Integrated geospatial,geostatistical, and remote-sensing approach to estimate groundwater level in North-western India

The depletion of groundwater resources in Northwest India has been extensively studied. The top priority to meet the scarcity of water for irrigation, industrial and domestic purposes is supplemented by groundwater. Geostatistical modelling approach is considered to be beneficial tool for the assessment, evaluation, monitoring, and management of groundwater resources. This study is an attempt to analyze the spatio-temporal variability of groundwater level in semi-arid region of Panipat district, Haryana, India using kriging technique to fill the data gaps. Ordinary kriging was found optimal for the interpolation of groundwater levels. The results revealed that there was not much seasonal variation and also the groundwater flow direction remained almost constant in the study area during the assessment period. Spatial variability analysis showed significant variation in groundwater level and further depicted that the study area had undergone more or less decline in groundwater over the period of time. To validate the observations and results geo spatial and remote sensing techniques including normalised difference vegetation index and impervious surface relationships were worked out. It was further co-related with the rainfall data and the canal network existing in Panipat region. The integrated approach substantiated the observed results with the ground reality and helped in better understanding of the causes of declining groundwater trend in central part of Panipat.     

Catastrophic landslip activity in two hard rock terrains of peninsular India

This paper presents the case histories of two catastrophic landslips in hard rock terrains with varied climatic and geological environments. The first slip is associated with a power project in very close proximity (200 m) of the Porthimund Dam (11°22N, 76°3430E), in a charnockitic terrain in the Nilgiri hills (Tamil Nadu), and the second is associated with a railroad structure (19°525N, 78°1720E), in Adilabad district (Andhra Pradesh), in a basaltic terrain.The landslip in the charnockites is attributable to: (1) a high degree of saprolitization in the charnockites, with maximum intensity in the crest portion; (2) the coincidence of a major joint pattern in a NE-SW direction, with the strike of the foliation; and (3) the poor-to-fair physical rock quality in the crest and scarp portions.The slips in the basaltic terrain are due to: (1) the partially altered, highly jointed nature of the regional trap rocks with boulder sizes varying from 20 cm to 250 cm in diameter and the debris accumulating in a precarious condition on the northeast side of the rail track, with unfavorable alignment direction; and (2) the instability created in the weak rock mass by the vibrational forces of heavily loaded running trains.The weathered state of the rock masses in both the cases, showing good agreement with their physical state, accounts for the landslips. The remedial measures suggested are also discussed.     

Integrated studies for characterization of lineaments used to locate groundwater potential zones in a hard rock region of Karnataka, India

An integrated study was carried out to investigate the subsurface geological conditions in a hard rock environment, with the aim of identifying zones with groundwater resource potential. The study, in Bairasagara watershed, Karnataka, India, considered geomorphology, water level, resistivity imaging, self potential, total magnetic field and susceptibility. The signatures due to lineaments have been clearly identified and their role in groundwater movement has been documented. Synthetic simulation methods were used to model the electrical response of the lineament using finite differential modeling scheme. The inverted image of the field data is compared with the synthetic image and iteration were performed on the initial model until a best match was obtained resulting on the generation of the calibrated resistivity image of the subsurface. Resistivity imaging revealed that the dykes are weathered/fractured to a depth of 6–8 m and are compact at deeper levels, and that they behave as barriers to groundwater movement, yet facilitate a good groundwater potential zone on the upgradient side. The results of magnetic surveys were utilized in differentiating granites and dolerite dykes with an insignificant resistivity contrast. Geomorphological expression alone cannot reveal the groundwater potential associated with a lineament. However, characterizing the nature of the feature at depth with integrated geophysical methods provides essential information for assessing that potential.The online version of the original article can be found at     

Integrated studies for characterization of lineaments used to locate groundwater potential zones in a hard rock region of Karnataka, India

