Degradation Of Groundwater Quality Research Articles

The influence of lithology and climatic conditions on the groundwater quality in the semi-arid-regions: case study of the Eastern Middle Cheliff alluvial aquifer (northwestern Algeria)

Over the last few years, the Eastern Middle Cheliff plain has witnessed remarkable economic growth, particularly in the agricultural sector. However, the overexploitation of the alluvial aquifer, coupled with agricultural practices involving the use of fertilizers and pesticides, significantly contributed to the degradation of groundwater quality. The primary objective of this study is to comprehend the mechanisms governing the water chemistry of the Eastern Middle Cheliff alluvial aquifer. A total of 42 samples were collected and analyzed during the dry periods of the 2012 and 2017. The data processing and representation involved the utilization of analytical tools including Principal Component Analysis (PCA), Piper diagram, Stabler classification, binary diagrams, base exchange indices, saturation indices, and geostatistical methods. The interpretation of these data revealed the following findings: i) the groundwater in both the dry periods of 2012 and 2017 is characterized by the presence of two dominant hydro-chemical facies, namely calcium chloride and sodium chloride, as indicated by the Piper and Stabler diagrams; ii) the hydrochemical quality of the groundwater varies across different regions of the aquifer, fair to poor in the eastern and central regions, with the presence of certain contaminants resulting from the application of nitrates in agricultural activities. The quality is classified as very poor in the western region, primarily due to high salinity influenced by the lithology of the aquifer, the rise of deep salty water through the Cheliff fault due to the earthquake of the year 1980 and possibility by two climatic factors, namely evaporation and rainfall. Overall, this study provides new insights into the water chemistry dynamics of the Eastern Middle Cheliff alluvial aquifer, highlighting the varying hydrochemical facies and the impact of agricultural activities and climatic factors on groundwater quality in different areas of the aquifer.

Groundwater for People and the Environment: A Globally Threatened Resource.

The intensity of global groundwater use rose from 124 m3 per capita in 1950 to 152 m3 in 2021, for a 22.6% rise in the annual per capita use. This rise in global per capita water use reflects rising consumption patterns. The global use of groundwater, which provides between 21% and 30% of the total freshwater annual consumption, will continue to expand due to the sustained population growth projected through most of the 21st century and the important role that groundwater plays in the water-food-energy nexus. The rise in groundwater use, on the other hand, has inflicted adverse impacts in many aquifers, such as land subsidence, sea water intrusion, stream depletion, and deterioration of groundwater-dependent ecosystems, groundwater-quality degradation, and aridification. This paper projects global groundwater use between 2025 and 2050. The projected global annual groundwater withdrawal in 2050 is 1535 km3 (1 km3 = 109 m3 = 810,713 acre-feet). The projected global groundwater depletion, that is, the excess of withdrawal over recharge, in 2050 equals 887 km3, which is about 61% larger than in 2021. This projection signals probable exacerbation of adverse groundwater-withdrawal impacts, which are worsened by climatic trends and the environmental requirement of groundwater flow unless concerted national and international efforts achieve groundwater sustainability.

Application of full-scale aerobic granular sludge technology for removing nitrate from groundwater intended for human consumption

The dependence on groundwater for human consumption has increased worldwide in the last decades. Nitrate (NO3−) often reaches groundwater and causes significant degradation in groundwater quality. In an effort to address this issue, a full-scale water treatment plant using aerobic granular sludge (AGS) technology was built to remove NO3− from nitrate-polluted groundwater intended for human consumption in a rural village. The impact of changes in the operational conditions of hydraulic retention time (HRT) and organic matter loading (OML) rate on NO3− removal, overall system performance, and the granule microbiome were studied. Regardless of the HRT, the AGS technology was successful in removing NO3− with removal rates >50 % with an optimal OML rate of 75 mg L−1. No significant variations in the total abundance of any of the denitrification genes were observed. The composition of prokaryotic and eukaryotic communities was affected by changes in the HRT and OML rate. Specific prokaryotic taxa were identified as responsive to changes in operational parameters and their abundances were linked to the removal of NO3−, confirming that the microbes are critical to the NO3− removal process. This study demonstrates that the AGS technology can be successfully implemented to treat nitrate-polluted groundwater in rural villages to produce water of drinking quality. In addition, the reported hydraulic retention times and organic matter loading rate can be used to further improve the system performance to remove nitrate from groundwater.

