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1.
Geophysical logs provide a strong mechanism for interpretation and determination of the depositional environments, facies and also help in interpretations of hydrogeologic units. Spontaneous potential (SP) and resistivity logs can be used as an indicator of textural parameters. Pondicherry region has a complicated geology and with formation of different ages. The boreholes (BH) of this region are examined for litholog, SP and resistivity from four different BH locations, viz, Ariyankuppam, Chinnaverampattinam, Thavalakuppam and Nallavadu. These locations were studied and interpreted by using the shapes of the curves to identify the depositional environments, and this was later compared with the vertical litholog profile. Comparing the variation of these logs, the lateral variation of sedimentary facies was also attempted. The average resistivity values of Ariyankuppam, Chinnaverampattinam, Thavalakuppam and Nallavadu are 42.4, 30.4, 50.4 and 28.3?Ωm, respectively. Majority of the resistivity values corresponds from fine- to medium-grained sand, clayey pebbles, fine to very coarse sand and clayey sand with lignite. Frequency of resistivity values in each BH were identified for determining the dominant representative grain size. The study has pointed out the lithological variation of the system laterally and vertically using geophysical well logs.  相似文献   
2.
A total of 162 groundwater samples for three representative seasons were collected from Salem district of Tamilnadu, India to decipher hydrogeochemistry and groundwater quality for determining its suitability for drinking and agricultural proposes. The water is neutral to alkaline in nature with pH ranging from 6.6 to 8.6 with an average of 8.0. Higher electrical conductivity was observed during post-monsoon season. The abundance of major ions in the groundwater was in the order of $ {\text{Na} > \text{Ca} > \text{Mg} > \text{K} = \text{Cl} > \text{HC}}{{\text{O}}_3}\; > \;{\text{S}}{{\text{O}}_4}\; > \;{\text{N}}{{\text{O}}_3} $ . Piper plot reveals the dominance of geochemical facies as mixed Ca–Mg–Cl, Na–Cl, Ca–HCO3, Ca–Na–HCO3, and Ca–Cl type. NO3, Cl, SO4, and F exceed the permissible limit during summer and post-monsoon seasons. Sodium adsorption ratio was higher during post-monsoon and southwest monsoon season indicating high and low salinity, satisfactory for plants having moderate salt tolerance on soils. Permeability index of water irrespective of season falls in class I and class II indicating water is moderate to good for irrigation purposes. As per the classification of water for irrigation purpose, water is fit for domestic and agricultural purposes with minor exceptions irrespective of seasons.  相似文献   
3.
Hydrogeochemistry of groundwater in hard rock terrain are mainly governed by lithology and land use practices. A study area near Madurai region of central Tamil Nadu was selected with various litho-units and a hard rock sedimentary contact with an unconformity. Land use practices in these regions are also varied with lithology. The study was conducted by collecting 54 groundwater samples spatially covering the major litho-units. Collected samples were analyzed for electrical conductivity, pH, total dissolved solids (TDS), temperature, Ca, Mg, Na, K, Cl, HCO3, NO3, H4SiO4, PO4, and SO4. The results of the samples analyzed found to vary spatially. Dominance of ion shows that the alkalies are predominant and HCO3 is the dominant anion. Piper facies show that the samples are alkali-carbonate type indicating the predominance of weathering. Most of the parameters exceed the drinking water permissible limit. Standard plots and statistical analysis also indicate weathering as the major process governing the hydrogeochemistry of the groundwater in the region. Relative mobility of cations indicates that the rate of liberation of alkalies from the lithology is more prominent.  相似文献   
4.
