curtain grouting in iron ore mines to reduce drainage of the aquifer; and drainage control in mining operations. Applying these methods, piezometric levels in the aquifer have increased by more than 30 m and previously dry springs are now flowing on a seasonal basis.

Ecohydrology of groundwater‐dependent grasslands of the semi‐arid Horqin sandy land of inner Mongolia focusing on evapotranspiration partition

AbstractThe Horqin sandy steppe is an ecosystem where groundwater‐dependent grasslands are main components. To study the dynamics of soil water and evapotranspiration, and its partition into transpiration and soil evaporation, the SIMDualKc model was applied to two sites in the Agula eco‐hydrological study area, Inner Mongolia, China. This model adopts the dual crop coefficient approach to compute daily crop evapotranspiration (ETc) and uses a parametric function to compute capillary rise from a shallow watertable. The application refers to three years of field observations, 2008 with high rainfall and higher watertable, 2009 with low rainfall and lower watertable, and 2011 with average rainfall and watertable conditions. Model calibration and validation were performed comparing simulated against observed soil water content throughout the vegetation seasons, with regression coefficients close to 1.0 and small root mean square errors (RMSE &lt; 0.013 cm3 cm−3). The groundwater contribution represented 41–47% of the actual ETc in the higher rainfall year and 56–59% in the dry year, which clearly shows the role of groundwater in sustaining grasslands in the Horqin steppe. The ratio between transpiration and actual ETc ranged 88 to 94%, which is much higher than observations in other grasslands because capillary rise contributes to extraction by crop roots, not to soil evaporation. Simulations relative to lowering the watertable show that groundwater contribution decreases up to 25% for a dry year with a consequent decrease of transpiration of 24%. Hence, there is the need for developing appropriate groundwater protection measures to preserve the Horqin landscape. Copyright © 2015 John Wiley &amp; Sons, Ltd.

Evaluating acceptability of groundwater protection measures under different agricultural policies

Water resources management is often characterized by conflicts in many arid and semi-arid regions, where agriculture is the main user of groundwater (GW). Conflicts could arise among different decision-makers and stakeholders. Moreover, different policies can interact each other hampering or facilitating their implementation and effectiveness. This contribution describes a new implementation of GeSAP, an integrated modelling tool for enabling local GW management by combining the need for GW protection with socio-economic and behavioural determinants of GW use. GeSAP is based on the involvement of multiple stakeholders and the use of Bayesian Belief Networks (BBN) to simulate and explore their attitude relative to GW exploitation and their responses to the introduction of new protection and agricultural policies. In this work, GeSAP was implemented in the area of the Capitanata Irrigation Users Organization, located in the Apulia region (southern Italy). It was used to simulate the reactions of the main stakeholders involved in GW protection policy implementation and to assess the policy's effectiveness in terms of actual reduction of GW exploitation. Furthermore, the interactions between the GW protection policy and the coming reform of the Common Agricultural Policy (CAP) was investigated. The results of the application proved the capability of the GeSAP tool to assess the actual effectiveness of GW protection policy by investigating how far this policy could be considered acceptable by farmers. In addition, this study demonstrates how the effectiveness of the GW protection policy could be affected by the interaction with the CAP reform. The latter could strongly impact the balance between water demand and availability with the effect of nullifying the positive synergy between CAP and GW protection policy. Although water management issues are not explicitly mentioned among the main scopes of the CAP, this work clearly demonstrates the impact that such policy could have on farmers’ decisions on water use.

Defining Groundwater Remediation Objectives with Cost-benefit Analysis: Does It Work?

The use of cost-benefit analysis (CBA) is increasingly advocated as a tool for supporting water planning decisions, in particular at the local (site) level. This paper questions whether CBA is relevant for evaluating groundwater management options at the scale of large regional aquifers. It highlights the difficulties related to estimating the cost of groundwater protection and remediation measures at the regional (water body) level. It also identifies methodological challenges in estimating the economic value of the benefits of groundwater protection. The paper is based on an original case study carried out on the upper Rhine valley aquifer in eastern France. The methodology deployed combines engineering approaches to assess the cost of remediation and economic methods (contingent valuation) to estimate the benefits associated with groundwater improvement.

Stygoregions – a promising approach to a bioregional classification of groundwater systems

Linked to diverse biological processes, groundwater ecosystems deliver essential services to mankind, the most important of which is the provision of drinking water. In contrast to surface waters, ecological aspects of groundwater systems are ignored by the current European Union and national legislation. Groundwater management and protection measures refer exclusively to its good physicochemical and quantitative status. Current initiatives in developing ecologically sound integrative assessment schemes by taking groundwater fauna into account depend on the initial classification of subsurface bioregions. In a large scale survey, the regional and biogeographical distribution patterns of groundwater dwelling invertebrates were examined for many parts of Germany. Following an exploratory approach, our results underline that the distribution patterns of invertebrates in groundwater are not in accordance with any existing bioregional classification system established for surface habitats. In consequence, we propose to develope a new classification scheme for groundwater ecosystems based on stygoregions.

Development of a conceptual hydrogeological model for the evaluation of residence times of water in soil and groundwater: the state of Hesse case study, Germany

A regional conceptual hydrogeological model has been developed for evaluating residence times of both, percolate water in the unsaturated zone and groundwater in upper aquifers. The model is based on digitally geo-data bases available at the regional level and has been applied for the entire Federal State of Hesse (Germany) with a spatial resolution of 60 × 60 m. Residence times determined for unconsolidated rock areas typically ranged between 10 and 25 years, whereas residence times of <5 years were assessed for consolidated rock areas. With regard to the implementation of the EU Water Framework Directive, the determined residence times may help to assess the time periods between the introduction of well-targeted groundwater protection measures and their impact on groundwater and surface water quality, respectively.

The study of hydrodynamic behaviour of a complex karst system under low-flow conditions using natural and artificial tracers (the catchment of the Unica River, SW Slovenia)

In this study a multi-tracer test with fluorescent tracers was combined with time series analyses of natural tracers to characterize the dynamics of the solute transport through different recharge pathways and to study hydraulic behaviour of a binary karst system under low-flow conditions. Fluorescent tracer testing included the introduction of uranine, amidorhodamine G, or naphthionate at three injection points. Sampling and monitoring took place at two karst springs (Malenscica, Unica) and at two underground rivers (Pivka, Rak) recharging the Unica River at the Polje of Planina, SW Slovenia. Other monitored parameters included precipitation, spring or underground river discharge, water temperature, and electrical conductivity. Water samples were collected and analyzed for total organic carbon, Mg2+, SO42−, and NO3− in the laboratory. In the study area, results of the tracer test suggest that contaminant transport in karst may be retarded for several weeks during low-flow conditions followed by increases in contaminant concentrations after subsequent rainfall events. Based on interpretation of tracer concentration breakthrough curves, low apparent dominant flow velocities (i.e., between 5.8 and 22.8 m/h through the well developed karst conduits, and 3.6 m/h through the prevailing vadose zone with a dominant influence of a diffuse recharge) were obtained. Together with analyses of hydro-chemographs the artificial tracing identified different origins of water recharging the studied aquifer. During prolonged low-water conditions the Malenscica spring is mainly recharged from the karst aquifer and the Unica spring by the sinking Pivka River. After more intensive rainfall events allogenic recharge from Cerknica prevails in the Malenscica spring, while the Unica spring drains mainly the allogenic water from the Pivka Valley. These findings of alternating hydraulic connections and drainage areas due to respective hydrological conditions are important and should be considered when monitoring water quality, implementing groundwater protection measures, and optimizing future water exploitation.