scholarly journals Hydrogeological characterization and groundwater quality assessment in an atoll island (Magoodhoo Island of Faafu Atoll - Maldives)

2021 ◽  
Author(s):  
Chiara Zanotti ◽  
Barbara Leoni ◽  
Veronica Nava ◽  
Luca Fallati ◽  
Marco Rotiroti ◽  
...  
Keyword(s):  
Groundwater Quality ◽  
Sea Level ◽  
Fresh Water ◽  
Major Ions ◽  
Resource Planning ◽  
Point Sources ◽  
Groundwater Depth ◽  
Quality Data ◽  
Rainwater Tank ◽  
Cross Correlation Analysis

<p>Although freshwater is a vital resource for domestic and productive purposes, it is a very limited and vulnerable resource on atoll islands. Besides precipitations, on coral atolls groundwater is the only source of fresh water, usually extending below sea level in the form of a thin fresh water lens. Several possible environmental hazard can affect the availability of the resource, ranging from salinization induced by overexploitation to deterioration induced by unsustainable land use. Therefore, it becomes important to understand and characterize atolls’ islands aquifers and identify sustainable and hazardous practices to support a wise and farsighted resource management.</p><p>In this work a detailed characterization of the aquifer of Magoodhoo Island (Faafu Atoll – Maldives) is performed, through a hydrogeological mapping and groundwater quality characterization.</p><p>The Magoodhoo Island, with an area of 0.213 km<sup>2</sup>, is a typical and representative native inhabited island (c.a. 850 people) not affected by intense tourist traffic.</p><p>In order to collect topographic data, a drone survey was performed, with a fly altitude set at 80 m a.s.l. to reach a 4 cm ground pixel resolution obtaining a Digital Elevation Model (DEM), with a resolution of 10 cm.</p><p>Groundwater depth (m a.s.l.) was measured in 37 monitoring wells using a water level dipper to obtain a piezometric map of the aquifer. Furthermore, two CTD-diver were used to measure groundwater depth in a monitoring well and tidal oscillation of the sea level simultaneously with a time-resolution of 15 minutes for 5 days.</p><p>Groundwater quality data were collected in 36 monitoring point, including a rainwater tank and analysed for physico-chemical parameters including water temperature  (T), electrical conductivity (EC), pH, dissolved oxygen (DO), and DO saturation (DO%), major ions (Cl, NO<sub>3</sub>-N, NO<sub>2</sub>-N, NH<sub>4</sub>-N, total phosphorus (TP), Si, SO<sub>4</sub>, Ca, Mg, Na, Sr, and K) and metals/semi-metals (As, Pb, Ni, Fe, Mn and Zn).</p><p>Results show that groundwater depth varies spatially from around 1 m a.s.l. in the north-eastern part (ocean side) to -1.2 m a.s.l. in the central-western part. On the time scale, a good correlation between groundwater level and tidal fluctuations is observed and a tidal lag of about 3.5 hours was determined through a cross-correlation analysis.</p><p>Groundwater quality data highlighted different pollution point sources. The main impact on water quality was related to domestic activities producing a great amount of organic matter and wastewater. Other cases of local pollution were identified and associated to farm (poultry) and gardening activities (fertilization).</p><p>This study allowed for an in-depth knowledge of the Maghoodoo island aquifer system, which can be extended to other Maldivian and atoll islands constituting a valuable support for future water resource planning and management.</p>

scholarly journals Association of Physicochemical Characteristics, Aggregate Indices, Major Ions, and Trace Elements in Developing Groundwater Quality Index (GWQI) in Agricultural Area

2021 ◽  
Vol 18 (9) ◽  
pp. 4562
Author(s):  
Hazimah Haspi Harun ◽  
Mohamad Roslan Mohamad Kasim ◽  
Siti Nurhidayu ◽  
Zulfa Hanan Ash’aari ◽  
Faradiella Mohd Kusin ◽  
...  
Keyword(s):  
Water Quality ◽  
Trace Elements ◽  
Groundwater Quality ◽  
Quality Index ◽  
Major Ions ◽  
Physicochemical Characteristics ◽  
Quality Data ◽  
Water Quality Data ◽  
Groundwater Quality Index

The aim of this study was to propose a groundwater quality index (GWQI) that presents water quality data as a single number and represents the water quality level. The development of the GWQI in agricultural areas is vital as the groundwater considered as an alternative water source for domestic purposes. The insufficiency of the groundwater quality standard in Malaysia revealed the importance of the GWQI development in determining the quality of groundwater. Groundwater samples were collected from thirteen groundwater wells in the Northern Kuala Langat and the Southern Kuala Langat regions from February 2018 to January 2019. Thirty-four parameters that embodied physicochemical characteristics, aggregate indicator, major ions, and trace elements were considered in the development of the GWQI. Multivariate analysis has been used to finalize the important parameters by using principal component analysis (PCA). Notably, seven parameters—electrical conductivity, chemical oxygen demand (COD), magnesium, calcium, potassium, sodium, and chloride were chosen to evaluate the quality of groundwater. The GWQI was then verified by comparing the groundwater quality in Kota Bharu, Kelantan. A sensitivity analysis was performed on this index to verify its reliability. The sensitivity GWQI has been analyzed and showed high sensitivity to any changes of the pollutant parameters. The development of GWQI should be beneficial to the public, practitioners, and industries. From another angle, this index can help to detect any form of pollution which ultimately could be minimized by controlling the sources of pollutants.