Application of Judgmental Sampling Approach for the Monitoring of Groundwater Quality and Quantity Evolution in Mediterranean Catchments

Groundwater monitoring is critically important, even though it is costly and often neglected. In this study, a judgmental monitoring of groundwater offering solutions based on a cost and time-effective research approach is presented. The method was performed in three Mediterranean areas in Greece and Italy to examine its advantages and disadvantages. As a first step, a multi-statistical analysis was practiced to assess and apportion the potential contributions of pollution sources of groundwater. Pearson correlation, principal component analysis, and factor analysis were applied to groundwater samples to characterize the evolution of hydrochemical processes. High concentrations of chlorides and nitrates highlight that salinization and the extensive use of nitrate fertilizers dominate in the coastal part of Eastern Thermaikos Gulf, the dissolution of carbonate rocks and livestock/industrial activities drive the groundwater quality status in the Upper Volturno basin, while in the Mouriki basin thermal power plant and the use of zinc fertilizers are the main factors of groundwater quality degradation. The determination of the critical sampling points was applied, considering the land use and hydrogeological and morphological characteristics of the areas. The application of the judgmental sampling approach provides reliable results regarding groundwater evolution. These results were compared to previous works and found that a non-probability sampling technique can provide the same results as a more costly method in the Mediterranean region. Thus, judgmental sampling is crucial for the optimal application of water resource management and control techniques in basins to avoid gaps in data collection.

Utilizing of aquifer hydraulic parameters to assess the groundwater sustainability in the new reclamation area of Moghra Oasis: Western Desert—Egypt

The sustainability of groundwater aquifers requires evaluating several parameters, the most important of which are hydraulic parameters. Therefore, the essential aim of this research is to develop a management plan for the Moghra aquifer in order to prevent the expanding of water level decline and degradation of groundwater quality due to overexploitation and scarcity of recharge. To achieve this goal, all aquifer hydraulic parameters such as transmissivity, hydraulic conductivity, radius of interference, specific capacity, resulted drawdown, well loss, formation loss, well efficiency, and optimum safe yield had been measured for 40 groundwater wells drilled in the new reclaimed areas of Moghra Oasis. Based on geographic information system (GIS), hydrogeological cross sections and thematic maps for all parameters were created such as aquifer thickness, water table, groundwater flow direction, drawdown and groundwater salinity maps. The results revealed that clay and shale beds separated the three water-bearing formations of the Moghra aquifer. The aquifer-saturated thickness ranged from 30 and 102 m, and the groundwater level was below the mean sea level for all wells (ranges from − 72 to − 26.6 m). The calculated hydraulic parameters based on the analysis of long-duration pumping tests indicated that the studied aquifer has a wide variety of transmissivity (T) between 631 and 3768 m2/day, hydraulic conductivity (K) between 13.4 and 104.6 m/day, radius of influence from 126.3 to 581.3 m and specific capacity between 377.14 and 883.72 m2/day. On the other hand, the evaluation of existing drilled wells performance based on the results of step tests showed that well loss coefficient ranges between 0.0004749 and 0.0676 (h2/m5), formation loss coefficient varies from 3.34 × 10–8 to 4.80 × 10–6 (h/m2), well efficiency (γ) ranged from 50.53 to 98.08%, and optimum safe yield ranged from 40 to 98 (m3/h). Results of aquifer mapping and pumping tests can be more important for solving water scarcity issues, non-polluting water issues, health issues, and source of fresh water on the surface of the earth. The characterization of aquifer parameters in the study area, however, should be a significant component in the scientific planning and sustainability of groundwater.

