Changes In Groundwater Quality Research Articles

Modeling groundwater quality and quantity to manage water resources in the Arak aquifer, Iran

Groundwater resources are increasingly exposed to significant overexploitation in many parts of the world, markedly in Iran, one of the most arid areas. The objective of the present study is to investigate the changes in groundwater levels and quality in the Arak aquifer. Groundwater fluctuation contour line maps provided in Geographic Information System (GIS) during 2006 to 2017 in this area indicate that excessive extraction of wells has led to major decline in water levels and a marked increase in concentration of total dissolved solids (TDS). The Groundwater Modeling System (GMS)—a three-dimensional MODFLOW model—paired with MT3D, was utilized to survey the aquifer characterization in the area. In the first step, the conceptual model was developed, and the calibration in both steady and transient states showed that the error between calculated and observed levels was in optimal level. Subsequently, two scenarios were considered to simulate quantity changes in the aquifer: simulation in drought and rainfall reduction and simulation with a 30% increase in well extraction. The results indicate that during both the drought period and increasing exploiting from the pumping wells, the level of water has fallen by more than 5 m. Finally, the calculated hydraulic heads and velocity of flow of ground water in the aquifer are retrieved in the mass transport modeling package MT3D to find the concentration of TDS in the groundwater. Simulation results indicate that concentration of TDS is with far more amount in the areas around the lake located in central parts due to evaporation of Meighan wetland and geological structure of the region. Scenarios considered for prediction by transport model indicate that concentration of TDS would increase if the current situation continues; however, this is mainly influenced by hydrology and geology of the area.

Monitoring Environmental Parameters with Oil and Gas Developments in the Permian Basin, USA.

This study evaluates the groundwater qualities and environmental changes to obtain information on the groundwater contamination in the Permian Basin, Texas. Coupled with the U.S. government’s open data, these analyses can identify regions where environmental change could have affected groundwater quality. A total of thirty-six wells were selected within the six counties: Andrews, Martin, Ector, Midland, Crane, and Upton. Spatial distribution maps were created for six different parameters: pH, total dissolved solids (TDS), chloride, fluoride, nitrate, and arsenic. Total groundwater quality maps incorporate all the contaminants and denote regions of poor, medium, and optimum conditions. To identify spatial changes in groundwater quality, maps were separated into two different time intervals, 1992–2005 and 2006–2019. We found that groundwater contamination resulted primarily from the mobilization of the contaminant from anthropogenic activities such as chemical fertilizers, oil and gas developments. Overall, groundwater quality decreased during the study period from 1992 to 2019 as population and urban growth began to develop in the Permian Basin. This study contributes on understanding of the response of groundwater quality associated with environmental change in the Permian Basin. Therefore, this research provides important information for groundwater managements in developing plans for the use of water resource in the future.

A multi-approach assessment of land use effects on groundwater quality in a karstic aquifer

Groundwater represents almost half of the drinking water worldwide and more than one third of water used for irrigation. Agro-industrial activities affect water resources in several manners; one of the most important is leaching of agrochemical residues. This research identifies the major contributors of changes in groundwater quality comparing two contrasting land uses in a karstic area of the Yucatan peninsula as case study. Using a multiple approach, we assess the impact of land use with physicochemical data, multivariate analyses, hydrogeochemistry and nitrate isotopic composition. We confirmed that agricultural land use has a greater impact on groundwater quality, observed in higher concentration of nitrates, ammonium, potassium and electrical conductivity. Seasonality has an influence on phosphates and the chemical composition of the groundwater, increasing the concentration of dissolved substances in the rainy season. There was a clear effect of manure application in the agricultural zone and the nitrate isotopic composition of groundwater points toward recharge in certain areas. We consider that seasonality and land use effects are intertwined and sometimes difficult to separate, likely because of land use intensity and hydrogeochemical process at a local scale. Finally, we observed poor groundwater quality in the agricultural area during the wet season; thus, it is desirable to maintain non-agricultural areas that provide groundwater of appropriate quality.

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.