scholarly journals The Hydrochemistry of Groundwater in Jambakan, Klaten Regency, Central Java Province, Indonesia

2019 ◽  
Vol 4 (4) ◽  
pp. 277-285
Author(s):  
Ekha Yogafanny ◽  
Ardian Novianto ◽  
Rika Ernawati ◽  
Wibiana Wulan Nandari
Keyword(s):  
Groundwater Quality ◽  
Calcium Chloride ◽  
Major Ions ◽  
Quality Parameters ◽  
Hydrochemical Facies ◽  
Quality Data ◽  
Type I ◽  
Water Type ◽  
Central Java ◽  
Central Java Province

Jambakan is a hamlet in Bayat District, Central Java Province, Indonesia, which commonly has brackish groundwater. Its unique geological profile leads to variation in groundwater quality that is even found between adjacent wells. This study was designed to identify the quality and hydrochemical type of groundwater and the distribution of brackish groundwater in Jambakan. It employed a quantitative method to analyzethe data collected in the field survey and groundwater quality data (major ions). Meanwhile, the hydrochemical facies of groundwater was interpreted from the plots of major ions on trilinear and quadrilateral Piper diagrams. The results showed that some of the groundwater quality parameters in six wells, namely A6, A34, A38, A65, A67, and A73, had exceeded the standard thresholds. The parameters in question were TDS, EC, salinity, sodium, calcium, chloride, sulfate, magnesium, and hardness. Compared with the six wells, A40 and A45 had better quality. The distribution of brackish groundwater could not be modeled horizontally because salinity highly depends on rock layers where the observed wells are located. Based on the trilinear Piper plots, the groundwater consisted of four hydrochemical facies, namely magnesium bicarbonate, a mixed type, calcium chloride, and sodium chloride. Meanwhile, the quadrilateral Piper diagrams showed the presence of Type I (bicarbonate water), Type II (semi-bicarbonate water), Type III (evaporite water), and Type IVb-IVc (sulfate water) in the groundwater of Jambakan Hamlet.

scholarly journals Investigating Groundwater Condition and Seawater Intrusion Status in Coastal Aquifer Systems of Eastern India

Water ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 1952
Author(s):  
Subrata Halder ◽  
Lingaraj Dhal ◽  
Madan K. Jha
Keyword(s):  
Groundwater Quality ◽  
Seawater Intrusion ◽  
Groundwater Level ◽  
Coastal Aquifer ◽  
Quality Data ◽  
Confined Aquifer ◽  
Groundwater Levels ◽  
Post Monsoon ◽  
Aquifer Systems ◽  
Sustainable Water Supply

Providing sustainable water supply for domestic needs and irrigated agriculture is one of the most significant challenges for the current century. This challenge is more daunting in coastal regions. Groundwater plays a pivotal role in addressing this challenge and hence, it is under growing stress in several parts of the world. To address this challenge, a proper understanding of groundwater characteristics in an area is essential. In this study, spatio-temporal analyses of pre-monsoon and post-monsoon groundwater-levels of two coastal aquifer systems (upper leaky confined and underlying confined) were carried out in Purba Medinipur District, West Bengal, India. Trend analysis of seasonal groundwater-levels of the two aquifers systems was also performed using Mann-Kendall test, Linear Regression test, and Innovative Trend test. Finally, the status of seawater intrusion in the two aquifers was evaluated using available groundwater-quality data of Chloride (Cl−) and Total Dissolve Solids (TDS). Considerable spatial and temporal variability was found in the seasonal groundwater-levels of the two aquifers. Further, decreasing trends were spotted in the pre-monsoon and post-monsoon groundwater-level time series of the leaky confined and confined aquifers, except pre-monsoon groundwater-levels in Contai-I and Deshpran blocks, and the post-monsoon groundwater-level in Ramnagar-I block for the leaky confined aquifer. The leaky confined aquifer in Contai-I, Contai-III, and Deshpran blocks and the confined aquifer in Nandigram-I and Nandigram-II blocks are vulnerable to seawater intrusion. There is an urgent need for the real-time monitoring of groundwater-levels and groundwater quality in both the aquifer systems, which can ensure efficient management of coastal groundwater reserves.

scholarly journals Natural and human-induced factors controlling the phreatic groundwater geochemistry of the Longgang River basin, South China

2020 ◽  
Vol 12 (1) ◽  
pp. 203-219
Author(s):  
Wei Li ◽  
Xiaohong Chen ◽  
Linshen Xie ◽  
Gong Cheng ◽  
Zhao Liu ◽  
...  
Keyword(s):  
Groundwater Quality ◽  
Chemical Evolution ◽  
South China ◽  
Major Ions ◽  
Negative Impact ◽  
Flow Direction ◽  
Anthropogenic Activities ◽  
Ionic Composition ◽  
Primary Source ◽  
Ammonia Concentration