Groundwater nitrate pollution risk assessment based on the potential impact of land use, nitrogen balance, and vulnerability

The predicting groundwater nitrate pollution risk, especially in terms of changes in fertilizing, has not been fully investigated so far. In particular, there is no comprehensive method to assess this risk in areas of different land use type, and not only in agricultural areas. The aim of this study was to develop a novel multicriteria methodology for groundwater nitrate pollution risk assessment, which meets these issues. A further aim was to determine how much this risk would change if the amount of organic and synthetic fertilization was reduced. An assumption was that groundwater pollution risk is a combination of the potential adverse impacts of land use, fertilization, and intrinsic groundwater vulnerability to pollution. The impact of fertilization was holistically evaluated by balancing nitrogen from spatially differentiated the size of the breeding, species of livestock, manure and synthetic fertilizers input, and spatially differentiated topsoil, with nitrogen uptake by different crops. The nitrate concentration in the leachate was used as a measure of the impact of fertilization. This concentration was compared to the natural baseline nitrate concentration in groundwater. Three fertilization scenarios for groundwater pollution risk assessment in two study areas were discussed. Under typical agricultural, climatic, soil, and geological conditions in Europe for the current total fertilization level of 95-120 kg N ha−1 groundwater nitrate pollution risk is low and moderate, but for fertilization of 150-180 kg N ha−1, a reduction in the total fertilization (synthetic and manure) by 40 to 50% may be required to achieve low risk of degradation of natural groundwater quality. Predictive simulations of groundwater nitrate pollution risk confirmed that reducing synthetic and organic fertilization has an effect, especially in areas with intensive fertilization. This method may allow for a holistic and scenario-based assessment of groundwater pollution risk and may help decision-makers introduce solutions to manage this risk under conditions of climate change, preservation of groundwater quality, and food security.

Assessing Groundwater Quality for Sustainable Drinking and Irrigation: A GIS-Based Hydro-Chemical and Health Risk Study in Kovilpatti Taluk, Tamil Nadu

The continuous investigation of water resources is essential to assess pollution risks. This study investigated a groundwater assessment in the coastal belt of Tamil Nadu’s Kovilpatti Taluk, Thoothukudi district. Twenty-one groundwater samples were collected during the pre-monsoon and post-monsoon seasons, analyzing water quality parameters, namely pH, EC, Cl−, SO42−, Ca2+, Mg2+, HCO3−, TH, Na2+, and K+. The Water Quality Index (WQI) was computed and it is observed that 5% of pre-monsoon and 9% of post-monsoon samples were unsuitable for drinking. SAR, MHR, RSC, %Na and Kelley’s index were used to determine irrigation suitability. Pre-monsoon shows 29% (MHR) and 71% (RSC) unsuitable, and post-monsoon shows 59% (MHR) and 9% (RSC) unsuitable. Coastal activity, urbanization, and industrialization in Kovilpatti resulted in the degradation of groundwater quality. Solving this coastal issue requires sustainable wastewater treatment and strict industrial discharge guidelines. Spatial distribution plots, Box plots, Gibbs plots, Piper plots, Wilcox plots and Correlation Matrices had similar results to the computed WQI and its physical–chemical parameters. According to the human health risk assessment, the Mooppanpatti, Illuppaiurani, and Vijayapuri regions show high health risks due to the nitrate and fluoride concentration in the groundwater. Kadambu, Melparaipatti, Therkuilandhaikulam, and Vadakku Vandanam have low levels, posing a minimal health risk.