An integrated study was carried out to investigate the subsurface geological conditions in a hard rock environment, with the aim of identifying zones with groundwater resource potential. The study, in Bairasagara watershed, Karnataka, India, considered geomorphology, water level, resistivity imaging, self potential, total magnetic field and susceptibility. The signatures due to lineaments have been clearly identified and their role in groundwater movement has been documented. Synthetic simulation methods were used to model the electrical response of the lineament using finite differential modeling scheme. The inverted image of the field data is compared with the synthetic image and iteration were performed on the initial model until a best match was obtained resulting on the generation of the calibrated resistivity image of the subsurface. Resistivity imaging revealed that the dykes are weathered/fractured to a depth of 6–8 m and are compact at deeper levels, and that they behave as barriers to groundwater movement, yet facilitate a good groundwater potential zone on the upgradient side. The results of magnetic surveys were utilized in differentiating granites and dolerite dykes with an insignificant resistivity contrast. Geomorphological expression alone cannot reveal the groundwater potential associated with a lineament. However, characterizing the nature of the feature at depth with integrated geophysical methods provides essential information for assessing that potential.An erratum to this article can be found at     

Mechanism of fluoride enrichment in groundwater of hard rock aquifers in Medak,Telangana State,South India

A total of 194 groundwater samples were collected from wells in hard rock aquifers of the Medak district, South India, to assess the distribution of fluoride in groundwater and to determine whether this chemical constituent was likely to be causing adverse health effects on groundwater user in the region. The study revealed that the fluoride concentration in groundwater ranged between 0.2 and 7.4 mg/L with an average concentration of 2.7 mg/L. About 57% of groundwater tested has fluoride concentrations more than the maximum permissible limit of 1.5 mg/L. The highest concentrations of fluoride were measured in groundwater in the north-eastern part of the Medak region especially in the Siddipeta, Chinnakodur, Nanganoor and Dubhaka regions. The areas are underlain by granites which contain fluoride-bearing minerals like apatite and biotite. Due to water–rock interactions, the fluoride has become enriched in groundwater due to the weathering and leaching of fluoride-bearing minerals. The pH and bicarbonate concentrations of the groundwater are varied from 6.6 to 8.8 and 18 to 527 mg/L, respectively. High fluoride concentration in the groundwater of the study area is observed when pH and the bicarbonate concentration are high. Data plotted in Gibbs diagram show that all groundwater samples fall under rock weathering dominance group with a trend towards the evaporation dominance category. An assessment of the chemical composition of groundwater reveals that most of the groundwater samples have compositions of Ca²⁺–Mg²⁺–Cl^? > Ca²⁺–Na⁺–HCO₃ ^? > Ca²⁺–HCO₃ ^? > Na⁺–HCO₃ ^?. This suggests that the characteristics of the groundwater flow regime, long residence time and the extent of groundwater interaction with rocks are the major factors that influence the concentration of fluoride. It is advised not to utilize the groundwater for drinking purpose in the areas delineated, and they should depend on alternate safe source.     

Geochemical characterization of groundwater from northeastern part of Nagpur urban,Central India

Hydrogeochemical investigations are carried out in the northeastern part of Nagpur urban to assess the quality of groundwater for its suitability for drinking and irrigation purposes. Groundwater samples are collected from both shallow and deep aquifers to monitor the hydrochemistry of various ions. The groundwater quality of the area is adversely affected by urbanization as indicated by distribution of EC and nitrate. In the groundwater of study area, Ca²⁺ is the most dominant cation and Cl⁻ and HCO₃ ⁻ are the dominant anions. Majority of the samples have total dissolved solids values above desirable limit and most of them belong to very hard type. As compared to deep aquifers, shallow aquifer groundwaters are more polluted and have high concentration of NO₃ ⁻. The analytical results reveal that most of the samples containing high nitrate also have high chloride. Major hydrochemical facies were identified using Piper trilinear diagram. Alkaline earth exceeds alkalis and weak acids exceed strong acids. Shoeller index values reveal that base-exchange reaction exists all over the area. Based on US salinity diagram most of samples belong to high salinity-low sodium type. A comparison of groundwater quality in relation to drinking water standards showed that most of the water samples are not suitable for drinking purpose.     