Salt Water Intrusion and Delineation of Groundwater Quality at Coastal Aquifers

Ground water quality changes or depleting day by day due to various contaminated substances presence in the environment and also other factors influences of excessive drawing of ground water, intrusion of septic sewage, improper dumping of solid waste disposal, untreated industrial effluents, sludge and waste water disposal without giving any treatment and also seasonal changes, etc., all are leads to decrease the quality and depth of ground water table, which leads to cause severe health issues like diarrhea, dysentery, digestive problems etc., on human life. In this contest an attempt has been made to find the ground water quality and also to know the level of contamination presents in Akividu area. About 16 number of ground water samples were collected, which covers the entire area of Akividu, by the estimation of ground water quality parameters includes pH, CO3 , HCO3 , NH3 , NO2 - , DO, Salinity, Hardness, Chlorine ,Total Alkalinity and Total Ammonia, during post monsoon months of October to November 2019. It was found that many of ground water samples have excess amount salinity and hardness and reaming parameters were in permissible range. All these accumulations of salinity (more than 0.5 ppm) and hardness (more than 600 ppm) may cause due to practices of aquaculture near and around the area of Akividu, and hence it is very necessary to done the periodical examination and also need to stop contaminate sources entering into nearby water bodies

Estimation of Natural and Artificial Recharge of Shahreza Plain Groundwater in Isfahan Using CRD and Hantush Models

Cumulative Rainfall Departure model (CRD) is widely used for estimation of ground natural recharge. This model is based on the groundwater balance and it requires random parameters. Moreover, an increase in the static level under artificial recharge facility is simulated using diffusion equations. Since Shahreza Plain is located in an arid and semi-arid area and given that rainfall is the major recharge source in such regions, in this study CRD model is applied in order to estimate natural recharge of Shahreza Plain groundwater. The amount of groundwater basin fed by rainfall was estimated about 177.2 million cubic meters using the CRD model. Also, by investigating and comparing available artificial recharge plans in Shahreza Plain it was known that in Kohrouyeh Project due to high soil permeability the increase in water table depth was higher than other projects and it achieves the maximum level of the water table within less time. By investigating the course of groundwater quality change in upstream and downstream boreholes of artificial recharge plans and given dewatering periods, we found that artificial recharge plans are generally effective in improving groundwater quality in the direction of groundwater movement but these changes are not significant. Hence, it is demonstrated that groundwater change mostly depends on the groundwater drop.

Long-term pumping-induced groundwater quality changes at a brackish-water desalination facility, Sanibel Island, Florida

Long-term pumping-induced groundwater quality changes at a brackish-water desalination facility, Sanibel Island, Florida

Assessing early warning for desertification hazard based on E-SMART indicators in arid regions of northeastern Iran

Desertification is a dynamic and complex system of land degradation. To understand it, physical and anthropogenic processes and their interrelations need to be identified. This study aimed to provide early warning information on desertification risk in the form of warning maps, using effective key indicators of land degradation in a 15-year period in the arid regions of northeastern Iran. E-SMART key Indicators should be E: Economic, S: Specific, M: Measurable, A: Achievable, R: Relevant, and T: Time-bound. Multiple regression analysis showed that the majority of indicators could accurately assess desertification risk at a 99% confidence level with R2 = 0.81. Furthermore, compared to the beginning of the study period, areas under desertification warning due to natural and anthropogenic factors had increased by about 78 percent in 2015. This observation is aligned with the impacts of drought, which has resulted from the continued reduction in rainfall. The expansion of at-risk areas has in turn exacerbated the adverse environmental conditions and amplified the effects of drought in the area. Spatio-temporal changes in soil salinity, groundwater quality, groundwater level, vegetation, agricultural development, and socioeconomic issues showed that the study area has suffered from land degradation and desertification between 2000 and 2015.

Mechanisms controlling groundwater chemistry and assessment of potential health risk: A case study from South India

Protection and management of groundwater resources depends on full understanding of the processes controlling the groundwater chemistry and associated health risks. In view of this, the rural part of Wanaparthy district, Telangana State, India was chosen for the present study and the groundwater samples collected from there were chemically analyzed. Quality of groundwater is of alkaline nature and mostly fresh water type. According to Trilinear Diagram, the change of groundwater quality from Ca2+- HCO3− type to Na+- Cl− type through mixed water type suggests the gradual influence of anthropogenic activities on the aquifer system. Gibbs Diagrams demonstrate that the chemistry of groundwater is mainly controlled by rock-water interactions and the rest by evaporation due to impact of anthropogenic sources. Bivariate Diagrams (Na+vsCl−, Ca2++Mg2+vsSO42−+ HCO3− and Ca2++Mg2+- SO42−- HCO3−vs Na+- Cl−) clearly specify that the processes of weathering and dissolution of minerals, and ion exchange are the dominant controlling factors of groundwater chemistry. Hierarchical R-type Cluster Analysis illustrates that Group I (Cl−- Na+ and HCO3−) is considered natural contribution, Group 2 (SO42−- Mg2+- Ca2+) is natural or anthropogenic source and Group 3 (NO3−- K2+ - F−) is anthropogenic influence. As per the estimation of sources of ions in the groundwater body by Unmix Model, the Source 1 (NO3−, Cl−, SO42− and Na+) is related to the anthropogenic activities; Source II (Ca2+, HCO3−, Na+, SO42−, Mg2+ and Cl−) to the weathering of silicate minerals, dissolution of chloride and sulfate minerals; and Source III (K+, F−, Ca2+, HCO3− and Mg2+) to the weathering of fluoride, calcium, magnesium and potassium bearing minerals or the application of chemical compounds of potassium and fluoride ions. These sources lead to groundwater contamination in some locations, thereby causing unfit for drinking purpose. Health Risk Assessment with respect to NO3− and F− ions suggests that the Total Hazard Index of non-carcinogenic risk (> 1.0) is observed from 26.67%, 26.67% and 43.33% of the total groundwater samples and the threat is to children compared to men and women due to their smaller body weights. Therefore, the health risk reduction measures are recommended to improve the groundwater quality in the study region.