Compounding effects of human activities and climatic changes on coexistence of oasis-desert ecosystems: Prioritizing resilient decision-making for a riskier world

Water-salt balance is critical for the stable coexistence of salt-affected and groundwater-fed oasis-desert ecosystems. Yet, a comprehensive investigation of how soil salinization and groundwater degradation threaten the coexistence of oasis-desert ecosystems is still scarce, especially under the compounding effects of human activities and climatic changes. Here, we assessed the impacts of irrigated agriculture on hydrological regimes in oasis-desert systems, investigated the spatio-temporal variations of soil salinization in irrigated cropland, and evaluated the implications of the interplays of soil salinization and groundwater degradation on the coexistence of oasis-desert ecosystems in northwestern China, based on meaningful modelling approaches and comprehensive measurements over 1995–2020. The results showed that the irrigation return flow coefficient decreased sharply from 0.21 ± 0.09 in the traditional irrigation period to 0.09 ± 0.01 in the water-saving irrigation period. The continuous drop in groundwater tables and significant degradation of groundwater quality are occurring throughout this watershed. The eco-environmental flows are reaching to their limit with watershed closures (i.e., the drainage from the oasis region into the desert region is being weakened or even eliminated), although these progressions were largely hidden by regional precipitation and streamflow variability. The process of salt migration and accumulation across different landscapes in oasis-desert system is being reshaped, and soil salinization in water-saving agricultural irrigated lands is accelerating with a regional average annual growth rate of 18%. The vegetation in this watershed is degrading, and anthropogenic disturbance accelerates this trend. Our results highlight that environmental stress adaptation strategies must account for resilience maintenance to avoid accelerating catastrophic transitions in oasis-desert ecosystems. Determining the optimal oasis scales and formulating the best irrigation management plans are effective and resilient decision-making ways to maintain the coexistence relationship of oasis-desert ecosystem in drylands.

Long-term groundwater geochemical evolution induced by coal mining activities-a case study of floor confined limestone aquifer in Yaoqiao Coal Mine, Jiangsu, China.

Groundwater chemical composition can be changed due to long-term coal mining activities, but it was unclear how it was induced in Taiyuan Formation limestone (TFL) regarding the lack of relevant quantitative studies. The aim of this research is to improve understanding of the chemical composition changes in groundwater of L4 limestone in the coal mining area based on the available hydrochemical and hydrodynamical reports and studies during the period 1978-2020. The systematical analysis of the groundwater composition and field allows to make the hydrogeological characterization with the relatively independent blocks by the factor groups "Planar division & Vertical zonation" and "High water pressure, Poor recharge & Little water inflow," which determines different hydrochemical types and high TDS concentration. The long-term groundwater drainage has caused the eastern and southern limestone aquifer to demonstrate a wide range of depression cones and depletion of groundwater resources, the majority areas were dewatered, and the karstification process changed significantly. An analysis of chemical compositions changes due to extensive permanent drainage of L4 limestone water revealed the decrease in the TDS concentration. The solubility of calcite, dolomite, and gypsum changed, which resulted in the decreasing tendency of Ca2+ + Mg2+ ions. Evaporation and concentration were found to be the main factors determining the L4 limestone water composition, whereas ion exchange was the primary factor for rock-water interaction. These findings are helpful for mine enterprises to take necessary measures for preventing and controlling the groundwater quality degradation from the extensive coalmine drainage.