Three-dimensional groundwater flow modeling approach for the groundwater management options for the Dakhla oasis,Western Desert,Egypt

In Dakhla oasis, Western Desert of Egypt, groundwater is the only resource for all anthropogenic activities. During the last 50 years, the Nubian Sandstone Aquifer System (NSAS) has been undergoing serious stress through withdrawing its storage. Plans for expanding the agricultural areas in Dakhla oasis were given by the government. This article is an attempt to investigate the best management option that meets development ambitions and groundwater availability. Based on a calibrated regional three-dimensional groundwater flow model for the NSAS using FEFLOW, a refined (high resolution) local scale model was developed to simulate and predict the impact of applying the actual and planned extractions rates on Dakhla oasis. Five management scenarios were suggested. The application of the actual extraction rate of 1.2 × 10⁶ m³/day for the oasis for the next 90 years resulted in a drawdown of 75 m and a depth to groundwater up to 75 m with an annual change in hydraulic head of 0.57 m. At the end of this simulation, only a few wells at the west of the oasis will still be free flowing. The application of the planned extraction rate (1.7 × 10⁶ m³/day) resulted in great depths to groundwater (>100 m) and formed huge cones of depressions that connected together to cover the whole oasis and extend further beyond its borders. It was found that the best option for groundwater management in the oasis is the implementation of an extraction rate of 1.46 × 10⁶ m³/day, as the depths to groundwater will never exceed the 100 m limit.     

Integrated approach for identification of potential groundwater zones in Seethanagaram Mandal of Vizianagaram District,Andhra Pradesh,India

Identifying a good site for groundwater exploration in hard rock terrain is a challenging task. In hard rocks, groundwater occurs in secondary porosity developed due to weathering, fracturing, faulting, etc., which is highly variable within short distance and contributing to near-surface inhomogeneity. In such situations topographic, hydrogeological and geomorphological features provide useful clues for the selection of suitable sites. Initially, based on satellite imagery, topographical, geomorphological and hydrogeological features, an area of about 149 km² was demarcated as a promising zone for groundwater exploration in the hard rock tract of Seethanagaram Mandal, Vizianagaram District, Andhra Pradesh, India. A total of 50 Vertical Electrical Soundings (VES) were carried out using Wenner electrode configuration. An interactive interpretation of the VES data sharpened the information inferred from geomorphological and hydrogeological reconnaissance. Ten sites were recommended for drilling. Drilling with Down-The-Hole Hammer (DTH) was carried out at the recommended sites down to 50 to 70 m depths. The interpreted VES results matched well with the drilled bore well lithologs. The yields of bore wells vary from 900 to 9000 liters per hour (lph).     

Identification of the geochemical processes in groundwater by factor analysis in hard rock aquifers of Madurai District,South India

A study was carried out in the Madurai district of Tamil Nadu, India to identify the hydrogeochemical processes using factor analysis as a predictive tool. It also focuses on characterizing the samples of these factors with respect to standard geochemical plots. In order to obtain a synoptic view of the statistics and the geochemical processes, a total of 53 groundwater samples are collected representing the entire district. The major ions were analyzed; the order of ion dominance are Ca²⁺?>?Na⁺?>?Mg²⁺?>?K⁺?=?Cl^??>?HCO^? ₃?>?H₄SiO^? ₄?>?NO^? ₃?>?SO^2? ₄?>?P^3? ₄. The samples are classified according to three factors. Factor 1 shows strong positive loadings of Cl^?, Ca²⁺, Mg²⁺, and NO^? ₃ with 36.98 % of the total variance (TV); factor 2 accounts for 13.72 % of TV with high loadings of Na⁺, K⁺, and HCO^? ₃; and factor 3 shows strong positive loadings of PO^3? ₄ and SO^2? ₄ with TV of 13.1 %. In the Piper plot, few samples fall in the mix region as evidenced by the mixing proportion of two samples using AQUACHEM software. The results suggest that different hydrogeochemical processes, like weathering, ion exchange processes, and anthropogenic activities (like sewage infiltration and agriculture), has predominant impact in the study area. Thus, the study highlights the factor analysis technique as a predictive and effective tool for groundwater evolution.     