Evaluation of Groundwater Quality Changes in at the Eastern Plains of Urmia Lake

Evaluation of Groundwater Quality Changes in at the Eastern Plains of Urmia Lake

Impact of sanitation and socio-economy on groundwater fecal pollution and human health towards achieving sustainable development goals\xa0across India from ground-observations and satellite-derived nightlight

Globally, ~1 billion people, mostly residing in Africa and South Asia (e.g. India), still lack access to clean drinking water and sanitation. Resulting, unsafe disposal of fecal waste from open-defecation to nearby drinking water sources severely endanger public health. Until recently, India had a huge open-defecating population, leading declining public health from water-borne diseases like diarrhoea by ingesting polluted water, mostly sourced to groundwater. However, in recent past, sanitation development to achieve Sustainable Development Goals (SDGs) has been encouraged throughout India, but their effect to groundwater quality and human health conditions are yet-unquantified. Here, for the first time, using long term, high-spatial resolution measurements (>1.7 million) across India and analyses, we quantified that over the years, groundwater fecal coliform concentration (2002–2017, −2.56 ± 0.06%/year) and acute diarrheal cases (1990–2016, −3.05 ± 0.01%/year) have significantly reduced, potentially influenced by sanitation development (1990–2017, 2.63 ± 0.01%/year). Enhanced alleviation of groundwater quality and human health have been observed since 2014, with initiation of acceletated constructions of sanitation infrastructures through Clean India (Swachh Bharat) Mission. However, the goal of completely faecal-pollution free, clean drinking water is yet to be achieved. We also evaluated the suitability of using satellite-derived night-time light (NLan, 1992–2013, 4.26 ± 0.05%/year) as potential predictor for such economic development. We observed that in more than 80% of the study region, night-time light demonstrated to be a strong predictor for observed changes in groundwater quality, sanitation development and water-borne disease cases. While sanitation and economic development can improve public health, poor education level and improper human practices can strongly influence on water-borne diseases loads and thus health in parts of India.

Assessing seasonal and long-term changes in groundwater quality due to over-abstraction using geostatistical techniques

Future climate change and the temporal variability of water availability may cause the deterioration of groundwater quality and increase depths to water tables. In this study, groundwater quality data of 347 monitoring sites from 2003 to 2016 from a region in Pakistan were used to analyze the spatiotemporal variability in different water quality parameters using the Mann–Kendall and Sen’s slope estimator tests. The results indicated a significant increasing trend (SIT) at 23% sites in pre-SAR (sodium adsorption ratio during the pre-monsoon season) and at 22% sites in pre-EC (electrical conductivity during the pre-monsoon season) over the entire study period. The spatial distribution modeling of groundwater quality trends indicated that a significant increasing trend was observed in EC at most of the monitoring sites during the pre-monsoon season (α = 0.05). The area with significant increasing trend of groundwater EC and SAR values increased during the pre-monsoon season and decreased during the post-monsoon season. A continuous significant increasing trend in EC and SAR was observed in the northern part of the study area during the period 2003–2016. This trend indicates that excessive groundwater abstraction in the area is causing adverse impacts on groundwater quality, and that management measures need to be urgently implemented to limit further degradation of groundwater quality.

