scholarly journals Delineation of Seawater Intrusion Using Geo-Electrical Survey in a Coastal Aquifer of Kamala Beach, Phuket, Thailand

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 506 ◽  
Author(s):  
Sakanann Vann ◽  
Avirut Puttiwongrak ◽  
Thongchai Suteerasak ◽  
Werapong Koedsin
Keyword(s):  
Seawater Intrusion ◽  
Coastal Aquifer ◽  
Empirical Relationship ◽  
Time Lapse ◽  
2D Inversion ◽  
Hydrologic Systems ◽  
Electrical Survey ◽  
Clay Layers ◽  
Sample Measurement ◽  
Subsurface Resistivity

The coastal areas of Phuket Island are facing the risk of seawater intrusion, because intense anthropic activity due to urbanization and the expansion of tourism influences coastal hydrologic systems. Indeed, the Kamala sub-district—on the western part of Phuket Island—is a well-known and attractive destination for tourists. Previous research indicates that there is likely to be a seawater intrusion in Kamala. The main purpose of this study was to delineate the seawater intrusion problem in a coastal aquifer in Kamala. Geo-electrical surveys of four lines were successfully conducted in the study area. Two-dimensional (2D) inversion models from the resistivity data show high-resolution subsurface resistivity anomalies of seawater intrusion. The concentration of the seawater intrusion decreases eastward toward the inland areas. Based on a sample measurement, the contaminated zone of seawater has a resistivity value smaller than 30 Ohm-m, and the empirical relationship between the formation conductivity and fluid conductivity of the study area was established. Finally, time-lapse Electrical Resistivity Imaging (time-lapse ERI) was conducted to prove that there was no presence of clay layers in study area; thus, the low resistivity plumes (smaller than 30 Ohm-m) were scientifically interpreted as being seawater intrusion.

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.

DETECTION OF FRACTURED AQUIFER USING COMBINATION OF RESISTIVITY AND INDUCED POLARIZATION ANALYSIS

2015 ◽  
Vol 76 (15) ◽  
Author(s):  
Mohamed Azwan Mohamed Zawawi ◽  
Noorellimia Mat Toridi ◽  
Aimrun Wayayok
Keyword(s):  
Clayey Soil ◽  
Induced Polarization ◽  
Polarization Analysis ◽  
Fractured Aquifer ◽  
Low Resistivity ◽  
Groundwater Occurrence ◽  
Electrical Survey ◽  
Geological Formation ◽  
Subsurface Resistivity

Subsurface geological formation is essential in investigating the groundwater occurrence. The formation can be determined from subsurface resistivity value through electrical survey. However, there is ambiguity in interpreting the subsurface resistivity. Therefore the purpose of this study is to delineate the subsurface geological formation through combination of resistivity and induced polarization analysis. The type of geological formation is determined from resistivity analysis and well lithology. Meanwhile the fracture, water in clayey soil and groundwater occurrence is identified through combination of resistivity and induced polarization analysis.  It has been identified that the study areas consist of fractured aquifer. Possible groundwater fractured area can be indicated by low resistivity ranged from 700 to 2000 Ωm and overlapped with low chargeability ranged from 1 msec to 2 msec. This study provides useful information on nature of groundwater occurrence especially fractured aquifer.

scholarly journals Time-lapse cross-hole electrical resistivity tomography (CHERT) for monitoring seawater intrusion dynamics in a Mediterranean aquifer

2019 ◽  
Author(s):  
Andrea Palacios ◽  
Juan José Ledo ◽  
Niklas Linde ◽  
Linda Luquot ◽  
Fabian Bellmunt ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Electrical Resistivity ◽  
Seawater Intrusion ◽  
Electrical Resistivity Tomography ◽  
Low Cost ◽  
Heavy Rain ◽  
Time Lapse ◽  
Resistivity Tomography ◽  
Bulk Electrical Conductivity ◽  
Spatial Coverage

Abstract. Surface electrical resistivity tomography (ERT) is a widely used tool to study seawater intrusion (SWI). It is noninvasive and offers a high spatial coverage at a low cost, but it is strongly affected by decreasing resolution with depth. We conjecture that the use of CHERT (cross-hole ERT) can partly overcome these resolution limitations since the electrodes are placed at depth, which implies that the model resolution does not decrease in the zone of interest. The objective of this study is to evaluate the CHERT for imaging the SWI and monitoring its dynamics at the Argentona site, a well-instrumented field site of a coastal alluvial aquifer located 40 km NE of Barcelona. To do so, we installed permanent electrodes around boreholes attached to the PVC pipes to perform time-lapse monitoring of the SWI on a transect perpendicular to the coastline. After two years of monitoring, we observe variability of SWI at different time scales: (1) natural seasonal variations and aquifer salinization that we attribute to long-term drought and (2) short-term fluctuations due to sea storms or flooding in the nearby stream during heavy rain events. The spatial imaging of bulk electrical conductivity allows us to explain non-trivial salinity profiles in open boreholes (step-wise profiles really reflect the presence of fresh water at depth). By comparing CHERT results with traditional in situ measurements such as electrical conductivity of water samples and bulk electrical conductivity from induction logs, we conclude that CHERT is a reliable and cost-effective imaging tool for monitoring SWI dynamics.

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