Piper (1944) diagram has been the basis for several important interpretations of the hydrogeochemical data. As seen in this diagram, most natural waters contain relatively few dissolved constituents, with cations (metals or bases) and anions (acid radicles) in chemical equilibrium with one another. Apart from the facies representation, the composition of the mixed sample can be identified in terms of the composition of the parental solution. To bring out this advantage of the Piper diagram, a study was conducted in the Kalpakkam region of Tamilnadu, South India. By taking the geology and water table into consideration, two sample locations were selected as parent solution and third one as the mixture sample. All three samples were analyzed for calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), chloride (Cl), sulphate (SO4) and phosphate (PO4) by Ion Chromatograph (Metrohm IC 861). HCO3 was determined by volumetric titration. The Piper diagram shows that parent solutions clustered towards Na-Mg-Ca-HCO3-Cl and Na-HCO3 facies, and the mixing sample belongs to Na-Mg-HCO3 facies. Phreeqc interac-tive (Ver 2.8) along with the original composition of the mixture sample was used to correlate the mixing proportion identified by the Piper diagram.  相似文献   
5.
Hydrogeochemical investigations are carried out in and around Perumal Lake, Cuddalore district, South India in order to assess its suitability in relation to domestic and agricultural uses. The water samples (surface water = 16; groundwater = 12) were analyzed for various physicochemical attributes like pH, electrical conductivity (EC), sodium (Na+), potassium (K+), calcium (Ca2+), magnesium (Mg2+), chloride (Cl−), bicarbonate (HCO3 −), sulfate (SO4 2−), phosphate (PO4), silica (H4SiO4) and total dissolved solids (TDS). Major hydrochemical facies were identified using Piper trilinear diagram. Hydrogeochemical processes controlling the water chemistry are water–rock interaction rather than evaporation and precipitation. Interpretation of isotopic signatures reveals that groundwater samples recharged by meteoric water with few water–rock interactions. A comparison of water quality in relation to drinking water quality standard proves that the surface water samples are suitable for drinking purpose, whereas groundwater in some areas exceeds the permissible limit. Various determinants such as sodium absorption ratio (SAR), percent sodium (Na%), residual sodium carbonate (RSC) and permeability index (PI) revealed that most of the samples are suitable for irrigation.  相似文献   
6.
The chemical composition of 29 bore well water samples throughout the Kalpakkam region, South India, was determined to identify the major hydrogeochemical processes and the suitability of groundwater for domestic and irrigation purposes. The hydrochemical data were analyzed with reference to World Health Organization (WHO) standards and their hydrochemical facies were determined. The Piper plot shows that most of the groundwater samples fall in the field of mixed calcium–sodium–bicarbonate type followed by sodium–chloride, calcium–bicarbonate and mixed calcium–magnesium–chloride water types. The concentration of total dissolved solids exceeds the desirable limit in about 14% of samples; alkalinity values exceed the desirable limit in about 34% of the samples. The concentration of sulphate is well within the desirable limit at all the locations. The dominance of various heavy metals in the groundwater followed the sequence: Zn > Fe > Mn > Cu > Ni > Pb > Cr > Cd. Among the metal ions, the concentration of chromium and cadmium are within the permissible limit. Data are plotted on the US Salinity Laboratory diagram, which illustrates that most of the samples fall in the field of high salinity and low sodium hazard, which can be used to irrigate salt tolerant and semi-tolerant crops under favorable drainage conditions. Based on the analytical results, chemical indices like sodium adsorption ratio and residual sodium carbonate were calculated which show that most of the samples are good for irrigation.  相似文献   
7.
A study was carried in Mettur taluk, Salem district of Tamilnadu, India to develop a DRASTIC vulnerability index in GIS environment owing to groundwater pollution with increasing population, industries, and agricultural activities. Seven DRASTIC layers were created from available data (depth to water table, net recharge, aquifer media, soil media, topography, impact of vadose zone, and hydraulic conductivity) and incorporated into DRASTIC model to create a groundwater vulnerability map by overlaying the hydrogeological parameters. The output map indicates southwestern part of the study area with high pollution potential, northern and northwestern parts as moderate pollution potential and northeastern parts as low and no risk of pollution potential. For validating the vulnerability assessment, a total of 46 groundwater samples were collected from different vulnerability zones of the study area for two different seasons (pre- and post-monsoon) and analyzed for major anions and cations. Higher ionic concentrations were noted in wells located near highly industrialized, urbanized, and agricultural active zones. The water types represent Na–Mg–HCO3 and Na–Cl–HCO3 type indicating dominance of anthropogenic-related activities. Nitrate and chloride were demarcated as pollution indicators and correlated with DRASTIC vulnerability map. The results show that southwestern, northwestern, and northern parts of the study area recorded with high and moderate vulnerable zones, record higher nitrate values. In contrast to DRASTIC method predicted, low vulnerable zones show higher chloride concentration may be due to agricultural and urban development.  相似文献   
8.