Nitrate Legacy in a Tropical and Complex Fractured Volcanic Aquifer System

AbstractNitrate legacy is affecting groundwater sources across the tropics. This study describes isotopic and ionic spatial trends across a tropical, fractured, volcanic multi‐aquifer system in central Costa Rica in relation to land use change over four decades. Springs and wells (from 800 to 2,400 m asl) were sampled for NO3− and Cl− concentrations, δ18Owater, δ15NNO3, and δ18ONO3. A Bayesian isotope mixing model was used to estimate potential source contributions to the nitrate legacy in groundwater. Land use change was evaluated using satellite imagery from 1979 to 2019. The lower nitrate concentrations (<1 mg/L NO3−N) were reported in headwater springs near protected forested areas, while greater concentrations (up to ∼63 mg/L) were reported in wells (mid‐ and low‐elevation sites in the unconfined unit) and low‐elevation springs. High‐elevation springs were characterized by low Cl− and moderate NO3−/Cl− ratios, indicating the potential influence of soil nitrogen (SN) inputs. Wells and low‐elevation springs exhibited greater NO3−/Cl− ratios and Cl− concentrations above 100 μmol/L. Bayesian calculations suggest a mixture of sewage (domestic septic tanks), SN (forested recharge areas), and chemical fertilizers (coffee plantations), as a direct result of abrupt land use change in the last 40 years. Our results confirm the incipient trend in increasing groundwater nitrogen and highlight the urgent need for a multi‐municipal plan to transition from domestic septic tanks to regional sewage treatment and sustainable agricultural practices to prevent future groundwater quality degradation effectively.

Nitrate contamination in groundwater and its health implications in a semi-urban region of Titrol block, Jagatsinghpur district, Odisha, India

Nitrate (NO3−) in drinking water poses serious health risks worldwide. Exposure to ionic sources of NO3− pollution in groundwater and health risks to children and adults require management measures to be taken prior to the development of urban activities. Groundwater samples were collected from a semi-urban region of Titrol block, Jagatsinghpur district, Odisha, and analysed for chemical variables. The content of NO3− ranged from 2 to 92 mg/L with an average of 34.26 mg/L, in which 83.33% of the groundwater samples contained NO3− above 10 mg/L. This is the starting point of water pollution activity in water. Computed values of the Nitrate Pollution Index (NPI) varied from −0.40 to 8.20 with an average of 2.42. According to NPI, 16.67%, 16.67%, 10%, 13.33%, and 43.33% of groundwater samples were unpolluted, slightly polluted, moderately polluted, significantly polluted, and very significantly polluted, covering 1.45%, 6.07%, 27.43%, 37.46%, and 27.59% of the study region, respectively. The correlation of NO3− with well depth and other chemical variables indicated significant degradation of groundwater quality by agricultural activities, leading to vulnerability of health conditions. According to Chronic Health Risk (CHR), CHR varied from 0.063 to 3.067 (1.067) for children and 0.042 to 1.917 (0.712) for adults, with 56.67% and 23.33% of groundwater samples above the acceptable level of 1.0. They covered 59.57% and 6.49% of the study region, respectively. Therefore, careful planning of prevention methods is necessary to reduce the health risk of NO3−.This study contributes to UNDP's Sustainable Development goals 2030 for a healthy environment.

Assessment of Intrinsic Vulnerability Using DRASTIC vs. Actual Nitrate Pollution: The Case of a Detrital Aquifer Impacted by Intensive Agriculture in Cádiz (Southern Spain)

The degradation of groundwater quality due to nitrate is a widespread issue in heavily agricultural areas and a major concern for public health. Improving knowledge of the intrinsic vulnerability of aquifers with respect to the actual contamination is crucial for adequate water management and for complying with the European directives aimed at protecting this valuable resource. In this study, we applied the well-established DRASTIC method to assess the intrinsic vulnerability of the Benalup aquifer, a detrital aquifer located in the southern Iberian Peninsula that supports important agricultural activity. The model was compared with in situ measurements of this ion, evidencing a lack of agreement between the most vulnerable zones and those that display higher nitrate concentrations. This fact should not be interpreted as an inadequacy in the vulnerability model, but as a result of several factors such as (i) the marked heterogeneity in land uses and the spatial variability in contaminant sources, (ii) the construction and exploitation characteristics of the water boreholes, (iii) the sampling procedure and depth to the water table, and (iv) transport and degradation processes within the porous medium. All these aspects can lead to discrepancies between the actual distribution of contamination and vulnerability models such as DRASTIC. All these factors should be carefully considered in the design of a sampling network in order to achieve a representative picture indicating the extent of contamination and the overall chemical quality of the system.