Timescales of water-quality change in a karst aquifer, south-central Texas

Understanding the drivers and timescales over which groundwater quality changes informs groundwater management, use, and protection. To better understand timescales of water-quality change over short (daily to monthly) and long (seasonal to decadal) timescales, the U.S. Geological Survey’s National Water-Quality Assessment (NAWQA) Enhanced Trends Network (ETN) program instrumented and sampled three wells in the Edwards aquifer in south-central Texas. The wells were instrumented to provide high-frequency continuous (subhourly) water-quality data (temperature, pH, specific conductance, and dissolved oxygen), which were augmented by the collection of discrete samples (about 6 per year) for a range of geochemical constituents (including selected isotopes and age tracers). ETN data (2013–2017) are considered with data from additional sites for the same time period, and also historical records (over more than 80 years) of climatic and hydrologic conditions. During the four-year study, hydrologic conditions transitioned from very dry to very wet. Sites in the updip/unconfined part of the aquifer showed notable changes in water level and geochemistry (1) in response to rainfall/recharge events, and (2) over the multiyear dry/wet cycle. Sites in the downdip/confined part of the aquifer showed changes in water level/spring discharge over similar timescales, although the response is more muted. Geochemistry at the downdip/confined sites, however, varied slowly and minimally, indicating that the geochemical response of the deeper aquifer is decoupled from recent hydrologic responses. Changes at the updip/unconfined sites reflect mixing with recent recharge, whereas the downdip/confined sites were dominated by mineral-solution reactions resulting from longer (decadal) residence times. Mean groundwater ages interpreted from measured age tracers and lumped parameter models range from 7 to >700 years (where mixed with premodern downdip water) but were mostly modern. The aquifer is characterized by updip-to-downdip trends in geochemistry with respect to water-rock interaction and groundwater age. Fourier spectral analysis of historical records indicate hydrologic variability has occurred at dominant periods of 30 and 15 years; in conjunction with age tracers, these results provide insight into timescales at which the aquifer’s public supply is vulnerable to changes in the water quality of recharge.

Predicting attenuation of salinized surface- and groundwater-resources from legacy energy development in the Prairie Pothole Region

Oil and gas (energy) development in the Williston Basin, which partly underlies the Prairie Pothole Region in central North America, has helped meet U.S. energy demand for decades. Historical handling and disposal practices of saline wastewater co-produced during energy development resulted in salinization of surface and groundwater at numerous legacy energy sites. Thirty years of monitoring (1988–2018) at Goose Lake, which has been producing since the 1960s, documents long-term spatial and temporal changes in water quality from legacy energy development. Surface water quality was highly variable and decoupled from changes in groundwater quality, likely due to annual and regional climatic fluctuations. Therefore, changes in surface water-quality were not considered a reliable indicator of subsurface chloride migration. However, chloride concentrations in monitoring wells near wastewater sources exhibited systematic temporal reductions allowing for estimates of the time required for natural attenuation of groundwater to U.S. Environmental Protection Agency acute and chronic chloride toxicity benchmarks and a local background level. Point attenuation rates differed based on sediment type (outwash vs till) and yielded a range of predicted years when water-quality targets will be reached: acute – 2045 to 2113; chronic – 2069 to 2160; background – 2126 to 2275. Bulk attenuation rates from four separate years of data were used to calculate the distances chloride could migrate downgradient from the largest wastewater source. Potential distances of downgradient migration before dilution to water-quality targets decreased from 1989 to 2018: acute – 949 to 673 m; chronic – 1220 to 922 m; background – 1878 to 1525 m. Several downgradient wetlands are within these distances and will continue to receive saline contaminated groundwater for years. While these results demonstrate chloride attenuation at a legacy energy site, they also highlight the persistence of saline wastewater contamination and the need to mitigate future spills to prevent long-term salinization from energy development.

Effect of Land Use Changes on Water Quality in an Ephemeral Coastal Plain: Khambhat City, Gujarat, India

Rapid changes in land use and land cover pattern have exerted an irreversible change on different natural resources, and water resources in particular, throughout the world. Khambhat City, located in the Western coastal plain of India, is witnessing a rapid expansion of human settlements, as well as agricultural and industrial activities. This development has led to a massive increase in groundwater use (the only source of potable water in the area), brought about significant changes to land management practices (e.g., increased fertilizer use), and resulted in much greater amounts of household and industrial waste. To better understand the impacts of this development on the local groundwater, this study investigated the relationship between groundwater quality change and land use change over the 2001–2011 period; a time during which rapid development occurred. Water quality measurements from 66 groundwater sampling wells were analyzed for the years 2001 and 2011, and two water quality indicators (NO3− and Cl− concentration) were mapped and correlated against the changes in land use. Our results indicated that the groundwater quality has deteriorated, with both nitrate (NO3−) and chloride (Cl−) levels being elevated significantly. Contour maps of NO3− and Cl− were compared with the land use maps for 2001 and 2011, respectively, to identify the impact of land use changes on water quality. Zonal statistics suggested that conversion from barren land to agricultural land had the most significant negative impact on water quality, demonstrating a positive correlation with accelerated levels of both NO3− and Cl−. The amount of influence of the different land use categories on NO3− increase was, in order, agriculture > bare land > lake > marshland > built-up > river. Whereas, for higher concentration of Cl− in the groundwater, the order of influence of the different land use categories was marshland > built-up > agriculture > bare land > lake > river. This study will help policy planners and decision makers to understand the trend of groundwater development and hence to take timely mitigation measures for its sustainable management.