Mountain-front recharge (MFR) is a process of recharging an aquifer by infiltration of surface flow from streams and adjacent basins in a mountain block and along a mountain front (MF). This is the first attempt in India to estimate MFR along the foothills of Courtallam using hydrogeochemistry and geostatistical tools. The estimation of MFR has been carried out by collecting groundwater samples along the foothills of Courtallam. Collected water samples were analyzed for major cations and anions using standard procedures. Hydrogeochemical facies show the existence of four water types in this region. Calcium-rich water derived from gneissic rock terrain indicates significant recharge from higher elevation. Log pCO2 and ionic strength of the samples were also calculated to identify the geochemical process. Majority of the collected samples have sodium-rich water and weak ionic strength, which indicate foothill recharge and low residence time. Silicate and carbonate weathering have an equal interplay along the foothills with a relatively large fraction of Mg from the MF. The spatial diagrams of three factors show that the southern part of the study area is dominated by both weathering and anthropogenic processes, whereas the northern part is dominated by both leaching and weathering processes. Thus, the dominant weathering process represented by the second factor indicates the large recharge process along the foothills.  相似文献   
9.
The study of groundwater hydrogeochemistry of a hard rock aquifer system in Thoothukudi district has resulted in a large geochemical data set. A total of 100 water samples representing various lithologies like Hornblende Biotite Gneiss, Alluvium Marine, alluvium Fluvial, Quartzite, Charnockite, Granite and Sandstone were collected for two different seasons and analyzed for major ions like Ca2+, Mg2+, Na+, K+, HCO3 ?, Cl?, SO4 2?, NO3 ?, PO4 ?, F? and H4SiO4. Statistical analysis of the data has been attempted to unravel the hidden relationship between ions. Correlation analyses and factor analyses were applied to classify the groundwater samples and to identify the geochemical processes controlling groundwater geochemistry. Factor analysis indicates that sea water intrusion followed by leaching of secondary salts, weathering and anthropogenic impacts are the dominant factors controlling hydrogeochemistry of groundwater in the study area. Factor score overlay indicate major active hydrogeochemical regimes are spread throughout the Eastern, Northwestern and Southeastern parts of the study area. The dominant ions controlling the groundwater chemistry irrespective of season are Cl?, Na+, Mg2+, Ca2+, SO4 2?, K+ and NO3 ?. An attempt has also been made to note the seasonal variation of the factor representations in the study area. This study also illustrates the usefulness of statistical analysis to improve the understanding of groundwater systems and estimates of the extent of salinity/salt water intrusion.  相似文献   
10.
A hydrogeochemical study was conducted in Thoothukudi district situated in the southeast coast of Tamil Nadu, India to identify the influence of saltwater intrusion and suitability of groundwater for domestic and agricultural purposes. Scattered studies of this coastal region have reported signs of seawater intrusion, salt pan and industrial activity together with natural weathering process. To have a holistic picture of geochemical processes in the entire district, a total of 135 groundwater samples were collected and analyzed for major cations and anions. The geochemical parameters were compared with world and Indian standards and it was found that most samples are unsuitable for drinking purpose. The geochemical facies of the groundwater showed Na–Cl as the dominant water type indicating the saline nature of the groundwater. Chadda’s plots show that most of the samples fall in the Na–Cl type of water due to seawater intrusion. The samples were classified with parameters like sodium absorption ratio, residual sodium carbonate, total hardness, chloride, index to base exchange, electrical conductivity and facies to determine their suitability for irrigation purpose. It was inferred that the samples falling along the coast are not suitable for the irrigation purpose. The seawater-mixing percentage indicates that strong mixing was observed in the near shore and at the proximity of the salt pan. The permanent hardness was predominant in all the samples compared to the carbonate hardness reducing its domestic usability.  相似文献   
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