Effects of Seawater Intrusion on the Groundwater Quality of Multi-Layered Aquifers in Eastern Saudi Arabia

The degradation of groundwater (GW) quality due to seawater intrusion (SWI) is a major water security issue in water-scarce regions. This study aims to delineate the impact of SWI on the GW quality of a multilayered aquifer system in the eastern coastal region of Saudi Arabia. The physical and chemical properties of the GW were determined via field investigations and laboratory analyses. Irrigation indices (electrical conductivity (EC), potential salinity (PS), sodium adsorption ratio (SAR), Na%, Kelly's ratio (KR), magnesium adsorption ratio (MAR), and permeability index (PI)) and a SWI index (fsea) were obtained to assess the suitability of GW for irrigation. K-mean clustering, correlation analysis, and principal component analysis (PCA) were used to determine the relationship between irrigation hazard indices and the degree of SWI. The tested GW samples were grouped into four clusters (C1, C2, C3, and C4), with average SWI degrees of 15%, 8%, 5%, and 2%, respectively. The results showed that the tested GW was unsuitable for irrigation due to salinity hazards. However, a noticeable increase in sodium and magnesium hazards was also observed. Moreover, increasing the degree of SWI (fsea) was associated with increasing salinity, sodium, and magnesium, with higher values observed in the GW samples in cluster C1, followed by clusters C2, C3, and C4. The correlation analysis and PCA results illustrated that the irrigation indices, including EC, PS, SAR, and MAR, were grouped with the SWI index (fsea), indicating the possibility of using them as primary irrigation indices to reflect the impact of SWI on GW quality in coastal regions. The results of this study will help guide decision-makers toward proper management practices for SWI mitigation and enhancing GW quality for irrigation.

Groundwater Quality Assessment Using Multi-Criteria GIS Modeling in Drylands: A Case Study at El-Farafra Oasis, Egyptian Western Desert

The most critical issue that was the main research interest is its groundwater quality which is vital for public health concerns. Groundwater is a significant worldwide water supply for diverse communities, especially in dryland regions. Groundwater quality assessment in desert systems is largely hindered by the lack of hydrological data and the remote location of desert Oases. This study provides a preliminary understanding of the influences of climate, land usage, and population growth on the groundwater quality in El-Farafra Oasis in the Western Desert in Egypt from 2000 to now. Therefore, the study’s main objective was to determine the extent of change in temporal water quality and the factors causing it. The present study integrates chemical analyses and geospatial modeling better to assess groundwater quality in the study area. A chemical analysis of thirty-one groundwater samples from wells representing each study area was carried out during three time periods (2000, 2010, and 2022). Several chemical properties of groundwater samples gathered from wells in the research area were analyzed. Furthermore, the groundwater quality trend from 2000 to the present was identified using three approaches: Wilcox and Schoeller Diagram in Aq.QA software, interpolation in the ArcGIS software, and Ground Water Quality Index (GWQI). Moreover, the influence of changing land usage on groundwater quality was studied, and it was found that the increase in agriculture and urbanization areas is linked to groundwater quality degradation. The findings revealed that the barren area in 2000, 2010, and 2022 was 371.7, 362.0, and 343.2 km2, respectively, which indicates a substantial decrease of 6.2% within this research timeframe. In contrast, agriculture and human-made structures have expanded by 1.8%. Also, population growth has led to an increase in water consumption as the population has grown at a rate of 7.52% annually from 2000 to 2020. As the climatic condition increases from 2000 to 2022, these changes could extend to the water quality in shallow aquifers with increasing evaporation. Based on the water quality spatial model, it is found that, despite a declining tendency in the rate of precipitation and an expansion in agricultural areas and population growth, the water quality was still appropriate for human and farming consumption in large areas of the study area. The presented approach is applicable to the assessment of groundwater in desert regions in the Middle East area.