AbstractGroundwater chemical evolution is the key to ensuring the sustainability of local society and economy development. In this study, four river sections and 59 groundwater wells are investigated in the Longgang River (L.R.) basin in South China. Comprehensive hydrochemical analysis methods are adopted to determine the dominant factors controlling the chemical evolution of the local phreatic groundwater and the potential impact of human activities on groundwater quality. The results indicate that the ionic composition of the local phreatic groundwater is dominated by Ca2+ (0.9–144.0 mg/L), HCO3− (4.4–280.0 mg/L), and SO42− (1.0–199.0 mg/L). Ca–Mg–HCO3, Ca–Na–HCO3, and Na–Ca–HCO3 are the major groundwater hydrochemical facies. Water–rock interactions, such as the dissolution of calcite and dolomite, are the primary source of the major ions in the local groundwater. Cation-exchange reaction has its effects on the contents of Ca2+, Mg2+, and Na+. Ammonia concentration of the sampling sections in the L.R. increases from 0.03 to 2.01 mg/L along the flow direction. Groundwater nitrate in the regions of the farmland is attributed to the lowest level of the groundwater quality standards of China, while the same test results are obtained for heavy metals in the industrial park and landfill, suggesting a negative impact of the anthropogenic activities on the local phreatic groundwater quality.

Analysis of sampling frequency in groundwater quality monitoring systems: a case study

1994 ◽  
Vol 30 (10) ◽  
pp. 73-78 ◽  
Author(s):  
Andrea Szucs ◽  
Gyözö Jordan
Keyword(s):  
Time Series ◽  
Groundwater Quality ◽  
Sampling Frequency ◽  
Quality Monitoring ◽  
Monitoring Systems ◽  
Additional Information ◽  
Alarm Systems ◽  
Cross Correlation Analysis ◽  
Two Samples ◽  
Groundwater Quality Monitoring

Sampling frequency is one of the most crucial factors in the design of groundwater quality monitoring systems. Monitoring systems in general have two major objectives: (1) to describe natural processes and long-term changes and (2) to serve as alarm-systems and detect single pollution events. A comparison between two data sequences of different sampling frequency - weekly and monthly - is made through an example of the groundwater quality monitoring system in the karstic region of the Transdanubian Mountains in Hungary. Hydrogeochemical time series were first decomposed into their components: trend, periodicity, autocorrelation, and rough in succession. In order to identify outliers within the rough, Exploratory Data Analysis (EDA) was applied. Optimal sampling frequency was determined based on the analysis of the above components. Results have shown that: (1) seasons shorter than two months do exist in the studied time series which cannot be captured by monthly sampling; (2) for monitoring seasonal processes samples should be collected at the Nyquist frequency (at least two samples per period); for pollution detection autocorrelation lag-time (or semi-variogram range in time) should determine the sampling distance; in the lack of autocorrelation property the analysis of outliers should guide the sampling design; (3) cross-correlation analysis between precipitation and the observed parameters indicative of pollutant travel time yields valuable additional information on the pollution sensitivity of the hydrogeological system.

Application of a GIS-based DRASTIC model and groundwater quality index method for evaluation of groundwater vulnerability: a case study, Sefid-Dasht

2015 ◽  
Vol 15 (4) ◽  
pp. 784-792 ◽  
Author(s):  
Nastaran Khodabakhshi ◽  
Gholamreza Asadollahfardi ◽  
Nima Heidarzadeh
Keyword(s):  
Groundwater Quality ◽  
Quality Index ◽  
Major Ions ◽  
Groundwater Vulnerability ◽  
Vulnerability Index ◽  
Aquifer Vulnerability ◽  
Index Method ◽  
Drastic Model ◽  
Groundwater Quality Index ◽  
The North

Pollution control and removal of pollutants from groundwater are a challenging and expensive task. The aims of this paper are to determine the aquifer vulnerability of Sefid-Dasht, in Chaharmahal and Bakhtiari province, Iran, using the DRASTIC model. In addition, the groundwater quality index (GQI) technique was applied to assess the groundwater quality and study the spatial variability of major ion concentrations using a geographic information system (GIS). The vulnerability index ranged from 65 to 132, classified into two classes: low and moderate vulnerability. In the southern part of the aquifer, the vulnerability was moderate. Furthermore, the results indicate that the magnitude of the GQI index varies from 92% to 95%. This means the water has a suitable quality. However, from the north to the south and southwest of the aquifer, the water quality has been deteriorating, and the highest concentration of major ions was found in the southwest of the Sefid-Dasht aquifer. A comparison of the vulnerability maps with the GQI index map indicated a poor relation between them. In the DRASTIC method, movement of groundwater is not considered and may be the reason for such inconsistency. However, the movement of groundwater can transport contaminants.

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