Integrated multi-parameter approach for delineating groundwater potential zones in a crystalline aquifer of southern India

Groundwater resources in the semi-arid regions of southern India are under immense pressure due to large-scale groundwater abstraction vis-à-vis meager rainfall recharge. Therefore, understanding and evaluating the spatial distribution of groundwater is essential for viable utilization of the resource. Here, we assess groundwater potential at the watershed scale, in a semi-arid environment with crystalline aquifer system without a perennial surface water source using remote sensing, geophysical, and GIS-based integrated multi-parameter approach. GIS-based weighed overlay analysis is performed with input parameters, viz., geology, geomorphology, lineament density, land use, soil, drainage density, slope, and aquifer thickness. The watershed is categorized into four zones, namely, “very good” (GWP4), “good” (GWP3), “moderate” (GWP2), and “low” (GWP1) in terms of groundwater potential. Overall, ~?70% of the study area falls under moderate to low groundwater potential, indicating a serious threat to the future availability of the resource. Therefore, serious measures are required for maintaining aquifer resilience in this over-exploited aquifer (e.g., restricting groundwater withdrawal from GWP1 and GWP2 zones). Further, as the aquifer is under tremendous anthropogenic pressure, rainwater harvesting and artificial recharge during monsoon are advocated for sustainable aquifer management. Due to the direct dependence of crop production vis-à-vis farmer economy on groundwater, this study is an important step towards sustainable groundwater management and can be applied in diverse hydrological terrains.     

Hydrogeochemical characterization and quality assessment of groundwater around Umrer coal mine area Nagpur District,Maharashtra, India

Quality assessment as well as hydrogeochemical characterization of 45 representative groundwater samples around Umrer coal mine area was undertaken. The pH of the water lies in the normal range i.e. from 7.5 to 8.5, the electrical conductivity varies from 826 to 1,741, the total hardness varies from 289 to 1,302 and the TDS values range from 528.6 to 1,114.2 mg/l which reflects variation in lithology and thus, the distinction in hydrogeological regime. The cation chemistry is dominated by Ca²⁺ and Mg²⁺ while anion chemistry is dominated by Cl^? and HCO₃ ^?. Out of total ten hydrochemical facies, the two dominant facies are Mg–Ca–HCO₃ (37.7 %) and Ca–Mg–SO₄–HCO₃ (17.7 %). The groundwater in the study area, in general, is useful for drinking and domestic use; however, it has marginal utility for irrigation purpose. Standard US Salinity Laboratory classification shows that water of the study area belongs to C2–S1 and C3–S1 classes. The concentration of 9 trace elements analysed from 18 samples did not exceed the desirable limit.     

A GIS and remote sensing based evaluation of groundwater potential zones in a hard rock terrain of Vaigai sub-basin, India

In this paper, remote sensing, geographic information systems (GIS) and fieldwork techniques were combined to study the groundwater conditions in Vaigai basin, Tamilnadu. Several digital image processing techniques, including standard color composites, intensity–hue–saturation transformation and decorrelation stretch were applied to map rock types. Remote sensing data were interpreted to produce lithological and lineament maps such as geology, geomorphology, soil hydrological group, land use/land cover and drainage map were prepared and analyzed using GIS Arc Map GIS Raster Calculator module as geomorphology?×?12?+?drainage?×?9?+?lineament?×?5?+?geology?×?8?+?land use?×?2?+?relief?×?4. The final cumulative map generated by applying the above equation had weight values ranging from 0.315 to 4.515. The overall results demonstrate that the use of remote sensing and GIS provide potentially powerful tools to study groundwater resources and design a suitable exploration plan, the thematic maps for the study area.     