Spatial and Multivariate Statistical Analyses of Human Health Risk Associated with the Consumption of Heavy Metals in Groundwater of Monterrey Metropolitan Area, Mexico

Groundwater is the main source of drinking water supply in most urban environments around the world. The content of potentially toxic elements is increasing in many groundwater systems owing to inadequate groundwater recharge, aquifer overexploitation, natural source release, or various anthropogenic activities that lead to groundwater quality degradation. The ingestion of groundwater contaminated with potentially toxic elements has been reported to have harmful health effects. This study aimed to assess the presence of several potentially toxic elements (Al, As, B, Cr, Cu, Fe, Mn, and Zn) in groundwater of the Monterrey metropolitan area in Northern Mexico and the carcinogenic and noncarcinogenic human health risks associated with exposure. Multivariate statistics and geospatial analysis were applied to identify the causative determinants that modify the groundwater quality along the metropolitan area. Mean concentrations of trace metals remained below drinking water standards and World Health Organization guidelines. The risk of harmful effects on human health due to ingestion of all eight metal(loid)s in groundwater was assessed as 2.52 × 10−2 for adults and 2.16 × 10−2 for children, which can be considered as negligible chronic risk and a very low cancer risk. However, the risks of oral consumption of Cr being carcinogenic to children and adults were 7.9 × 10−3 and 9.2 × 10−4, respectively. As these values exceeded the target risk of 1 × 10−4, it can thus be considered “unacceptable”.

Assessment of groundwater quality in Ranchi district, Jharkhand, India, using water evaluation indices and multivariate statistics.

Groundwater is the most abundant liquid freshwater on earth. Rapid urbanization in developing nations (like India) has led to increased groundwater withdrawal, adversely affecting the physicochemical characteristics. Ranchi district, Jharkhand, is a part of the smart city mission development plan of the government of India. Hence, to ensure safe and clean drinking water, it is necessary to assess groundwater quality and devise development plans. Seventeen physicochemical properties and metal(loid)s contents were analyzed to determine the groundwater quality. Various pollution indices such as water quality index (WQI), metal evaluation index (MI), heavy metal pollution index (HPI), and modified degree of contamination (mCd) are evaluated using arithmetic weighted value index and presented in a map using Arc GIS inverse distance weighting interpolation method. Chemometric analyses such as correlation, principal component, and cluster analysis were done to identify the source and determine the pollution state. A multiple linear regression model is employed to predict the impact of heavy metal and metalloid concentration on the WQI of the region. WQI shows that groundwater quality in Khelari (100.95) and Bundu (92.52) regions are highly degraded, whereas MI and HPI suggest that Ormanjhi (MI = 53.98) and Rahe (HPI = 109.20) are highly affected by metal contamination. The mCd suggests that Ormanjhi (97.15) has the highest degree of contamination. The contaminant sources were natural (geogenic processes) and anthropogenic (mining and industrial emissions). The high metal(loid)s concentration may soon result in groundwater quality degradation in the metal-affected regions.

Joint geophysical and hydrogeochemical assessment of groundwater quality degradation in coastal aquifer systems at a suburb of Kosofe, Lagos, southwest Nigeria

Joint geophysical and hydrogeochemical assessment of groundwater quality degradation in coastal aquifer systems at a suburb of Kosofe, Lagos, southwest Nigeria

Science and policy delay leading to loss of natural capital: case study of Te Waihora/Lake Ellesmere

ABSTRACT The paper analyses sources of delay in developing environmental interventions to address overallocation of groundwater and water quality degradation for Te Waihora/Lake Ellesmere, a coastal lake in the Canterbury Region of New Zealand. The analysis highlighted the length of time required to collect the science to understand an issue and to formulate and implement policy responses. It also identified delays due to scientific uncertainty, scientific controversies, disregarding science, decision processes, and the response time of the natural system. The absence of clear policy approaches and environmental outcomes in order to implement environmental legislation was a significant source of delay. Delays in implementing environmental interventions led to loss of natural capital with groundwater overallocation reducing flows in groundwater-fed streams and freshwater inflows to the lake, and land use intensification degrading groundwater, groundwater-fed streams, and lake water quality. The extent of development beyond sustainable limits during these delays may have permanently compromised the ability to implement comprehensive environmental interventions.