Hydrogeological and geoecological risks while forecasting the quality of underground drinking water during its use (study, analysis, forecasting, management)

The hydrogeological, geoecological and economical risks connected with the non-confirmation of groundwater discharge, levels and quality forecast calculations while the evaluation of the reserves, have been considered. Improving the reliability of the forecasts of the potable groundwater quality changes and the corresponding reduction in the risks associated with their non-confirmation, can be achieved by carrying out the special hydrogeochemical researches of operated deposits, including isotope researches. On the basis of such studies, a comparison ofprediction calculations on the observed data of the results of the exploration and actually observed indicators of the quality of groundwater can be made, and the theoretical and methodical bases of subsoil study and forecasting can be performed.

Temperature-associated changes in groundwater quality

Climate change and urbanization are currently leading to a warming of the subsurface worldwide with yet unforeseen consequences for groundwater quality. The temperature-sensitivity of chemical and biological processes suggests that small temperature changes driven by current warming should have a detectable effect on the ecology of aquifers and the composition of groundwater itself, but field observations covering temperatures that are environmentally relevant are sparse. The analysis of a large data set provides field-scale evidence that, within the naturally occurring temperature range between 5 and 20 °C, temperature affects the quality of groundwater. A difference in temperature of +1 K is linked to a 4% decline in oxygen saturation and a pH drop of 0.02 due to the accumulation of carbon dioxide. Further, warmer groundwater shows signs of enhanced mineral weathering and higher concentrations of drinking water-relevant elements such as manganese. The observed trends in groundwater quality are consistent with a temperature-associated intensification of microbial metabolic rates and enhanced organic matter mineralization at warmer temperatures either within the aquifers or in the overlying soils. A times series analysis reveals that soil and groundwater temperatures in the studied area have been increasing at a rate of 0.1–0.4 K per decade -comparable to recent global warming- driving subtle, but distinct changes in groundwater pH and oxygen concentrations. The results confirm, that certain but central aspects of groundwater quality (pH, O2, pCO2, Mn, DOC) change due to warming, which may increase the costs for purification when drinking water is produced from groundwater resources and may turn some aquifers uninhabitable for groundwater biota.

Evaluation of groundwater quality changes following the establishment of a sewage network

Evaluation of groundwater quality changes following the establishment of a sewage network

GROUND WATER QUALITY ASSESSMENT BY USING GEOGRAPHICAL INFORMATION SYSTEM AND WATER QUALITY INDEX: A CASE STUDY OF CHOKERA, FAISALABAD, PAKISTAN

Water quality is considered as a major issue in mega cities of developing countries. The city of Faisalabad has over 4 million population. Groundwater is the main source of drinking water in Faisalabad. The groundwater quality should be regularly monitored in order to cope with the drinking water quality issues. An attempt has been made to understand the groundwater quality by using water quality index (WQI) at Chokera area, Faisalabad, Pakistan. It is a technique of rating water quality, is an effective tool to assess spatial and temporal changes in groundwater quality. Sixty groundwater samples were collected and analyzed for physico-chemical parameters using standard method of analysis. From the data obtained, the water quality index was calculated by adopting the method developed by Tiwari and Mishra. Water quality index rating was carried out to quantify overall ground water quality status of the area. The WQI index of the same has been calculated and the values ranged from 73 to 272. The WQI values from present study indicate the very poor water quality in the area. The analysis reveals the fact that the groundwater of the Chokera area needs a degree of treatment before consumption and needs to be protected from further contamination

The effect of salt basins on the trend of groundwater quality changes in the surrounding basins (case study: Tabriz plain, northwest of Iran)

The effect of salt basins on the trend of groundwater quality changes in the surrounding basins (case study: Tabriz plain, northwest of Iran)