New approach of gradient profiling for tracking of low resistivity shallow fracture in hard rock area for groundwater exploration

The resistivity survey for the study of subsurface hydrogeology is a continuously evolving science, which either adopts different techniques or combination of techniques to standardize the approach. The gradient profiling is done in the presence of horizontal electric field which is one of the techniques to locate the low resistivity response within the hard rock formations. This low is obtained due to presence of inhomogeneity in the host rocks. The attempt has been made to develop the concept of parallel gradient sub-profile, formulation and computation of geometrical factor, and demonstration through an actual field example in the hard rock area. The present study clearly shows that the region of low resistivity zone can easily be delineated to select a point for conducting geoelectrical sounding for knowing the information about its depth, thickness, and resistivity which are necessary requirements for ground water exploration. It can be inferred from the above study that parallel gradient sub-profile with respect to main gradient profile is useful tool for delineating low resistivity zone due to presence of fractured sandstone rocks saturated with groundwater which can be exploited.     

Statistical analysis of the hydrogeochemical evolution of groundwater in hard rock coastal aquifers of Thoothukudi district in Tamil Nadu, India

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.     

A study on the status of fluoride ion in groundwater of coastal hard rock aquifers of south India

India has an increasing incidence of fluorosis, dental and skeletal, with nearly about 62 million people at risk. High fluoride groundwaters are present especially in the hard rock areas of the country. This paper analyzes the most extensive database on fluoride and other chemical constituent distribution in the coastal hard rock aquifers of Thoothukudi district. A total of 135 samples were collected and analyzed for major cations and anions to assess the geochemical process. The fluoride concentration in drinking waters varied from BDL to 3.2 mg?l^?1 in the study area. Majority of the samples do not comply with WHO standards for most of the water quality parameters. The saturation index of fluorite saturation index was used to correlate with F^? to identify their relationship to increase of fluoride levels. The correlation between the F^? concentration and the water type was also attempted. Spatial distribution of fluoride in groundwater was studied to understand the influencing factors. The relationship of F^? with HCO^? _3, Na⁺ and pH concentrations were studied and found that HCO^? ₃, has good correlation with F^? than the other parameters.     

Integrated approach for delineating potential zones to explore for groundwater in the Pageru River basin, Cuddapah District, Andhra Pradesh, India

Hydrogeomorphological, hydrogeological and geophysical investigations were carried out in the Pageru River basin of Cuddapah district, Andhra Pradesh, to delineate potential zones for future groundwater exploration. The study area is underlain by Proterozoic formations of the Indian Peninsula comprising limestones and shales as the sedimentary cover. Limestone and shale formations of the Cuddapah Super group that are later overlain by the Kurnool group (shale, limestone and quartzite) are exposed extensively. The high drainage density (2.61 km/km²) in the western region also suggests that the area is characterized by low permeable zones compared with low drainage density (1.04 km/km²) of the flood plains, which form the potential aquifers in the east. The hydro-geomorphological data are further supported from evidence of the water-table fluctuation in wells and resistivity of the saturated formations. The results indicate that the favourable, moderately favourable and poor zones characterized geomorphologically, have water-level fluctuations in the range of 0–2, 2–6 and above 6 m, respectively. The resistivities of these zones are also in the range of 1–26, 40–466, and >1,900 ohm-m. A few pumping tests have also been conducted to assess the broad range in the values of aquifer parameters. Based on these data, good to poor potential zones for obtaining groundwater have been delineated in the study area.