Simulation and Evaluation of Water Resources Management Scenarios Under Climate Change for Adaptive Management of Coastal Agricultural Watersheds

The main objective of this paper is to analyze the impact of climate change on water resources management and groundwater quantity and quality in the coastal agricultural Almyros Basin, in Greece. Intensive groundwater abstractions for irrigation and nitrogen fertilization for crop production maximization, have caused a large water deficit, nitrate pollution, as well as seawater intrusion in the Almyros aquifer system. Multi-model climate projections for Representative Concentration Pathways (RCPs 4.5 and 8.5) from the Med-CORDEX database for precipitation and temperature have been used to evaluate the impacts of climate change on the study area. The multi-model climate projections have been bias-corrected with Delta, Delta change of Mean and Variance, Quantile Delta Change, Quantile Empirical Mapping, and Quantile Gamma Mapping methods, and statistically tested to find the best GCM/RCM multi-model ensemble. Simulation of coastal water resources has been performed using an Integrated Modelling System (IMS) that contains connected models of surface hydrology (UTHBAL), groundwater hydrology (MODFLOW), nitrate leaching/crop growth (REPIC), nitrate pollution (MT3DMS), and seawater intrusion (SEAWAT). The results indicate that the best climate multi-model ensemble consists of three (3) climate models for both RCP4.5 and RCP8.5 using the Quantile Empirical Mapping bias-correction method. The IMS was applied for historical and future periods with observed and simulated meteorological inputs (e.g. precipitation and temperature) and various irrigation and agronomic scenarios and water storage works development (i.e. reservoirs). The results indicate that at least deficit irrigation and deficit irrigation along with rain-fed cultivation schemes, combined with or without the development and operation of reservoirs, should be applied to overcome the degradation of groundwater quality and quantity in the study basin. Based on the findings of this work, the water resources management should be adaptive to tackle the water resources problems of the Almyros Basin.

Spatiotemporal characteristics of groundwater quality and health risk assessment in Jinghe River Basin, Chinese Loess Plateau

Groundwater is a very important natural resource for humanity, however, the degradation of groundwater quality caused by anthropogenic activities may pose a serious hazard to human health and ecosystem. In this study, 143 groundwater samples were analyzed to investigate the spatiotemporal variations of hydrochemistry, groundwater quality and potential human health risk of groundwater in Jinghe River Basin, Chinese Loess Plateau. Based on the mean concentrations value (MCV) and over-standard rate (OSR), the groundwater in Jinghe River Basin were divided into three groups: Group Ⅰ (high MCV: greater than standard values and high OSR: ≥ 10 %) contains TDS (total dissolved solids), TH (total harness), SO42-, F- and Fe; Group Ⅱ (low MCV and high OSR) contains pH, Cl-, NO3-, Cr6+ and As, Group Ⅲ (low MCV and low OSR) contains NO2-, NH4+, Zn, Mn, Pb, I- and Cd. The results of set pair assessment indicated that the unsuitable and doubtful class of comprehensive groundwater quality are mainly distributed in the northern part of study area, accounting for 29 % and 13.6 % of the area in 2004 and 2015, respectively. Human health risk assessment based on the triangular fuzzy number suggested that the variation of risk levels in different age groups is Children > Adult Men > Adult Women. Average carcinogenic risks of As in groundwater for the three groups exceed the acceptable level, and non-carcinogenic risk of NO3- for Children is higher than the acceptable threshold. The findings of this study provide valuable insight into the spatiotemporal characteristics of groundwater quality and potential health risks of polluted groundwater by anthropogenic activities.