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Resumen Se llevaron a cabo investigaciones hidrogeomorfológicas, hidrogeológicas y geofísicas en la cuenca del Río Pageru del distrito Cuddapah, Andhra Pradesh, con objeto de delimitar zonas potenciales para exploración futura de aguas subterráneas. El área de estudio consiste de formaciones Proterozoicas de la Península India con calizas y lutitas como cubierta sedimentaria. Las formaciones de caliza y lutita del Grupo Cuddapah Superior afloran extensamente y están cubiertas por el Grupo Kurnool (lutita, caliza, y cuarcita). La alta densidad de drenaje (2.61 km/km²) en la región occidental también indica que el área se caracteriza por zonas de baja permeabilidad en comparación con las planicies de inundación de baja densidad (1.04 km/km²) que forman los acuíferos potenciales del oriente. Los datos hidrogeomorfológicos tienen apoyo adicional a partir de evidencia proveniente de la fluctuación del nivel freático en pozos y resistividad de las formaciones saturadas. Los resultados indican que las zonas caracterizadas geomorfológicamente como zonas favorables, moderadamente favorables, y pobres tienen fluctuaciones de niveles de agua en el rango de 0–2, 2–6, y mayor de 6 m, respectivamente. Las resistividades de estas zonas también se encuentran en el rango de 1–26, 40–466, y mayores de 1,900 ohm-m. Se realizaron algunas pruebas de bombeo para evaluar los amplios rangos que tienen los valores de los parámetros de los acuíferos. Basado en esta información se delimitaron zonas con potencial bueno a pobre para obtener agua subterránea en la zona de estudio.

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Résumé Des investigations hydrogéomorphologiques, hydrogéologiques et géophysiques ont été menées sur le bassin de la rivière Pageru du district de Cuddapah, Andhra Pradesh, pour délimiter les zones potentielles dans la future recherche deaux souterraines. La zone étudiée est, à la base, constituée par les formations protérozoïques de la péninsule indienne comprenant les calcaires et les shales de la couverture sédimentaire. Les calcaires et les shales du Super Groupe Cuddapah qui sont recouverts par le Groupe Kurnool (shale, calcire, quartzite) sont exposés de manière extensive. La densité importante de drainage (2.61 km/km²) dans la région ouest montre également que la zone est caractérisée par des perméabilités faibles par comparaison avec les plaines dinondation (densité de drainage: 1.04 km/km²), formant les aquifères potentiels de lEst. Les données hydrogéomorphologiques vont également dans le sens des données de fluctuation de la nappe et de résistivité des formations saturées. Les résultats indiquent que les zones caractérisées géomorphologiquement comme favorables, moyennement favorables et pauvres, possèdent des fluctuations respectives de lordre de 0 à 2, 2 à 6 et de plus de 6 m. La résistivité de ces zones est également de lordre de 1 à 26, 40 à 466 et de plus de 1900 ohm-m. Quelques pompages dessais ont également été conduits pour déterminer les valeurs moyennes des paramètres de laquifère. En se basant sur ces données, des zones potentielles bonnes à pauvres pour lexploitation des eaux souterraines ont été délimitées.

     

沿海地区地下水模拟优化管理模型

针对中国一些沿海地区地下水超采及由此带来的海水入侵问题,将地表水补给、抽水量及地下水位等相嵌在一起,建立了沿海地区地下水模拟优化管理模型。将人工鱼群算法和基于MODFLOW2000的变密度地下水流及溶质运移模型耦合起来,对沿海地区地下水模拟优化管理模型进行求解。以山东省威海市节水示范区为例,验证模型的有效性和可靠性。结果表明,10、11、12月份抽水量最大,以后至第2年5月份依次是减少的;从区域分布上看,在临海区域1号井处抽水量是3500～1120m3/月,在其它井处是6540～2920m3/月;与现行方案相比,增加总有效供水1990m3,地下水平均水位升高0.29m,海水入侵问题能够得到解决。计算结果合理可行,为沿海地区地下水资源的科学管理和持续利用提供可靠依据。     

Groundwater exploration using integrated geophysics method in hard rock terrains in Mount Betung Western Bandar Lampung,Indonesia

The presence of hard rock in Mount Betung has caused the misalignment of the groundwater aquifers,and resulted in many drilling failures for groundwater.An integrated geophysics method using gravity survey and Geoelectric Vertical Electrical Soundings(VES)were conducted to study the effect of basement and hard rock on groundwater prospects.From the gravity method,38 mapping points were carried out randomly,with a distance of 1-2 km in-between.Meanwhile,from the geoelectric method,51 VES points were acquired at the foot of Mount Betung.The acquisition was conducted with a Schlumberger configuration with AB/2=1 m to 250 m.The results show the Bouguer Anomaly in the west is 50-68 mgal due to the presence of hard rock in Mount Betung.This anomaly responds to relatively shallow hard rocks near surface.Hard rocks composed of andesite and breccia normally present at the depth of 5-180 m during well construction.Resistivity isopach mapping from VES data(at AB/2=50 m,100 m,and 150 m)shows the dominant constituents of hard rock.Fractures in hard rock contribute to secondary porosity,which could be a prospect zone that transmit groundwater.This finding shows that the fractures are randomly scattered,causing several well failures that have been worked.Furthermore,the fractures in the hard rock at the foot of Mount Betung acts as conduits between recharge at Mount Betung and the aquifer in the Bandar Lampung Basin.     

Evaluation of regional fracture properties for groundwater development using hydrolithostructural domain approach in variably fractured hard rocks of Purulia district,West Bengal,India

Estimation of geohydrologic properties of fractured aquifers in hard crystalline and/or metamorphosed country rocks is a challenge due to the complex nature of secondary porosity that is caused by differential fracturing. Hydrologic potentiality of such aquifers may be assessed if the geological controls governing the spatial distribution of these fracture systems are computed using a software-based model. As an exemplar, the Precambrian metamorphics exposed in and around the Balarampur town of Purulia district, West Bengal (India) were studied to find out the spatial pattern and consistency of such fracture systems. Surfer and Statistica softwares were used to characterize these rock masses in terms of hydrological, structural and lithological domains. The technique is based on the use of hydraulically significant fracture properties to generate representative modal and coefficient of variance (Cν) of fracture datasets of each domain. The Cν is interpreted to obtain the spatial variability of hydraulically significant fracture properties that, in turn, define and identify the corresponding hydrolithostructural domains. The groundwater flow estimated from such a technique is verified with the routine hydrological studies to validate the procedure. It is suggested that the hydrolithostructural domain approach is a useful alternative for evaluation of fracture properties and aquifer potentiality, and development of a regional groundwater model thereof.     

A proposed new approach for groundwater resources assessment in India

Assessment of groundwater resources in India is guided by National Water Policy (1987, 2002) which states that groundwater resources can be exploited only up to its recharge limit. The methodology for groundwater resources assessment in India is broadly based on Ground Water Resources Estimation Methodology, 1997 and it involves assessment of annual replenishable groundwater resources (recharge), annual groundwater draft (utilization) and the percentage of utilization with respect to recharge (stage of development). The assessment units (blocks/watersheds) are categorized based on stage of groundwater development (utilization) and the long term water level trend. The present methodology though useful in identification and prioritization of areas for groundwater management, falls short of addressing several critical issues like spatial and temporal variation of groundwater availability within the aquifer, accessibility of groundwater resources and quality of groundwater. This paper introduces a new categorisation scheme considering the above issues. The proposed scheme takes into account four criteria, viz. (i) stage of exploitation, (ii) extractability factor, (iii) temporal availability factor and (iv) quality factor. In comparison to the existing method used for categorisation, the proposed approach is more inclusive. The methodology is also equally suitable for both alluvial and hard rock terrain since it takes into consideration the variable characteristics of different types of aquifers and convergence of quantitative and qualitative assessment. The categorisation proposed here involves GIS based integration of different parameters/ themes. This allows better representation of spatial variability. The proposed methodology is demonstrated in this paper taking a case study from a hard rock terrain in central India.